|
Trends in Pharmacological Sciences
Volume 26, Issue 11 , November 2005, Pages 578-586
Copyright © 2005 Elsevier Ltd All rights reserved.
From waking to sleeping: neuronal and chemical substrates
Barbara E. Jones, Department of Neurology and Neurosurgery, McGill
University, Montreal Neurological Institute, Montreal, Quebec H3A
2B4, Canada
Multiple arousal systems maintain waking through the actions of
chemical neurotransmitters that are released from broadly distributed
nerve terminals when the neurons fire.
Among these, noradrenaline-, histamine- and orexin-containing neurons
fire during waking with behavioral arousal, decrease firing during
slow-wave sleep (SWS) and cease firing during paradoxical sleep (PS),
which is also known as rapid-eye-movement sleep. By contrast, acetylcholine
(ACh)-containing neurons discharge during waking, decrease firing
during SWS and fire at high rates during PS in association with fast
cortical activity.
Neurons that do not contain ACh, including GABA-containing neurons
in the basal forebrain and preoptic area, are active in a reciprocal
manner to the neurons of the arousal systems: one group discharges
with slow cortical activity during SWS, and another discharges with
behavioral quiescence and loss of postural muscle tone during SWS
and PS. The reciprocal activities and interactions of these wake-active
and sleep-active cell groups determine the alternation between waking
and sleeping. Selective enhancement and attenuation of their discharge,
transmitter release and postsynaptic actions comprise the substrates
for the major stimulant and hypnotic drugs.
|
