Dual-hemispheric transcranial direct current stimulation (tDCS) over primary motor cortex does not affect movement...

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Neuroscience

Background:

• Volition and sense of agency are crucial for internally generated movements.
• Previous research indicates primary motor cortex stimulation affects volition and movement selection.

Purpose of the Study:

• To investigate if modulating primary motor cortex excitability with transcranial direct current stimulation (tDCS) influences movement selection.
• To test the hypothesis that anodal tDCS enhances motor cortical excitability, favoring contralateral hand selection.

Main Methods:

• 13 healthy adults performed a movement selection task under real/sham tDCS.
• A C3-C4 dual-hemispheric electrode montage was used to modulate primary motor cortex excitability.
• Movement selection was assessed in free-choice and externally-cued conditions.

Main Results:

• Transcranial direct current stimulation (tDCS) did not significantly alter movement selection at individual or group levels.
• A consistent preference for the dominant right hand was observed in right-handed participants.
• Internally generated movements showed longer reaction times than externally triggered movements.

Conclusions:

• Primary motor cortex excitability modulation via tDCS does not influence movement selection.
• Brain regions preceding the primary motor cortex in the motor pathway are potential targets for influencing movement selection.
• Handedness influences movement selection, with a bias towards the dominant limb.