Degree
Doctor of Philosophy (PhD)
Department
Comparative Biomedical Sciences
Document Type
Dissertation
Abstract
Negative encoding is a major process by which an organism is able to adapt to its environment and avoid major aversive stimuli. However, maladaptation in this process underlies anxiogenic pathologies and avoidant behavior. Traditionally, subcortical and cortical pathways have been viewed through a framework that relegates the hippocampus to a passive relay center rather than an active participant in stress processing. This thesis aimed to test the hypothesis that the ventral hippocampus is a driver (rather than a processor) for negative stimulus behavior through extrahippocampal projections to form cortical and hypothalamic glutamatergic ensembles. Through our retrograde viral tracing experiments we mapped two novel, direct glutamatergic projections originating from ventral hippocampal subfields. The ventral CA1 (vCA1) to the infralimbic cortex (IL) ensemble and the ventral CA3 (vCA3) to paraventricular nucleus of the hypothalamus (PVN). Chemogenetic modulation of these ensembles revealed that vCA1→IL drove higher order valence (associative learning) whilst vCA3→PVN ensembles drove innate order valence (innate responses). Our electrophysiology work revealed that the firing patterns of the glutamatergic units were altered in a manner similar to that seen in the chemogenetic experiments. Namely, the cortical ensemble was necessary for driving associative learning whilst the hypothalamic ensemble drove the adaptation to innate order negative valence encoding. We also observed that the vCA1 neurons showed a stronger degree of spatial context discrimination in a zone-dependent manner. xiii Taken together the work establishes that the ventral hippocampal subfields execute specialized, parallel computations via direct glutamatergic projections to their target to drive appropriate behavioral responses to a negative stimulus.
Date
8-11-2026
Recommended Citation
Vats, Ajn, "Ventral Hippocampal Glutamatergic Ensembles Drive Aversive Modality Through Cortical and Hypothalamic Projections" (2026). LSU Doctoral Dissertations. 7194.
https://repository.lsu.edu/gradschool_dissertations/7194
Committee Chair
Ogundele, Olalekan M.
LSU Acknowledgement
1
LSU Accessibility Acknowledgment
1