Overnight memory transformation in the human brain– from perceptual detail to conceptual gist

Poster Session C - Sunday, April 14, 2024, 5:00 – 7:00 pm EDT, Sheraton Hall ABC

Simon Faghel-Soubeyrand¹ (simon.faghel-soubeyrand@psy.ox.ac.uk), Polina Perzich¹, Bernhard Staresina¹; ¹University of Oxford, Department of Experimental Psychology

How do memories change over time? Recent work suggests that in the process of consolidation, memory representations undergo transformations across a perceptual-to-conceptual gradient. While sleep is strongly implicated in memory consolidation, its impact on this gradient remains poorly understood. Here we used high-density scalp electroencephalography (EEG) to track memories across i) encoding, ii) pre-sleep retrieval, iii) whole-night sleep and iv) post-sleep retrieval. Participants (n=24) learned word-image associations (verb-object and verb-scene) across two separate experimental sessions. We used support vector machine (SVM) classifiers to decode memory representations at two different levels of abstraction: lower-level perceptual (i.e., image-based) and higher-level categorical (i.e., object vs. scene). This was done by using brain activity from an independent one-back task and by testing the classifiers' decoding accuracies during pre- and post-sleep retrieval. Results revealed a dissociation of representational decodability from pre-to post sleep retrieval. Specifically, while lower-level perceptual decoding was greater during pre-sleep compared to post-sleep retrieval, the inverse was true for higher-level categorical decoding. These findings are consistent with the notion that (sleep) consolidation transforms memory representations from high-fidelity reinstantiations into more schema-like, conceptual ‘gists’.

Topic Area: LONG-TERM MEMORY: Episodic