Navigating transcranial magnetic stimulation by functional MRI

Central nervous information processing can be studied with transcranial mag netic stimulation (TMS). On a single subject basis, functional MRI date can be used to select the site of magnetic stimulation. With a neuronavigation al system (Surgical Tool Navigator, Zeiss), it is possible to guide the mag netic coil for focused stimulation to the cortical area, that is activated by the performance of a specific neuropsychological task as revealed by fMR I. The anatomical correspondence between the fMRI activation areas and the TMS stimulation site as visualized by the navigational system, was tested. Eig ht normal subjects performed a rhythmic movement of the right thumb during on fMRI-scan. The magnetic coil was then navigated to the left motorcortica l area that was activated in the fMRI. The area was stimulated and the moto r response of the M. abductor pollicis brevis was recorded. All subjects sh owed a motor response by stimulating the described area. The navigated TEAS is useful for stimulating individually determined functional cortical area s.