Theses Doctoral

Multiple Population Codes in Ventral CA1 for Anxiogenic Stimuli and Behavioral States

Lim, Sean Chih-Hsiung

The hippocampus has long been known to play a role in learning and memory as well as spatial navigation. However, studies over the past several decades have shown that the hippocampus is not just a cognitive structure, but is also involved in emotional behaviors, particularly through its ventral pole. Recent experiments, from our lab and others, have revealed that ventral CA1 neural activity is strongly modulated by anxiogenic environments.

Furthermore, optogenetic manipulation of ventral CA1 cell bodies and projections modifies anxiety-like behavior in the open field and elevated plus maze. However, it is still unknown if ventral CA1 represents anxiogenic stimuli through a single cell or a population code. Additionally, whether ventral CA1 encodes the moment-to-moment behavioral state changes caused by anxiogenic stimuli is unresolved. I investigate these questions using in-vivo freely moving calcium imaging in combination with neural population decoding analysis and unsupervised behavioral segmentation.

My results show that ventral CA1 encodes anxiogenic stimuli through a high dimensional, distributed population code that allows for the separation of aversive stimuli with different sensory properties. I also demonstrate that ventral CA1 represents behavioral states through a low dimensional, distributed population code that generalizes across distinct contexts. Thus, ventral CA1 possesses multiple population codes that represent different kinds of information.


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More About This Work

Academic Units
Neurobiology and Behavior
Thesis Advisors
Hen, Rene
Ph.D., Columbia University
Published Here
April 12, 2023