Sleep is an important time during which newly learned information is consolidated into a more permanent form. However, emerging evidence suggests that memory may also be consolidated during short periods of quiet waking rest interspersed throughout the day. The conditions under which this occurs remain unknown, and the neurophysiology supporting consolidation during periods of waking rest has not been described. The long- term goal of this research is to understand the cognitive function of rest states during wakefulness. The objective of the current project is to define the features of waking rest that contribute to its memory-enhancing effect, and to isolate the neurophysiological mechanisms responsible. Initial studies will systematically vary the behavioral features of a post-learning rest period in order to identify the characteristics accounting for its beneficial efect on memory. Preliminary data suggest that wakeful rest supports consolidation only when attention to sensory input is minimized, and in the absence of competing cognitive demands. Second, a direct comparison of rest and sleep periods following learning will assess the extent to which waking rest can produce the same memory benefits as sleep. If waking rest contributes to the consolidation of memories across the 24- hour cycle, under some conditions the memory benefit of waking rest may equal that of sleep. Finally, using high-density EEG combined with noninvasive brain stimulation techniques, this research will assess the causal contribution of resting state brain oscillations to memory consolidation. Initial experiments will establish the EEG correlates of consolidation during waking rest. Based on preliminary data, we expect that an electrophysiological signature of decreased high-frequency activity and increased slow oscillatory activity (<1Hz) will predict a superior memory outcome. The causal contribution of these neural oscillations to the consolidation process will be tested using noninvasive brain stimulation methods to manipulate resting state brain activity. The current proposal is unique in its multilevel approach to describing and manipulating resting state memory consolidation outside of sleep per se. By manipulating both behavior and neurophysiology, we will isolate the general characteristics of a neurobehavioral state that optimize memory processing. This work will enable a broader understanding of how conscious states contribute to memory consolidation, defining the necessary and sufficient conditions for consolidation to occur in wakefulness or sleep.
This research will benefit public health by facilitating a greater understanding of long-term memory consolidation during wake and sleep, as well as the dysfunction of this process in memory- and sleep-related disorders. In the long term, this work could lead to new methods of enhancing memory retention in patients suffering from age-related memory decline or other memory disorders.