Neural NoiseTranscranial magnetic stimulation (TMS) is a non-invasive brain-stimulation technique that uses rapidly changing magnetic fields generated by a coil placed on the scalp to induce electric currents in underlying cortical tissue. Single-pulse TMS can transiently excite or disrupt focal brain regions, while repetitive TMS (rTMS) protocols can produce longer-lasting changes in cortical excitability that outlast the stimulation period.
TMS has established clinical applications in the treatment of major depressive disorder, where high-frequency rTMS of the left dorsolateral prefrontal cortex received FDA clearance in 2008. Research applications span motor cortex mapping, causal studies of brain-behavior relationships, and investigation of cortical plasticity. TMS combined with eeg or neuroimaging provides a powerful tool for probing brain connectivity and excitability.
Theta burst stimulation (TBS) protocols, H-coil designs for deeper stimulation, and navigated TMS systems represent ongoing technical developments. Closed-loop and state-dependent TMS approaches, where stimulation timing is locked to specific brain states, are emerging as methods to enhance the specificity and efficacy of transcranial magnetic stimulation interventions.