Enhancement of synchronization between hippocampal and amygdala theta waves associated with pontine wave density

Theta waves in the amygdala are known to be synchronized with theta waves in the hippocampus. Synchronization between amygdala and hippocampal theta waves is considered important for neuronal communication between these regions during the memory-retrieval process. These theta waves are also observed...

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Bibliographic Details
Published in:Journal of neurophysiology 2010-05, Vol.103 (5), p.2318-2325
Main Authors: Karashima, Akihiro, Katayama, Norihiro, Nakao, Mitsuyuki
Format: Article
Language:English
Subjects:
Amygdala - physiology
Animals
Cortical Synchronization
Electrodes, Implanted
Electromyography
Hippocampus - physiology
Microelectrodes
Pons - injuries
Pons - physiology
Rats
Rats, Sprague-Dawley
Signal Processing, Computer-Assisted
Sleep, REM - physiology
Theta Rhythm
Time Factors
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Summary:Theta waves in the amygdala are known to be synchronized with theta waves in the hippocampus. Synchronization between amygdala and hippocampal theta waves is considered important for neuronal communication between these regions during the memory-retrieval process. These theta waves are also observed during rapid eye movement (REM) sleep. However, few studies have examined the mechanisms and functions of theta waves during REM sleep. This study examined correlations between the dynamics of hippocampal and amygdala theta waves and pontine (P) waves in the subcoeruleus region, which activates many brain areas including the hippocampus and amygdala, during REM sleep in rats. We confirmed that the frequency of hippocampal theta waves increased in association with P wave density, as shown in our previous study. The frequency of amygdala theta waves also increased with in associated with P wave density. In addition, we confirmed synchronization between hippocampal and amygdala theta waves during REM sleep in terms of the cross-correlation function and found that this synchronization was enhanced in association with increased P wave density. We further studied theta wave synchronization associated with P wave density by lesioning the pontine subcoeruleus region. This lesion not only decreased hippocampal and amygdala theta frequency, but also degraded theta wave synchronization. These results indicate that P waves enhance synchronization between regional theta waves. Because hippocampal and amygdala theta waves and P waves are known to be involved in learning and memory processes, these results may help clarify these functions during REM sleep.
ISSN:0022-3077
1522-1598
DOI:10.1152/jn.00551.2009