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OVER 100 PUBLICATIONS WITH INSCOPIX TECHNOLOGY

CurrentBiology

A Role for Astroglial Calcium in Mammalian Sleep and Sleep Regulation

Ashley M. Ingiosi, Christopher R. Hayworth, Daniel O. Harvey, Kristan G. Singletary, Michael J. Rempe, Jonathan P. Wisor, Marcos G. Frank
Current Biology
September 24, 2020

Mammalian sleep expression and regulation have historically been thought to reflect the activity of neurons. Changes in other brain cells (glia) across the sleep-wake cycle and their role in sleep regulation are comparatively unexplored. We show that sleep and wakefulness are accompanied by state-dependent changes in astroglial activity. Using a miniature microscope in freely behaving mice and a two-photon microscope in head-fixed, unanesthetized mice, we show that astroglial calcium signals are highest in wake and lowest in sleep and are most pronounced in astroglial processes. We also find that astroglial calcium signals during non-rapid eye movement sleep change in proportion to sleep need. In contrast to neurons, astrocytes become less synchronized during non-rapid eye movement sleep after sleep deprivation at the network and single-cell level. Finally, we show that conditionally reducing intracellular calcium in astrocytes impairs the homeostatic response to sleep deprivation. Thus, astroglial calcium activity changes dynamically across vigilance states, is proportional to sleep need, and is a component of the sleep homeostat.

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Nature

Stimulus-specific hypothalamic encoding of a persistent defensive state

Ann Kennedy, Prabhat S. Kunwar, Ling-yun Li, Stefanos Stagkourakis, Daniel A. Wagenaar & David J. Anderson
Nature
September 16, 2020

Persistent neural activity in cortical, hippocampal, and motor networks has been described as mediating working memory for transiently encountered stimuli. Internal emotional states, such as fear, also persist following exposure to an inciting stimulus, but it is unclear whether slow neural dynamics are involved in this process. Neurons in the dorsomedial and central subdivisions of the ventromedial hypothalamus (VMHdm/c) that express the nuclear receptor protein NR5A1 (also known as SF1) are necessary for defensive responses to predators in mice. Optogenetic activation of these neurons, referred to here as VMHdmSF1 neurons, elicits defensive behaviours that outlast stimulation, which suggests the induction of a persistent internal state of fear or anxiety. Here we show that in response to naturalistic threatening stimuli, VMHdmSF1 neurons in mice exhibit activity that lasts for many tens of seconds. This persistent activity was correlated with, and required for, persistent defensive behaviour in an open-field assay, and depended on neurotransmitter release from VMHdmSF1 neurons. Stimulation and calcium imaging in acute slices showed that there is local excitatory connectivity between VMHdmSF1 neurons. Microendoscopic calcium imaging of VMHdmSF1 neurons revealed that persistent activity at the population level reflects heterogeneous dynamics among individual cells. Unexpectedly, distinct but overlapping VMHdmSF1 subpopulations were persistently activated by different modalities of threatening stimulus. Computational modelling suggests that neither recurrent excitation nor slow-acting neuromodulators alone can account for persistent activity that maintains stimulus identity. Our results show that stimulus-specific slow neural dynamics in the hypothalamus, on a time scale orders of magnitude longer than that of working memory in the cortex, contribute to a persistent emotional state.

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Cell

Hindbrain Double-Negative Feedback Mediates Palatability-Guided Food and Water Consumption

Rong Gong, Shengjin Xu, Ann Hermundstad, Yang Yu, Scott M. Sternson
Cell
August 24, 2020

Hunger and thirst have distinct goals but control similar ingestive behaviors, and little is known about neural processes that are shared between these behavioral states. We identify glutamatergic neurons in the peri-locus coeruleus (periLCVGLUT2 neurons) as a polysynaptic convergence node from separate energy-sensitive and hydration-sensitive cell populations. We develop methods for stable hindbrain calcium imaging in free-moving mice, which show that periLC VGLUT2neurons are tuned to ingestive behaviors and respond similarly to food or water consumption. PeriLC VGLUT2 neurons are scalably inhibited by palatability and homeostatic need during consumption. Inhibition of periLC VGLUT2 neurons is rewarding and increases consumption by enhancing palatability and prolonging ingestion duration. These properties comprise a double-negative feedback relationship that sustains food or water consumption without affecting food- or water-seeking. PeriLC VGLUT2 neurons are a hub between hunger and thirst that specifically controls motivation for food and water ingestion, which is a factor that contributes to hedonic overeating and obesity.

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circle-cropped

Concussion increases CA1 activity during prolonged inactivity in a familiar environment

Shanti R. Tummala, Matthew A. Hemphill, Andrea Nam, David F. Meaney
Experimental Neurology
August 17, 2020

Although hippocampal damage plays a key role in impairments after concussion, differences in hippocampal information processing during recovery are unknown. Micro-endoscopic calcium imaging was performed before and after primary blast injury in freely behaving mice in two environments: their familiar home cage and a novel open field. Results show that after concussion CA1 activity increased in the familiar environment in which animals were awake and mostly immobile but was unaltered in a novel environment which the animals actively and constantly explored. As awake immobility parallels cognitive rest, a common treatment for patients, the results imply that prolonged cognitive rest may unwittingly impede concussion recovery.

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circle-cropped (1)

Reduced activity of GAD67 expressing cells in the reticular thalamusenhance thalamic excitatory activity and varicella zoster virus associated pain

Rebecca Hornung, Addison Pritchard, Paul R. Kinchington, Phillip R. Kramer
Neuroscience Letters
August 4, 2020

Within the reticular thalamic nucleus neurons express gamma aminobutyric acid (GABA) and these cells project to the ventral posteromedial thalamic nucleus. When GABA activity decreases the activity of excitatory cells in the ventral posteromedial nucleus would be expected to increase. In this study, we addressed the hypothesis that attenuating GABAergic cells in the reticular thalamic nucleus increases excitatory activity in the ventral posteromedial nucleus increasing varicella zoster virus (VZV) associated pain in the orofacial region. Adeno-associated virus (AAV) was infused in the reticular thalamic nucleus of Gad1-Cre rats. This virus transduced a G inhibitory designer receptor exclusively activated by designer drugs (DREADD) gene that was Cre dependent. A dose of estradiol that was previously shown to reduce VZV pain and increase GABAergic activity was administered to castrated and ovariectomized rats. Previous studies suggest that estradiol attenuates herpes zoster pain by increasing the activity of inhibitory neurons and decreasing the activity of excitatory cells within the lateral thalamic region. The ventral posteromedial nucleus was infused with AAV containing a GCaMP6f expression construct. A glass lens was implanted for miniscope imaging. Our results show that the activity of GABA cells within the reticular thalamic region decreased with clozapine N-oxide treatment concomitant with increased calcium activity of excitatory cells in the ventral posteromedial nucleus and an increased orofacial pain response. The results suggest that estradiol attenuates herpes zoster pain by increasing the activity of inhibitory neurons within the reticular thalamus that then inhibit excitatory activity in ventral posteromedial nucleus causing a reduction in orofacial pain.

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PNAS

REM sleep stabilizes hypothalamic representation of feeding behavior

Lukas T. Oesch, Mary Gazea, Thomas C. Gent, Mojtaba Bandarabadi, Carolina Gutierrez Herrera and Antoine R. Adamantidis
PNAS
July 30, 2020

During rapid eye movement (REM) sleep, behavioral unresponsiveness contrasts strongly with intense brain-wide neural network dynamics. Yet, the physiological functions of this cellular activation remain unclear. Using in vivo calcium imaging in freely behaving mice, we found that inhibitory neurons in the lateral hypothalamus (LHvgat) show unique activity patterns during feeding that are reactivated during REM, but not non-REM, sleep. REM sleep-specific optogenetic silencing of LHvgat cells induced a reorganization of these activity patterns during subsequent feeding behaviors accompanied by decreased food intake. Our findings provide evidence for a role for REM sleep in the maintenance of cellular representations of feeding behavior.

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Cell Reports-1

Dysregulation of the Synaptic Cytoskeleton in the PFC Drives Neural Circuit Pathology, Leading to Social Dysfunction

Il Hwan Kim, Namsoo Kim, Sunwhi Kim, Koji Toda, Christina M. Catavero, Jamie L. Courtland, Henry H. Yin, Scott H. Soderling 
Cell Reports
July 28, 2020

Psychiatric disorders are highly heritable pathologies of altered neural circuit functioning. How genetic mutations lead to specific neural circuit abnormalities underlying behavioral disruptions, however, remains unclear. Using circuit-selective transgenic tools and a mouse model of maladaptive social behavior (ArpC3 mutant), we identify a neural circuit mechanism driving dysfunctional social behavior. We demonstrate that circuit-selective knockout (ctKO) of the ArpC3 gene within prefrontal cortical neurons that project to the basolateral amygdala elevates the excitability of the circuit neurons, leading to disruption of socially evoked neural activity and resulting in abnormal social behavior. Optogenetic activation of this circuit in wild-type mice recapitulates the social dysfunction observed in ArpC3 mutant mice. Finally, the maladaptive sociability of ctKO mice is rescued by optogenetically silencing neurons within this circuit. These results highlight a mechanism of how a gene-to-neural circuit interaction drives altered social behavior, a common phenotype of several psychiatric disorders.

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Nature Communications

Contextual fear memory retrieval by correlated ensembles of ventral CA1 neurons

Jessica C. Jimenez, Jack E. Berry, Sean C. Lim, Samantha K. Ong, Mazen A. Kheirbek & Rene Hen
Nature Communications
July 13, 2020

Ventral hippocampal CA1 (vCA1) projections to the amygdala are necessary for contextual fear memory. Here we used in vivo Ca2+ imaging in mice to assess the temporal dynamics by which ensembles of vCA1 neurons mediate encoding and retrieval of contextual fear memories. We found that a subset of vCA1 neurons were responsive to the aversive shock during context conditioning, their activity was necessary for memory encoding, and these shockresponsive neurons were enriched in the vCA1 projection to the amygdala. During memory retrieval, a population of vCA1 neurons became correlated with shock-encoding neurons, and the magnitude of synchronized activity within this population was proportional to memory strength. The emergence of these correlated networks was disrupted by inhibiting vCA1 shock responses during memory encoding. Thus, our findings suggest that networks of cells that become correlated with shock-responsive neurons in vCA1 are essential components of contextual fear memory ensembles.

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Neuron

Precision Calcium Imaging of Dense Neural Populations via a Cell-Body-Targeted Calcium Indicator

Or A. Shemesh, Changyang Linghu, Kiryl D. Piatkevich, Daniel Goodwin, Orhan Tunc Celiker, Howard J. Gritton, Michael F. Romano, Ruixuan Gao, Chih-Chieh (Jay)Yu, Hua-An Tseng, Seth Bensussen, Sujatha Narayan, Chao-Tsung Yang, Limor Freifeld, Cody A. Siciliano, Ishan Gupta, Joyce Wang, Nikita Pak, Young-Gyu Yoon, Jeremy F.P.Ullmann, Burcu Guner-Ataman, Habiba Noamany, Zoe R.Sheinkopf, Won Min Park, Shoh Asano, Amy E. Keating, James S.Trimmer, Jacob Reimer, Andreas S.Tolias, Mark F.Bear, Kay M.Tye, Xue Han, Misha B.Ahrens, Edward S.Boyden
Neuron
June 26, 2020

Methods for one-photon fluorescent imaging of calcium dynamics can capture the activity of hundreds of neurons across large fields of view at a low equipment complexity and cost. In contrast to two-photon methods, however, one-photon methods suffer from higher levels of crosstalk from neuropil, resulting in a decreased signal-to-noise ratio and artifactual correlations of neural activity. We address this problem by engineering cell-body-targeted variants of the fluorescent calcium indicators GCaMP6f and GCaMP7f. We screened fusions of GCaMP to natural, as well as artificial, peptides and identified fusions that localized GCaMP to within 50 μm of the cell body of neurons in mice and larval zebrafish. One-photon imaging of soma-targeted GCaMP in dense neural circuits reported fewer artifactual spikes from neuropil, an increased signal-to-noise ratio, and decreased artifactual correlation across neurons. Thus, soma-targeting of fluorescent calcium indicators facilitates usage of simple, powerful, one-photon methods for imaging neural calcium dynamics.

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Neuron

Soma-Targeted Imaging of Neural Circuits by Ribosome Tethering

Yiming Chen, Heeun Jang, Perry W.E. Spratt, Seher Kosar, David E. Taylor, Rachel A. Essner, Ling Bai, David E. Leib, Tzu-Wei Kuo, Yen-Chu Lin, Mili Patel, Aygul Subkhangulova, Saul Kato, Evan H. Feinberg, Kevin J. Bender, Zachary A. Knight, Jennifer L. Garrison
Neuron
June 22, 2020

Neuroscience relies on techniques for imaging the structure and dynamics of neural circuits, but the cell bodies of individual neurons are often obscured by overlapping fluorescence from axons and dendrites in surrounding neuropil. Here, we describe two strategies for using the ribosome to restrict the expression of fluorescent proteins to the neuronal soma. We show first that a ribosome-tethered nanobody can be used to trap GFP in the cell body, thereby enabling direct visualization of previously undetectable GFP fluorescence. We then design a ribosome-tethered GCaMP for imaging calcium dynamics. We show that this reporter faithfully tracks somatic calcium dynamics in the mouse brain while eliminating cross-talk between neurons caused by contaminating neuropil. In worms, this reporter enables whole-brain imaging with faster kinetics and brighter fluorescence than commonly used nuclear GCaMPs. These two approaches provide a general way to enhance the specificity of imaging in neurobiology.

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Neuron

A Distributed Neural Code in the Dentate Gyrus and in CA1

Fabio Stefanini, Lyudmila Kushnir, Jessica C. Jimenez, Joshua H. Jennings, Nicholas I. Woods, Garret D. Stuber, Mazen A. Kheirbek, Rene´ Hen, and Stefano Fusi1
Neuron
June 9, 2020

Neurons are often considered specialized functional units that encode a single variable. However, many neurons are observed to respond to a mix of disparate sensory, cognitive, and behavioral variables. For such representations, information is distributed across multiple neurons. Here we find this distributed code in the dentate gyrus and CA1 subregions of the hippocampus. Using calcium imaging in freely moving mice, we decoded an animal’s position, direction of motion, and speed from the activity of hundreds of cells. The response properties of individual neurons were only partially predictive of their importance for encoding position. Non-place cells encoded position and contributed to position encoding when combined with other cells. Indeed, disrupting the correlations between neural activities decreased decoding performance, mostly in CA1. Our analysis indicates that population methods rather than classical analyses based on single-cell response properties may more accurately characterize the neural code in the hippocampus.

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Cell Reports

Heterogeneous Habenular Neuronal Ensembles during Selection of Defensive Behaviors

Salvatore Lecca, Vijay M.K. Namboodiri, Leonardo Restivo, Nicolas Gervasi, Giuliano Pillolla, Garret D. Stuber, Manuel Mameli
Cell Reports
June 9, 2020

Optimal selection of threat-driven defensive behaviors is paramount to an animal’s survival. The lateral habenula (LHb) is a key neuronal hub coordinating behavioral responses to aversive stimuli. Yet, how individual LHb neurons represent defensive behaviors in response to threats remains unknown. Here, we show that in mice, a visual threat promotes distinct defensive behaviors, namely runaway (escape) and action-locking (immobile-like). Fiber photometry of bulk LHb neuronal activity in behaving animals reveals an increase and a decrease in calcium signal time-locked with runaway and action-locking, respectively. Imaging single-cell calcium dynamics across distinct threat-driven behaviors identify independently active LHb neuronal clusters. These clusters participate during specific time epochs of defensive behaviors. Decoding analysis of this neuronal activity reveals that some LHb clusters either predict the upcoming selection of the defensive action or represent the selected action. Thus, heterogeneous neuronal clusters in LHb predict or reflect the selection of distinct threat-driven defensive behaviors.

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Neuron

Sparse Activity of Hippocampal Adult-Born Neurons during REM Sleep Is Necessary for Memory Consolidation

Deependra Kumar, Iyo Koyanagi, Alvaro Carrier-Ruiz, Pablo Vergara, Sakthivel Srinivasan, Yuki Sugaya, Masatoshi Kasuya, Tzong-Shiue Yu, Kaspar E. Vogt, Masafumi Muratani, Takaaki Ohnishi, Sima Singh, Catia M. Teixeira, Yoan Chérasse, Toshie Naoi, Szu-Han Wang, Pimpimon Nondhalee, Boran A.H. Osman, Naoko Kaneko, Kazunobu Sawamoto, Steven G. Kernie, Takeshi Sakurai, Thomas J. McHugh, Masanobu Kano, Masashi Yanagisawa, Masanori Sakaguchi
Neuron
June 4, 2020

The occurrence of dreaming during rapid eye movement (REM) sleep prompts interest in the role of REM sleep in hippocampal-dependent episodic memory. Within the mammalian hippocampus, the dentate gyrus (DG) has the unique characteristic of exhibiting neurogenesis persisting into adulthood. Despite their small numbers and sparse activity, adult-born neurons (ABNs) in the DG play critical roles in memory; however, their memory function during sleep is unknown. Here, we investigate whether young ABN activity contributes to memory consolidation during sleep using Ca2+ imaging in freely moving mice. We found that contextual fear learning recruits a population of young ABNs that are reactivated during subsequent REM sleep against a backdrop of overall reduced ABN activity. Optogenetic silencing of this sparse ABN activity during REM sleep alters the structural remodeling of spines on ABN dendrites and impairs memory consolidation. These findings provide a causal link between ABN activity during REM sleep and memory consolidation.

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JNMethods

Ca2+ imaging of neurons in freely moving rats with automatic post hoc histological identification

Philip Anner, Johannes Passecker, Thomas Klausberger, Georg Dorffner
Journal of Neuroscience Methods
May 11th, 2020

Background

Cognitive neuroscientists aim to understand behavior often based on the underlying activity of individual neurons. Recently developed miniaturized epifluorescence microscopes allow recording of cellular calcium transients, resembling neuronal activity, of individual neurons even in deep brain areas in freely behaving animals. At the same time, molecular markers allow the characterization of diverse neuronal subtypes by post hoc immunohistochemical labeling. Combining both methods would allow researchers to increase insights into how individual neuronal activity and entities contribute to behavior.

