The neurobiology of sleep is well studied and fundamental to our understanding of how we sleep, but have you ever asked the question of why we sleep? This is the basis of the research in the Marcos Frank lab at Washington State University, where an arsenal of neuroscience tools are used to study various aspects of sleep biology including the role of sleep in the development of central visual pathways, the interactions between sleep regulation and sleep function and the cellular basis for sleep homeostasis .
The lattermost research focus has been led by Dr. Ashley Ingiosi, a postdoctoral researcher in the Frank lab. Her recently published work examining astroglial biology in sleep and sleep homeostasis demonstrates their dynamic and sophisticated role. Thank you for taking your coffee break with us, Ashley, we are so honored to be supporting your work!
What is your background and how did you become a circuit neuroscientist?
I got BS degrees in Biopsychology and General Biology as well as a PhD in Neuroscience from the University of Michigan to study sleep and sleep regulation. I had a light bulb moment in graduate school that we did not know much about the role of non-neuronal cells, like glia, in sleep. I became particularly interested in glial cells called astrocytes. We know that there are sleep- and wake-promoting neuronal populations and circuits in the brain that regulate sleep-wake behavior, but I wanted to find out if astrocytes played any part in sleep regulation. One challenge for studying glia was (is) that there were not as many tools to study astrocytes compared to the tools used for neurons. So I made transgenic mouse lines to study astroglial- and neuronal-specific contributions to sleep regulation. While I was working on that project, one of the first papers demonstrating a role for astrocytes in sleep regulation in vivo was published. A postdoctoral opportunity became available with the senior author of that paper, Dr. Marcos Frank. During my postdoc with Dr. Frank, we started to take a closer look at astroglial activity in sleep and sleep regulation.
What do you study in the Frank lab at Washington State University?
I study the role of astroglial calcium activity in sleep and sleep regulation using in vivo calcium imaging techniques in freely behaving (miniscope) and unanesthetized, head-fixed mice (two-photon microscope). Unlike neurons, astrocytes are not electrically excitable and instead use calcium to mediate intracellular functions. So calcium imaging of astrocytes is a great tool for investigating the role of astroglial activity in neurophysiology and behavior. Our lab just published these studies in Current Biology!
Congratulations on your publication- the first ever Inscopix imaging study in astrocytes- that's amazing and we're so proud! What are the main takeaways from the paper, and what direction do you hope it provides for the field?
Thank you! We already knew that neuronal activity changes dynamically with sleep and wake and that neurons played a role in sleep regulation. Our paper shows that astrocytes also change dynamically across sleep, wake, and sleep loss and that astroglial calcium signaling plays a role in compensatory responses to sleep deprivation. We also found that astroglial calcium activity changes with sleep need. Finally, these studies revealed that synchrony of astroglial calcium activity changes with arousal state and sleep loss in a way that differs from neuronal electrical activity. Because astrocyte activity does not mirror neuronal activity, this finding suggests that astrocytes might play a more direct role in regulating sleep than we previously thought.
Overall, we identified a new level of brain organization in a non-neuronal cell type that changes dynamically with arousal state and plays a role in sleep regulation. These findings provide new insights for understanding normal and abnormal sleep and may provide new therapeutic targets for sleep disorders. More broadly, these studies lend additional evidence to the importance of considering the role of non-neuronal cells in the processes, behaviors, and disorders that we study.
Video of astrocyte activity in the brain during non-rapid eye movement sleep (NREMS), rapid eye movement sleep (REMS) and wakefulness (WAKE) as captured with a genetically encoded calcium indicator and Inscopix miniscope. Video shown is 8 times faster than normal speed.
What are some of your favorite circuit neuroscience techniques to study sleep & wake neurobiology?
The miniscope is a game-changer for studying sleep & wake neurobiology because we can image cell activity as animals naturally cycle through their sleep and wake cycles without restricting their behavior. This is especially true for glia since the primary way we can study their activity in real time is through in vivo calcium imaging. Pairing miniscope imaging of astrocytes with gold standard electrophysiological measures of sleep-wake behavior (i.e. electroencephalography) allows us to quantify astroglial and neuronal activity in parallel. Two-photon microscopy is also useful for identifying how calcium activity changes in the fine astroglial processes that interact with neurons and the vasculature. Finally, optogenetics is a very useful tool for studying sleep-wake circuits.
What should we look forward to seeing from you in the future?
We studied astrocyte activity in one part of the brain, but sleep-wake behavior is mediated by many different sleep- and wake-promoting brain regions. So one of the next major steps is to determine if astrocyte activity is the same or different in these sleep- and wake-promoting brain regions.
What is the best piece of career advice that you have ever been given that you'd like to share with your peers?
For trainees, I would say to choose mentors and lab environments that align with both your professional and personal goals and values. Having support in lab and in life can have a major impact on your training experiences.
What do you enjoy doing outside of the lab?
I love to sing! Between symphony choruses, musical theater, and a cappella, singing is a major creative outlet for me. I also have 2 kids that keep me busy and test my own limits of sleep regulation at times!