Disruption of MT impairs motion processing.

Functional magnetic resonance imaging (fMRI) studies have associated motion processing with cortical region MT+, which includes sub-region MT that preferentially processes motion in the contralateral visual field. Transcranial magnetic stimulation (TMS) has been used to temporarily disrupt MT+ which impaired motion perception, suggesting this region is necessary for motion processing. In the present study, we used fMRI guided TMS to disrupt MT and determine whether this sub-region is necessary for motion processing. On an individual participant basis, MT was localized in each hemisphere using motion related fMRI activity on the posterior bank of the ascending limb of the inferior temporal sulcus. In the first experiment, 1 Hz TMS of left MT preferentially impaired motion detection in the contralateral versus ipsilateral visual field. In the second experiment, single-pulse TMS of MT impaired motion processing to a greater degree than color processing. These results provide convergent evidence that sub-region MT is necessary for motion processing.