Neurocognitive Dynamics Of Sleep Onset

Harvard University, Cambridge MA

Investigators

Abstract

With National Science Foundation support, Dr. Walker will conduct a year long investigation of the human brain systems which control the descent from full consciousness into the reduced consciousness of sleep and produce the cognitive experience of sleep onset dreaming. Sleep is an essential part of human life, occupying approximately one third of our time. The shift from wake to sleep arguably represents the most striking transition that the human brain and mind normally experiences. Although we are beginning to understand what brain mechanisms trigger this shift, the actual processes that produce the state of sleep remain unknown. Of additional interest is the type of mental experience that accompanies this wake-sleep transition, often involving brief hallucinations/dreams containing visual and auditory events as well as feelings of movement. Recent studies have suggested that these sleep-onset dreams are related to the re-play and consolidation of memories of novel daytime experiences, particularly those requiring the learning of new skills (e.g. engage in novel physical or mental activities for extended periods of time such as the first day of skiing). Dr. Walker and colleagues have been able to reliably produce near identical, stereotyped sleep-onset dreams by having human subjects play a ski simulator game for extended periods during the day. The present project uses this method to observe and control the cognitive processes of sleep onset dreaming as volunteers brains are being imaged in functional magnetic resonance scanner. Identifying the brain mechanisms involved in the sleep-onset process would provide information of wide value to both the basic neurosciences and to clinical research. It would not only increase our understanding of the neurocognitive basis of both the sleeping brain and the dreaming mind, but would also expand our understanding of human sensory and perceptual experience and of how new knowledge and skills are acquired, learned and reprocessed. This information would also provide a platform for new theories of human perception, cognition and learning, and will assist in the formulation of new treatments for a variety of neurological and sleep disorders.