INCREASED BLOOD-FLOW IN BROCA AREA DURING AUDITORY HALLUCINATIONS IN SCHIZOPHRENIA

Verbal auditory hallucinations are common in schizophrenia but little is known about how they arise. We have used single photon emission tom ography (SPET) to measure regional cerebral blood flow with the aim of identifying brain areas that are especially active during auditory ha llucinations. We scanned twelve men with schizophrenia while they were experiencing hallucinations. The subjects were rescanned under identi cal conditions when their hallucinations had resolved (mean 19 weeks l ater). Blood flow was significantly greater during hallucinations than in the non-hallucinating state in Broca's area (mean count density on SPET 1.18 [SD 0.04] vs 1.13 [0.06]; p<0.001); flow was also higher du ring hallucinations in the left anterior cingulate cortex and regions in the left temporal lobe, but these differences did not achieve signi ficance. The increased flow in Broca's area was not accounted for by c hanges in other clinical variables nor by changes in the dose of neuro leptic drugs. These findings suggest that the production of auditory h allucinations in schizophrenia is associated with increased activity i n a network of cortical areas specialised for language.