0102 The Relationship Between Overnight Consolidation and Next-Day Learning

Abstract

Abstract Introduction Contemporary models of sleep-associated consolidation posit that overnight memory processing paves the way for next-day learning in hippocampus. However, the extent to which new hippocampal learning is dependent on overnight consolidation has yet to be investigated. In this study, we compared the impacts of sleep and sleep deprivation on the consolidation and encoding of hippocampus-dependent memories and, importantly, examined whether individual differences in consolidation were associated with individual differences in encoding. Methods Thirty healthy adults (17 females, mean age 20.1±1.65) were trained on a spatial memory task in the evening before a night of sleep or total sleep deprivation (repeated measures). Participants completed a spatial memory test the following morning, and then encoded a novel set of word-image pairs. Two days later (after recovery sleep), memory for the word-image pairs was tested. We predicted that participants’ spatial memory recall would predict performance on the word-image test, suggesting that overnight consolidation lays the groundwork for new encoding in hippocampus. Results Sleep (vs. sleep deprivation) improved spatial memory accuracy the following morning (t(29)=3.93, p<.001, d=0.72) and word-image recall two days later (t(29)=12.19, p<.001, d=2.23), suggesting that sleep facilitated the consolidation and encoding of hippocampus-dependent memories, respectively. However, the benefit of sleep for spatial memory recall was not significantly correlated with the benefit of sleep for word-image encoding (r(28)= 0.01, p=0.971), suggesting that hippocampal encoding was not contingent on foregoing overnight consolidation processes. Conclusion In support of previous findings, overnight sleep improved consolidation and next-day encoding, as compared to an equivalent period of sleep deprivation. However, the present results did not reveal any relationship between an individual’s sleep-associated consolidation and their next-day learning. Support Department of Psychology, University of York scholarship to A.áV.G. Medical Research Council Career Development Award (MR/P020208/1) to S.A.C.