Induction of hippocampal long-term potentiation during waking leads to increased extrahippocampal zif-268 expression during ensuing rapid-eye-movement sleep.
Abstract
Rapid-eye-movement (REM) sleep plays a key role in the consolidation of memories acquired
during waking (WK). The search for mechanisms underlying that role has revealed significant
correlations in the patterns of neuronal firing, regional blood flow, and expression
of the activity-dependent gene zif-268 between WK and subsequent REM sleep. Zif-268
integrates a major calcium signal transduction pathway and is implicated by several
lines of evidence in activity-dependent synaptic plasticity. Here we report that the
induction of hippocampal long-term potentiation (LTP) during WK in rats leads to an
upregulation of zif-268 gene expression in extrahippocampal regions during subsequent
REM sleep episodes. This upregulation occurs predominantly in the amygdala, entorhinal,
and auditory cerebral cortices during the first REM sleep episodes after LTP induction
and reaches somatosensory and motor cerebral cortices as REM sleep recurs. We also
show that hippocampal inactivation during REM sleep blocks extrahippocampal zif-268
upregulation, indicating that cortical and amygdalar zif-268 expression during REM
sleep is under hippocampal control. Thus, expression of an activity-dependent gene
involved in synaptic plasticity propagates gradually from the hippocampus to extrahippocampal
regions as REM sleep recurs. These findings suggest that a progressive disengagement
of the hippocampus and engagement of the cerebral cortex and amygdala occurs during
REM sleep. They are also consistent with the view that REM sleep constitutes a privileged
window for hippocampus-driven cortical activation, which may play an instructive role
in the communication of memory traces from the hippocampus to the cerebral cortex.
Type
Journal articleSubject
AmygdalaAnimals
Brain
Cerebral Cortex
DNA-Binding Proteins
Early Growth Response Protein 1
Gene Expression Regulation
Hippocampus
Immediate-Early Proteins
Long-Term Potentiation
Male
Neural Pathways
RNA, Messenger
Rats
Rats, Sprague-Dawley
Sleep, REM
Transcription Factors
Up-Regulation
Wakefulness
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Show full item recordScholars@Duke
Erich David Jarvis
Adjunct Professor in the Dept. of Neurobiology
Dr. Jarvis' laboratory studies the neurobiology of vocal communication. Emphasis is
placed on the molecular pathways involved in the perception and production of learned
vocalizations. They use an integrative approach that combines behavioral, anatomical,
electrophysiological and molecular biological techniques. The main animal model used
is songbirds, one of the few vertebrate groups that evolved the ability to learn vocalizations.
The generality of the discoveries is tested in other vocal

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