New method

Here, we present a novel method for identifying the same neurons, recorded with calcium imaging using a miniaturized epifluorescence microscope, post hoc in fixed histological sections. This allows immunohistochemical investigations to detect the molecular signature of in vivo recorded neurons. Our method utilizes the structure of blood vessels for aligning in vivo acquired 2D images with a reconstructed 3D histological model.

Results

We automatically matched, 60 % of all in vivo recorded cells post hoc in histology. Across all animals, we successfully matched 43 % to 89 % of the recorded neurons. We provide a measure for the confidence of matched cells and validated our method by multiple simulation studies.

Comparison with existing methods

To our knowledge, we present the first method for matching cells, recorded with a miniaturized epifluorescence microscope in freely moving animals, post hoc in histological sections.

Conclusions

Our method allows a comprehensive analysis of how cortical circuits relate to freely moving animal behavior by combining functional activity of individual neurons with their underlying histological profiles.

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Nature Neuro

General anesthetics activate a potent central pain-suppression circuit in the amygdala

Thuy Hua, Bin Chen, Dongye Lu, Katsuyasu Sakurai, Shengli Zhao, Bao-Xia Han, Jiwoo Kim, Luping Yin, Yong Chen, Jinghao Lu & Fan Wang
Nature Neuroscience
May 18th, 2020

General anesthesia (GA) can produce analgesia (loss of pain) independent of inducing loss of consciousness, but the underlying mechanisms remain unclear. We hypothesized that GA suppresses pain in part by activating supraspinal analgesic circuits. We discovered a distinct population of GABAergic neurons activated by GA in the mouse central amygdala (CeAGA neurons). In vivo calcium imaging revealed that different GA drugs activate a shared ensemble of CeAGA neurons. CeAGA neurons also possess basal activity that mostly reflects animals’ internal state rather than external stimuli. Optogenetic activation of CeAGA potently suppressed both pain-elicited reflexive and self-recuperating behaviors across sensory modalities and abolished neuropathic pain-induced mechanical (hyper-)sensitivity. Conversely, inhibition of CeAGA activity exacerbated pain, produced strong aversion and canceled the analgesic effect of low-dose ketamine. CeAGA neurons have widespread inhibitory projections to many affective pain-processing centers. Our study points to CeAGA as a potential powerful therapeutic target for alleviating chronic pain.

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Nature Communications

Trajectory-modulated hippocampal neurons persist throughout memory-guided navigation

Nathaniel R. Kinsky, William Mau, David W. Sullivan, Samuel J. Levy, Evan A. Ruesch & Michael E. Hasselmo
Nature Communications
May 15th, 2020

Trajectory-dependent splitter neurons in the hippocampus encode information about a rodent’s prior trajectory during performance of a continuous alternation task. As such, they provide valuable information for supporting memory-guided behavior. Here, we employed single-photon calcium imaging in freely moving mice to investigate the emergence and fate of trajectory-dependent activity through learning and mastery of a continuous spatial alternation task. In agreement with others, the quality of trajectory-dependent information in hippocampal neurons correlated with task performance. We thus hypothesized that, due to their utility, splitter neurons would exhibit heightened stability. We find that splitter neurons were more likely to remain active and retained more consistent spatial information across multiple days than other neurons. Furthermore, we find that both splitter neurons and place cells emerged rapidly and maintained stable trajectory-dependent/spatial activity thereafter. Our results suggest that neurons with useful functional coding exhibit heightened stability to support memory guided behavior.

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Frontiers

High-Throughput Task to Study Memory Recall During Spatial Navigation in Rodents

Lucia Morales, David P. Tomàs,  Josep Dalmau, Jaime de la Rocha and Pablo E. Jercog
Frontiers in Behavioral Neuroscience
May 15, 2020

Spatial navigation is one of the most frequently used behavioral paradigms to study memory formation in rodents. Commonly used tasks to study memory are labor-intensive, preventing the simultaneous testing of multiple animals with the tendency to yield a low number of trials, curtailing the statistical power. Moreover, they are not tailored to be combined with neurophysiology recordings because they are not based on overt stereotyped behavioral responses that can be precisely timed. Here we present a novel task to study long-term memory formation and recall during spatial navigation. The task consists of learning sessions during which mice need to find the rewarding port that changes from day to day. Hours after learning, there is a recall session during which mice search for the location of the memorized rewarding port. During the recall sessions, the animals repeatedly poke the remembered port over many trials (up to ∼20) without receiving a reward (i.e., no positive feedback) as a readout of memory. In this task, mice show memory of port locations learned on up to three previous days. This eight-port maze task requires minimal human intervention, allowing for simultaneous and unsupervised testing of several mice in parallel, yielding a high number of recall trials per session over many days, and compatible with recordings of neural activity.

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PNAS

A neuronal signature for monogamous reunion

Jennifer L. Scribner, Eric A. Vance, David S. W. Protter, William M. Sheeran, Elliott Saslow, Ryan T. Cameron, Eric M. Klein, Jessica C. Jimenez, Mazen A. Kheirbek, and  Zoe R. Donaldson
PNAS
May 7th, 2020

Pair-bond formation depends vitally on neuromodulatory signaling within the nucleus accumbens, but the neuronal dynamics underlying this behavior remain unclear. Using 1-photon in vivo Ca2+ imaging in monogamous prairie voles, we found that pair bonding does not elicit differences in overall nucleus accumbens Ca2+ activity. Instead, we identified distinct ensembles of neurons in this region that are recruited during approach to either a partner or a novel vole. The partner-approach neuronal ensemble increased in size following bond formation, and differences in the size of approach ensembles for partner and novel voles predict bond strength. In contrast, neurons comprising departure ensembles do not change over time and are not correlated with bond strength, indicating that ensemble plasticity is specific to partner approach. Furthermore, the neurons comprising partner and novel-approach ensembles are nonoverlapping while departure ensembles are more overlapping than chance, which may reflect another key feature of approach ensembles. We posit that the features of the partner-approach ensemble and its expansion upon bond formation potentially make it a key neuronal substrate associated with bond formation and maturation.

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CurrentBiology

Multiple Maps of the Same Spatial Context Can Stably Coexist in the Mouse Hippocampus

Liron Sheintuch, Nitzan Geva, Hadas Baumer, Yoav Rechavi, Alon Rubin, Yaniv Ziv
Current Biology
April 20th, 2020

Hippocampal place cells selectively fire when an an- imal traverses a particular location and are consid- ered a neural substrate of spatial memory. Place cells were shown to change their activity patterns (remap) across different spatial contexts but to maintain their spatial tuning in a fixed familiar context. Here, we show that mouse hippocampal neurons can globally remap, forming multiple distinct representations (maps) of the same familiar environment, without any apparent changes in sensory input or behavior. Alternations between maps occurred only across separate visits to the environment, implying switch- ing between distinct stable attractors in the hippo- campal network. Importantly, the different maps were spatially informative and persistent over weeks, demonstrating that they can be reliably stored and retrieved from long-term memory. Taken together, our results suggest that a memory of a given spatial context could be associated with multiple distinct neuronal representations, rather than just one.

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Neuron

Postingestive Modulation of Food Seeking Depends on Vagus-Mediated Dopamine Neuron Activity

Ana B. Fernandes, Joaquim Alves da Silva, Joana Almeida, Guohong Cui, Charles R. Gerfen, Rui M. Costa, Albino J. Oliveira-Maia
Neuron
April 6th, 2020

Postingestive nutrient sensing can induce food preferences. However, much less is known about the ability of postingestive signals to modulate food-seeking behaviors. Here we report a causal connection between postingestive sucrose sensing and vagus-mediated dopamine neuron activity in the ventral tegmental area (VTA), supporting food seeking. The activity of VTA dopamine neurons increases significantly after administration of intragastric sucrose, and deletion of the NMDA receptor in these neurons, which affects bursting and plasticity, abolishes lever pressing for postingestive sucrose delivery. Furthermore, lesions of the hepatic branch of the vagus nerve significantly impair postingestive-dependent VTA dopamine neuron activity and food seeking, whereas optogenetic stimulation of left vagus nerve neurons significantly increases VTA dopamine neuron activity. These data establish a necessary role of vagus-mediated dopamine neuron activity in postingestive-dependent food seeking, which is independent of taste signaling.

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Nature Neuro

Hippocampal neurons represent events as transferable units of experience

Chen Sun, Wannan Yang, Jared Martin & Susumu Tonegawa
Nature Neuroscience
April 6th, 2020

The brain codes continuous spatial, temporal and sensory changes in daily experience. Recent studies suggest that the brain also tracks experience as segmented subdivisions (events), but the neural basis for encoding events remains unclear. Here, we designed a maze for mice, composed of four materially indistinguishable lap events, and identify hippocampal CA1 neurons whose activity are modulated not only by spatial location but also lap number. These ‘event-specific rate remapping’ (ESR) cells remain lap-specific even when the maze length is unpredictably altered within trials, which suggests that ESR cells treat lap events as fundamental units. The activity pattern of ESR cells is reused to represent lap events when the maze geometry is altered from square to circle, which suggests that it helps transfer knowledge between experiences. ESR activity is separately manipulable from spatial activity, and may therefore constitute an independent hippocampal code: an ‘event code’ dedicated to organizing experience by events as discrete and transferable units.

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ScientificReports

Action representation in the mouse parieto-frontal network

Tuce Tombaz, Benjamin A. Dunn, Karoline Hovde, Ryan John Cubero, Bartul Mimica, Pranav Mamidanna, Yasser Roudi & Jonathan R. Whitlock
Scientific Reports
March 27th, 2020

The posterior parietal cortex (PPC) and frontal motor areas comprise a cortical network supporting goal-directed behaviour, with functions including sensorimotor transformations and decision making. In primates, this network links performed and observed actions via mirror neurons, which fire both when individuals perform an action and when they observe the same action performed by a conspecific. Mirror neurons are believed to be important for social learning, but it is not known whether mirror-like neurons occur in similar networks in other social species, such as rodents, or if they can be measured in such models using paradigms where observers passively view a demonstrator. Therefore, we imaged Ca2+ responses in PPC and secondary motor cortex (M2) while mice performed and observed pellet-reaching and wheel-running tasks, and found that cell populations in both areas robustly encoded several naturalistic behaviours. However, neural responses to the same set of observed actions were absent, although we verified that observer mice were attentive to performers and that PPC neurons responded reliably to visual cues. Statistical modelling also indicated that executed actions outperformed observed actions in predicting neural responses. These results raise the possibility that sensorimotor action recognition in rodents could take place outside of the parieto-frontal circuit, and underscore that detecting socially-driven neural coding depends critically on the species and behavioural paradigm used.

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Molecular Psychiatry in circle

Stress peptides sensitize fear circuitry to promote passive coping

Pinelopi Pliota, Vincent Böhm, Florian Grössl, Johannes Griessner, Ornella Valenti, Klaus Kraitsy, Joanna Kaczanowska, Manuel Pasieka, Thomas Lendl, Jan M. Deussing and Wulf Haubensak
Molecular Psychiatry 
February 17th, 2020

Survival relies on optimizing behavioral responses through experience. Animals often react to acute stress by switching to passive behavioral responses when coping with environmental challenge. Despite recent advances in dissecting mammalian circuitry for Pavlovian fear, the neuronal basis underlying this form of non-Pavlovian anxiety-related behavioral plasticity remains poorly understood. Here, we report that aversive experience recruits the posterior paraventricular thalamus (PVT) and corticotropin-releasing hormone (CRH) and sensitizes a Pavlovian fear circuit to promote passive responding. Site-specific lesions and optogenetic manipulations reveal that PVT-to-central amygdala (CE) projections activate anxiogenic neuronal populations in the CE that release local CRH in response to acute stress. CRH potentiates basolateral (BLA)-CE connectivity and antagonizes inhibitory gating of CE output, a mechanism linked to Pavlovian fear, to facilitate the switch from active to passive behavior. Thus, PVT-amygdala fear circuitry uses inhibitory gating in the CE as a shared dynamic motif, but relies on different cellular mechanisms (postsynaptic long-term potentiation vs. presynaptic facilitation), to multiplex active/passive response bias in Pavlovian and non-Pavlovian behavioral plasticity. These results establish a framework promoting stress-induced passive responding, which might contribute to passive emotional coping seen in human fear- and anxiety-related disorders.

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Cell Reports

Opposing Regulation of Cocaine Seeking by Glutamate and GABA Neurons in the Ventral Pallidum

Jasper A. Heinsbroek, Ana-Clara Bobadilla, Eric Dereschewitz, Ahlem Assali, Reda M. Chalhoub, Christopher W. Cowan, Peter W. Kalivas
Cell Reports
February 11th, 2020

Projections from the nucleus accumbens to the ventral pallidum (VP) regulate relapse in animal models of addiction. The VP contains GABAergic (VPGABA) and glutamatergic (VPGlu) neurons, and a subpopulation of GABAergic neurons co-express enkephalin (VPPenk). Rabies tracing reveals that VPGlu and VPPenk neurons receive preferential innervation from upstream D1- relative to D2-expressing accumbens neurons. Chemogenetic stimulation of VPGlu neurons inhibits, whereas stimulation of VPGABA and VPPenk neurons potentiates cocaine seeking in mice withdrawn from intravenous cocaine self-administration. Calcium imaging reveals cell type-specific activity patterns when animals learn to suppress drug seeking during extinction training versus engaging in cue-induced cocaine seeking. During cued seeking, VPGABA neurons increase their overall activity, and VPPenk neurons are selectively activated around nose pokes for cocaine. In contrast, VPGlu neurons increase their spike rate following extinction training. These data show that VP subpopulations differentially encode and regulate cocaine seeking, with VPPenk and VPGABA neurons facilitating and VPGlu neurons inhibiting cocaine seeking.

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Nature Communications

Persistent Activation of Central Amygdala CRF Neurons Helps Drive the Immediate Fear Extinction Deficit

Yong S. Jo, Vijay Mohan K. Namboodiri, Garret D. Stuber & Larry S. Zweifel
Nature Communications
January 22nd, 2020

Fear extinction is an active learning process whereby previously established conditioned responses to a conditioned stimulus are suppressed. Paradoxically, when extinction training is performed immediately following fear acquisition, the extinction memory is weakened. Here, we demonstrate that corticotrophin-releasing factor (CRF)-expressing neurons in the central amygdala (CeA) antagonize the extinction memory following immediate extinction training. CeA-CRF neurons transition from responding to the unconditioned stimulus to the conditioned stimulus during the acquisition of a fear memory that persists during immediate extinction training, but diminishes during delayed extinction training. Inhibition of CeA-CRF neurons during immediate extinction training is sufficient to promote enhanced extinction memories, and activation of these neurons following delay extinction training is sufficient to reinstate a previously extinguished fear memory. These results demonstrate CeA-CRF neurons are an important substrate for the persistence of fear and have broad implications for the neural basis of persistent negative affective behavioral states.

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elife

Generality and opponency of rostromedial tegmental (RMTg) roles in valence processing

Hao Li, Dominika Pullmann, Jennifer Y Cho, Maya Eid, Thomas C Jhou
eLife
January 22nd, 2020

The rostromedial tegmental nucleus (RMTg), a GABAergic afferent to midbrain dopamine (DA) neurons, has been hypothesized to be broadly activated by aversive stimuli. However, this encoding pattern has only been demonstrated for a limited number of stimuli, and the RMTg influence on ventral tegmental (VTA) responses to aversive stimuli is untested. Here, we found that RMTg neurons are broadly excited by aversive stimuli of different sensory modalities and inhibited by reward-related stimuli. These stimuli include visual, auditory, somatosensory and chemical aversive stimuli, as well as “opponent” motivational states induced by removal of sustained rewarding or aversive stimuli. These patterns are consistent with broad encoding of negative valence in a subset of RMTg neurons. We further found that valence-encoding RMTg neurons preferentially project to the DA-rich VTA versus other targets, and excitotoxic RMTg lesions greatly reduce aversive stimulus-induced inhibitions in VTA neurons, particularly putative DA neurons, while also impairing conditioned place aversion to multiple aversive stimuli. Together, our findings indicate a broad RMTg role in encoding aversion and driving VTA responses and behavior.

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Molecular Brain Logo

Pcdhβ deficiency affects hippocampal CA1 ensemble activity and contextual fear discrimination

Hirotaka Asai, Noriaki Ohkawa, Yoshito Saitoh, Khaled Ghandour, Emi Murayama, Hirofumi Nishizono, Mina Matsuo, Teruyoshi Hirayama, Ryosuke Kaneko, Shin-ichi Muramatsu, Takeshi Yagi & Kaoru Inokuchi
Molecular Brain
January 20th, 2020

Clustered protocadherins (Pcdhs), a large group of adhesion molecules, are important for axonal projections and dendritic spread, but little is known about how they influence neuronal activity. The Pcdhβ cluster is strongly expressed in the hippocampus, and in vivo Ca2+ imaging in Pcdhβ-deficient mice revealed altered activity of neuronal ensembles but not of individual cells in this region in freely moving animals. Specifically, Pcdhβ deficiency increased the number of large-size neuronal ensembles and the proportion of cells shared between ensembles. Furthermore, Pcdhβ-deficient mice exhibited reduced repetitive neuronal population activity during exploration of a novel context and were less able to discriminate contexts in a contextual fear conditioning paradigm. These results suggest that one function of Pcdhβs is to modulate neural ensemble activity in the hippocampus to promote context discrimination.

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Frontiers

Opposing Somatic and Dendritic Expression of Stimulus-Selective Response Plasticity in Mouse Primary Visual Cortex

Taekeun Kim, Francesca A. Chaloner, Sam F. Cooke, Mark T. Harnett and Mark F. Bear
Frontiers in Cellular Neuroscience
January 14th, 2020

Daily exposure of awake mice to a phase-reversing visual grating stimulus leads to enhancement of the visual-evoked potential (VEP) in layer 4 of the primary visual cortex (V1). This stimulus-selective response potentiation (SRP) resembles and shares mechanistic requirements with canonical long-term synaptic potentiation (LTP). However, it remains to be determined how this augmentation of a population response translates into altered neuronal activity of individual V1 neurons. To address this question, we performed longitudinal calcium imaging of layer 4 excitatory neurons in V1 and tracked changes associated with the induction and expression of SRP. We found no evidence for a net change in the fraction of visually responsive neurons as the stimulus became familiar. However, endoscopic calcium imaging of layer 4 principal neurons revealed that somatic calcium transients in response to phase-reversals of the familiar visual stimulus are reduced and undergo strong within-session adaptation. Conversely, neuropil calcium responses and VEPs are enhanced during familiar stimulus viewing, and the VEPs show reduced within-session adaptation. Consistent with the exquisite selectivity of SRP, the plasticity of cellular responses to phase-reversing gratings did not translate into altered orientation selectivity to drifting gratings. Our findings suggest a model in which augmentation of fast, short-latency synaptic (dendritic) responses, manifested as enhanced layer 4 VEPs, recruits inhibition to suppress cellular activity. Reduced cellular activity to the familiar stimulus may account for the behavioral correlate of SRP, orientation-selective long-term habituation.

