Abstract:
Light is an important regulator of
behavioral state in mammals. In addition to effects on the circadian clock,
changes in lighting condi=
tions
can induce immediate changes in sleep-wakefulness. For example, light
increases wakefulness in humans and induces sleep in nocturnal rodents. We have used the albino rat as a
model to study acute effects of light-dark shifts on sleep patterns. Albino
rats show exaggerated resp=
onses
to abrupt lighting changes, particularly in their rapid eye-movement (REM)
sleep patterns; following lights-off, they exhibit large increases in REM sleep (REM sle=
ep
triggering), whereas lights-on suppresses REM sleep. In addition, light
acutely increases non- R=
EM
(NREM) sleep and dark increases waking in both albino and pigmented rats.
During the past 4 years of funding, we have characterized acute sleep-wakefulness respons=
es to
changes in light conditions and demonstrated that lesions of the superior =
colliculus (SC) and pretectum (PT) attenuate these
responses in albino rats. We propose an integrated series of studies to
further elucidate the
mechanisms by which the SC-PT region regulates sleep-wakefulness in respon=
se
to lighting changes: (1) Localize areas within the SC and PT which mediate REM sleep, NREM sleep and/or =
waking
responses to light-dark shifts; (2) Describe connections between the SC-=
span>PT and brain regions known to be involved in media=
ting
sleep and waking; (3) Use immediate early gene expression to identify brai=
n regions which respond to acute lighting changes and
correlate with behavioral responses; and (4) Determine the effects of SCN
lesions on sleep-waking res=
ponses
to light-dark shifts. Results from these studies should increase our
understanding of how light affects the nervous system, including effects of light therapy on slee=
p and
mood. Furthermore, we hope to elucidate the role of the SC-PT in REM sleep=
regulation, which may have relevance to disorders
characterized by abnormalities in REM sleep, and depression
=
span>
Thesaurus
Terms:
circadian rhythm,
ethology, photobiology, sleep, REM
sleep, brain mapping, gene expression, light intensity, mesencephalon,
neuronal transport,
photostimulus, regulatory gene, superior colliculus, suprachiasmatic nucle=
us,
visual pathway, visual photosensitivity, wakefulness, albino rat, behavioral /social science
research tag, electroencephalography, electromyography, experimental brain
lesion, genetic strain,
laboratory rat, stereotaxic technique
Fis=
cal
Year: 2003
Dep=
artment:
PSYCHIATRY
Pro=
ject
Start: 01-JAN-1995
Pro=
ject
End: 30-JUN-2006=
ICD=
: NATIONAL
INSTITUTE OF MENTAL HEALTH
IRG=
: ZRG1