A role for the inferior colliculus in multisensory speech integration

Multisensory integration can occur at relatively low levels within the central nervous system. Recent evidence suggests that multisensory audio-visual integration for speech may have a subcortical component, as acoustic processing in the human brainstem is influenced by lipreading during speech perception. Here, stimuli depicting the McGurk illusion (a demonstration of auditory–visual integration using speech stimuli) were presented to a 12-year-old child (FX) with a circumscribed unilateral lesion of the right inferior colliculus. When McGurk-type stimuli were presented in the contralesional hemifield, illusory perception reflecting bimodal integration was significantly reduced compared with the ipsilesional hemifield and a group of age-matched controls. These data suggest a functional role for the inferior colliculus in the audio-visual integration of speech stimuli.