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Neuron

Amygdala Reward Neurons Form and Store Fear Extinction Memory

Xiangyu Zhang, Joshua Kim, Susumu Tonegawa
Neuron
January 14th, 2020

The ability to extinguish conditioned fear memory is critical for adaptive control of fear response, and its impairment is a hallmark of emotional disorders like post-traumatic stress disorder (PTSD). Fear extinction is thought to take place when animals form a new memory that suppresses the original fear memory. However, little is known about the nature and the site of formation and storage of this new extinction memory. Here we demonstrate that a fear extinction memory engram is formed and stored in a genetically distinct basolateral amygdala (BLA) neuronal population that drives reward behaviors and antagonizes the BLA’s original fear neurons. Activation of fear extinction engram neurons and natural reward-responsive neurons overlap significantly in the BLA. Furthermore, these two neuronal subsets are mutually interchangeable in driving reward behaviors and fear extinction behaviors. Thus, fear extinction memory is a newly formed reward memory.

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Neuron

Endocannabinoid Signaling Collapse Mediates Stress-Induced Amygdalo-Cortical Strengthening

David J. Marcus, Gaurav Bedse, Andrew D. Gaulden, James D. Ryan, Veronika Kondev, Nathan D. Winters, Luis E. Rosas-Vidal, Megan Altemus, Ken Mackie, Francis S. Lee, Eric Delpire, Sachin Patel 
Neuron
January 13th, 2020

Functional coupling between the amygdala and the dorsomedial prefrontal cortex (dmPFC) has been implicated in the generation of negative affective states; however, the mechanisms by which stress increases amygdala-dmPFC synaptic strength and generates anxiety-like behaviors are not well understood. Here, we show that the mouse basolateral amygdala (BLA)-prelimbic prefrontal cortex (plPFC) circuit is engaged by stress and activation of this pathway in anxiogenic. Furthermore, we demonstrate that acute stress exposure leads to a lasting increase in synaptic strength within a reciprocal BLA-plPFC-BLA subcircuit. Importantly, we identify 2-arachidonoylglycerol (2-AG)-mediated endocannabinoid signaling as a key mechanism limiting glutamate release at BLA-plPFC synapses and the functional collapse of multimodal 2-AG signaling as a molecular mechanism leading to persistent circuit-specific synaptic strengthening and anxiety-like behaviors after stress exposure. These data suggest that circuit-specific impairment in 2-AG signaling could facilitate functional coupling between the BLA and plPFC and the translation of environmental stress to affective pathology.

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Nature Neuro

Somatostatin interneurons in the prefrontal cortex control affective state discrimination in mice

Diego Scheggia, Francesca Managò, Federica Maltese, Stefania Bruni, Marco Nigro, Daniel Dautan, Patrick Latuske, Gabriella Contarini, Marta Gomez-Gonzalo, Linda Maria Requie, Valentina Ferretti, Giulia Castellani, Daniele Mauro, Alessandra Bonavia, Giorgio Carmignoto, Ofer Yizhar & Francesco Papaleo
Nature Neuroscience
December 16, 2019

The prefrontal cortex (PFC) is implicated in processing of the affective state of others through non-verbal communication. This social cognitive function is thought to rely on an intact cortical neuronal excitatory and inhibitory balance. Here combining in vivo electrophysiology with a behavioral task for affective state discrimination in mice, we show a differential activation of medial PFC (mPFC) neurons during social exploration that depends on the affective state of the conspecific. Optogenetic manipulations revealed a double dissociation between the role of interneurons in social cognition. Specifically, inhibition of mPFC somatostatin (SOM+), but not of parvalbumin (PV+) interneurons, abolishes affective state discrimination. Accordingly, synchronized activation of mPFC SOM+interneurons selectively induces social discrimination. As visualized by in vivo single-cell microendoscopic Ca2+ imaging, an increased synchronous activity of mPFC SOM+ interneurons, guiding inhibition of pyramidal neurons, is associated with affective state discrimination. Our findings provide new insights into the neurobiological mechanisms of affective state discrimination.

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Science

A cortical-brainstem circuit predicts and governs compulsive alcohol drinking

Cody A. Siciliano, Habiba Noamany, Chia-Jung Chang, Alex R. Brown, Xinhong Chen, Daniel Leible, Jennifer J. Lee, Joyce Wang, Amanda N. Vernon, Caitlin M. Vander Weele, Eyal Y. Kimchi, Myriam Heiman, Kay M. Tye
Science
Nov 22, 2019

What individual differences in neural activity predict the future escalation of alcohol drinking from casual to compulsive? The neurobiological mechanisms that gate the transition from moderate to compulsive drinking remain poorly understood. We longitudinally tracked the development of compulsive drinking across a binge-drinking experience in male mice. Binge drinking unmasked individual differences, revealing latent traits in alcohol consumption and compulsive drinking despite equal prior exposure to alcohol. Distinct neural activity signatures of cortical neurons projecting to the brainstem before binge drinking predicted the ultimate emergence of compulsivity. Mimicry of activity patterns that predicted drinking phenotypes was sufficient to bidirectionally modulate drinking. Our results provide a mechanistic explanation for individual variance in vulnerability to compulsive alcohol drinking.

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Molecular Brain Logo

Novel nose poke-based temporal discrimination tasks with concurrent in vivo calcium imaging in freely moving mice

William D. Marks, Hisayuki Osanai, Jun Yamamoto, Sachie K. Ogawa & Takashi Kitamura
Molecular Brain
Nov 6, 2019

The hippocampus has been known to process temporal information as part of memory formation. While time cells have been observed in the hippocampus and medial entorhinal cortex, a number of the behavioral tasks used present potential confounds that may cause some contamination of time cell observations due to animal movement. Here, we report the development of a novel nose poke-based temporal discrimination task designed to be used with in vivo calcium imaging for the analysis of hippocampal time cells in freely moving mice. First, we developed a ten second held nose poke paradigm for use in mice to deliver a purer time metric for the analysis of time cell activity in hippocampus CA1. Second, we developed a temporal discrimination task that involves the association of held nose poke durations of differing lengths with differential spatial cues presented in arms on a linear I-maze. Four of five mice achieved successful temporal discrimination within three weeks. Calcium imaging has been successfully performed in each of these tasks, with time cell activity being detected in the 10s nose poke task, and calcium waves being observed in discrete components of the temporal discrimination task. The newly developed behavior tasks in mice serve as novel tools to accelerate the study of time cell activity and examine the integration of time and space in episodic memory formation.

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Nature Neuro

Adaptive disinhibitory gating by VIP interneurons permits associative learning

Sabine Krabbe, Enrica Paradiso, Simon d’Aquin, Yael Bitterman, Julien Courtin, Chun Xu, Keisuke Yonehara, Milica Markovic, Christian Müller, Tobias Eichlisberger, Jan Gründemann, Francesco Ferraguti & Andreas Lüthi
Nature Neuroscience
Oct 21, 2019

Learning drives behavioral adaptations necessary for survival. While plasticity of excitatory projection neurons during associative learning has been extensively studied, little is known about the contributions of local interneurons. Using fear conditioning as a model for associative learning, we found that behaviorally relevant, salient stimuli cause learning by tapping into a local microcircuit consisting of precisely connected subtypes of inhibitory interneurons. By employing deep-brain calcium imaging and optogenetics, we demonstrate that vasoactive intestinal peptide (VIP)-expressing interneurons in the basolateral amygdala are activated by aversive events and provide a mandatory disinhibitory signal for associative learning. Notably, VIP interneuron responses during learning are strongly modulated by expectations. Our findings indicate that VIP interneurons are a central component of a dynamic circuit motif that mediates adaptive disinhibitory gating to specifically learn about unexpected, salient events, thereby ensuring appropriate behavioral adaptations.

 

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Nature Communications

Revealing neural correlates of behavior without behavioral measurements

Alon Rubin, Liron Sheintuch, Noa Brande-Eilat, Or Pinchasof, Yoav Rechavi, Nitzan Geva, and Yaniv Ziv
Nature Communications
Oct 18, 2019

Measuring neuronal tuning curves has been instrumental for many discoveries in neuroscience but requires a priori assumptions regarding the identity of the encoded variables. We applied unsupervised learning to large-scale neuronal recordings in behaving mice from circuits involved in spatial cognition and uncovered a highly-organized internal structure of ensemble activity patterns. This emergent structure allowed defining for each neuron an ‘internal tuning-curve’ that characterizes its activity relative to the network activity, rather than relative to any predefined external variable, revealing place-tuning and head-direction tuning without relying on measurements of place or head-direction. Similar investigation in prefrontal cortex revealed schematic representations of distances and actions, and exposed a previously unknown variable, the ‘trajectory-phase’. The internal structure was conserved across mice, allowing using one animal’s data to decode another animal’s behavior. Thus, the internal structure of neuronal activity itself enables reconstructing internal representations and discovering new behavioral variables hidden within a neural code.

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Molecular Brain Logo

Cortical ensemble activity discriminates auditory attentional states

Pan-tong Yao, Jia Shen, Liang Chen, Shaoyu Ge & Qiaojie Xiong
Molecular Brain
Oct 17, 2019

Selective attention modulates sensory cortical activity. It remains unclear how auditory cortical activity represents stimuli that differ behaviorally. We designed a cross-modality task in which mice made decisions to obtain rewards based on attended visual or auditory stimuli. We recorded auditory cortical activity in behaving mice attending to, ignoring, or passively hearing auditory stimuli. Engaging in the task bidirectionally modulates neuronal responses to the auditory stimuli in both the attended and ignored conditions compared to passive hearing. Neuronal ensemble activity in response to stimuli under attended, ignored and passive conditions are readily distinguishable. Furthermore, ensemble activity under attended and ignored conditions are in closer states compared to passive condition, and they share a component of attentional modulation which drives them to the same direction in the population activity space. Our findings suggest that the ignored condition is very different from the passive condition, and the auditory cortical sensory processing under ignored, attended and passive conditions are modulated differently.

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rAQA6ZGF

Mutant neuropeptide S receptor reduces sleep duration with preserved memory consolidation

Lijuan Xing, Guangsen Shi, Yulia Mostovoy, Nicholas W. Gentry, Zenghua Fan, Thomas B. Mcmahon, Pui-Yan Kwok, Christopher R. Jones, Louis J. Ptáček, Ying-Hui Fu
Science Translational Medicine
October 16, 2019

Sleep is a crucial physiological process for our survival and cognitive performance, yet the factors controlling human sleep regulation remain poorly understood. Here, we identified a missense mutation in a G protein–coupled neuropeptide S receptor 1 (NPSR1) that is associated with a natural short sleep phenotype in humans. Mice carrying the homologous mutation exhibited less sleep time despite increased sleep pressure. These animals were also resistant to contextual memory deficits associated with sleep deprivation. In vivo, the mutant receptors showed increased sensitivity to neuropeptide S exogenous activation. These results suggest that the NPS/NPSR1 pathway might play a critical role in regulating human sleep duration and in the link between sleep homeostasis and memory consolidation.

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Neuron

Control of Non-REM Sleep by Midbrain Neurotensinergic Neurons

Peng Zhong, Zhe Zhang, Zeke Barger, Chenyan Ma, Danqian Liu, Xinlu Ding, Yang Dan
Neuron
Sept 30, 2019

The periaqueductal gray (PAG) in the midbrain is known to coordinate behavioral and autonomic responses to threat and injury through its descending projections to the brainstem. Here, we show that neurotensin (NTS)-expressing glutamatergic neurons in the ventrolateral PAG (vlPAG) powerfully promote non-rapid eye movement (NREM) sleep partly through their projection to the caudal medulla. Optogenetic and chemogenetic activation of vlPAG NTS neurons strongly enhanced NREM sleep, whereas their inactivation increased wakefulness. Calcium imaging and optrode recording showed that they are preferentially active during NREM sleep. The NREM-promoting effect of vlPAG NTS neurons is partly mediated by their projection to the caudal ventromedial medulla, where they excite GABAergic neurons. Bidirectional optogenetic and chemogenetic manipulations showed that the medullary GABAergic neurons also promote NREM sleep, and they innervate multiple monoaminergic populations. Together, these findings reveal a novel pathway for NREM sleep generation, in which glutamatergic neurons drive broad GABAergic inhibition of wake-promoting neuronal populations.

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Science

REM sleep–active MCH neurons are involved in forgetting hippocampus-dependent memories

Shuntaro Izawa, Srikanta Chowdhury, Toh Miyazaki, Yasutaka Mukai, Daisuke Ono, Ryo Inoue, Yu Ohmura, Hiroyuki Mizoguchi, Kazuhiro Kimura, Mitsuhiro Yoshioka, Akira Terao, Thomas S. Kilduff, Akihiro Yamanaka
Science
Sept 20, 2019

The neural mechanisms underlying memory regulation during sleep are not yet fully understood. We found that melanin concentrating hormone–producing neurons (MCH neurons) in the hypothalamus actively contribute to forgetting in rapid eye movement (REM) sleep. Hypothalamic MCH neurons densely innervated the dorsal hippocampus. Activation or inhibition of MCH neurons impaired or improved hippocampus-dependent memory, respectively. Activation of MCH nerve terminals in vitro reduced firing of hippocampal pyramidal neurons by increasing inhibitory inputs. Wake- and REM sleep–active MCH neurons were distinct populations that were randomly distributed in the hypothalamus. REM sleep state–dependent inhibition of MCH neurons impaired hippocampus-dependent memory without affecting sleep architecture or quality. REM sleep–active MCH neurons in the hypothalamus are thus involved in active forgetting in the hippocampus.

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Neuron

A Rare Mutation of β1-Adrenergic Receptor Affects Sleep/Wake Behaviors

Guangsen Shi, Lijuan Xing, David Wu, Bula J. Bhattacharyya, Christopher R. Jones, Thomas McMahon, S.Y. Christin Chong, Jason A. Chen, Giovanni Coppola, Daniel Geschwind, Andrew Krystal, Louis J. Ptáček, Ying-Hui Fu 
Neuron
August 28th, 2019

Sleep is crucial for our survival, and many diseases are linked to long-term poor sleep quality. Before we can use sleep to enhance our health and performance and alleviate diseases associated with poor sleep, a greater understanding of sleep regulation is necessary. We have identified a mutation in the β1-adrenergic receptor gene in humans who require fewer hours of sleep than most. In vitro, this mutation leads to decreased protein stability and dampened signaling in response to agonist treatment. In vivo, the mice carrying the same mutation demonstrated short sleep behavior. We found that this receptor is highly expressed in the dorsal pons and that these ADRB1+neurons are active during rapid eye movement (REM) sleep and wakefulness. Activating these neurons can lead to wakefulness, and the activity of these neurons is affected by the mutation. These results highlight the important role of β1-adrenergic receptors in sleep/wake regulation.

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elife

Activity dynamics of amygdala GABAergic neurons during cataplexy of narcolepsy

Ying Sun, Carlos Blanco-Centurion, Emmaline Bendell, Aurelio Vidal-Ortiz, Siwei Luo, Meng Liu
eLife
August 14, 2019

Recent studies showed activation of the GABAergic neurons in the central nucleus of the amygdala (CeA) triggered cataplexy of sleep disorder narcolepsy. However, there is still no direct evidence on CeA GABAergic neurons’ real-time dynamic during cataplexy. We used a deep brain calcium imaging tool to image the intrinsic calcium transient as a marker of neuronal activity changes in the narcoleptic VGAT-Cre mice by expressing the calcium sensor GCaMP6 into genetically defined CeA GABAergic neurons. Two distinct GABAergic neuronal groups involved in cataplexy were identified: spontaneous cataplexy-ON and predator odor-induced cataplexy-ON neurons. Majority in the latter group were inactive during regular sleep/wake cycles but were specifically activated by predator odor and continued their intense activities into succeeding cataplexy bouts. Furthermore, we found that CeA GABAergic neurons became highly synchronized during predator odor-induced cataplexy. We suggest that the abnormal activation and synchronization of CeA GABAergic neurons may trigger emotion-induced cataplexy.

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Nature Communications

Lateral dispersion is required for circuit integration of newly generated dentate granule cells

Jia Wang, Jia Shen, Gregory W. Kirschen, Yan Gu, Sebastian Jessberger, Shaoyu Ge
Nature Communications
June 29, 2019

The process of circuit integration of newly-generated dentate granule cells of the hippo- campus has been presumed to be a dynamic process. In fact, little is known regarding the initial development of newly generated neurons prior to circuit integration and the sig- nificance of this stage for circuit integration. Here, using advanced live imaging methods, we systematically analyze the dynamic dispersion of newly generated neurons in the neurogenic zone and observe that cells that are physically adjacent coordinate their lateral dispersion. Whole-cell recordings of adjacent newly generated neurons reveal that they are coupled via gap junctions. The dispersion of newly generated cells in the neurogenic zone is restricted when this coupling is disrupted, which severely impairs their subsequent integration into the hippocampal circuit. The results of this study reveal that the dynamic dispersion of newly generated dentate granule cells in the neurogenic zone is a required developmental stage for circuit integration.

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Neuron

Neurovascular coupling in the dentate gyrus regulates adult hippocampal neurogenesis

Jia Shen, Depeng Wang, Xinxing Wang, Qiaojie Xiong, Jun Xia, Shaoyu Ge
Neuron
June 27, 2019

Newborn dentate granule cells (DGCs) are continuously generated in the adult brain. The mechanism underlying how the adult brain governs hippocampal neurogenesis remains poorly understood. In this study, we investigated how coupling of pre-existing neurons to the cerebrovascular system regulates hippocampal neurogenesis. Using a new in vivo imaging method in freely moving mice, we found that hippocampus-engaged behaviors, such as exploration in a novel environment, rapidly increased microvascular blood-flow velocity in the dentate gyrus. Importantly, blocking this exploration-elevated blood flow dampened experience-induced hippocampal neurogenesis. By imaging the neurovascular niche in combination with chemogenetic manipulation, we revealed that pre-existing DGCs actively regulated microvascular blood flow. This neurovascular coupling was linked by parvalbumin-expressing interneurons, primarily through nitric-oxide signaling. Further, we showed that insulin growth factor 1 signaling participated in functional hyperemia-induced neurogenesis. Together, our findings revealed a neurovascular coupling network that regulates experience-induced neurogenesis in the adult brain.

