Neuronal discharge of preoptic/anterior hypothalamic
thermosensitive neurons: relation to non rapid eye movement
sleep.
Alam, Md. Noor, Dennis McGinty, and Ronald Szymusiak.
Departments of Psychology, and Medicine, University of California,
Los Angeles (U.S.A.); Department of Veterans Administration Medical
Center, Sepulveda, California (U.S.A.).
APStracts 2:0177R, 1995.
Thermosensitive neurons of the preoptic/anterior hypothalamic area
(POAH) have been implicated in the regulation of non rapid eye
movement (NREM) sleep. We attempted to identify those medial POAH
thermosensitive neurons that may be involved in NREM sleep
regulation. The thermosensitivity of medial POAH neurons was studied
in five freely moving adult cats by local cooling or warming of the
medial POAH with a water perfused thermode. Of 308 neurons, 65 (21%)
were classified as thermosensitive including 31 (10%) warm-sensitive
and 34 (11%) cold-sensitive neurons. The spontaneous discharge rates
of 28 warm-sensitive, 34 cold-sensitive and 115 randomly selected
thermo-insensitive neurons were recorded through 1-3 sleep-waking
cycles. Patterns of spontaneous activity for warm- and cold-sensitive
neurons were different. Of 28 warm-sensitive neurons, 18 (64%)
exhibited increased discharge rate during NREM sleep as compared to
waking (NREM/Wake ratio, > 1.2). This subpopulation of warm
-sensitive neurons also exhibited significantly increased
thermosensitivity when tested during NREM sleep. Of 34 cold-sensitive
neurons, 25 (74%) discharged more slowly during NREM sleep as
compared to waking (NREM/Wake ratio, < 0.8). This subpopulation
of cold-sensitive neurons exhibited decreased thermosensitivity
during NREM sleep. These results are consistent with a hypothesis
that the activation of sleep-related warm-sensitive neurons and the
deactivation of wake-related cold-sensitive neurons may play a key
role in the onset and regulation of NREM sleep.
Received 28 December 1994; accepted in final form 12 June 1995.
APS Manuscript Number R738-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.