Transcranial Magnetic Stimulation for Modulating Muscle Response in Humans

Begin with a participant fitted with EMG electrodes on the right-hand FDI muscle, which controls index finger movement.

Attach reflective markers to the forehead to track and stabilize the TMS coil position.

Place the coil over the left primary motor cortex and deliver magnetic pulses to excite pyramidal neurons.

This cortical activation elicits contraction of the FDI muscle, producing an EMG response.

Identify the cortical site that produces maximal muscle contraction.

Then, lower the stimulation intensity to sufficiently activate motor neurons and produce a minimal contraction.

Finally, reduce the intensity further to induce cortical excitation without triggering muscle contraction.

Next, instruct the participant to press the finger against a weight to maintain neuronal activation and muscle engagement.

In the brain, the reduced stimulation intensity activates GABAergic interneurons, triggering GABA release and inhibiting pyramidal neurons.

This prevents unnecessary muscle activation and suppresses EMG activity, improving muscle movement control.

Begin by placing the reflective markers on the participant's forehead with double-sided adhesive tape.

Use a figure-of-eight coil attached to a TM