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Frontiers

In vivo calcium imaging reveals that cortisol treatment reduces the number of place cells in Thy1-GCaMP6f transgenic mice.

Tim Indersmitten, Michael J Schachter, Stephanie Young, Natalie Welty, Stephani Otte, Jonathan J Nassi, Timothy Lovenberg, Pascal Bonaventure, and Ryan M Wyatt
Frontiers in Neuroscience
March 1, 2019

The hippocampus, a structure essential for spatial navigation and memory undergoes anatomical and functional changes during chronic stress. Here, we investigate the effects of chronic stress on the ability of place cells to encode the neural representation of a linear track. To model physiological conditions of chronic stress on hippocampal function, transgenic mice expressing the genetically encoded calcium indicator GCaMP6f in CA1 pyramidal neurons were chronically administered with 40 mg/ml of cortisol for 8 weeks. Cortisol-treated mice exhibited symptoms typically observed during chronic stress, including diminished reward seeking behavior and reduced adrenal gland and spleen weights. In vivo imaging of hippocampal cellular activity during linear track running behavior revealed a reduced number of cells that could be recruited to encode spatial position, despite an unchanged overall number of active cells, in cortisol-treated mice. The properties of the remaining place cells that could be recruited to encode spatial information, however, was unperturbed. Bayesian decoders trained to estimate the mouse’s position on the track using single neuron activity data demonstrated reduced performance in a cue richness-dependent fashion in cortisol-treated animals. The performance of decoders utilizing data from the entire neuronal ensemble was unaffected by cortisol treatment. Finally, to test the hypothesis that an antidepressant drug could prevent the effects of cortisol, we orally administered a group of mice with 10 mg/kg citalopram during cortisol administration. Citalopram prevented the cortisol induced decrease in single-neuron decoder performance but failed to significantly prevent anhedonia and the cortisol-induced reduction in the proportion place cells. The dysfunction observed at the single-neuron level indicates that chronic stress may impair the ability of the hippocampus to encode individual neural representations of the mouse’s spatial position, a function pivotal to forming an accurate navigational map of the mouse’s external environment; however, the hippocampal ensemble as a whole is resilient to any cortisol-induced insults to single neuronal place cell function on the linear track.

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Nature Communications

Orchestrated ensemble activities constitute a hippocampal memory engram

Khaled Ghandour, Noriaki Ohkawa, Chi Chung Alan Fung, Hirotaka Asai, Yoshito Saitoh, Takashi Takekawa, Reiko Okubo-Suzuki, Shingo Soya, Hirofumi Nishizono, Mina Matsuo, Makoto Osanai, Masaaki Sato, Masamichi Ohkura, Junichi Nakai, Yasunori Hayashi, Takeshi Sakurai, Takashi Kitamura, Tomoki Fukai & Kaoru Inokuchi
Nature Communications
June 14, 2019

The brain stores and recalls memories through a set of neurons, termed engram cells. However, it is unclear how these cells are organized to constitute a corresponding memory trace. We established a unique imaging system that combines Ca2+ imaging and engram identification to extract the characteristics of engram activity by visualizing and discriminating between engram and non-engram cells. Here, we show that engram cells detected in the hippocampus display higher repetitive activity than non-engram cells during novel context learning. The total activity pattern of the engram cells during learning is stable across post-learning memory processing. Within a single engram population, we detected several sub-ensembles composed of neurons collectively activated during learning. Some sub-ensembles preferentially reappear during post-learning sleep, and these replayed sub-ensembles are more likely to be reactivated during retrieval. These results indicate that sub-ensembles represent distinct pieces of information, which are then orchestrated to constitute an entire memory.

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elife

Transitioning between preparatory and precisely sequenced neuronal activity in production of a skilled behavior

Vamsi K Daliparthi, Ryosuke O Tachibana, Brenton G Cooper, Richard HR Hahnloser, Satoshi Kojima, Samuel J Sober, Todd F Roberts
eLife
June 11, 2019

Precise neural sequences are associated with the production of well-learned skilled behaviors. Yet, how neural sequences arise in the brain remains unclear. In songbirds, premotor projection neurons in the cortical song nucleus HVC are necessary for producing learned song and exhibit precise sequential activity during singing. Using cell-type specific calcium imaging we identify populations of HVC premotor neurons associated with the beginning and ending of singing-related neural sequences. We characterize neurons that bookend singing-related sequences and neuronal populations that transition from sparse preparatory activity prior to song to precise neural sequences during singing. Recordings from downstream premotor neurons or the respiratory system suggest that pre-song activity may be involved in motor preparation to sing. These findings reveal population mechanisms associated with moving from non-vocal to vocal behavioral states and suggest that precise neural sequences begin and end as part of orchestrated activity across functionally diverse populations of cortical premotor neurons.

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Nature Communications

Engram-specific transcriptome profiling of contextual memory consolidation

Priyanka Rao-Ruiz, Jonathan J. Couey, Ivo M. Marcelo, Christian G. Bouwkamp, Denise E. Slump, Mariana R. Matos, Rolinka J. van der Loo, Gabriela J. Martins, Mirjam van den Hout, Wilfred F. van IJcken, Rui M. Costa, Michel C. van den Oever & Steven A. Kushner
Nature Communications
May 20, 2019

Sparse populations of neurons in the dentate gyrus (DG) of the hippocampus are causally implicated in the encoding of contextual fear memories. However, engram-specific molecular mechanisms underlying memory consolidation remain largely unknown. Here we perform unbiased RNA sequencing of DG engram neurons 24 h after contextual fear conditioning to identify transcriptome changes specific to memory consolidation. DG engram neurons exhibit a highly distinct pattern of gene expression, in which CREB-dependent transcription features prominently (P = 6.2 × 10−13), including Atf3 (P = 2.4 × 10−41), Penk(P = 1.3 × 10−15), and Kcnq3 (P = 3.1 × 10−12). Moreover, we validate the functional relevance of the RNAseq findings by establishing the causal requirement of intact CREB function specifically within the DG engram during memory consolidation, and identify a novel group of CREB target genes involved in the encoding of long-term memory.

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Neuron

Increased Cocaine Motivation Is Associated with Degraded Spatial and Temporal Representations in IL-NAc Neurons

Courtney M. Cameron, Malavika Murugan, Jung Yoon Choi, Esteban A. Engel, Ilana B. Witten
Neuron
May 14, 2019

Craving for cocaine progressively increases in cocaine users during drug-free periods, contributing to relapse. The projection from the infralimbic cortex to the nucleus accumbens shell (IL-NAc) is thought to inhibit cocaine seeking. However, it is not known whether and how IL-NAc neurons contribute to the increased motivation associated with a drug-free period. We first performed cellular resolution imaging of IL-NAc neurons in rats during a drug-seeking test. This revealed neurons with spatial selectivity within the cocaine-associated context, a decrease in activity around the time of cocaine seeking, and an inverse relationship between cocaine-seeking activity and subsequent cocaine motivation. All these properties were reduced by a drug-free period. Next, we transiently activated this projection, which resulted in reduced drug seeking, regardless of the drug-free period. Taken together, this suggests that altered IL-NAc activity after a drug-free period may enhance cocaine motivation without fundamentally altering the projection’s ability to inhibit drug seeking.

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Neuron

VIP interneurons contribute to avoidance behavior by regulating information flow across hippocampal-prefrontal networks

Anthony T. Lee, Margaret M. Cunniff, Jermyn Z. See, Scott A. WIlke, Francisco J. Luongo, Ian T. Ellwood, Srimadh Ponnavolu, and Vikaas S. Sohal
Neuron
April 30, 2019

Inhibitory interneurons expressing vasoactive intestinal polypeptide (VIP) are known to disinhibit cortical neurons. However, it is unclear how disinhibition, occurring at the single-cell level, interacts with network-level patterns of activity to shape complex behaviors. To address this, we examined the role of prefrontal VIP interneurons in a widely studied mouse behavior: deciding whether to explore or avoid the open arms of an elevated plus maze. VIP interneuron activity increases in the open arms and disinhibits prefrontal responses to hippocampal inputs which are known to transmit signals related to open arm avoidance. Indeed, inhibiting VIP interneurons disrupts network-level representations of the open arms and decreases open arm avoidance specifically when hippocampal-prefrontal theta synchrony is strong. Thus, VIP interneurons effectively gate the ability of hippocampal input to generate prefrontal representations, which drive avoidance behavior. This shows how VIP interneurons enable cortical circuits to integrate specific inputs into network-level representations that guide complex behaviors.

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JournalofNeuroscience

Dynamic network activation of hypothalamic MCH neurons in REM sleep and exploratory behavior

Carlos Blanco-Centurion, SiWei Luo, Daniel J. Spergel, Aurelio Vidal-Ortiz, Sorinel Oprisen, Anthony N. Van den Pol, Meng Liu and Priyattam J. Shiromani
J Neuroscience
April 29, 2019

Most brain neurons are active in waking, but hypothalamic neurons that synthesize the neuropeptide melanin-concentrating hormone (MCH) are claimed to be active only during sleep, particularly REM sleep. Here we use deep-brain imaging to identify changes in fluorescence of the genetically encoded calcium (Ca2+) indicator GCaMP6 in individual hypothalamic neurons that contain MCH. An in-vitro electrophysiology study determined a strong relationship between depolarization and Ca2+ fluorescence in MCH neurons. In ten freely-behaving MCH-cre mice (male and female), highest fluorescence occurred in all recorded neurons (n=106) in REM sleep relative to quiet waking or non-REM sleep. Unexpectedly, 70% of the MCH neurons had strong fluorescence activity when the mice explored novel objects. Spatial and temporal mapping of the change in fluorescence between pairs of MCH neurons revealed dynamic activation of MCH neurons during REM sleep and activation of a subset of the same neurons during exploratory behavior. Functional network activity maps will facilitate comparisons of not only single neuron activity but also network responses in different conditions and disease.

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Science

Amygdala ensembles encode behavioral states

Jan Gründemann, Yael Bitterman, Tingjia Lu, Sabine Krabbe, Benjamin F. Grewe, Mark J. Schnitzer, Andreas Lüthi
Science
April 19, 2019

Internal states, including affective or homeostatic states, are important behavioral motivators. The amygdala regulates motivated behaviors, yet how distinct states are represented in amygdala circuits is unknown. By longitudinally imaging neural calcium dynamics in freely moving mice across different environments, we identified opponent changes in activity levels of two major, nonoverlapping populations of basal amygdala principal neurons. This population signature does not report global anxiety but predicts switches between exploratory and nonexploratory, defensive states. Moreover, the amygdala separately processes external stimuli and internal states and broadcasts state information via several output pathways to larger brain networks. Our findings extend the concept of thalamocortical “brain-state” coding to include affective and exploratory states and provide an entry point into the state dependency of brain function and behavior in defined circuits.

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Nature

A gut-to-brain signal of fluid osmolarity controls thirst satiation

Christopher A. Zimmerman, Erica L. Huey, Jamie S. Ahn, Lisa R. Beutler, Chan Lek Tan, Seher Kosar, Ling Bai, Yiming Chen, Timothy V. Corpuz, Linda Madisen, Hongkui Zeng & Zachary A. Knight
Nature
March 27, 2019

Satiation is the process by which eating and drinking reduce appetite. For thirst, oropharyngeal cues have a critical role in driving satiation by reporting to the brain the volume of fluid that has been ingested1,2,3,4,5,6,7,8,9,10,11,12. By contrast, the mechanisms that relay the osmolarity of ingested fluids remain poorly understood. Here we show that the water and salt content of the gastrointestinal tract are precisely measured and then rapidly communicated to the brain to control drinking behaviour in mice. We demonstrate that this osmosensory signal is necessary and sufficient for satiation during normal drinking, involves the vagus nerve and is transmitted to key forebrain neurons that control thirst and vasopressin secretion. Using microendoscopic imaging, we show that individual neurons compute homeostatic need by integrating this gastrointestinal osmosensory information with oropharyngeal and blood-borne signals. These findings reveal how the fluid homeostasis system monitors the osmolarity of ingested fluids to dynamically control drinking behaviour.

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elife

Cholinergic modulation of hippocampal calcium activity across the sleep-wake cycle

Heng Zhou, Kevin R Neville, Nitsan Goldstein, Shushi Kabu, Naila Kausar, Rong Ye, Thuan Tinh Nguyen, Noah Gelwan, Bradley T Hyman, Stephen N Gomperts
eLife
March 7th, 2019

Calcium is a critical second messenger in neurons that contributes to learning and memory, but how the coordination of action potentials of neuronal ensembles with the hippocampal local field potential (LFP) is reflected in dynamic calcium activity remains unclear. Here, we recorded hippocampal calcium activity with endoscopic imaging of the genetically encoded fluorophore GCaMP6 with concomitant LFP in freely behaving mice. Dynamic calcium activity was greater in exploratory behavior and REM sleep than in quiet wakefulness and slow wave sleep, behavioral states that differ with respect to theta and septal cholinergic activity, and modulated at sharp wave ripples (SWRs). Chemogenetic activation of septal cholinergic neurons expressing the excitatory hM3Dq DREADD increased calcium activity and reduced SWRs. Furthermore, inhibition of muscarinic acetylcholine receptors (mAChRs) reduced calcium activity while increasing SWRs. These results demonstrate that hippocampal dynamic calcium activity depends on behavioral and theta state as well as endogenous mAChR activation.

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Nature Neuro

Divergent medial amygdala projections regulate approach–avoidance conflict behavior

Samara M. Miller, Daniele Marcotulli, Angela Shen & Larry S. Zweifel
Nature Neuroscience
February 25th, 2019

Avoidance of innate threats is often in conflict with motivations to engage in exploratory approach behavior. The neural pathways that mediate this approach–avoidance conflict are not well resolved. Here we isolated a population of dopamine D1 receptor (D1R)-expressing neurons within the posteroventral region of the medial amygdala (MeApv) in mice that are activated either during approach or during avoidance of an innate threat stimulus. Distinct subpopulations of MeApv-D1R neurons differentially innervate the ventromedial hypothalamus and bed nucleus of the stria terminalis, and these projections have opposing effects on investigation or avoidance of threatening stimuli. These projections are potently modulated through opposite actions of D1R signaling that bias approach behavior. These data demonstrate divergent pathways in the MeApv that can be differentially weighted toward exploration or evasion of threats.

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Molecular Psychiatry in circle

A hypothalamus-habenula circuit controls aversion

Iakovos Lazaridis, Ourania Tzortzi, Moritz Weglage, Antje Märtin, Yang Xuan, Marc Parent, Yvonne Johansson, Janos Fuzik, Daniel Fürth, Lief E. Fenno, Charu Ramakrishnan, Gilad Silberberg, Karl Deisseroth, Marie Carlén & Konstantinos Meletis
Molecular Psychiatry
February 12th, 2019

Encoding and predicting aversive events are critical functions of circuits that support survival and emotional well-being. Maladaptive circuit changes in emotional valence processing can underlie the pathophysiology of affective disorders. The lateral habenula (LHb) has been linked to aversion and mood regulation through modulation of the dopamine and serotonin systems. We have defined the identity and function of glutamatergic (Vglut2) control of the LHb, comparing the role of inputs originating in the globus pallidus internal segment (GPi), and lateral hypothalamic area (LHA), respectively. We found that LHb-projecting LHA neurons, and not the proposed GABA/glutamate co-releasing GPi neurons, are responsible for encoding negative value. Monosynaptic rabies tracing of the presynaptic organization revealed a predominantly limbic input onto LHA Vglut2 neurons, while sensorimotor inputs were more prominent onto GABA/glutamate co-releasing GPi neurons. We further recorded the activity of LHA Vglut2 neurons, by imaging calcium dynamics in response to appetitive versus aversive events in conditioning paradigms. LHA Vglut2 neurons formed activity clusters representing distinct reward or aversion signals, including a population that responded to mild foot shocks and predicted aversive events. We found that the LHb-projecting LHA Vglut2 neurons encode negative valence and rapidly develop a prediction signal for negative events. These findings establish the glutamatergic LHA-LHb circuit as a critical node in value processing.

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elife

Unsupervised discovery of temporal sequences in high-dimensional datasets, with applications to neuroscience

Emily L Mackevicius, Andrew H Bahle, Alex H Williams, Shijie Gu, Natalia I Denisenko, Mark S Goldman , Michale S Fee
eLife
February 5th, 2019

Identifying low-dimensional features that describe large-scale neural recordings is a major challenge in neuroscience. Repeated temporal patterns (sequences) are thought to be a salient feature of neural dynamics, but are not succinctly captured by traditional dimensionality reduction techniques. Here, we describe a software toolbox—called seqNMF—with new methods for extracting informative, non-redundant, sequences from high-dimensional neural data, testing the significance of these extracted patterns, and assessing the prevalence of sequential structure in data. We test these methods on simulated data under multiple noise conditions, and on several real neural and behavioral data sets. In hippocampal data, seqNMF identifies neural sequences that match those calculated manually by reference to behavioral events. In songbird data, seqNMF discovers neural sequences in untutored birds that lack stereotyped songs. Thus, by identifying temporal structure directly from neural data, seqNMF enables dissection of complex neural circuits without relying on temporal references from stimuli or behavioral outputs.

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Nature Neuro

Dorsolateral septum somatostatin interneurons gate mobility to calibrate context-specific behavioral fear responses

Antoine Besnard, Yuan Gao, Michael TaeWoo Kim, Hannah Twarkowski, Alexander Keith Reed, Tomer Langberg, Wendy Feng, Xiangmin Xu, Dieter Saur, Larry S. Zweifel, Ian Davison & Amar Sahay
Nature Neuroscience
February 4th, 2019

Adaptive fear responses to external threats rely upon efficient relay of computations underlying contextual encoding to subcortical circuits. Brain-wide analysis of highly coactivated ensembles following contextual fear discrimination identified the dorsolateral septum (DLS) as a relay of the dentate gyrus–CA3 circuit. Retrograde monosynaptic tracing and electrophysiological whole-cell recordings demonstrated that DLS somatostatin-expressing interneurons (SST-INs) receive direct CA3 inputs. Longitudinal in vivo calcium imaging of DLS SST-INs in awake, behaving mice identified a stable population of footshock-responsive SST-INs during contextual conditioning whose activity tracked and predicted non-freezing epochs during subsequent recall in the training context but not in a similar, neutral context or open field. Optogenetic attenuation or stimulation of DLS SST-INs bidirectionally modulated conditioned fear responses and recruited proximal and distal subcortical targets. Together, these observations suggest a role for a potentially hard-wired DLS SST-IN subpopulation as arbiters of mobility that calibrate context-appropriate behavioral fear responses.

