Role of the posterior parietal cortex in spatial hearing

The human posterior parietal cortex (PPC) is well known to be involved in various functions of multisensory spatial perception. However, the specific role of the PPC in hearing has, up to now, remained unclear. To allow more reliable conclusions to be drawn on this issue, we have used repetitive transcranial magnetic stimulation in healthy subjects. Focal stimulation of the PPC induced a systematic shift in the lateralization of interaural time differences (ITDs, a main cue for auditory azimuth), whereas the acuity of ITD discrimination was unaffected. We propose that the PPC is specifically involved in relating azimuthal angles of sound to the body coordinates and is part of a "where" stream in cortical processing of auditory information.