About the mechanisms of auditory verbal hallucinations: A positron emission tomographic study

Objective: Auditory verbal hallucinations (AVHs) likely result from disorders, as yet unspecified, of the neural mechanisms of language. Here we examine the functional neuroanatomy of single-word reading in patients with and without a history of AVH. Method: Eighteen medicated schizophrenia patients (8 with AVH and 10 without AVH) and 12 healthy control subjects were scanned with PET ¹⁵O-water technique under 2 conditions: reading aloud English nouns and passively looking at English nouns without reading them. Results: The contrast between the 2 conditions shows higher activation in Wernicke's area during the reading condition in the patient group and a reversed laterally index for the supplementary motor area in the AVH group. Conclusions: These findings provide indications about the possible mechanisms of AVH. We suggest that the abnormal laterality of the supplementary motor area activity accounts for the failure to attribute speech generated by one's own brain to one's self and that the activation of Wernicke's area accounts for the perceptual nature (hearing) of the patient's experience.