Masking visual stimuli by transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) applied over the occipital pole can suppress visual perception. Since its first description in 1989 by Amassian et al., this technique has widely been used to investigate visual processing at the cortical level. This article presents a review of experiments masking visual stimuli by TMS. The psychophysical characterization of TMS masking, the dependence on stimulus onset asynchrony between visual stimulus and TMS pulse, and the topography of masking within the visual field are considered. The relation between visual masking and the generation of phosphenes is discussed as well as the underlying physiological mechanisms.