Neuropsychological correlates of auditory and visual hallucinations.

Investigations of possible mechanisms underlying hallucinations have indicated that abnormal excitation of brain tissue and abnormal regulation of cognitive activity may contribute to hallucinations. The cognitive control deficits in auditory hallucinations are in some ways similar to those in persons with damage to the frontal lobes of the brain. An examination of the Luria-Nebraska Neuropsychological Battery performance of 10 psychiatric patients with auditory hallucinations, 10 patients with visual hallucinations and 20 patients with no hallucinations showed evidence of general cognitive impairment with a left frontal focus in the auditory group and no evidence of neuropsychological impairment in the visual group. Both self-awareness and control of internal speech involve left frontal mediation and the possible contribution of deficiencies in these functions to the appearance of auditory hallucinations is discussed.