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Emily D. Grossman, Lorella Battelli, Alvaro Pascual Leone; TMS over STSp disrupts perception of biological motion. Journal of Vision 2004;4(8):239. doi: https://doi.org/10.1167/4.8.239.
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© ARVO (1962-2015); The Authors (2016-present)
Neuroimaging work has identified the posterior extent of human superior temporal sulcus (STSp) to be activated during perception of biological events. Patients with lesions over posterior parietal cortex, including the STS, have impaired perception of biological motion. However it is difficult to assess from brain imaging and lesion studies the extent to which a cortical region is critical in a given cognitive task. To directly assess the importance of the STS in biological motion perception, we have applied 1Hz repetitive transcranial magnetic stimulation (rTMS) over STSp and measured the effects on observer sensitivity of biological motion. Observers viewed 100 trials of point-light presentations depicting either a human performing an activity (such as running, jumping and throwing), the same sequences inverted, or motion-matched control stimuli (“scrambled” animations). The animations were masked in noise dots also drawn from the biological sequences to ensure threshold performance prior to stimulation. We applied 1 Hz rTMS for 10 minutes over two brain sites. The right STSp site of stimulation was identified as T6 using the EEG 10/20 coordinate system, which corresponds to the dorsal bend of the STS. As a control site, we applied stimulation over left MT/V5, localized using previous successful studies and verified in some observers by the experience of phosphenes following single pulse stimulation. The order of stimulation was counterbalanced across observers. Immediately after stimulation, observers discriminated 80 trials of biological motion. Following stimulation over STSp, observers' sensitivity on the upright trials deteriorated by .4 d-prime units on average, while sensitivity to inverted animations was unchanged. Stimulation over MT/V5 did not alter sensitivity to inverted biological motion. These experiments provide direct evidence that STSp is critical for perception of biological motion in point-light animations.
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