Poster E70, Monday, March 26, 2:30-4:30 pm, Exhibit Hall C
Prioritization of weakly-encoded information for sleep-dependent consolidation
Dan Denis1,2, Verda Bursal1,2, Shanice Oquin1,2, Alexandra Morgan1,2, Robert Stickgold1,2; 1Beth Israel Deaconess Medical Center, 2Harvard Medical School
A large body of evidence has shown that sleep plays an important role in the consolidation of declarative memory. More recently, it has been suggested that the brain prioritizes certain memories to be consolidated over others. The mechanisms underlying this remain unclear. This study investigated the role initial encoding strength may play in the selection of memories that undergo consolidation. Participants learnt unrelated word-pairs to 3 different levels of encoding. Encoding strength was manipulated by the number of times each word-pair was presented. Following learning, an immediate free-recall test showed that the encoding strength manipulation successfully led to 3 distinct levels of encoding. Then, half the participants (n = 20) returned for a delayed test 12 hours later (constituting a wake group), with the other half (n = 20) returning 24 hours later (constituting a sleep group). At delayed test, it was found that the 24-hour group showed less forgetting across all encoding strength conditions compared to the 12-hour group, suggesting a general beneficial role of sleep on delayed test performance. Furthermore, a significant group x encoding condition interaction showed that, in the 24 hour group, there was significantly less forgetting for the most weakly encoded items compared to the other levels of encoding. These results suggest that sleep is important for the consolidation of declarative memory, and the brain prioritizes those items that are weakly encoded over more strongly learnt information.
Topic Area: LONG-TERM MEMORY: Episodic