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Poster D in Poster Session D: Wednesday, August 5, 2:00 – 3:45 pm, Kimmel Center, Shorin & Rosenthal Rooms

Single-Neuron Evidence for Hippocampal Long-Axis Gradient Supporting Semantic Coding in Humans

Sophia Cheng¹, Natalia Kurilenko¹, Chrystal M. Reed¹, William Anderson², Taufik Valiante³, Adam Mamelak¹, Ueli Rutishauser¹; ¹Cedars-Sinai Medical Center, ²Johns Hopkins University, ³University Health Network

Presenter: Sophia Cheng

The hippocampus (HPC) has been proposed to map both physical and abstract semantic spaces. In rodents, the size of place cells that map physical space varies systematically along the hippocampal long axis (HLA). We asked whether, in humans, properties of cells implicated in mapping semantic space vary similarly along the HLA. We analyzed a large single-neuron dataset (n=1383) from epilepsy patients implanted with hippocampal depth electrodes. We found that cells that selectively respond to different semantic categories were more prevalent and respond earlier in anterior HPC (aHPC) than posterior HPC (pHPC). Moreover, contrary to place cells in rodent, these cells had stronger selectivity in aHPC than in pHPC, suggesting a fundamental difference between the two cell types contrary to proposed unifying theories of cognitive maps.

Topic Area: Memory, Learning & Knowledge Structures