Subcortical Mechanisms of Unihemispheric Sleep in the Fur Seal

Sepulveda Research Corporation, North Hills CA

Investigators

Abstract

Dolphins display an unusual form of sleep called unihemispheric slow wave sleep (USWS), in which brain waves typical of sleep appear in only one half of the cortex at a time. They do not exhibit rapid eye movement (REM) sleep at any time. This laboratory and their collaborators have found that when fur seals are on land they have both bilateral sleep, and REM sleep resembling the sleep seen in humans and all other land mammals. However, when fur seals are in water, their home for 6 months of the year, they have USWS and little or no REM sleep, like dolphins. Therefore, the sleep behavior of fur seals provides a unique opportunity to determine how the brain waves of sleep are generated and why, although all other mammals have REM sleep, this state is absent or greatly reduced when USWS occurs. To answer these questions, the project will focus on the changes going on below the cortex, determining the nature of the neurotransmitters that are released in subcortical regions during the various waking and sleep states. It is expected that this will lead to fundamental new understandings of "why we sleep" and "why we dream," two of the most important unanswered questions in neuroscience. Three graduate students will be trained and will complete their Ph.D.s during this project. This project represents a model international collaboration between a Russian marine mammal facility that is currently the only place in the world with the facilities and expertise to study sleep in marine mammals and laboratories in the USA, Japan, South Africa and Switzerland. This award is co-funded by NSF's Office of International Science and Engineering.