Summary: 6
6
Role of the locus coeruleus-norepinephrine
system in arousal and circadian regulation of
the sleep­wake cycle
Gary Aston-Jones, Ph.D., Monica Gonzalez, and Scott Doran
University of Pennsylvania, Philadelphia, USA
Introduction
A variety of previous results indicate that the norepinephrine (NE) locus coeruleus
(LC) system is integrally involved in regulation of sleep and waking. In particular,
LC activation promotes wakefulness. This appears to be one of the major arousal
systemsinthebrain.TheLCwasalsofoundtobecriticalforreboundsleepfollowing
sleep deprivation, and increased sleep that occurs following a stressor. We recently
identified a circuit from the suprachiasmatic nucleus (SCN) to the LC, in which the
dorsomedialhypothalamus(DMH)servesasarelay.Thefunctionalityofthiscircuit
was confirmed in our studies, showing that LC neurons have a circadian rhythm in
their firing activity and that this circadian fluctuation in the LC requires an intact
DMH. Other recent studies have also shown that lesions of the LC decrease the
amplitude of the circadian rhythm in the sleep­wake cycle. These results indicate
that the LC may be an important component in SCN efferent circuitry for driving

Source: Aston-Jones, Gary - Department of Neurosciences, Medical University of South Carolina

Collections: Biology and Medicine