**Please note new start time of 2:30pm.**
Animals rely on olfaction for a wide range of natural behaviors. To support behaviors such as foraging and navigation, the brain must integrate odor information with an internal model of the spatial environment to produce flexible behavior . In order to understand neural circuits underlying the dynamic integration of sensory and spatial information, we designed an odor-cued spatial choice task for freely-moving rats, where rats use odor information for allocentric navigation. The highly recurrent and plastic nature of excitatory circuits in primary olfactory (piriform) cortex (PCx), together with abundant connections with higher order structures, make PCx an excellent site to investigate interactions between sensory information and associational or cognitive processes . We recorded from posterior PCx (pPCx) in rats with stable task performance. We found that individual pPCx neurons were not only odor-selective, but also fired differentially to the same odor sampled at different locations, forming an “odor-place map”. Spatial locations could be successfully decoded from simultaneously recorded pPCx population. Strikingly, we found that location representation in pPCx did not depend on direct sensory drive and was maintained across behavioral contexts and during intertrial intervals. We quantified spatial information carried by pPCx spikes on the behavioral arena during inter-trial intervals , and found that spatial information carried by pPCx spikes was maximal at odor port locations, and decreased as a function of distance to ports. This result pointed to the associative nature of location representations in pPCx. Using simultaneous recordings in hippocampus (HPC) and coherence analysis of pPCx spike times and HPC local field potentials (LFPs), we found that HPC projections preferentially drive those pPCx neurons with higher spatial selectivity. Together, our results reveal an associative odor-place map in pPCx that is well-suited to guide olfactory navigation, and challenge the conventional view of how spatial information is represented in the brain. A cognitive map of space in primary sensory cortex allows incoming sensory evidence to directly update an internal model, and could be critical for a wide range of spatial behaviors where seamless and dynamic integration of sensory information and cognitive maps are critical.
1. Baker KL, Dickinson M, Findley TM, et al. Algorithms for Olfactory Search across Species. J Neurosci. 2018;38(44):9383-9389.
2. Haberly LB, Bower JM. Olfactory cortex: model circuit for study of associative memory? Trends Neurosci. 1989;12(7):258-264.
3. Skaggs WE, McNaughton BL, Gothard KM, Markus EJ. An information-theoretic approach to deciphering the hippocampal code. Advances in Neural Information Processing Systems 5. 1993. pp. 1030–1037.
For questions about this seminar, please contact Carl Schoonover, PhD.