Auditory Hallucinations and the Temporal Cortical Response to Speech in Schizophrenia: A Functional Magnetic Resonance Imaging Study

TLDR

The study examined whether atypical lateralization of temporal language areas in schizophrenia predicts auditory hallucinations and whether hallucinations diminish cortical response to speech. Functional MRI measured BOLD responses to spoken speech in eight hallucination‑prone patients, seven non‑hallucination patients, eight controls, and in seven patients during and after hallucinations. Schizophrenia showed decreased left superior temporal and increased right middle temporal activation to speech, with no difference between hallucination‑prone and non‑prone patients; during hallucinations activity, especially in the right middle temporal gyrus, was further suppressed. Published in Am J Psychiatry 1997; 154:1676–1682.

Abstract

OBJECTIVE: The authors explored whether abnormal functional lateralization of temporal cortical language areas in schizophrenia was associated with a predisposition to auditory hallucinations and whether the auditory hallucinatory state would reduce the temporal cortical response to external speech. METHOD: Functional magnetic resonance imaging was used to measure the blood-oxygenation-level-dependent signal induced by auditory perception of speech in three groups of male subjects: eight schizophrenic patients with a history of auditory hallucinations (trait-positive), none of whom was currently hallucinating; seven schizophrenic patients without such a history (trait-negative); and eight healthy volunteers. Seven schizophrenic patients were also examined while they were actually experiencing severe auditory verbal hallucinations and again after their hallucinations had diminished. RESULTS: Voxel-by-voxel comparison of the median power of subjects' responses to periodic external speech revealed that this measure was reduced in the left superior temporal gyrus but increased in the right middle temporal gyrus in the combined schizophrenic groups relative to the healthy comparison group. Comparison of the trait-positive and trait-negative patients revealed no clear difference in the power of temporal cortical activation. Comparison of patients when experiencing severe hallucinations and when hallucinations were mild revealed reduced responsivity of the temporal cortex, especially the right middle temporal gyrus, to external speech during the former state. CONCLUSIONS: These results suggest that schizophrenia is associated with a reduced left and increased right temporal cortical response to auditory perception of speech, with little distinction between patients who differ in their vulnerability to hallucinations. The auditory hallucinatory state is associated with reduced activity in temporal cortical regions that overlap with those that normally process external speech, possibly because of competition for common neurophysiological resources. (Am J Psychiatry 1997; 154:1676–1682)