Vestibular Stimulation Therapy for Prosopagnosia.

People with prosopagnosia may fail to recognise even the closest friends and relatives, and some even fail to recognise their own image in a mirror. Yet despite the negative impact this has for a reported 2.5 per cent of the population who have the condition, surprisingly few attempts have been made at developing a therapy, and even fewer have been successful. Caloric vestibular stimulation, or temperature changes surrounding the balance organs, affects blood flow to brain areas known to contribute towards memory and face processing. The effect this technique would have on memory and face recognition was therefore experimentally tested. Eight prosopagnosic patients and 11 age-matched controls were required to indicate the nationality of 60 celebrities while EEG was recorded, first with then without stimulation. Across all groups, stimulation significantly reduced reaction times with no loss in accuracy. Mapped to this behavioural change was a significantly reduced N400, an event related potential commonly associated with semantic activity. These findings lead the authors to describing the stimulation as acting synonymously with repetition priming effects. These experiments open a path to an empirically supported therapy to the hundreds of thousands of face-blindness sufferers.