The Organization of the Suprachiasmatic Circadian Pacemaker of the Rat and its Regulation by Neurotransmitters and Modulators

This research addresses the cellular organization and regulation of a biological clock that controls daily (circadian) rhythms of behavior (e.g., performance), physiology and metabolism in mammals. This clock, located in the brain's suprachiasmatic nucleus (SCN), can be removed in a slice of hypothalamus, maintained in a life support system for up to 3 days and studied directly. Using this approach, progress in year 1 of this award has been made in (1) localizing time-keeping properties within the SCN of rat, (2) establishing the regulatory role of serotonin, a neuromodulatory input from the brain's arousal center in the raphe nucleus, and (3) examining the release of excitatory amino acids from the optic tract in the region of the SCN. This project involves both individual and interactive research projects at the University of Illinois and the USAF SChool of Aerospace Medicine.