Hearing voices: A role of interhemispheric auditory connectivity?

Abstract

Objectives. Auditory verbal hallucinations (AVH) are among the most common symptoms in schizophrenia. Earlier studies suggest changes in the structural connectivity of auditory areas involved in the pathophysiology of auditory hallucinations. Combining diffusion tensor imaging (DTI) and fibre tractography provides a unique opportunity to visualize and quantify entire fibre bundles. Methods. Fibre tracts connecting homotopic auditory areas via the corpus callosum were identified with DTI in ten first episode paranoid schizophrenia patients and ten healthy controls. Regions of interest were drawn manually, to guide tractography, and fractional anisotropy (FA) – a measure of fibre integrity – was calculated and averaged over the entire tract for each subject. Results. There was no difference in the FA of the interhemispheric auditory fibres between schizophrenic patients and healthy controls. However, the subgroup of patients hearing conversing voices showed increased FA relative to patients without these symptoms (P = 0.047) and trendwise increased FA relative to healthy controls (P = 0.066). In addition, a trendwise correlation between FA values and AVH symptoms (P = 0.089) was found. Conclusions. Our findings suggest that in addition to local deficits in the left auditory cortex and disturbed fronto-temporal connectivity, the interhemispheric auditory pathway might be involved in the pathogenesis of AVH.

Key words::

• Schizophrenia
• brain imaging
• MRI
• positive symptoms
• biological psychiatry

Acknowledgments

This work was supported by a grant of the German Society for Psychiatry, Psychotherapy and Neurology (Imaging Award 2007)(CM), by an Overseas-Based Biomedical Training Fellowship from the National Health and Medical Research Council of Australia (NHMRC 520627), administered through the Melbourne Neuropsychiatry Centre at the University of Melbourne (TW), by. the Department of Veterans Affairs (Merit Award to RWM and to MES, Schizophrenia Center Award to RWM and MES, Middleton Award to RWM), by the National Institute of Health (R01 MH 40799, R01 MH 052807, P50MH080272 to RWM; R01 MH58704 to DFS, and R01 MH 50740 to MES and a K05 MH 070047 award to MES), and NARSAD awards (DFS and MES). Kathrin Holzschneider was involved in the final editing of the paper.

Statement of Interest

None to declare.