Biological motion perception, the recognition of human action depicted in sparse dot displays, is supported by a network of brain areas including the human posterior superior temporal sulcus (pSTS). We have used repetitive transcranial magnetic stimulation (rTMS) to temporarily disrupt cortical activity within the pSTS and subsequently measured sensitivity to biological motion. Sensitivity was measured for canonical (upright) point-light animations and for animations inverted 180 deg, a manipulation that renders biological motion more difficult to recognize. Observers were markedly less sensitive to upright biological motion following pSTS stimulation. In contrast, performance remained normal for inverted biological motion following pSTS stimulation, and normal for upright and inverted biological motion following stimulation over visual motion sensitive area MT+/V5. In connection with previous brain imaging results, our findings demonstrate that normal functioning of the posterior STS is required for intact perception of biological motion.

The order of events, whether two events are seen as simultaneous or successive, sets the stage for the moment-to-moment interpretation of the visual world. Evidence from patients who have lesions to the parietal lobes and transcranial magnetic stimulation studies in normal subjects suggest that the right inferior parietal lobe underlies this analysis of event timing. Judgment of temporal order, simultaneity and high-level motion are all compromised following right parietal lesions and degraded after transcranial magnetic stimulation over the right parietal but not elsewhere. The results suggest that the right parietal lobe serves as part of a when pathway for both visual fields. We propose that the disruption of this mechanism is the underlying cause of a wide range of seemingly unrelated tasks being impaired in right parietal patients.

Transcranial magnetic stimulation (TMS) can be used to simulate the e¡ects of highly circumscribed brain damage permanently present in some neuropsychological patients, by reversibly disrupting the normal functioning of the cortical area to which it is applied. By using TMS we attempted to recreate de¢cits similar to those reported in a motion-blind patient and to assess the speci¢city of de¢cits when TMS is applied over human area V5. We used six visual search tasks and showed that subjects were impaired in a motion but not a form`pop-out' task when TMS was applied over V5. When motion was present, but irrelevant, or when attention to colour and form were required, TMS applied to V5 enhanced performance. When attention to motion was required in a motion^form conjunction search task, irrespective of whether the target was moving or stationary, TMS disrupted performance. These data suggest that attention to di¡erent visual attributes involves mutual inhibition between di¡erent extrastriate visual areas.