Hearing voices: a role of interhemispheric auditory connectivity?

Area of Science:

• Neuroimaging
• Schizophrenia Research
• Auditory Neuroscience

Background:

• Auditory verbal hallucinations (AVH) are a core symptom of schizophrenia.
• Previous research indicates altered structural connectivity in auditory processing areas in schizophrenia patients.
• Diffusion tensor imaging (DTI) and fibre tractography enable visualization and quantification of white matter tracts.

Purpose of the Study:

• To investigate the structural integrity of interhemispheric auditory pathways in first-episode schizophrenia patients.
• To explore the relationship between fibre integrity and the presence/severity of AVH.

Main Methods:

• Used DTI and fibre tractography to identify and analyze fibre tracts connecting homotopic auditory areas via the corpus callosum.
• Calculated fractional anisotropy (FA), a measure of fibre integrity, in ten schizophrenia patients and ten healthy controls.
• Defined regions of interest manually to guide tractography.

Main Results:

• No significant difference in FA of interhemispheric auditory fibres between schizophrenia patients and controls.
• Patients experiencing conversing voices exhibited increased FA compared to those without this symptom and trendwise increased FA compared to controls.
• A trendwise correlation was observed between FA values and AVH symptom severity.

Conclusions:

• The interhemispheric auditory pathway may play a role in the pathogenesis of AVH, alongside previously identified local deficits and fronto-temporal connectivity disturbances.
• Findings suggest that alterations in white matter integrity of the corpus callosum's auditory connections are relevant to AVH in schizophrenia.