Primary Sensorimotor Cortex Drives the Common Cortical Network for Gamma Synchronization in Voluntary Hand Movements

Area of Science:

• Neuroscience
• Motor Control
• Brain Oscillations

Background:

• Gamma synchronization (GS) is hypothesized to facilitate communication between cortical and subcortical neural populations.
• Understanding GS sources and information flow is crucial for deciphering neural processing during motor tasks.

Purpose of the Study:

• To identify the sources of gamma synchronization (GS) during voluntary hand movements.
• To analyze the direction of information flow within cerebral networks during phasic and isometric hand contractions.

Main Methods:

• Electroencephalography (EEG) and surface electromyography (sEMG) were recorded from 11 healthy volunteers.
• Time-frequency analysis using the multitaper method identified GS sources via beamformer inverse solution.
• Renormalized partial directed coherence estimated information flow direction, with surrogate testing for significance.

Main Results:

• Common GS sources across tasks included contralateral primary sensorimotor cortex (S1M1), dorsolateral prefrontal cortex (dPFC), and supplementary motor cortex (SMA).
• GS was observed in specific low and high gamma frequency bands in the contralateral thalamus and ipsilateral cerebellum.
• S1M1 demonstrated efferent information flow to SMA and dPFC; dPFC showed no detected afferent connections in the gamma range.

Conclusions:

• A distinct cortical network for GS was identified during voluntary hand movement tasks.
• S1M1 actively modulates interconnected cortical areas via GS, while subcortical structures dynamically influence motor networks.
• Cortical-subcortical information flow via GS is dynamically variable and specific to the movement program.