9728574 Gannon Afferent Regulation of Circadian Rhythms Most, if not all, living organisms synchronize the daily activity with the day-night cycle of an earth day. This synchronization is accomplished in higher-order organisms, such as mammals, by a network of neural cells in a small region of the brain called the suprachiasmatic nucleus. This neural network forms a "biological clock" that acts as the dominant time-keeping mechanism in mammals, and ensures that all physiological body systems are in synchrony. It is now becoming apparent that the biological clock in mammals does not act independently, but rather the clock' s timing can be influenced by input from other regions of the brain. This study seeks to identify how activation of these other brain regions can affect the timing of the biological clock. The results of this investigation will likely demonstrate that the biological clock in the suprachiasmatic nucleus is part of a larger pacemaker system in the mammalian brain, and that the clock integrates input from other brain regions before sending out a synchronizing signal to the body. This study will also significantly enhance the training of undergraduate students in the sciences, both by the acquisition of new tools which can be utilized for research and teaching, and by employing undergraduate students in every aspect of the research performed in accomplishing the objectives of this proposal.
