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Distinct roles of the anterior and posterior medial temporal lobe in memory retrieval revealed by intracranial EEG

Poster Session C - Sunday, March 8, 2026, 5:00 – 7:00 pm PDT, Fairview/Kitsilano Ballroom

Qin Yin¹ (), Elizabeth Johnson², Robert Knight³, Eishi Asano^4,5, Noa Ofen^1,5; ¹University of Texas at Dallas, Dallas, TX, ²Northwestern University, Chicago, IL, ³University of California, Berkeley, CA, ⁴Children’s Hospital of Michigan, Detroit, MI, ⁵Wayne State University, Detroit, MI

The medial temporal lobe (MTL) is crucial for episodic memory, with anterior and posterior regions posited to differentially support memory. In this study, we aimed to elucidate the time-resolved contributions of anterior (aMTL) and posterior (pMTL) MTL to memory retrieval by examining pediatric intracranial EEG from 19 subjects (5.9-20.5 years). Subjects completed a scene recognition memory task and made old/new judgments during recognition. We analyzed high-frequency activity (HFA; 70-150Hz) for hit (old responses to studied scenes) and miss (new responses to studied scenes) trials. The timing of HFA differed between pMTL and aMTL, such that in pMTL, HFA peaked after scene onset, while in aMTL, HFA peaked at the time when subjects made retrieval responses. Successful retrieval effects (contrasting HFA between hit and miss trials) were analyzed by aligning pMTL data to scene onset and aMTL data to the old/new response onset. In the pMTL, there were no activity differences between hits and misses. In contrast, in the aMTL, hit trials were associated with increased HFA. Importantly, this anterior HFA increase occurred around the time of the retrieval response. This effect did not differ by age. Taken together, these findings support a functional gradient of the MTL and highlight the importance of aMTL activity in memory decisions across development.

Topic Area: LONG-TERM MEMORY: Episodic