Dual origins of measured phase-amplitude coupling reveal distinct neural mechanisms underlying episodic memory in the human cortex

Neuroimage. 2017 Mar 1:148:148-159. doi: 10.1016/j.neuroimage.2017.01.001. Epub 2017 Jan 6.

Abstract

Phase-amplitude coupling (PAC) is hypothesized to coordinate neural activity, but its role in successful memory formation in the human cortex is unknown. Measures of PAC are difficult to interpret, however. Both increases and decreases in PAC have been linked to memory encoding, and PAC may arise due to different neural mechanisms. Here, we use a waveform analysis to examine PAC in the human cortex as participants with intracranial electrodes performed a paired associates memory task. We found that successful memory formation exhibited significant decreases in left temporal lobe and prefrontal cortical PAC, and these two regions exhibited changes in PAC within different frequency bands. Two underlying neural mechanisms, nested oscillations and sharp waveforms, were responsible for the changes in these regions. Our data therefore suggest that decreases in measured cortical PAC during episodic memory reflect two distinct underlying mechanisms that are anatomically segregated in the human brain.

Keywords: Nested oscillations; Sharp waveforms; iEEG.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adult
  • Algorithms
  • Association
  • Brain Mapping
  • Cerebral Cortex / physiology*
  • Drug Resistant Epilepsy / diagnostic imaging
  • Drug Resistant Epilepsy / surgery
  • Electrodes, Implanted
  • Electroencephalography
  • Entropy
  • Female
  • Humans
  • Male
  • Memory, Episodic*
  • Psychomotor Performance / physiology
  • Wavelet Analysis