Modulation of motor cortical excitability with auditory stimulation

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Motor Control

Background:

• Loud sounds can enhance motor cortex excitability when transcranial magnetic stimulation (TMS) is synchronized with the auditory evoked N100 potential.
• The N100 potential reflects auditory processing and arousal, originating from the brainstem and influencing central nervous system activity.

Purpose of the Study:

• To investigate differences in motor evoked potentials (MEPs) using deviant and novelty auditory stimuli interspersed with standard tones.
• To compare the effects of TMS synchronized with the N100 potential versus TMS at a 200 ms delay after sound onset.

Main Methods:

• Twelve healthy subjects received auditory stimuli (standard, deviant, novelty) with randomly interspersed TMS.
• TMS was synchronized with the N100 potential or applied 200 ms after sound onset.
• Motor cortex excitability was measured via motor evoked potentials (MEPs).

Main Results:

• All sound stimuli increased motor cortex excitability, regardless of sound type.
• TMS applied 200 ms after sound onset significantly increased MEPs.
• Contrary to the hypothesis, TMS synchronized with N100 did not yield greater MEPs than TMS at a 200 ms delay.

Conclusions:

• Auditory stimuli can modulate motor cortical excitability.
• The timing of TMS relative to auditory stimuli influences motor cortex excitability, with a 200 ms delay showing a significant effect.
• The precise mechanism for the observed MEP modulation requires further investigation.