Schedule of Events | Symposia

Sleep predicts a hippocampal-cortical shift during memory recall

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Mathew Thomas Kollamkulam¹ (mathew.thomaskollamkulam@psy.ox.ac.uk), Simon Faghel-Soubeyrand¹, Katrijn Schruers¹, Bernhard Staresina¹; ¹University of Oxford

Consolidation theory proposes that sleep supports a shift in memory processing from the hippocampus to cortical regions. This study tests this hypothesis and examines the role of sleep architecture in consolidation. In a combined EEG-MRI experiment, participants completed an object-scene associative memory task. Half the stimuli were tested in the evening before sleep (PM session) and the other half in the morning after sleep (AM session). Behavioural results confirmed expected overnight forgetting, albeit at different rates across participants. Univariate fMRI analyses revealed session-dependent differences in brain activity during successful compared to unsuccessful recall (recall effect). Hippocampal and ventral visual cortex recall effects decreased in the AM session compared to the PM session, consistent with reduced hippocampal involvement and decreased vividness after sleep. Conversely, enhanced recall activity was observed in medial prefrontal regions during the AM session, consistent with prior findings. Importantly, the proportion of time spent in non-rapid eye movement (NREM) sleep correlated with both better memory performance and hippocampal activity modulation, highlighting the role of NREM sleep in memory consolidation. Together, these findings suggest a link between hippocampal-cortical activity changes, sleep architecture, and behavioural measures of memory consolidation.

Topic Area: LONG-TERM MEMORY: Episodic