Figure 3.
The cortex surrounding the posterior superior temporal sulcus (pSTS) is integrally involved in the integration of visual and auditory information. A. The pSTS as defined as the conjunction of brain regions functionally responsive to intact auditory stimuli over their scrambled equivalents AND intact visual stimuli over their scrambled equivalents. The pSTS is located directly between auditory-only and visually-only responsive regions, making it a logical site for audiovisual convergence and integration. Adapted From James et al, 2012. B. Subregions of pSTS appear to be engaged in different multisensory processes. The subregion of pSTS defined as responding more to synchronous as opposed to asynchronous stimuli does not respond differentially according to the individual's perceptual reports (pink and light blue bars). In contrast, the subregion of pSTS defined as a conjunction of auditory and visual responsive regions (see Figure 3A) responds differentially according to the individual's perceptual reports (pink and light blue bars), even when the stimuli are identical. These data suggest that this may be the region of perceptual “binding” for the auditory and visual stimuli. Adapted from Stevenson et al, 2011. C. When given perceptual feedback training to improve multisensory temporal processing, the neural analogs of this change are centered about pSTS. The BOLD responses from these regions show more efficient processing of synchronous (and thus likely perceptually bound) stimuli. Adapted from Powers et al, 2012. D. When TMS is applied to pSTS during presentation of stimulus pairs that typically result in the McGurk illusion, individuals’ ability to perceptually bind the auditory and visual components is impaired, resulting in decreases in perception of the illusion. Adapted from Beauchamp et al, 2010.