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 between the region of interest and neighboring brain areas. Contrary to the hypothesized role of synchronous gamma oscillations in memory formation, we found that many key regions that showed power increases during successful memory encoding also exhibited decreases in global synchrony. Similarly, cortical theta activity that decreases during memory encoding exhibits both increased and decreased global synchrony depending on region and stage of encoding. We suggest that network synchrony analyses, as used here, can help to distinguish between two major types of spectral modulations: (1) those that reflect synchronous engagement of regional neurons with neighboring brain areas, and (2) those that reflect either asynchronous modulations of neural activity or local synchrony accompanied by global disengagement from neighboring regions. We show that these two kinds of spectral modulations have distinct spatiotemporal profiles during memory encoding.
Synchronous and Asynchronous Theta and Gamma Activity during Episodic Memory Formation
John F. Burke,K. Zaghloul,J. Jacobs,Ryan B Williams,M. Sperling,A. Sharan,M. Kahana
Published 2013 in Journal of Neuroscience
ABSTRACT
PUBLICATION RECORD
- Publication year
2013
- Venue
Journal of Neuroscience
- Publication date
2013-01-02
- Fields of study
Biology, Medicine, Psychology
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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