Auditory verbal hallucinations (AVHs), the perception of voices in the absence of auditory stimuli, are common and distressing symptoms reported by 50%-80% of patients with schizophrenia. However, the results in a number of imaging and electrophysiological studies on the origins of AVH are not consistent, and the underlying path physiology remains unclear. The authors enrolled a group of schizophrenia patients and normal-control subjects, age 18-45 years. Two patient groups participated in the study; 1) a group of 8 patients with drug-resistant spontaneous AVHs; and 2) a group of 7 patients whose AVHs were successfully controlled with neuroleptic medication; along with 16 normal-control subjects. The entire sample had EEG recording done, with the AVH group told to press a button when they experienced a hallucination, and the other two groups randomly told when to press the button. In the AVH group, hallucinations were longer in the "eyes-closed" than "eyes-open" condition. There was spreading phase-coupling in the AVH group, intra- and inter-hemispherically, at left and right frontal and temporal areas, under both eyes-closed and eyes-open condition, during the experience of AVH. There was a statistically significant increase of a-band frequency-specific synchrony maximum values in the AVH group. AVHs are considered to be complex features, and, as such, they reflect abnormal functional connectivity in multiple related regions in both intra-and inter-hemispherical brain sites, primarily defined by phase-integration.
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