A
group of neurons in the intergericulate nucleus stained
with the immediate early gene, FOS, when the rat is
exposed to an abrupt shift from darkness to light.
Abrupt
changes in lighting conditions have a profound effect on
behavior, regardless of whether these changes in illumination
occur during the day or the night. What components of the
visual system are involved in mediating the effects of acute
changes in lighting on sleep patterns? In collaboration with
Dr. Ruth Benca (Department of Psychiatry), we have begun
to explore this question. Our initial findings indicate that
the superior colliculus and pretectum are involved. In particular,
removal of the pretectum eliminates the characteristic REM
sleep triggering response that is seen in albino rats following
a light-to-dark transition. Using FOS immediate early gene
expression, we have localized neurons in small regions of
the pretectum that are active during acute light-dark transitions.
Some pretectal nuclei are particularly responsive at midnight,
others at midday, suggesting that the illuminance detection
system is linked to the circadian system. We next asked the
question: does rearing rats in continuous dark or continuous
light have an impact on sleep, or on the response to acute
changes in lighting conditions? Preliminary findings from
dark-reared rats show a reduced retinal input to subcortical
visual structures. Interestingly, these rats show no changes
in overall sleep and wakefulness. However, they do show enhanced
REM triggering in response to light-dark transitions, suggesting
that disturbances in illumination during development have
lasting effects on aspects of sleep-wake behavior. We hope
these studies will lead to a better understanding of how
light affects normal individuals as well as those with seasonal
depression, and pre-term infants that have been exposed to
continuous illumination in hospital settings.These studies
are supported by the National
Institutes of Mental Health.
Publications
Related to This Topic:
Miller,
A.M., W.H. Obermeyer, M. Behan and R.M. Benca. 1998 Effects
of superior colliculus-pretectal lesions on sleep: a novel
site for mediating light induced sleep-behaviors. Proc. Natl.
Acad. Sci. 95: 8957-8962. [Abstract] [Full
Text] [Full
Text (PDF)]
Miller,
A.M., R.B. Miller, W.H. Obermeyer, M. Behan and R.M. Benca.
1999 The pretectum mediates rapid eye movement (REM)
sleep regulation by light. Behav. Neurosci. 113:755-765. [Abstract]
Prichard,
J.R., Stoffel R.T., Quimby, D.L., Obermeyer, W.H. Benca,
R.M. and M. Behan, 2002. Fos immunoreactivity in rat subcortical
visual shell in response to illuminance changes. Neuroscience
114:781-793.[Full
text]
Prichard,
J.R., Fahy, J.L., Obermeyer, W.H., Behan, M. and Benca, R.M,
2004. Sleep responses to light and dark are shaped by early
experience. Behav. Neurosci. 118:1262-1273 [Abstract]
Fleming,
M.D., Benca, R.M. and M. Behan. 2006. Retinal projections to
the subcortical visual system in congenic albino and pigmented
rats. Neuroscience. 143: 895-904. [Abstract]
Prichard, JR., Benca, R.M., and M.Behan. 2007. Light-dependent
retinal innervation of the rat superior colliculus. Anat.
Rec. 290:341-348. [Abstract]
