Re-evaluating transcranial static magnetic stimulation (tSMS): No inhibitory effects on motor cortex across...

Area of Science:

• Neuroscience
• Neurophysiology

Background:

• Transcranial static magnetic stimulation (tSMS) is explored for its potential to modulate human motor cortex excitability.
• Previous research has yielded mixed results regarding tSMS efficacy and hemispheric differences.

Purpose of the Study:

• To investigate if tSMS inhibits the human motor cortex.
• To determine if tSMS effects differ between dominant and non-dominant hemispheres.

Main Methods:

• A between-subject design involved 38 participants receiving tSMS or sham stimulation targeting the left (dominant) or right (non-dominant) motor cortex.
• Corticospinal excitability was assessed using transcranial magnetic stimulation (TMS)-evoked motor potentials (MEPs) and paired-pulse paradigms (SICI, ICF).
• Neuronavigation was employed for precise hotspot localization.

Main Results:

• No significant differences in MEP amplitudes were found between tSMS and sham conditions.
• While paired-pulse measures confirmed robust SICI and ICF, tSMS did not modulate these measures.
• Neither the dominant nor the non-dominant hemisphere showed modulation of excitability by tSMS.

Conclusions:

• tSMS does not appear to modulate motor cortex excitability in either hemisphere.
• The findings question the robustness of previously reported tSMS effects.
• Methodological rigor, including neuronavigation and adequate trial numbers, is crucial for future tSMS research.