Modulating activity in the motor cortex affects performance for the two hands differently depending upon which...

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Previous studies indicated that altering neural excitability in the dominant motor cortex affects performance in both hands.
• Ipsilateral hand effects were hypothesized to be mediated by interhemispheric inhibition, with evidence suggesting asymmetry between motor cortices.

Purpose of the Study:

• To investigate hemispheric asymmetry in behavioral effects when modulating neural excitability in the human motor cortex.
• To determine if stimulating the dominant versus non-dominant motor cortex yields different performance outcomes for ipsilateral and contralateral hands.

Main Methods:

• Anodal and cathodal transcranial direct current stimulation (tDCS) were applied to the dominant and non-dominant motor cortices of 17 participants.
• Participants performed a finger-sequence coordination task before and after stimulation, with performance measured by correct keystrokes.

Main Results:

• Modulating excitability in the dominant motor cortex significantly impacted performance for both contralateral and ipsilateral hands.
• Modulating excitability in the non-dominant motor cortex significantly affected only the contralateral hand's performance.

Conclusions:

• The study provides evidence for hemispheric asymmetry in the ipsilateral effects of motor cortex excitability modulation.
• These findings may have implications for understanding motor recovery and developing clinical interventions.