Abstract Details

Title Identification of Phase-amplitude Coupling in the Human Hippocampus During Episodic Memory Processing

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) P8 - Poster Session 8 (11:45 AM-12:45 PM)

Poster/Presentation
Number 10-010

Objective

Our objective was to characterize phase-amplitude coupling (PAC) along the hippocampal longitudinal axis, including PAC frequency distribution and association with successful memory encoding.

Background PAC provides an oscillatory framework for memory formation. The analysis of PAC in human electrophysiological data has proven challenging due to the transient nature of lower frequency power changes during mnemonic processing, as well as inter-subject heterogeneity.

Design/Methods

We used a bispectral analysis as a novel method of PAC quantification to characterize phase-amplitude coupling during episodic memory processing in the human hippocampus. Intracranial recordings from 49 neurosurgical patients, who performed an episodic memory paradigm, revealed PAC centered at a 2.5 Hz slow oscillation. We compared PAC frequency distributions between the anterior and posterior hippocampus. We also studied the relationship among PAC frequency, PAC event rate, and successful memory encoding.

Results We found PAC associated with successful memory encoding, which was more prevalent in the posterior hippocampus. We found an association between PAC event rate in the anterior hippocampus and encoding, as well as between posterior hippocampal PAC and retrieval.

Conclusions Our results link PAC to successful memory formation and reveal dissociation in activity during memory processing along the hippocampal longitudinal axis in the preferred frequency of modulation and in encoding versus retrieval effects. We link our results to theoretical models of phase organization of memory items positing distinct anterior versus posterior hippocampal networks supporting memory activity.

Authors/Disclosures
Danial Syed, MD (Baylor College of Medicine) PRESENTER	Dr. Syed has nothing to disclose.
Christopher K. Kovach, PhD	The institution of Prof. Kovach has received research support from NIH. Prof. Kovach has received intellectual property interests from a discovery or technology relating to health care.
Bradley Lega, MD (UT Southwestern)	The institution of Bradley Lega has received research support from NIH.

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