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Intense threat switches dorsal raphe serotonin neurons to a paradoxical operational mode

Changwoo Seo, Akash Guru, Michelle Jin, Brendan Ito, Brianna J. Sleezer, Yi-Yun Ho, Elias Wang, Christina Boada, Nicholas A. Krupa, Durgaprasad S. Kullakanda, Cynthia X. Shen, Melissa R. Warden
Science
January 31st, 2019

Survival depends on the selection of behaviors adaptive for the current environment. For example, a mouse should run from a rapidly looming hawk but should freeze if the hawk is coasting across the sky. Although serotonin has been implicated in adaptive behavior, environmental regulation of its functional role remains poorly understood. In mice, we found that stimulation of dorsal raphe serotonin neurons suppressed movement in low- and moderate-threat environments but induced escape behavior in high-threat environments, and that movement-related dorsal raphe serotonin neural dynamics inverted in high-threat environments. Stimulation of dorsal raphe γ-aminobutyric acid (GABA) neurons promoted movement in negative but not positive environments, and movement-related GABA neural dynamics inverted between positive and negative environments. Thus, dorsal raphe circuits switch between distinct operational modes to promote environment-specific adaptive behaviors.

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An amygdalar neural ensemble that encodes the unpleasantness of pain

Gregory Corder, Biafra Ahanonu, Benjamin F. Grewe, Dong Wang, Mark J. Schnitzer, Grégory Scherrer
Science
January 17th, 2019

Pain is an unpleasant experience. How the brain’s affective neural circuits attribute this aversive quality to nociceptive information remains unknown. By means of time-lapse in vivo calcium imaging and neural activity manipulation in freely behaving mice encountering noxious stimuli, we identified a distinct neural ensemble in the basolateral amygdala that encodes the negative affective valence of pain. Silencing this nociceptive ensemble alleviated pain affective-motivational behaviors without altering the detection of noxious stimuli, withdrawal reflexes, anxiety, or reward. Following peripheral nerve injury, innocuous stimuli activated this nociceptive ensemble to drive dysfunctional perceptual changes associated with neuropathic pain, including pain aversion to light touch (allodynia). These results identify the amygdalar representations of noxious stimuli that are functionally required for the negative affective qualities of acute and chronic pain perception.

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GABA and glutamate neurons in the VTA regulate sleep and wakefulness

Xiao Yu, Wen Li, Ying Ma, Kyoko Tossell, Julia J. Harris, Edward C. Harding, Wei Ba, Giulia Miracca, Dan Wang, Long Li, Juan Guo, Ming Chen, Yuqi Li, Raquel Yustos, Alexei L. Vyssotski, Denis Burdakov, Qianzi Yang, Hailong Dong, Nicholas P. Franks & William Wisden
Nature Neuroscience
December 17th, 2018

We screened for novel circuits in the mouse brain that promote wakefulness. Chemogenetic activation experiments and electroencephalogram recordings pointed to glutamatergic/nitrergic (NOS1) and GABAergic neurons in the ventral tegmental area (VTA). Activating glutamatergic/NOS1 neurons, which were wake- and rapid eye movement (REM) sleep-active, produced wakefulness through projections to the nucleus accumbens and the lateral hypothalamus. Lesioning the glutamate cells impaired the consolidation of wakefulness. By contrast, activation of GABAergic VTA neurons elicited long-lasting non-rapid-eye-movement-like sleep resembling sedation. Lesioning these neurons produced an increase in wakefulness that persisted for at least 4 months. Surprisingly, these VTA GABAergic neurons were wake- and REM sleep-active. We suggest that GABAergic VTA neurons may limit wakefulness by inhibiting the arousal-promoting VTA glutamatergic and/or dopaminergic neurons and through projections to the lateral hypothalamus. Thus, in addition to its contribution to goal- and reward-directed behaviors, the VTA has a role in regulating sleep and wakefulness.

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eneurocircle

Activity Patterns in the Neuropil of Striatal Cholinergic Interneurons in Freely Moving Mice Represent Their Collective Spiking Dynamics

Rotem Rehani, Yara Atamna, Lior Tiroshi, Wei-Hua Chiu, José de Jesús Aceves Buendía, Gabriela J. Martins, Gilad A. Jacobson and Joshua A. Goldberg
eNeuro
January 4th, 2019

Cholinergic interneurons (CINs) are believed to form synchronous cell assemblies that modulate the striatal microcircuitry and possibly orchestrate local dopamine release. We expressed GCaMP6s, a genetically encoded calcium indicator (GECIs), selectively in CINs, and used microendoscopes to visualize the putative CIN assemblies in the dorsal striatum of freely moving mice. The GECI fluorescence signal from the dorsal striatum was composed of signals from individual CIN somata that were engulfed by a widespread fluorescent neuropil. Bouts of synchronous activation of the cholinergic neuropil revealed patterns of activity that preceded the signal from individual somata. To investigate the nature of the neuropil signal and why it precedes the somatic signal, we target-patched GECI-expressing CINs in acute striatal slices in conjunction with multiphoton imaging or wide-field imaging that emulates the microendoscopes’ specifications. The ability to detect fluorescent transients associated with individual action potential was constrained by the long decay constant of GECIs (relative to common inorganic dyes) to slowly firing (<2 spikes/s) CINs. The microendoscopes’ resolving power and sampling rate further diminished this ability. Additionally, we found that only back-propagating action potentials but not synchronous optogenetic activation of thalamic inputs elicited observable calcium transients in CIN dendrites. Our data suggest that only bursts of CIN activity (but not their tonic firing) are visible using endoscopic imaging, and that the neuropil patterns are a physiological measure of the collective recurrent CIN network spiking activity.

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Nature Communications

Population coding of valence in the basolateralamygdala

Xian Zhang & Bo Li
Nature Communications
December 5th, 2018

The basolateral amygdala (BLA) plays important roles in associative learning, by representing conditioned stimuli (CSs) and unconditioned stimuli (USs), and by forming associations between CSs and USs. However, how such associations are formed and updated remains unclear. Here we show that associative learning driven by reward and punishment profoundly alters BLA population responses, reducing noise correlations and transforming the representations of CSs to resemble the valence-specific representations of USs. This transformation is accompanied by the emergence of prevalent inhibitory CS and US responses, and by the plasticity of CS responses in individual BLA neurons. During reversal learning wherein the expected valences are reversed, BLA population CS representations are remapped onto ensembles representing the opposite valences and predict the switching in valence-specific behaviors. Our results reveal how signals predictive of opposing valences in the BLA evolve during learning, and how these signals are updated during reversal learning thereby guiding flexible behaviors.

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Dopamine enhances signal-to-noise ratio in cortical-brainstem encoding of aversive stimuli

Caitlin M. Vander Weele, Cody A. Siciliano, Gillian A. Matthews, Praneeth Namburi, Ehsan M. Izadmehr, Isabella C. Espinel, Edward H. Nieh, Evelien H. S. Schut, Nancy Padilla-Coreano, Anthony Burgos-Robles, Chia-Jung Chang, Eyal Y. Kimchi, Anna Beyeler, Romy Wichmann, Craig P. Wildes & Kay M. Tye
Nature
November 7th, 2018

Dopamine modulates medial prefrontal cortex (mPFC) activity to mediate diverse behavioural functions1,2; however, the precise circuit computations remain unknown. One potentially unifying model by which dopamine may underlie a diversity of functions is by modulating the signal-to-noise ratio in subpopulations of mPFC neurons3,4,5,6, where neural activity conveying sensory information (signal) is amplified relative to spontaneous firing (noise). Here we demonstrate that dopamine increases the signal-to-noise ratio of responses to aversive stimuli in mPFC neurons projecting to the dorsal periaqueductal grey (dPAG). Using an electrochemical approach, we reveal the precise time course of pinch-evoked dopamine release in the mPFC, and show that mPFC dopamine biases behavioural responses to aversive stimuli. Activation of mPFC–dPAG neurons is sufficient to drive place avoidance and defensive behaviours. mPFC–dPAG neurons display robust shock-induced excitations, as visualized by single-cell, projection-defined microendoscopic calcium imaging. Finally, photostimulation of dopamine terminals in the mPFC reveals an increase in the signal-to-noise ratio in mPFC–dPAG responses to aversive stimuli. Together, these data highlight how dopamine in the mPFC can selectively route sensory information to specific downstream circuits, representing a potential circuit mechanism for valence processing.

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Hippocampal Place Fields Maintain a Coherent and Flexible Map across Long Timescales

Nathaniel R. Kinsky, David W. Sullivan, William Mau, Michael E. Hasselmo, Howard B. Eichenbaum
Current Biology
November 1st, 2018

To provide a substrate for remembering where in space events have occurred, place cells must reliably encode the same positions across long timescales. However, in many cases, place cells exhibit instability by randomly reorganizing their place fields between experiences, challenging this premise. Recent evidence suggests that, in some cases, instability could also arise from coherent rotations of place fields, as well as from random reorganization. To investigate this possibility, we performed in vivo calcium imaging in dorsal hippocampal region CA1 of freely moving mice while they explored two arenas with different geometry and visual cues across 8 days. The two arenas were rotated randomly between sessions and then connected, allowing us to probe how cue rotations, the integration of new information about the environment, and the passage of time concurrently influenced the spatial coherence of place fields. We found that spatially coherent rotations of place-field maps in the same arena predominated, persisting up to 6 days later, and that they frequently rotated in a manner that did not match that of the arena rotation. Furthermore, place-field maps were flexible, as mice frequently employed a similar, coherent configuration of place fields to represent each arena despite their differing geometry and eventual connection. These results highlight the ability of the hippocampus to retain consistent relationships between cells across long timescales and suggest that, in many cases, apparent instability might result from a coherent rotation of place fields.

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Parabrachial CGRP Neurons Establish and Sustain Aversive Taste Memories

Jane Y. Chen, Carlos A. Campos, Brooke C. Jarvie, Richard D. Palmiter
Neuron
October 18th, 2018

Food aversions develop when the taste of a novel food is associated with sickness, which often occurs after food poisoning or chemotherapy treatment. We identified calcitonin-gene-related peptide (CGRP) neurons in the parabrachial nucleus (PBN) as sufficient and necessary for establishing a conditioned taste aversion (CTA). Photoactivating projections from CGRPPBN neurons to either the central nucleus of the amygdala or the bed nucleus of the stria terminalis can also induce robust CTA. CGRPPBN neurons undergo plasticity following CTA, and inactivation of either Arc or Grin1 (genes involved in memory consolidation) prevents establishment of a strong CTA. Calcium imaging reveals that the novel food re-activates CGRPPBN neurons after conditioning. Inhibition of these neurons or inactivation of the Grin1 gene after conditioning attenuates CTA expression. Our results indicate that CGRPPBN neurons not only play a key role for learning food aversions but also contribute to the maintenance and expression of those memories.

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Touch and Tactile Neuropathic Pain Sensitivity Are Set by Corticospinal Projections

Yuanyuan Liu, Alban Latremoliere, Xinjian Li, Zicong Zhang, Mengying Chen, Xuhua Wang, Chao Fang, Junjie Zhu, Chloe Alexandre, Zhongyang Gao, Bo Chen, Xin Ding, Jin-Yong Zhou, Yiming Zhang, Chinfei Chen, Kuan Hong Wang, Clifford J. Woolf & Zhigang He
Nature
September 12th, 2018

Current models of somatosensory perception emphasize transmission from primary sensory neurons to the spinal cord and on to the brain1,2,3,4. Mental influence on perception is largely assumed to occur locally within the brain. Here we investigate whether sensory inflow through the spinal cord undergoes direct top-down control by the cortex. Although the corticospinal tract (CST) is traditionally viewed as a primary motor pathway5, a subset of corticospinal neurons (CSNs) originating in the primary and secondary somatosensory cortex directly innervate the spinal dorsal horn via CST axons. Either reduction in somatosensory CSN activity or transection of the CST in mice selectively impairs behavioural responses to light touch without altering responses to noxious stimuli. Moreover, such CSN manipulation greatly attenuates tactile allodynia in a model of peripheral neuropathic pain. Tactile stimulation activates somatosensory CSNs, and their corticospinal projections facilitate light-touch-evoked activity of cholecystokinin interneurons in the deep dorsal horn. This touch-driven feed-forward spinal–cortical–spinal sensitization loop is important for the recruitment of spinal nociceptive neurons under tactile allodynia. These results reveal direct cortical modulation of normal and pathological tactile sensory processing in the spinal cord and open up opportunities for new treatments for neuropathic pain.

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Calcium Transient Dynamics of Neural Ensembles in the Primary Motor Cortex of Naturally Behaving Monkeys

Takahiro Kondo, Risa Saito, Masaki Otaka, Kimika Yoshino-Saito, Akihiro Yamanaka, Kenji F. Tanaka, Junichi Ushiba, Hideyuki Okano
Cell Reports
August 21st, 2018

To understand brain circuits of cognitive behaviors under natural conditions, we developed techniques for imaging neuronal activities from large neuronal populations in the deep layer cortex of the naturally behaving common marmoset. Animals retrieved food pellets or climbed ladders as a miniature fluorescence microscope monitored hundreds of calcium indicator-expressing cortical neurons in the right primary motor cortex. This technique, which can be adapted to other brain regions, can deepen our understanding of brain circuits by facilitating longitudinal population analyses of neuronal representation associated with cognitive naturalistic behaviors and their pathophysiological processes.

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Simultaneous Optogenetics and Cellular Resolution Calcium Imaging During Active Behavior Using a Miniaturized Microscope

Alice M. Stamatakis, Mike J. Schachter, Srishti Gulati, Kevin T. Zitelli, Sam Malanowski, Arash Tajik, Christopher Fritz, Mark Trulson and Stephani L. Otte
Frontiers in Neuroscience
July 24th, 2018

The ability to precisely monitor and manipulate neural circuits is essential to understand the brain. Advancements over the last decade in optical techniques such as calcium imaging and optogenetics have empowered researchers to gain insight into brain function by systematically manipulating or monitoring defined neural circuits. Combining these cutting-edge techniques enables a more direct mechanism for ascribing neural dynamics to behavior. Here, we developed a miniaturized integrated microscope that allows for simultaneous optogenetic manipulation and cellular-resolution calcium imaging within the same field of view in freely behaving mice. The integrated microscope has two LEDs, one filtered with a 435–460 nm excitation filter for imaging green calcium indicators, and a second LED filtered with a 590–650 nm excitation filter for optogenetic modulation of red-shifted opsins. We developed and tested this technology to minimize biological and optical crosstalk. We observed insignificant amounts of biological and optical crosstalk with regards to the optogenetic LED affecting calcium imaging. We observed some amounts of residual crosstalk of the imaging light on optogenetic manipulation. Despite residual crosstalk, we have demonstrated the utility of this technology by probing the causal relationship between basolateral amygdala (BLA) -to- nucleus accumbens (NAc) circuit function, behavior, and network dynamics. Using this integrated microscope we were able to observe both a significant behavioral and cellular calcium response of the optogenetic modulation on the BLA-to-NAc circuit. This integrated strategy will allow for routine investigation of the causality of circuit manipulation on cellular-resolution network dynamics and behavior.

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Dorsal tegmental dopamine neurons gate associative learning of fear

Florian Groessl, Thomas Munsch, Susanne Meis, Johannes Griessner, Joanna Kaczanowska, Pinelopi Pliota, Dominic Kargl, Sylvia Badurek, Klaus Kraitsy, Arash Rassoulpour, Johannes Zuber, Volkmar Lessmann & Wulf Haubensak
Nature Neuroscience
June 27, 2018

Functional neuroanatomy of Pavlovian fear has identified neuronal circuits and synapses associating conditioned stimuli with aversive events. Hebbian plasticity within these networks requires additional reinforcement to store particularly salient experiences into long-term memory. Here we have identified a circuit that reciprocally connects the ventral periaqueductal gray and dorsal raphe region with the central amygdala and that gates fear learning. We found that ventral periaqueductal gray and dorsal raphe dopaminergic (vPdRD) neurons encode a positive prediction error in response to unpredicted shocks and may reshape intra-amygdala connectivity via a dopamine-dependent form of long-term potentiation. Negative feedback from the central amygdala to vPdRD neurons might limit reinforcement to events that have not been predicted. These findings add a new module to the midbrain dopaminergic circuit architecture underlying associative reinforcement learning and identify vPdRD neurons as a critical component of Pavlovian fear conditioning. We propose that dysregulation of vPdRD neuronal activity may contribute to fear-related psychiatric disorders.

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Hippocampal neurogenesis confers stress resilience by inhibiting the ventral dentate gyrus

Christoph Anacker, Victor M. Luna, Gregory S. Stevens, Amira Millette, Ryan Shores, Jessica C. Jimenez, Briana Chen & René Hen
Nature
June 27, 2018

Adult neurogenesis in the dentate gyrus of the hippocampus is highly regulated by environmental influences, and functionally implicated in behavioural responses to stress and antidepressants1,2,3,4. However, how adult-born neurons regulate dentate gyrus information processing to protect from stress-induced anxiety-like behaviour is unknown. Here we show in mice that neurogenesis confers resilience to chronic stress by inhibiting the activity of mature granule cells in the ventral dentate gyrus (vDG), a subregion that is implicated in mood regulation. We found that chemogenetic inhibition of adult-born neurons in the vDG promotes susceptibility to social defeat stress, whereas increasing neurogenesis confers resilience to chronic stress. By using in vivo calcium imaging to record neuronal activity from large cell populations in the vDG, we show that increased neurogenesis results in a decrease in the activity of stress-responsive cells that are active preferentially during attacks or while mice explore anxiogenic environments. These effects on dentate gyrus activity are necessary and sufficient for stress resilience, as direct silencing of the vDG confers resilience whereas excitation promotes susceptibility. Our results suggest that the activity of the vDG may be a key factor in determining individual levels of vulnerability to stress and related psychiatric disorders.

