Motor cortex brain activity induced by 1-Hz transcranial magnetic stimulation is similar in location and level to that for volitional movement

RATIONALE AND OBJECTIVES. The relatively high temporal and spatial resoluti on of functional MR imaging was used to compare the blood oxygenation level dependent (BOLD) response associated with movement induced by transcranial magnetic stimulation (TMS) with that for a similar movement executed volit ionally (VOL). METHODS. Seven healthy adults were studied in a 1.5-T MR scanner. One hertz TMS at 110% of motor threshold was applied over the motor cortex for the t humb in 21-pulse trains in alternation,vith VOL every 63 seconds and interl eaved with functional MR imaging. RESULTS. BOLD increases in motor cortex associated with TMS and VOL movemen t were similar (2%-3%). Mean separation of their centers of activity was 3. 7 +/- 1.9 mm (mean displacement: left/right = 0.3 +/- 4.1 mm; superior/infe rior = 0.7 +/- 1.9 mm), There was no indication of supraphysiological brain activity, CONCLUSIONS. Motor cortex BOLD response associated with thumb movement indu ced by 1-Hz TMS at 110% motor threshold is similar in both location and lev el to that caused by a similar movement executed volitionally.