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Related Experiment Video

Updated: Mar 29, 2026

Combined Invasive Subcortical and Non-invasive Surface Neurophysiological Recordings for the Assessment of Cognitive and Emotional Functions in Humans

Combined Invasive Subcortical and Non-invasive Surface Neurophysiological Recordings for the Assessment of Cognitive and Emotional Functions in Humans

Published on: May 19, 2016

Different coupling modes mediate cortical cross-frequency interactions.

Randolph F Helfrich¹, Christoph S Herrmann², Andreas K Engel³

¹Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA.

|November 27, 2015

Summary

This summary is machine-generated.

This study investigates cross-frequency coupling (CFC) in the brain. Using transcranial alternating current stimulation (tACS), researchers found that alpha oscillations modulate gamma power (phase-amplitude coupling), while gamma oscillations affect alpha power (amplitude-envelope correlations), impacting visual processing.

Keywords:

Cross-frequency coupling Entrainment Intrinsic coupling modes Oscillatory alpha–gamma interplay Phase-amplitude coupling Transcranial alternating current stimulation

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Analyzing Neural Activity and Connectivity Using Intracranial EEG Data with SPM Software

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Published on: October 30, 2018

Area of Science:

Neuroscience
Cognitive Neuroscience
Computational Neuroscience

Background:

Cross-frequency coupling (CFC) is crucial for brain information processing, integrating signals across different scales.
The roles of low-frequency (alpha) and high-frequency (gamma) oscillations in orchestrating CFC remain unclear.
Distinct CFC modes, phase-amplitude coupling (PAC) and amplitude-envelope correlations (AEC), may serve different cortical functions.

Purpose of the Study:

To investigate the causal roles of alpha and gamma oscillations in modulating CFC.
To differentiate the functional contributions of PAC and AEC.
To explore the impact of selective neural entrainment on CFC dynamics.

Main Methods:

Utilized transcranial alternating current stimulation (tACS) to selectively entrain alpha or gamma oscillations.
Measured changes in CFC, specifically PAC and AEC, during neural entrainment.
Analyzed the differential effects of low-frequency vs. high-frequency entrainment on oscillatory interactions.

Main Results:

Entraining alpha oscillations increased PAC, locking gamma power to alpha troughs.
Entraining gamma oscillations enhanced AECs and reduced alpha power.
Demonstrated differential modulation of CFC by selective frequency entrainment.

Conclusions:

Provided causal evidence for the distinct roles of alpha and gamma oscillations in CFC.
Highlighted the functional significance of coupled alpha and gamma oscillations in visual processing.
Established tACS as a tool to probe the causal underpinnings of CFC.