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The Striatum Organizes 3D Behavior via Moment-to-Moment Action Selection

Jeffrey E. Markowitz, Winthrop F. Gillis, Celia C. Beron, Shay Q. Neufeld, Keiramarie Robertson, Neha D. Bhagat, Ralph E. Peterson, Emalee Peterson, Minsuk Hyun, Scott W. Linderman, Bernardo L. Sabatini, Sandeep Robert Datta
Cell
May 17th, 2018

Many naturalistic behaviors are built from modular components that are expressed sequentially. Although striatal circuits have been implicated in action selection and implementation, the neural mechanisms that compose behavior in unrestrained animals are not well understood. Here, we record bulk and cellular neural activity in the direct and indirect pathways of dorsolateral striatum (DLS) as mice spontaneously express action sequences. These experiments reveal that DLS neurons systematically encode information about the identity and ordering of sub-second 3D behavioral motifs; this encoding is facilitated by fast-timescale decorrelations between the direct and indirect pathways. Furthermore, lesioning the DLS prevents appropriate sequence assembly during exploratory or odor-evoked behaviors. By characterizing naturalistic behavior at neural timescales, these experiments identify a code for elemental 3D pose dynamics built from complementary pathway dynamics, support a role for DLS in constructing meaningful behavioral sequences, and suggest models for how actions are sculpted over time.

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Diametric neural ensemble dynamics in parkinsonian and dyskinetic states

Jones G. Parker, Jesse D. Marshall, Biafra Ahanonu, Yu-Wei Wu, Tony Hyun Kim, Benjamin F. Grewe, Yanping Zhang, Jin Zhong Li, Jun B. Ding, Michael D. Ehlers & Mark J. Schnitzer
Nature
May 02nd, 2018

Loss of dopamine in Parkinson's disease is hypothesized to impede movement by inducing hypo- and hyperactivity in striatal spiny projection neurons (SPNs) of the direct (dSPNs) and indirect (iSPNs) pathways in the basal ganglia, respectively. The opposite imbalance might underlie hyperkinetic abnormalities, such as dyskinesia caused by treatment of Parkinson’s disease with the dopamine precursor L-DOPA. Here we monitored thousands of SPNs in behaving mice, before and after dopamine depletion and during L-DOPA-induced dyskinesia. Normally, intermingled clusters of dSPNs and iSPNs coactivated before movement. Dopamine depletion unbalanced SPN activity rates and disrupted the movement-encoding iSPN clusters. Matching their clinical efficacy, L-DOPA or agonism of the D2 dopamine receptor reversed these abnormalities more effectively than agonism of the D1dopamine receptor. The opposite pathophysiology arose in L-DOPA-induced dyskinesia, during which iSPNs showed hypoactivity and dSPNs showed unclustered hyperactivity. Therefore, both the spatiotemporal profiles and rates of SPN activity appear crucial to striatal function, and next-generation treatments for basal ganglia disorders should target both facets of striatal activity.

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The Same Hippocampal CA1 Population Simultaneously Codes Temporal Information over Multiple Timescales

William Mau, David W. Sullivan, Nathaniel R. Kinsky, Michael E. Hasselmo, Marc W. Howard, Howard Eichenbaum
Current Biology
April 26th, 2018

It has long been hypothesized that a primary function of the hippocampus is to discover and exploit temporal relationships between events. Previously, it has been reported that sequences of “time cells” in the hippocampus extend for tens of seconds. Other studies have shown that neuronal firing in the hippocampus fluctuates over hours and days. Both of these mechanisms could enable temporal encoding of events over very different timescales. However, thus far, these two classes of phenomena have never been observed simultaneously, which is necessary to ascribe broad-range temporal coding to the hippocampus. Using in vivo calcium imaging in unrestrained mice, we observed sequences of hippocampal neurons that bridged a 10 s delay. Similar sequences were observed over multiple days, but the set of neurons participating in those sequences changed gradually. Thus, the same population of neurons that encodes temporal information over seconds can also be used to distinguish periods of time over much longer timescales. These results unify two previously separate paradigms of temporal processing in the hippocampus that support episodic memory.

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Neural Circuit Mechanisms of Social Behavior

Patrick Chen, Weizhe Hong
Neuron
April 4th, 2018

We live in a world that is largely socially constructed, and we are constantly involved in and fundamentally influenced by a broad array of complex social interactions. Social behaviors among conspecifics, either conflictive or cooperative, are exhibited by all sexually reproducing animal species and are essential for the health, survival, and reproduction of animals. Conversely, impairment in social function is a prominent feature of several neuropsychiatric disorders, such as autism spectrum disorders and schizophrenia. Despite the importance of social behaviors, many fundamental questions remain unanswered. How is social sensory information processed and integrated in the nervous system? How are different social behavioral decisions selected and modulated in brain circuits? Here we discuss conceptual issues and recent advances in our understanding of brain regions and neural circuit mechanisms underlying the regulation of social behaviors.

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Encoding of Danger by Parabrachial CGRP Neurons

Carlos A. Campos, Anna J. Bowen, Carolyn W. Roman & Richard D. Palmiter
Nature
March 21st, 2018

Animals must respond to various threats to survive. Neurons that express calcitonin gene-related peptide in the parabrachial nucleus (CGRPPBN neurons) relay sensory signals that contribute to satiation and pain-induced fear behaviour, but it is unclear how they encode these distinct processes. Here, by recording calcium transients in vivo from individual neurons in mice, we show that most CGRPPBN neurons are activated by noxious cutaneous (shock, heat, itch) and visceral stimuli (lipopolysaccharide). The same neurons are inhibited during feeding, but become activated during satiation, consistent with evidence that CGRPPBN neurons prevent overeating. CGRPPBN neurons are also activated during consumption of novel foods or by an auditory cue that has previously been paired with electrical footshocks. Correspondingly, silencing of CGRPPBN neurons attenuates the expression of food neophobia and conditioned fear responses. Therefore, in addition to transducing primary sensory danger signals, CGRPPBN neurons promote affective-behavioural states that limit harm in response to potential threats.

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Cell Reports

Silk Fibroin Films Facilitate Single-Step Targeted Expression of Optogenetic Proteins

Skyler L. Jackman, Christopher H. Chen, Selmaan N.Chettih, Shay Q.Neufeld, Iain R.Drew, Chimuanya K.Agba, Isabella Flaquer, Alexis N.Stefano, Thomas J.Kennedy, Justine E.Belinsky, Keira marie Roberston, Celia C.Beron, Bernardo L.Sabatini, Christopher D.Harvey, Wade G.Regehr
Cell Reports
March 20th, 2018

Optical methods of interrogating neural circuits have emerged as powerful tools for understanding how the brain drives behaviors. Optogenetic proteins are widely used to control neuronal activity, while genetically encoded fluorescent reporters are used to monitor activity. These proteins are often expressed by injecting viruses, which frequently leads to inconsistent experiments due to misalignment of expression and optical components. Here, we describe how silk fibroin films simplify optogenetic experiments by providing targeted delivery of viruses. Films composed of silk fibroin and virus are applied to the surface of implantable optical components. After surgery, silk releases the virus to transduce nearby cells and provide localized expression around optical fibers and endoscopes. Silk films can also be used to express genetically encoded sensors in large cortical regions by using cranial windows coated with a silk/virus mixture. The ease of use and improved performance provided by silk make this a promising approach for optogenetic studies.

 
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Efficient and accurate extraction of in vivo calcium signals from microendoscopic video data

Pengcheng Zhou, Shanna L Resendez, Jose Rodriguez-Romaguera, Jessica C Jimenez, Shay Q Neufeld, Andrea Giovannucci, Johannes Friedrich, Eftychios A Pnevmatikakis, Garret D Stuber, Rene Hen, Mazen A Kheirbek, Bernardo L Sabatini, Robert E Kass, Liam Paninski
eLife
February 22, 2018

In vivo calcium imaging through microendoscopic lenses enables imaging of previously inaccessible neuronal populations deep within the brains of freely moving animals. However, it is computationally challenging to extract single-neuronal activity from microendoscopic data, because of the very large background fluctuations and high spatial overlaps intrinsic to this recording modality. Here, we describe a new constrained matrix factorization approach to accurately separate the background and then demix and denoise the neuronal signals of interest. We compared the proposed method against previous independent components analysis and constrained nonnegative matrix factorization approaches. On both simulated and experimental data recorded from mice, our method substantially improved the quality of extracted cellular signals and detected more well-isolated neural signals, especially in noisy data regimes. These advances can in turn significantly enhance the statistical power of downstream analyses, and ultimately improve scientific conclusions derived from microendoscopic data.

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A Hypothalamic Switch for REM and Non-REM Sleep

Kai-Siang Chen, Min Xu, Zhe Zhang, Wei-Cheng Chang, Thomas Gaj, David V. Schaffer, Yang Dan
Neuron
February 22, 2018

Rapid eye movement (REM) and non-REM (NREM) sleep are controlled by specific neuronal circuits. Here we show that galanin-expressing GABAergic neurons in the dorsomedial hypothalamus (DMH) comprise separate subpopulations with opposing effects on REM versus NREM sleep. Microendoscopic calcium imaging revealed diverse sleep-wake activity of DMH GABAergic neurons, but the galanin-expressing subset falls into two distinct groups, either selectively activated (REM-on) or suppressed (REM-off) during REM sleep. Retrogradely labeled, preoptic area (POA)-projecting galaninergic neurons are REM-off, whereas the raphe pallidus (RPA)-projecting neurons are primarily REM-on. Bidirectional optogenetic manipulations showed that the POA-projecting neurons promote NREM sleep and suppress REM sleep, while the RPA-projecting neurons have the opposite effects. Thus, REM/NREM switch is regulated antagonistically by DMH galaninergic neurons with intermingled cell bodies but distinct axon projections.

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Genetically encoded calcium indicator with NTnC-like design and enhanced fluorescence contrast and kinetics

D. A. Doronin,N. V. Barykina†,O. M. Subach,V. P. Sotskov,V. V. Plusnin,O. A. Ivleva,E. A. Isaakova,A. M. Varizhuk,G. E. Pozmogova,A. Y. Malyshev,I. V. Smirnov,K. D. Piatkevich,K. V. Anokhin,G. N. Enikolopov and F. V. Subach
BMC Biotechnology
February 13th, 2018

We demonstrate that expanding the family of NTnC-like calcium indicators is a promising strategy for the development of the next generation of GECIs with smaller molecule size and lower Ca2+ ions buffering capacity as compared with commonly used GECIs.

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Fast-Spiking Interneurons Supply Feedforward Control of Bursting, Calcium, and Plasticity for Efficient Learning

Scott F. Owen, Joshua D. Berke, Anatol C. Kreitzer
Cell
February 8th, 2018

Fast-spiking interneurons (FSIs) are a prominent class of forebrain GABAergic cells implicated in two seemingly independent network functions: gain control and network plasticity. Little is known, however, about how these roles interact. Here, we use a combination of cell-type-specific ablation, optogenetics, electrophysiology, imaging, and behavior to describe a unified mechanism by which striatal FSIs control burst firing, calcium influx, and synaptic plasticity in neighboring medium spiny projection neurons (MSNs). In vivo silencing of FSIs increased bursting, calcium transients, and AMPA/NMDA ratios in MSNs. In a motor sequence task, FSI silencing increased the frequency of calcium transients but reduced the specificity with which transients aligned to individual task events. Consistent with this, ablation of FSIs disrupted the acquisition of striatum-dependent egocentric learning strategies. Together, our data support a model in which feedforward inhibition from FSIs temporally restricts MSN bursting and calcium-dependent synaptic plasticity to facilitate striatum-dependent sequence learning.

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Dopamine neuron activity before action initiation gates and invigorates future movements

Joaquim Alves da Silva, Fatuel Tecuapetla, Vitor Paixão & Rui M. Costa
Nature
January 31st, 2018

Deciding when and whether to move is critical for survival. Loss of dopamine neurons (DANs) of the substantia nigra pars compacta (SNc) in patients with Parkinson’s disease causes deficits in movement initiation and slowness of movement1. The role of DANs in self-paced movement has mostly been attributed to their tonic activity, whereas phasic changes in DAN activity have been linked to reward prediction2,3. This model has recently been challenged by studies showing transient changes in DAN activity before or during self-paced movement initiation4,5,6,7. Nevertheless, the necessity of this activity for spontaneous movement initiation has not been demonstrated, nor has its relation to initiation versus ongoing movement been described. Here we show that a large proportion of SNc DANs, which did not overlap with reward-responsive DANs, transiently increased their activity before self-paced movement initiation in mice. This activity was not action-specific, and was related to the vigour of future movements. Inhibition of DANs when mice were immobile reduced the probability and vigour of future movements. Conversely, brief activation of DANs when mice were immobile increased the probability and vigour of future movements. Manipulations of dopamine activity after movement initiation did not affect ongoing movements. Similar findings were observed for the initiation and execution of learned action sequences. These findings causally implicate DAN activity before movement initiation in the probability and vigour of future movements.

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Anxiety Cells in a Hippocampal-Hypothalamic Circuit

Jessica C. Jimenez, Katy Su, Alexander R. Goldberg, Victor M. Luna, Jeremy S. Biane, Gokhan Ordek, Pengcheng Zhou, Samantha K. Ong, Matthew A. Wright, Larry Zweifel, Liam Paninski, René Hen, Mazen A. Kheirbek
Neuron
January 31st, 2018

The hippocampus is traditionally thought to transmit contextual information to limbic structures where it acquires valence. Using freely moving calcium imaging and optogenetics, we show that while the dorsal CA1 subregion of the hippocampus is enriched in place cells, ventral CA1 (vCA1) is enriched in anxiety cells that are activated by anxiogenic environments and required for avoidance behavior. Imaging cells defined by their projection target revealed that anxiety cells were enriched in the vCA1 population projecting to the lateral hypothalamic area (LHA) but not to the basal amygdala (BA). Consistent with this selectivity, optogenetic activation of vCA1 terminals in LHA but not BA increased anxiety and avoidance, while activation of terminals in BA but not LHA impaired contextual fear memory. Thus, the hippocampus encodes not only neutral but also valence-related contextual information, and the vCA1-LHA pathway is a direct route by which the hippocampus can rapidly influence innate anxiety behavior.

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Reward-Predictive Neural Activities in Striatal Striosome Compartments

Tomohiko Yoshizawa, Makoto Ito and Kenji Doya
eNeuro
January 29th, 2018

The striatum has been shown to play a critical role in reward prediction. It is composed of two neurochemically and anatomically distinct compartments known as the striosomes and the matrix. The striosomes comprise only about 15% of the striatum by volume and are distributed mosaically therein. Accordingly, it has been difficult to identify striosomal neurons in electrophysiological recordings and it has been unclear whether striosomal neurons, which project to midbrain dopaminergic neurons, engage in reward prediction. In this study, we utilized a mouse line (Sepw1-NP67) selectively expressing Cre in striosomal neurons, combined with endoscopic in vivo calcium imaging to selectively record activities of striosomal neurons during an odor-conditioning task. As mice learned the task, striosomal neurons in the dorsomedial striatum showed predictive activities to odor cues that were associated with water rewards or aversive air puffs. These activities were proportional to the expected reward or air-puff intensity. Intriguingly, repeated recordings of the same striosomal neurons over a period of weeks revealed that predictive activities were learning-stage specific. That is, these activities disappeared after continuous training. Furthermore, presentations of rewards or air puffs activated some striosomal neurons. These findings suggest that the striosomes participate in reward prediction with learning stage-specific neural ensembles, and that they also send reward and aversive signals to dopaminergic neurons.

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Regulation of REM and Non-REM Sleep by Periaqueductal GABAergic Neurons

Franz Weber, Johnny Phong Hoang Do, Shinjae Chung, Kevin T. Beier, Mike Bikov , Mohammad Saffari Doost & Yang Dan
Nature Communications
January 24th, 2018

Mammalian sleep consists of distinct rapid eye movement (REM) and non-REM (NREM) states. The midbrain region ventrolateral periaqueductal gray (vlPAG) is known to be important for gating REM sleep, but the underlying neuronal mechanism is not well understood. Here, we show that activating vlPAG GABAergic neurons in mice suppresses the initiation and maintenance of REM sleep while consolidating NREM sleep, partly through their projection to the dorsolateral pons. Cell-type-specific recording and calcium imaging reveal that most vlPAG GABAergic neurons are strongly suppressed at REM sleep onset and activated at its termination. In addition to the rapid changes at brain state transitions, their activity decreases gradually between REM sleep and is reset by each REM episode in a duration-dependent manner, mirroring the accumulation and dissipation of REM sleep pressure. Thus, vlPAG GABAergic neurons powerfully gate REM sleep, and their firing rate modulation may contribute to the ultradian rhythm of REM/NREM alternation.

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Locus coeruleus input to hippocampal CA3 drives single-trial learning of a novel context

Akiko Wagatsumaa, Teruhiro Okuyamaa, Chen Suna, Lillian M. Smitha, Kuniya Abeb, and Susumu Tonegawa
PNAS
December 26, 2017

The memory for a new episode is formed immediately upon experience and can last up to a lifetime. It has been shown that the hippocampal network plays a fundamental role in the rapid acquisition of a memory of a one-time experience, in which the novelty component of the experience promotes the prompt formation of the memory. However, it remains unclear which neural circuits convey the novelty signal to the hippocampus for the single-trial learning. Here, we show that during encoding neuromodulatory input from locus coeruleus (LC) to CA3, but not CA1 or to the dentate gyrus, is necessary to facilitate novel contextual learning. Silencing LC activity during exposure to a novel context reduced subsequent reactivation of the engram cell ensembles in CA3 neurons and in downstream CA1 upon reexposure to the same context. Calcium imaging of the cells reactivated in both novel and familiar contexts revealed that suppression of LC inputs at the time of encoding resulted in more variable place fields in CA3 neurons. These results suggest that neuromodulatory input from LC to CA3 is crucial for the formation of a persistent memory in the hippocampus.

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Modulation of SF1 Neuron Activity Coordinately Regulates Both Feeding Behavior and Associated Emotional States

Paulius Viskaitis, Elaine E. Irvine, Mark A. Smith, Agharul I. Choudhury, Elisa Alvarez-Curto, Justyna A. Glegola, Darran G. Hardy, Silvia M.A. Pedroni, Maria R. Paiva Pessoa, Anushka B.P. Fernando, Loukia Katsouri, Alessandro Sardini, Mark A. Ungless, Graeme Milligan, Dominic J. Withers
Cell Reports
December 19, 2017

Feeding requires the integration of homeostatic drives with emotional states relevant to food procurement in potentially hostile environments. The ventromedial hypothalamus (VMH) regulates feeding and anxiety, but how these are controlled in a concerted manner remains unclear. Using pharmacogenetic, optogenetic, and calcium imaging approaches with a battery of behavioral assays, we demonstrate that VMH steroidogenic factor 1 (SF1) neurons constitute a nutritionally sensitive switch, modulating the competing motivations of feeding and avoidance of potentially dangerous environments. Acute alteration of SF1 neuronal activity alters food intake via changes in appetite and feeding-related behaviors, including locomotion, exploration, anxiety, and valence. In turn, intrinsic SF1 neuron activity is low during feeding and increases with both feeding termination and stress. Our findings identify SF1 neurons as a key part of the neurocircuitry that controls both feeding and related affective states, giving potential insights into the relationship between disordered eating and stress-associated psychological disorders in humans.

