Neurophysiological Basis of Sleep's Function on Memory and Cognition

Abstract

A wealth of recent studies support a function of sleep on memory and cognitive processing. At a physiological level, sleep supports memory in a number of ways including neural replay and enhanced plasticity in the context of reduced ongoing input. This paper presents behavioral evidence for sleep's role in selective remembering and forgetting of declarative memories, in generalization of these memories, and in motor skill consolidation. Recent physiological data reviewed suggests how these behavioral changes might be supported by sleep. Importantly, in reviewing these findings, an integrated view of how distinct sleep stages uniquely contribute to memory processing emerges. This model will be useful in developing future behavioral and physiological studies to test predictions that emerge.

Figure 1

Model of the neurophysiological basis of sleep’s function on memory and cognition. Brain states cycle throughout the night between nREM and REM sleep stages. Early in the night (a), SWS predominates with interleaving bouts of REM sleep. The evolution of the memory varies across these cycles (b). At the beginning of the night (A), recent memories (represented by various shapes) are active. In early SWS, overlapping recent memories (illustrated as circles and squares) are integrated. During interleaving REM (B), similar existing memories (circles and squares) and new memories with future relevance are tagged for integration in subsequent SWS bouts (C).