Neural correlates of the misattribution of speech in schizophrenia

Abstract

Background: The neurocognitive basis of auditory verbal hallucinations is unclear. Aims: To investigate whether people with a history of such hallucinations would misattribute their own speech as external and show differential activation in brain areas implicated in hallucinations compared with people without such hallucinations. Method: Participants underwent functional magnetic resonance imaging (fMRI) while listening to pre-recorded words. The source (self/non-self) and acoustic quality (undistorted/distorted) were varied across trials. Participants indicated whether the speech they heard was their own or that of another person. Twenty people with schizophrenia (auditory verbal hallucinations n=10, no hallucinations n=10) and healthy controls (n=11) were tested. Results: The hallucinator group made more external misattributions and showed altered activation in the superior temporal gyrus and anterior cingulate compared with both other groups. Conclusions: The misidentification of self-generated speech in patients with auditory verbal hallucinations is associated with functional abnormalities in the anterior cingulate and left temporal cortex. This may be related to impairment in the explicit evaluation of ambiguous auditory verbal stimuli.