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Combined Social and Spatial Coding in a Descending Projection from the Prefrontal Cortex

Malavika Murugan, Hee Jae Jang, Michelle Park, Ellia M. Miller, Julia Cox, Joshua P. Taliaferro, Nathan F. Parker, Varun Bhave, Hong Hur, Yupu Liang, Alexander R. Nectow, Jonathan W. Pillow, & Ilana B. Witten
Cell
December 7th, 2017

Social behaviors are crucial to all mammals. Although the prelimbic cortex (PL, part of medial prefrontal cortex) has been implicated in social behavior, it is not clear which neurons are relevant or how they contribute. We found that PL contains anatomically and molecularly distinct subpopulations that target three downstream regions that have been implicated in social behavior: the nucleus accumbens (NAc), amygdala, and ventral tegmental area. Activation of NAc-projecting PL neurons (PL-NAc), but not the other subpopulations, decreased the preference for a social target. To determine what information PL-NAc neurons convey, we selectively recorded from them and found that individual neurons were active during social investigation, but only in specific spatial locations. Spatially specific manipulation of these neurons bidirectionally regulated the formation of a social-spatial association. Thus, the unexpected combination of social and spatial information within the PL-NAc may contribute to social behavior by supporting social-spatial learning.

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Oxytocin-receptor-expressing neurons in the parabrachial nucleus regulate fluid intake

Philip J. Ryan, Silvano I. Ross, Carlos A. Campos, Victor A. Derkach & Richard D. Palmiter
Nature Neuroscience
November 27 2017

Brain regions that regulate fluid satiation are not well characterized, yet are essential for understanding fluid homeostasis. We found that oxytocin-receptor-expressing neurons in the parabrachial nucleus of mice (OxtrPBN neurons) are key regulators of fluid satiation. Chemogenetic activation of OxtrPBN neurons robustly suppressed noncaloric fluid intake, but did not decrease food intake after fasting or salt intake following salt depletion; inactivation increased saline intake after dehydration and hypertonic saline injection. Under physiological conditions, OxtrPBN neurons were activated by fluid satiation and hypertonic saline injection. OxtrPBN neurons were directly innervated by oxytocin neurons in the paraventricular hypothalamus (OxtPVH neurons), which mildly attenuated fluid intake. Activation of neurons in the nucleus of the solitary tract substantially suppressed fluid intake and activated OxtrPBN neurons. Our results suggest that OxtrPBN neurons act as a key node in the fluid satiation neurocircuitry, which acts to decrease water and/or saline intake to prevent or attenuate hypervolemia and hypernatremia.

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The central amygdala controls learning in the lateral amygdala

Kai Yu, Sandra Ahrens, Xian Zhang, Hillary Schiff, Charu Ramakrishnan, Lief Fenno, Karl Deisseroth, Fei Zhao, Min-Hua Luo, Ling Gong, Miao He, Pengcheng Zhou, Liam Paninski & Bo Li
Nature Neuroscience
October 23 2017

Experience-driven synaptic plasticity in the lateral amygdala is thought to underlie the formation of associations between sensory stimuli and an ensuing threat. However, how the central amygdala participates in such a learning process remains unclear. Here we show that PKC-δ-expressing central amygdala neurons are essential for the synaptic plasticity underlying learning in the lateral amygdala, as they convey information about the unconditioned stimulus to lateral amygdala neurons during fear conditioning.

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Neuronal Representation of Social Information in the Medial Amygdala of Awake Behaving Mice

Ying Li, Alexander Mathis, Benjamin F. Grewe, Jessica A. Osterhout, Biafra Ahanonu, Mark J. Schnitzer, Venkatesh N. Murthy, Catherine Dulac
Cell
October 26 2017

The medial amygdala (MeA) plays a critical role in processing species- and sex-specific signals that trigger social and defensive behaviors. However, the principles by which this deep brain structure encodes social information is poorly understood. We used a miniature microscope to image the Ca2+dynamics of large neural ensembles in awake behaving mice and tracked the responses of MeA neurons over several months. These recordings revealed spatially intermingled subsets of MeA neurons with distinct temporal dynamics. The encoding of social information in the MeA differed between males and females and relied on information from both individual cells and neuronal populations. By performing long-term Ca2+ imaging across different social contexts, we found that sexual experience triggers lasting and sex-specific changes in MeA activity, which, in males, involve signaling by oxytocin. These findings reveal basic principles underlying the brain’s representation of social information and its modulation by intrinsic and extrinsic factors.

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Tracking the Same Neurons across Multiple Days in Ca2+ Imaging Data

Liron Sheintuch, Alon Rubin, Noa Brande-Eilat, Nitzan Geva, Noa Sadeh, Or Pinchasof, Yaniv Ziv
Cell Reports
October 24, 2017

Ca2+ imaging techniques permit time-lapse recordings of neuronal activity from large populations over weeks. However, without identifying the same neurons across imaging sessions (cell registration), longitudinal analysis of the neural code is restricted to population-level statistics. Accurate cell registration becomes challenging with increased numbers of cells, sessions, and inter-session intervals. Current cell registration practices, whether manual or automatic, do not quantitatively evaluate registration accuracy, possibly leading to data misinterpretation. We developed a probabilistic method that automatically registers cells across multiple sessions and estimates the registration confidence for each registered cell. Using large-scale Ca2+ imaging data recorded over weeks from the hippocampus and cortex of freely behaving mice, we show that our method performs more accurate registration than previously used routines, yielding estimated error rates <5%, and that the registration is scalable for many sessions. Thus, our method allows reliable longitudinal analysis of the same neurons over long time periods.

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Social behaviour shapes hypothalamic neural ensemble representations of conspecific sex

Ryan Remedios, Ann Kennedy, Moriel Zelikowsky, Benjamin F. Grewe, Mark J. Schnitzer & David J. Anderson
Nature
October 19, 2017

All animals possess a repertoire of innate (or instinctive1, 2) behaviours, which can be performed without training. Whether such behaviours are mediated by anatomically distinct and/or genetically specified neural pathways remains unknown3, 4, 5. Here we report that neural representations within the mouse hypothalamus, that underlie innate social behaviours, are shaped by social experience. Oestrogen receptor 1-expressing (Esr1+) neurons in the ventrolateral subdivision of the ventromedial hypothalamus (VMHvl) control mating and fighting in rodents6, 7, 8. We used microendoscopy9 to image Esr1+ neuronal activity in the VMHvl of male mice engaged in these social behaviours. In sexually and socially experienced adult males, divergent and characteristic neural ensembles represented male versus female conspecifics. However, in inexperienced adult males, male and female intruders activated overlapping neuronal populations. Sex-specific neuronal ensembles gradually separated as the mice acquired social and sexual experience. In mice permitted to investigate but not to mount or attack conspecifics, ensemble divergence did not occur. However, 30 minutes of sexual experience with a female was sufficient to promote the separation of male and female ensembles and to induce an attack response 24 h later. These observations uncover an unexpected social experience-dependent component to the formation of hypothalamic neural assemblies controlling innate social behaviours. More generally, they reveal plasticity and dynamic coding in an evolutionarily ancient deep subcortical structure that is traditionally viewed as a ‘hard-wired’ system.

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Deconstruction of Corticospinal Circuits for Goal-Directed Motor Skills

Xuhua Wang, Yuanyuan Liu, Xinjian Li, Zicong Zhang, Hengfu Yang, Yu Zhang, Philip R. Williams, Noaf S.A. Alwahab, Kush Kapur, Bin Yu, Yiming Zhang, Mengying Chen, Haixia Ding, Charles R. Gerfen, Kuan Hong Wang, Zhigang He
Cell
September 21, 2017

Corticospinal neurons (CSNs) represent the direct cortical outputs to the spinal cord and play important roles in motor control across different species. However, their organizational principle remains unclear. By using a retrograde labeling system, we defined the requirement of CSNs in the execution of a skilled forelimb food-pellet retrieval task in mice. In vivo imaging of CSN activity during performance revealed the sequential activation of topographically ordered functional ensembles with moderate local mixing. Region-specific manipulations indicate that CSNs from caudal or rostral forelimb area control reaching or grasping, respectively, and both are required in the transitional pronation step. These region-specific CSNs terminate in different spinal levels and locations, therefore preferentially connecting with the premotor neurons of muscles engaged in different steps of the task. Together, our findings suggest that spatially defined groups of CSNs encode different movement modules, providing a logic for parallel-ordered corticospinal circuits to orchestrate multistep motor skills.

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The Spatiotemporal Organization of the Striatum Encodes Action Space

Andreas Klaus, Gabriela J. Martins, Vitor B. Paixao, Pengcheng Zhou, Liam Paninski, Rui M. Costa
Neuron
August 30, 2017

Activity in striatal direct- and indirect-pathway spiny projection neurons (SPNs) is critical for proper movement. However, little is known about the spatiotemporal organization of this activity. We investigated the spatiotemporal organization of SPN ensemble activity in mice during self-paced, natural movements using microendoscopic imaging. Activity in both pathways showed predominantly local but also some long-range correlations. Using a novel approach to cluster and quantify behaviors based on continuous accelerometer and video data, we found that SPN ensembles active during specific actions were spatially closer and more correlated overall. Furthermore, similarity between different actions corresponded to the similarity between SPN ensemble patterns, irrespective of movement speed. Consistently, the accuracy of decoding behavior from SPN ensemble patterns was directly related to the dissimilarity between behavioral clusters. These results identify a predominantly local, but not spatially compact, organization of direct- and indirect-pathway SPN activity that maps action space independently of movement speed.

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Central amygdala circuits modulate food consumption through a positive-valence mechanism

Amelia M Douglass, Hakan Kucukdereli, Marion Ponserre, Milica Markovic, Jan Gründemann, Cornelia Strobel, Pilar L Alcala Morales, Karl-Klaus Conzelmann, Andreas Lüthi & Rüdiger Klein
Nature Neuroscience
August 21, 2017

The complex behaviors underlying reward seeking and consumption are integral to organism survival. The hypothalamus and mesolimbic dopamine system are key mediators of these behaviors, yet regulation of appetitive and consummatory behaviors outside of these regions is poorly understood. The central nucleus of the amygdala (CeA) has been implicated in feeding and reward, but the neurons and circuit mechanisms that positively regulate these behaviors remain unclear. Here, we defined the neuronal mechanisms by which CeA neurons promote food consumption. Using in vivo activity manipulations and Ca2+ imaging in mice, we found that GABAergic serotonin receptor 2a (Htr2a)-expressing CeA neurons modulate food consumption, promote positive reinforcement and are active in vivo during eating. We demonstrated electrophysiologically, anatomically and behaviorally that intra-CeA and long-range circuit mechanisms underlie these behaviors. Finally, we showed that CeAHtr2a neurons receive inputs from feeding-relevant brain regions. Our results illustrate how defined CeA neural circuits positively regulate food consumption.

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Skin suturing and cortical surface viral infusion improves imaging of neuronal ensemble activity with head-mounted miniature microscopes

XinjianLi, Vania Y.Cao, Wenyu Zhang, Surjeet S.Mastwal, Qing Liu, Stephani Otte, Kuan Hong Wang
Journal of Neuroscience Methods
August 19, 2017

In vivo optical imaging of neural activity provides important insights into brain functions at the single-cell level. Cranial windows and virally delivered calcium indicators are commonly used for imaging cortical activity through two-photon microscopes in head-fixed animals. Recently, head-mounted one-photon microscopes have been developed for freely behaving animals. However, minimizing tissue damage from the virus injection procedure and maintaining window clarity for imaging can be technically challenging.

We used a wide-diameter glass pipette at the cortical surface for infusing the viral calcium reporter AAV-GCaMP6 into the cortex. After infusion, the scalp skin over the implanted optical window was sutured to facilitate postoperative recovery. The sutured scalp was removed approximately two weeks later and a miniature microscope was attached above the window to image neuronal activity in freely moving mice.

We found that cortical surface virus infusion efficiently labeled neurons in superficial layers, and scalp skin suturing helped to maintain the long-term clarity of optical windows. As a result, several hundred neurons could be recorded in freely moving animals.

Compared to intracortical virus injection and open-scalp postoperative recovery, our methods minimized tissue damage and dura overgrowth underneath the optical window, and significantly increased the experimental success rate and the yield of identified neurons.

Our improved cranial surgery technique allows for high-yield calcium imaging of cortical neurons with head-mounted microscopes in freely behaving animals. This technique may be beneficial for other optical applications such as two-photon microscopy, multi-site imaging, and optogenetic modulation.

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Distinct Neural Circuits for the Formation and Retrieval of Episodic Memories

Dheeraj S. Roy, Takashi Kitamura, Teruhiro Okuyama, Sachie K. Ogawa, Chen Sun, Yuichi Obata, Atsushi Yoshiki, and Susumu Tonegawa
Cell
August 17, 2017

The formation and retrieval of a memory is thought to be accomplished by activation and reactivation, respectively, of the memory-holding cells (engram cells) by a common set of neural circuits, but this hypothesis has not been established. The medial temporal-lobe system is essential for the formation and retrieval of episodic memory for which individual hippocampal subfields and entorhinal cortex layers contribute by carrying out specific functions. One subfield whose function is poorly known is the subiculum. Here, we show that dorsal subiculum and the circuit, CA1 to dorsal subiculum to medial entorhinal cortex layer 5, play a crucial role selectively in the retrieval of episodic memories. Conversely, the direct CA1 to medial entorhinal cortex layer 5 circuit is essential specifically for memory formation. Our data suggest that the subiculum-containing detour loop is dedicated to meet the requirements associated with recall such as rapid memory updating and retrieval-driven instinctive fear responses.

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Multi-layer cortical calcium imaging in freely moving mice with prism probes and miniaturized fluorescence microscopy

Srishti Gulati, Vania Cao, Stephani Otte
JoVE
June 13, 2017

In vivo circuit and cellular level functional imaging is a critical tool for understanding the brain in action. High resolution imaging of mouse cortical neurons with two-photon microscopy has provided unique insights into cortical structure, function and plasticity. However, these studies are limited to head fixed animals, greatly reducing the behavioral complexity available for study. In this paper, we describe a procedure for performing chronic fluorescence microscopy with cellular-resolution across multiple cortical layers in freely behaving mice. We used an integrated miniaturized fluorescence microscope paired with an implanted prism probe to simultaneously visualize and record the calcium dynamics of hundreds of neurons across multiple layers of the somatosensory cortex as the mouse engaged in a novel object exploration task, over several days. This technique can be adapted to other brain regions in different animal species for other behavioral paradigms.

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Dorsal-CA1 hippocampal neuronal ensembles encode nicotine-reward contextual associations

Li Xia, Stephanie K. Nygard, Gabe G. Sobczak, Nicholas J. Hourguettes, Michael R. Bruchas
Cell Reports
June 6, 2017

Natural and drug rewards increase the motivational valence of stimuli in the environment that, through Pavlovian learning mechanisms, become conditioned stimuli that directly motivate behavior in the absence of the original unconditioned stimulus. While the hippocampus has received extensive attention for its role in learning and memory processes, less is known regarding its role in drug-reward associations.

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Identification of a motor-to-auditory pathway important for vocal learning

Todd F Roberts, Erin Hisey, Masashi Tanaka, Matthew G Kearney, Gaurav Chattree, Cindy F Yang, Nirao M Shah, Richard Mooney
Nature Neuroscience
May 15, 2017

Learning to vocalize depends on the ability to adaptively modify the temporal and spectral features of vocal elements. Neurons that convey motor-related signals to the auditory system are theorized to facilitate vocal learning, but the identity and function of such neurons remain unknown. Here we identify a previously unknown neuron type in the songbird brain that transmits vocal motor signals to the auditory cortex. Genetically ablating these neurons in juveniles disrupted their ability to imitate features of an adult tutor's song.

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Delay activity of specific prefrontal interneuron subtypes modulates memory-guided behavior

Tsukasa Kamigaki, Yang Dan
Nature Neuroscience
April 24, 2017

Memory-guided behavior requires maintenance of task-relevant information without sensory input, but the underlying circuit mechanism remains unclear. Calcium imaging in mice performing a delayed Go or No-Go task revealed robust delay activity in dorsomedial prefrontal cortex, with different pyramidal neurons signaling Go and No-Go action plans.

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Engrams and circuits crucial for systems consolidation of a memory

Takashi Kitamura, Sachie K. Ogawa, Dheeraj S. Roy, Teruhiro Okuyama, Mark D. Morrissey, Lillian M. Smith, Roger L. Redondo, Susumu Tonegawa
Science
April 7, 2017

Episodic memories initially require rapid synaptic plasticity within the hippocampus for their formation and are gradually consolidated in neocortical networks for permanent storage. However, the engrams and circuits that support neocortical memory consolidation have thus far been unknown.We found that neocortical prefrontal memory engram cells, which are critical for remote contextual fear memory, were rapidly generated during initial learning through inputs from both the hippocampal–entorhinal cortex network and the basolateral amygdala.

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Active dentate granule cells encode experience to promote the addition of adult-born hippocampal neurons

Gregory W. Kirschen, Jia Shen, Mu Tian, Bryce Schroeder, Jia Wang, Guoming Man, Song Wu and Shaoyu Ge
The Journal of Neuroscience
April 3, 2017

The continuous addition of new dentate granule cells, exquisitely regulated by brain activity, renders the hippocampus plastic. However, how neural circuits encode experiences to impact the addition of adult-born neurons remains unknown. Here, we used endoscopic Ca2+ imaging to track the real-time activity of individual dentate granule cells in freely-behaving mice.

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Neural ensemble dynamics underlying a long-term associative memory

Benjamin F. Grewe, Jan Gründemann, Lacey J. Kitch, Jerome A. Lecoq, Jones G. Parker, Jesse D. Marshall, Margaret C. Larkin, Pablo E. Jercog, Francois Grenier, Jin Zhong Li, Andreas Lüthi, Mark J. Schnitzer
Nature
March 22, 2017

The brain’s ability to associate different stimuli is vital for long-term memory, but how neural ensembles encode associative memories is unknown. Here we studied how cell ensembles in the basal and lateral amygdala encode associations between conditioned and unconditioned stimuli (CS and US, respectively). Using a miniature fluorescence microscope, we tracked the Ca2+dynamics of ensembles of amygdalar neurons during fear learning and extinction over 6 days in behaving mice.

