Ventriloquist effect reinstates responsiveness to auditory stimuli in the 'ignored' space in patients with hemispatial neglect

We examined 6 patients with robust visual neglect following right hemisphere damage. All of them had signs of auditory neglect as documented by the inferior identification of syllables delivered through a loudspeaker on the left side. When the same stimuli on the left were administered in the presence of a fictitious source of sound (a dummy loudspeaker) visible in the homolesional space, a significant increase in the identification score of sounds was obtained (the "ventriloquist" effect). The result is in keeping with a notion of a strong coupling between auditory and visual systems. The effect is attributed to the activation by the fictitious source of sound of the audio-visual map in the left hemisphere. We draw attention to the possibility that loss of awareness of auditory input may arise due to the disconnection of the visual input from the audio-visual template.