Brain and Behaviour Seminar Series: Hippocampus and Value

Hybrid Zoom link: https://utoronto.zoom.us/j/88607630965

The hippocampus has long been considered to process primarily cognitive variables related to spatial navigation and episodic memory, while value-related signals are processed elsewhere in the brain, such as the ventral striatum and orbitofrontal cortex. In this talk, I will present evidence indicating that the hippocampus encodes robust value signals and that, among its subregions, CA1 plays a particularly critical role in value processing. Building on these findings and neuroecological considerations, I will introduce a new model of the hippocampus—the simulation-selection model. According to this model, the mammalian hippocampus has evolved to simulate and evaluate arbitrary navigation routes. Specifically, we propose that CA3 has evolved to simulate unexperienced navigation sequences in addition to remembering experienced ones, while CA1 has evolved to select from these CA3-generated sequences, reinforcing those likely to maximize reward. We argue that the simulation-selection organization of the hippocampus has evolved in mammals, but not in birds, because of the unique ecological and navigational needs of land animals. Although solid empirical evidence is missing for many aspects of the model, it may account for why the mammalian hippocampus has evolved not only to remember, but also to imagine future episodes, and how this might be implemented in its neural circuits.

To request an individual meeting with the speaker, please contact Kaori Takehara (kaori.nishiuchi@utoronto.ca).

Visit https://www.takeharalab.com/bbseminar for further information.