High gamma coherence between task-responsive sensory-motor cortical regions in a motor reaction-time task

Area of Science:

• Neuroscience
• Electrophysiology
• Systems Neuroscience

Background:

• High gamma activity (70-170 Hz) typically reflects local cortical ensemble activity.
• Neural synchrony (coherence) is hypothesized to mediate inter-areal communication for cognition.
• High gamma activity has mainly been studied as a local amplitude phenomenon.

Purpose of the Study:

• To investigate the synchronization of high gamma activity within sensory-motor cortex.
• To determine if local high gamma power explains high gamma coherence during motor tasks.
• To characterize high gamma coherence in sensory-motor networks.

Main Methods:

• Analysis of electrocorticography (ECoG) data from human subjects.
• Subjects performed a motor response to sensory cues.
• Characterization of high gamma coherence and power during task performance.

Main Results:

• High gamma coherence significantly increased during motor response compared to sensory cue.
• High gamma power poorly predicted high gamma coherence, despite a similar time course.
• High gamma coherence persisted longer than high gamma power.

Conclusions:

• High gamma coherence is a distinct physiological phenomenon during sensory-motor tasks.
• Active task participation may be required for the emergence of high gamma coherence.
• High gamma coherence may indicate increased synaptic communication on short timescales.