Task-dependent visual coding of sound position in visuospatial neglect patients

Recent neurophysiological evidence has shown that sound position can be coded in multiple frames of reference in the animal brain (i.e. head-centred, eye-centred, or intermediate head/eye centred). Here, we provide evidence for multiple coding of sound positions in humans, by studying pointing to sounds in 14 right brain-damaged (RBD) patients with or without visual neglect (a visuospatial neurological disturbance typically affecting contralesional space). Patients were asked to indicate the position of free-field sounds, either with a hand-pointing or with a head-turning response. Pointing movements were performed either blindfolded or with eyes open, but no visual feedback was available about sound position or the motor response. All RBD patients showed some impairment in sound localisation, particularly for sounds towards the contralesional side. In addition, task-irrelevant vision was more detrimental for hand-pointing than head-turning responses, only for neglect patients. We prop...