Poster Session C, Sunday, March 24, 5:00 – 7:00 pm, Pacific Concourse
Predictors of sleep-dependent memory consolidation
Dan Denis1,2, Verda Bursal1, Craig Poskanzer1, Lily Charron1, Robert Stickgold1,2; 1Beth Israel Deaconess Medical Center, 2Harvard Medical School
A large body of evidence has shown that sleep plays a critical role in the consolidation of memories. It is less clear how the brain selects and prioritizes which memories get consolidated during sleep. Here, we used EEG to identify neural activity during initial memory encoding that can be used to predict subsequent memory consolidation during sleep. Participants learnt pairs of words at a computer, followed immediately by a cued recall test. Six hours later, participants performed a second recall test. N = 20 participants stayed awake for the full six hour period, whilst N = 25 had a two-hour nap opportunity followed by four hours awake. EEG was recorded throughout encoding, recall, and the nap. The nap group showed superior memory retention at the delayed test compared to the wake group. Theta (4-8Hz) activity at the moment of encoding significantly predicted memory consolidation in the nap group. A mediated regression model showed that this relationship was mediated by sleep spindles. Additionally, successful memory recall after sleep was associated with significantly lower theta activity than successful recall following a period of wake. These results show that neural activity occurring during initial memory encoding contains information that can be used to predict consolidation processes. Our results suggest that theta activity during encoding may act as a potential ‘tagging’ mechanism for consolidation. Finally, we found that sleep reduces the amount of theta activity associated with successful memory recall. This may reflect a sleep-dependent transfer of information from mediotemporal to neocortical networks.
Topic Area: LONG-TERM MEMORY: Episodic