FriSem

Alice Xue, Ph.D. Student in Psychology, admitted Autumn 2022

Title: Rhythms in Learning and Memory: Investigating Theta-Phase Coding of Memory States

Abstract: Remembering relevant past experiences can support adaptive behavior in the moment, while future behavior can be facilitated by encoding information from current experience into memory. Research on the neural mechanisms underlying memory encoding and retrieval frequently attempts to isolate these processes, advancing understanding of the neural circuits — such as the hippocampus — and computations that support learning and remembering independently. However, learning is enhanced when encoding and retrieval computations are dynamically engaged, as is frequently the case. Computational models of the hippocampus propose that dynamic switching between encoding and retrieval computations may be coordinated by oscillatory activity within the theta band, such that encoding is optimal at one phase of hippocampal theta and retrieval is optimal at the opposing phase. To test these model predictions and additionally investigate complementary questions regarding the role of mnemonic prediction errors in memory formation, we recorded scalp EEG and pupillometry as 39 young, healthy human adults performed an associative novelty task, wherein they encoded verb-image pairings and then performed a cued associative match/mismatch retrieval task. In my talk, I will first present our approach for integrating scalp EEG data, individual structural MRIs, and behavioral performance to investigate theta-phase coding of memory states. Then, I will share some initial findings as we analyze the behavior and pupillometry, isolate content (animate/inanimate category-level) representations in EEG data, and examine neural evidence of memory content reinstatement. Altogether, this work examines open questions regarding the temporal dynamics of neural mechanisms governing learning and memory.