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Poster E35

Temporal dynamics of memory encoding and retrieval in the human medial temporal lobe and prefrontal cortex

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Adam Dede1 (, Zachariah Cross1, Samantha Gray1, Qin Yin2, Parisa Vahidi2, Eishi Asano2, Stephan Schuele1, Joshua Rosenow1, Joyce Wu1,3, Sandi Lam1,3, Jeffrey Raskin1,3, Jack Lin4, Olivia Kim-McManus5, Shifteh Sattar5, Ammar Shaikhouni6, David King-Stephens7,8, Peter Weber7, Kenneth Laxer7, Peter Brunner9, Jarod Roland9,10, Saez Ignacio11,12, Fady Girgis11,13, Robert Knight14, Noa Ofen2, Lisa Johnson1; 1Northwestern University, 2Wayne State University, 3The Ann & Robert H. Lurie Children's Hospital of Chicago, 4University of California Davis, 5University of California San Diegoand UCSD Rady Children's Hospital, 6Ohio State University, 7California Pacific Medical Center, 8Yale University, 9Washington University in St. Louis, 10St. Louis Children's Hospital, 11University of California Davis, 12Ichan School of Medicine at Mount Sinai, 13University of Calgary, 14University of California Berkeley

The medial temporal lobe and prefrontal cortex coordinate their activity in the service of memory. We used intracranial recordings from 36 neurosurgical patients (22 male, 19 ± 4.7 years old) to investigate the relative timing of activity in these regions during encoding and recognition testing of natural scene images. From an initial set of 605 channels, we selected only those with task-related high frequency broadband (HFB; 70-150 Hz) responses--which index neuronal population activity--yielding 181 dorsolateral prefrontal cortex channels, 30 anterior cingulate cortex channels, 30 polar prefrontal cortex channels, 67 parahippocampal and rhinal cortex (PHRC) channels, and 29 hippocampal (HC) channels. Linear mixed-effects modeling revealed a three-way interaction between hit/miss, region, and encoding/retrieval in predicting the latency of peak HFB activity. During successful encoding, PHRC was active first, followed by HC and then frontal regions. By contrast, during unsuccessful encoding, there was no difference in the timing of PHRC and HC activity. The HC’s HFB power also differentiated successful over unsuccessful encoding at the time of its peak activity. During successful retrieval, HC was active first, followed by PHRC and frontal regions in tight succession. By contrast, during unsuccessful retrieval, there was no difference in the timing of PHRC and HC activity, and frontal regions were more spread out in time. These results suggest that during encoding, HC receives information from PHRC, functioning as an extension of perception. During retrieval, HC functions as part of a top-down circuit involving the prefrontal cortex.

Topic Area: LONG-TERM MEMORY: Episodic


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