Implications of Anesthetics on Sleep Consolidation

Study Summary

Sleep leads to consolidation of learning in humans, restoring memories that were forgotten over a waking day and protecting memories against future forgetting. Although theories of consolidation have linked sleep spindles seen on electroencephalography to consolidation due to their putative role in hippocampal transfer to the neocortex (Antony et al, 2019; Antony \& Paller, 2017), spindles have not yet been linked to consolidation of perceptual learning or generalized learning. Prior research by a collaborator on this project has shown that sleep specifically aids in the consolidation of generalized perceptual learning of speech (Fenn, Nusbaum, \& Margoliash, 2003). Subjects show a 10-point reduction in performance after a waking retention period, while no loss is found after a retention period containing sleep (Fenn et al., 2003). Various measurable activities in the brain are associated with memory consolidation during sleep. This project intends study the effect of dexmedetomidine on memory consolidation during sleep Hypothesis 1 The gain in perceptual learning after a 90 minute natural sleep nap will also occur after 90 minutes of a sufficient dose of IV dexmedetomidine to replicate sleep. This result would suggest that consolidation can occur under this anesthetic state of consciousness. Hypothesis 2 The number and quality of sleep spindles seen on EEG in subjects administered dexmedetomidine will correlate with this gain in perceptual learning. This result would suggest that biomimetic sleep spindles are sufficient for producing memory consolidation. Only those subjects capable of giving their own consent will be considered for this study. The study will enroll 20 healthy subjects for this study between the ages of 18 and 35. All volunteers will be fit and healthy, meeting the American Society of Anesthesiologists (ASA) physical status classification ASA 1 (normal healthy subjects) and ASA 2 (stable chronic condition) and of normal body habitus. Prior to

Primary Outcome

Subjects are tested in the morning for word recognition on hard-to-understand speech, then trained on this speech (never hearing the same words twice) which produces about 20 percentage points of improvement. After sedation subjects are re-tested. During the morning, afternoon and evening post-tests, subjects will be tested on new spoken words. At each time point where the perceptual learning protocol is administered the number of words correctly perceived out of 50 will be measured.

Interventions

• DRUG Dexmedetomidine