The temporal coincidence of multisensory inputs plays a strong role in perceptual binding; the more temporally proximate two stimuli are, the higher the likelihood of binding. The superior temporal sulcus (STS) has been implicated in binding audiovisual stimuli and temporal processing. Here, we used fMRI-guided repetitive transcranial magnetic stimulation (rTMS) to assess the contribution of STS to multisensory temporal processing. A pre-TMS anatomical and functional MRI was acquired, and multisensory (A∩V, STS), auditory (A>V, Hechl’s gyrus), and visual (V>A, striate cortex) regions of interest (ROIs) were localized. During separate sessions, each of these ROIs was stimulated for 20 minutes at 1Hz prior to collection of behavioral data, in addition to a no-TMS condition. For the behavioral task, participants were presented with flash-beep stimuli at parametrically-varied stimulus-onset asynchronies (SOAs) while performing a simultaneity judgment task. Temporal binding windows (TBW; the range of SOAs within which a participant perceived the flash and beep to be synchronous 50% of the time) were calculated from these responses. Relative to the no-TMS condition, stimulation of auditory cortex induced a broadening of the TBW with auditory-leading stimuli, and stimulation of visual cortex induced a broadening of the TBW with visual-leading stimuli. Stimulation of STS induced a significant change in the full TBW, driven primarily by an increased tolerance for visual-leading stimuli. Changes specific to the more ecologically valid visual-leading stimuli with STS disruption suggest that multisensory temporal processing in STS reflects learned environmental statistics.

Temporal processing; TMS; fMRI; superior temporal sulcus; synchrony; psychophysics; multisensory; audiovisual