Autonomic Mechanisms of Sleep-Dependent Memory Consolidation

The goal of the proposed project is to identify the impact vagal activity during sleep for memory formation. Nearly 100 years of research contends that sleep plays a critical role in memory consolidation (i.e. the transformation of recent experiences into stable, long-term memories), yet much of this literature has focused on the central nervous system and technologies like electroencephalography (EEG) to unpack neural correlates involved in memory processing. Sleep is also a unique period of autonomic variation and an expansive literature has indicated the critical importance of the autonomic nervous system for memory formation. This project would be amongst the first to examine the autonomic nervous system during sleep as a critical, causal pathway linking sleep to memory processing. The investigators will assess the impact of non-invasive, transcutaneous vagal nerve stimulation on sleep and post-sleep memory performance. Autonomic physiology, including electrocardiography and impedance cardiography, will be gathered at baseline, before the memory task and continuously during sleep to examine vagal tone (i.e. heart rate variability) and sympathetic activation (i.e. pre-ejection period) in response to both active and sham stimulation conditions. Polysomnography will also be gathered during the nap to examine sleep architecture. The proposed research will address a critical gap in the literature by: 1) examining the causal role of the ANS for memory functioning in humans, 2) extending the current understanding of sleep's impact on memory processing, and 3) set the groundwork for novel, sleep-based interventions with the goal of improving cognitive health.