Presentation Details
| Don Tucker Finalist: Olfactory coding across ventral subregions of the hippocampus Anna C.Kolstad1, 2, Karol P.Szymula1, 2, Krishnan Padmanabhan1, 3, 4. 1Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA.2Medical Scientist Training Program, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.3Department of Neuroscience, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.4Center for Visual Science, University of Rochester, Rochester, NY, USA |
Abstract
While ventral hippocampus (VH) historically has been associated with memory, navigation, and anxiety, evidence increasingly suggests that chemosensory stimuli may influence VH neural responses. Although olfaction is involved in many hippocampal-related behaviors, how VH represents olfactory stimuli remains an open question. As the ventral CA1 (vCA1) subregion of VH receives both direct projections from olfactory cortex and indirect projections via the lateral entorhinal cortex through the CA3 and dentate gyrus (DG) VH subregions, vCA1 is likely a hub for both chemosensory and cognitive encoding. A necessary first step toward understanding how VH integrates sensory and cognitive representations is to identify what features of olfactory stimuli such as odorant identity are encoded for in neural firing, and how these patterns of firing vary across VH subregions. To address this question, we performed high-density extracellular electrophysiology recordings across vCA1, CA3, and DG in awake head-fixed 2-4-month-old C57BL/6J mice as they ran on a wheel while passively exposed to a panel of eleven odorants. When we examined neural activity from eight mice (4F/4M; n = 79 vCA1 units, n = 59 CA3 units, n = 28 DG units), we found across all three subregions neurons that are tuned to odors. Both increased and decreased single unit firing in response to odors was observed in all three subregions. Odor-tuned neurons were more prevalent in vCA1 compared to CA3 (67% vs. 34%, P <0.001). Odorant tuning profiles were more similar across DG neurons compared to in vCA1 or CA3. Taken together, our work suggests that different VH subregions have distinct strategies for encoding odors, suggesting that chemosensory stimuli may differentially impact cognitive representations across VH.
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