The Journal of Neuroscience http://jneurosci.msubmit.net Synchronous and asynchronous theta and gamma activity during episodic memory formation JN-RM-2057-12R1
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چکیده
Although it has been hypothesized that neural oscillations synchronize to mediate memory formation, direct evidence linking oscillatory phase-synchrony to successful memory encoding is limited. Using electrocorticography (ECoG) recorded from 68 neurosurgical patients participating in a free recall task, we compared phase-synchrony and spectral power during successful versus unsuccessful encoding using a region of interest approach and a graph theoretic metric. During successful memory encoding, theta synchrony increased in the left prefrontal cortex immediately after word presentation. Following this encoding related increase in theta synchrony we observed decreases in theta synchrony, and theta power, in both the prefrontal cortex as well as more widespread brain regions. Whereas gamma power increased during successful memory encoding, increases in gamma synchrony were limited to a small network in the right peri-sylvian region. In the left hemisphere, where gamma power displayed maximal increases during encoding, gamma activity was more asynchronous than expected by chance, contrary to theoretical predictions concerning the role of gamma power during memory formation. Our results demonstrate the dissociation between spectral power and phase-synchronous oscillations, and highlight the need to directly assess network interactions when interpreting the electrophysiologic correlates of cognitive functions.
منابع مشابه
Synchronous and asynchronous theta and gamma activity during episodic memory formation.
To test the hypothesis that neural oscillations synchronize to mediate memory encoding, we analyzed electrocorticographic recordings taken as 68 human neurosurgical patients studied and subsequently recalled lists of common words. To the extent that changes in spectral power reflect synchronous oscillations, we would expect those power changes to be accompanied by increases in phase synchrony b...
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تاریخ انتشار 2012