Relationship of auditory verbal hallucinations with cerebral asymmetry in patients with schizophrenia: an event-related fMRI study.

The purpose of this study was to explore whether there are differences in cerebral asymmetry between subgroups of schizophrenic patients with or without auditory verbal hallucinations (AVHs) and normal controls by using event-related functional magnetic resonance imaging (efMRI). A total of 26 Chinese Han male patients with paranoid schizophrenia (diagnosed by DSM IV, including 13 patients with AVHs and 13 patients without) and 13 matched normal controls were recruited for the present study. The participants had been instructed to listen to short sentences from left or right side and to indicate laterality during efMRI scanning. Functional data were acquired using a 1.5T MR, and were analyzed using statistical parametric mapping. A random-effect model was employed to asses the difference in blood oxygen level dependent response between "left-sided" and "right-sided" conditions. The results from the present study have shown (1) within group comparisons: right precuneus and right superior parietal lobule were significantly activated showed significantly greater activation by left-sided voices than right-sided ones in controls. However, no significant difference in activation was found in any brain region between left and right-sided voices in either of the two patient subgroups, (2) between group comparisons: in comparison with AVHs patients, right middle frontal gyrus (MFG) was markedly activated when control subjects were differentiating right-sided voices. In comparison with patients without AVHs, right-side stimuli significantly activated bilateral MFG and left postcentral gyrus in control group. Furthermore, compared to the non-hallucination group, left Wernicke's area, including supramarginal gyrus, angular gyrus and superior temporal gyrus, was significantly activated by both left and right-sided voices in the hallucination group. In summary, auditory-related asymmetry in control subjects is attenuated in schizophrenic patients. The symptoms of AVHs in schizophrenia are possibly correlated with left hemispheric, particularly auditory and language-related areas dysfunction.