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Distinct hippocampal pathways mediate dissociable roles of context in memory retrieval

Chun Xu, Sabine Krabbe, Jan Gründemann, Paolo Botta, Jonathan P. Fadok, Fumitaka Osakada, Dieter Saur, Benjamin F. Grewe, Mark J. Schnitzer, Edward M. Callaway, Andreas Lüthi
Cell
October 20, 2016

Memories about sensory experiences are tightly linked to the context in which they were formed. Memory contextualization is fundamental for the selection of appropriate behavioral reactions needed for survival, yet the underlying neuronal circuits are poorly understood. By combining trans-synaptic viral tracing and optogenetic manipulation, we found that the ventral hippocampus (vHC) and the amygdala, two key brain structures encoding context and emotional experiences, interact via multiple parallel pathways.

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Circuit-based interrogation of sleep control

Franz Weber, Yang Dan
Nature
October 5, 2016

Sleep is a fundamental biological process observed widely in the animal kingdom, but the neural circuits generating sleep remain poorly understood. Understanding the brain mechanisms controlling sleep requires the identification of key neurons in the control circuits and mapping of their synaptic connections. Technical innovations over the past decade have greatly facilitated dissection of the sleep circuits. This has set the stage for understanding how a variety of environmental and physiological factors influence sleep.

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Ventral CA1 neurons store social memory

Teruhiro Okuyama, Takashi Kitamura, Dheeraj S. Roy, Shigeyoshi Itohara, Susumu Tonegawa
Science
September 30, 2016

The medial temporal lobe, including the hippocampus, has been implicated in social memory. However, it remains unknown which parts of these brain regions and their circuits hold social memory. Here, we show that ventral hippocampal CA1 (vCA1) neurons of a mouse and their projections to nucleus accumbens (NAc) shell play a necessary and sufficient role in social memory. Both the proportion of activated vCA1 cells and the strength and stability of the responding cells are greater in response to a familiar mouse than to a previously unencountered mouse.

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A new design for a green calcium indicator with a smaller size and a reduced number of calcium-binding sites

Natalia V. Barykina, Oksana M. Subach, Danila A. Doronin, Vladimir P. Sotskov, Marina A. Roshchina, Tatiana A. Kunitsyna, Aleksey Y. Malyshev, Ivan V. Smirnov, Asya M. Azieva, Ilya S. Sokolov, Kiryl D. Piatkevich, Mikhail S. Burtsev, Anna M. Varizhuk, Galina E. Pozmogova, Konstantin V. Anokhin, Fedor V. Subach, Grigori N. Enikolopov
Scientific Reports
September 28, 2016

Genetically encoded calcium indicators (GECIs) are mainly represented by two- or one-fluorophore-based sensors. One type of two-fluorophore-based sensor, carrying Opsanus troponin C (TnC) as the Ca2+-binding moiety, has two binding sites for calcium ions, providing a linear response to calcium ions. One-fluorophore-based sensors have four Ca2+-binding sites but are better suited for in vivo experiments.

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Decreasing striatopallidal pathway function enhances motivation by energizing the initiation of goal-directed action

Fernanda Carvalho Poyraz, Eva Holzner, Matthew R. Bailey, Jozsef Meszaros, Lindsay Kenney, Mazen A. Kheirbek, Peter D. Balsam, Christoph Kellendonk
The Journal of Neuroscience
June 1, 2016

Altered dopamine D2 receptor (D2R) binding in the striatum has been associated with abnormal motivation in neuropsychiatric disorders, including schizophrenia. Here, we tested whether motivational deficits observed in mice with upregulated D2Rs (D2R-OEdev mice) are reversed by decreasing function of the striatopallidal “no-go” pathway. To this end, we expressed the Gαi-coupled designer receptor hM4D in adult striatopallidal neurons and activated the receptor with clozapine-N-oxide (CNO).

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Calcium imaging of basal forebrain activity during innate and learned behaviors

Thomas C. Harrison, Lucas Pinto, Julien R. Brock, Yang Dan
Frontiers in Neural Circuits
May 9, 2016

The basal forebrain (BF) plays crucial roles in arousal, attention, and memory, and its impairment is associated with a variety of cognitive deficits. The BF consists of cholinergic, GABAergic, and glutamatergic neurons. Electrical or optogenetic stimulation of BF cholinergic neurons enhances cortical processing and behavioral performance, but the natural activity of these cells during behavior is only beginning to be characterized. Even less is known about GABAergic and glutamatergic neurons.

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Large-scale fluorescence calcium-imaging methods for studies of long-term memory in behaving mammals

Pablo Jercog, Thomas Rogerson, Mark J. Schnitzer
Cold Spring Harbor Perspectives In Biology
April 5, 2016

During long-term memory formation, cellular and molecular processes reshape how individual neurons respond to specific patterns of synaptic input. It remains poorly understood how such changes impact information processing across networks of mammalian neurons. To observe how networks encode, store, and retrieve information, neuroscientists must track the dynamics of large ensembles of individual cells in behaving animals, over timescales commensurate with long-term memory.

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Direct imaging of hippocampal epileptiform calcium motifs following kainic acid administration in freely behaving mice

Tamara K. Berdyyeva, E. Paxon Frady, Jonathan J. Nassi, Leah Aluisio, Yauheniya Cherkas, Stephani Otte, Ryan M. Wyatt, Christine Dugovic, Kunal K. Ghosh, Mark J. Schnitzer, Timothy Lovenberg, Pascal Bonaventure
Frontiers in Neuroscience
February 29, 2016

Prolonged exposure to abnormally high calcium concentrations is thought to be a core mechanism underlying hippocampal damage in epileptic patients; however, no prior study has characterized calcium activity during seizures in the live, intact hippocampus. We have directly investigated this possibility by combining whole-brain electroencephalographic (EEG) measurements with microendoscopic calcium imaging of pyramidal cells in the CA1 hippocampal region of freely behaving mice treated with the pro-convulsant kainic acid (KA). 

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Calcium imaging of sleep–wake related neuronal activity in the dorsal pons

Julia Cox, Lucas Pinto, Yang Dan
Nature Communications
February 25, 2016

The dorsal pons has long been implicated in the generation of rapid eye movement (REM) sleep, but the underlying circuit mechanisms remain poorly understood. Using cell-type-specific microendoscopic Ca2+ imaging in and near the laterodorsal tegmental nucleus, we found that many glutamatergic neurons are maximally active during REM sleep (REM-max), while the majority of GABAergic neurons are maximally active during wakefulness (wake-max).

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Visualization of cortical, subcortical and deep brain neural circuit dynamics during naturalistic mammalian behavior with head-mounted microscopes and chronically implanted lenses

Shanna L Resendez, Josh H Jennings, Randall L Ung, Vijay Mohan K Namboodiri, Zhe Charles Zhou, James M Otis, Hiroshi Nomura, Jenna A McHenry, Oksana Kosyk, Garret D Stuber
Nature Protocols
February 25, 2016

Genetically encoded calcium indicators for visualizing dynamic cellular activity have greatly expanded our understanding of the brain. However, owing to the light-scattering properties of the brain, as well as the size and rigidity of traditional imaging technology, in vivo calcium imaging has been limited to superficial brain structures during head-fixed behavioral tasks.

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Hippocampal ensemble dynamics timestamp events in long-term memory

Alon Rubin, Nitzan Geva, Liron Sheintuch, Yaniv Ziv
eLife
December 18, 2015

The capacity to remember temporal relationships between different events is essential to episodic memory, but little is currently known about its underlying mechanisms. We performed time-lapse imaging of thousands of neurons over weeks in the hippocampal CA1 of mice as they repeatedly visited two distinct environments. Longitudinal analysis exposed ongoing environment-independent evolution of episodic representations, despite stable place field locations and constant remapping between the two environments.

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Entorhinal cortical ocean cells encode specific contexts and drive context-specific fear memory

Takashi Kitamura, Chen Sun, Jared Martin, Lacey J. Kitch, Mark J. Schnitzer, Susumu Tonegawa
Neuron
September 23, 2015
Forming distinct representations and memories of multiple contexts and episodes is thought to be a crucial function of the hippocampal-entorhinal cortical network. The hippocampal dentate gyrus (DG) and CA3 are known to contribute to these functions, but the role of the entorhinal cortex (EC) is poorly understood. Read
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Distinct speed dependence of entorhinal island and ocean cells, including respective grid cells

Chen Sun, Takashi Kitamura, Jun Yamamoto, Jared Martin, Michele Pignatelli, Lacey J. Kitch, Mark J. Schnitzer, Susumu Tonegawa
PNAS
July 13, 2015

Entorhinal–hippocampal circuits in the mammalian brain are crucial for an animal’s spatial and episodic experience, but the neural basis for different spatial computations remain unknown. Medial entorhinal cortex layer II contains pyramidal island and stellate ocean cells. Here, we performed cell type-specific Ca2+ imaging in freely exploring mice using cellular markers and a miniature head-mounted fluorescence microscope.

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Cell-type-specific activity in prefrontal cortex during goal-directed behavior

Lucas Pinto, Yang Dan
Neuron
July 2, 2015

The prefrontal cortex (PFC) plays a key role in controlling goal-directed behavior. Although a variety of task-related signals have been observed in the PFC, whether they are differentially encoded by various cell types remains unclear. Here we performed cellular-resolution microendoscopic Ca2+ imaging from genetically defined cell types in the dorsomedial PFC of mice performing a PFC-dependent sensory discrimination task.

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Mesoscopic patterns of neural activity support songbird cortical sequences

Jeffrey E. Markowitz, William A. Liberti III, Grigori Guitchounts, Tarciso Velho, Carlos Lois, Timothy J. Gardner
PLOS Biology
June 3, 2015

Time-locked sequences of neural activity can be found throughout the vertebrate forebrain in various species and behavioral contexts. From “time cells” in the hippocampus of rodents to cortical activity controlling movement, temporal sequence generation is integral to many forms of learned behavior. However, the mechanisms underlying sequence generation are not well known. Here, we describe a spatial and temporal organization of the songbird premotor cortical microcircuit that supports sparse sequences of neural activity.

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Miniature microscopes for large-scale imaging of neuronal activity in freely behaving rodents

Yaniv Ziv, Kunal Ghosh
Current Opinion in Neurobiology
May 16, 2015

Recording neuronal activity in behaving subjects has been instrumental in studying how information is represented and processed by the brain. Recent advances in optical imaging and bioengineering have converged to enable time-lapse, cell-type specific recordings of neuronal activities from large neuronal populations in deep-brain structures of freely behaving rodents. We will highlight these advancements, with an emphasis on miniaturized integrated microscopy for large-scale imaging in freely behaving mice.

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Neurons for hunger and thirst transmit a negative-valence teaching signal

J. Nicholas Betley, Shengjin Xu, Zhen Fang Huang Cao, Rong Gong, Christopher J. Magnus, Yang Yu & Scott M. Sternson
Nature
April 27, 2016

Homeostasis is a biological principle for regulation of essential physiological parameters within a set range. Behavioural responses due to deviation from homeostasis are critical for survival, but motivational processes engaged by physiological need states are incompletely understood. We examined motivational characteristics of two separate neuron populations that regulate energy and fluid homeostasis by using cell-type-specific activity manipulations in mice.

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Cellular level brain imaging in behaving mammals: an engineering approach

Elizabeth J.O. Hamel, Benjamin F. Grewe, Jones G. Parker, Mark J. Schnitzer
Neuron
April 8, 2015

Fluorescence imaging offers expanding capabilities for recording neural dynamics in behaving mammals, including the means to monitor hundreds of cells targeted by genetic type or connectivity, track cells over weeks, densely sample neurons within local microcircuits, study cells too inactive to isolate in extracellular electrical recordings, and visualize activity in dendrites, axons, or dendritic spines.

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Visualizing hypothalamic network dynamics for appetitive and consummatory behaviors

J. Jennings, R. L. Ung, S.L. Resendez, A.M. Stamatakis, J.G. Taylor, J. Huang, K. Veleta, P.A. Kantak, M. Aita, K. Shilling-Scrivo, C. Ramakrishnan, K. Deisseroth, S. Otte, G.D. Stuber
Cell
January 29, 2015

Optimally orchestrating complex behavioral states, such as the pursuit and consumption of food, is critical for an organism's survival. The lateral hypothalamus (LH) is a neuroanatomical region essential for appetitive and consummatory behaviors, but whether individual neurons within the LH differentially contribute to these interconnected processes is unknown.

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Zolpidem reduces hippocampal neuronal activity in freely behaving mice: a large scale calcium imaging study with miniaturized fluorescence microscope

Tamara Berdyyeva, Stephani Otte, Leah Aluisio, Yaniv Ziv, Laurie D. Burns, Christine Dugovic, Sujin Yun, Kunal K. Ghosh, Mark J. Schnitzer, Timothy Lovenberg, Pascal Bonaventure
PLOS ONE
November 5, 2014

Therapeutic drugs for cognitive and psychiatric disorders are often characterized by their molecular mechanism of action. Here we demonstrate a new approach to elucidate drug action on large-scale neuronal activity by tracking somatic calcium dynamics in hundreds of CA1 hippocampal neurons of pharmacologically manipulated behaving mice. We used an adeno-associated viral vector to express the calcium sensor GCaMP3 in CA1 pyramidal cells under control of the CaMKII promoter and a miniaturized microscope to observe cellular dynamics.

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Tools for resolving functional activity and connectivity within intact neural circuits

Joshua H. Jennings, Garret D. Stuber
Current Biology
January 6, 2014

Mammalian neural circuits are sophisticated biological systems that choreograph behavioral processes vital for survival. While the inherent complexity of discrete neural circuits has proven difficult to decipher, many parallel methodological developments promise to help delineate the function and connectivity of molecularly defined neural circuits. Here, we review recent technological advances designed to precisely monitor and manipulate neural circuit activity.

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Imaging neuronal populations in behaving rodents: paradigms for studying neural circuits underlying behavior in the mammalian cortex

Chen J., Andermann M., Keck T., Xu N., Ziv Y.
The Journal of Neuroscience
November 6, 2013

Understanding the neural correlates of behavior in the mammalian cortex requires measurements of activity in awake, behaving animals. Rodents have emerged as a powerful model for dissecting the cortical circuits underlying behavior attributable to the convergence of several methods. Genetically encoded calcium indicators combined with viral-mediated or transgenic tools enable chronic monitoring of calcium signals in neuronal populations and subcellular structures of identified cell types.

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Engineering approaches to illuminating brain structure and dynamics

Deisseroth K., Schnitzer M.
Neuron
October 30, 2013

Historical milestones in neuroscience have come in diverse forms, ranging from the resolution of specific biological mysteries via creative experimentation to broad technological advances allowing neuroscientists to ask new kinds of questions. The continuous development of tools is driven with a special necessity by the complexity, fragility, and inaccessibility of intact nervous systems, such that inventive technique development and application drawing upon engineering and the applied sciences has long been essential to neuroscience.

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Nanotools for neuroscience and brain activity mapping

Alivisatos A.P., Andrews A., Boyden E., Chun M., Church G., Deisseroth K., Donoghue J., Fraser S., Lippincott-Schwartz J., Looger L., Masmanidis S., McEuen P., Nurmikko A., Park H., Peterka D., Reid C., Roukes M., Scherer A., Schnitzer M., Sejnowski T., Shepard K., Tsao D., Turrigiano G., Weiss P., Xu C., Yuste R., Zhuang X.
ACS Nano
March 20, 2013

Neuroscience is at a crossroads. Great effort is being invested into deciphering specific neural interactions and circuits. At the same time, there exist few general theories or principles that explain brain function. We attribute this disparity, in part, to limitations in current methodologies. Traditional neurophysiological approaches record the activities of one neuron or a few neurons at a time. Neurochemical approaches focus on single neurotransmitters. Yet, there is an increasing realization that neural circuits operate at emergent levels, where the interactions between hundreds or thousands of neurons, utilizing multiple chemical transmitters, generate functional states. Brains function at the nanoscale, so tools to study brains must ultimately operate at this scale, as well. Nanoscience and nanotechnology are poised to provide a rich toolkit of novel methods to explore brain function by enabling simultaneous measurement and manipulation of activity of thousands or even millions of neurons. We and others refer to this goal as the Brain Activity Mapping Project. In this Nano Focus, we discuss how recent developments in nanoscale analysis tools and in the design and synthesis of nanomaterials have generated optical, electrical, and chemical methods that can readily be adapted for use in neuroscience. These approaches represent exciting areas of technical development and research. Moreover, unique opportunities exist for nanoscientists, nanotechnologists, and other physical scientists and engineers to contribute to tackling the challenging problems involved in understanding the fundamentals of brain function.

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Long-term dynamics of CA1 hippocampal place codes

Ziv Y., Burns L., Cocker E., Hamel E., Ghosh K., Kitch L., Gamal A., Schnitzer M.
Nature Neuroscience
February 10, 2013

Using Ca2+ imaging in freely behaving mice that repeatedly explored a familiar environment, we tracked thousands of CA1 pyramidal cells' place fields over weeks. Place coding was dynamic, as each day the ensemble representation of this environment involved a unique subset of cells. However, cells in the ∼15-25% overlap between any two of these subsets retained the same place fields, which sufficed to preserve an accurate spatial representation across weeks.

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Miniaturized integration of a fluorescence microscope

Ghosh K., Burns L., Cocker E., Nimmerjahn A., Ziv Y., Gamal A., Schnitzer M.
Nature Methods
September 11, 2011

The light microscope is traditionally an instrument of substantial size and expense. Its miniaturized integration would enable many new applications based on mass-producible, tiny microscopes. Key prospective usages include brain imaging in behaving animals for relating cellular dynamics to animal behavior. Here we introduce a miniature (1.9 g) integrated fluorescence microscope made from mass-producible parts, including a semiconductor light source and sensor. This device enables high-speed cellular imaging across ∼0.5 mm2 areas in active mice.

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Hunger logic

Richard Palmiter
Nature Neuroscience
May 26, 2015

Activation of AgRP-expressing 'hunger' neurons promotes robust feeding. Recent studies reveal the valence, dynamics and neural circuits engaged by AgRP neurons.

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