Introduction:
Evidence from neuroanatomical, neurophysiological and functional neuroimaging studies has indicated that patients prone to auditory hallucinations (AHs) have structural and functional abnormalities affecting brain regions involved in a number of cognitive and emotional functions. Our previous work has shown deficits in the central auditory system of patients with AHs. In the current study, we hypothesized that this deficit is the result of interhemispheric pathway dysfunctions of the primary and secondary auditory cortices (PAC and SAC). The aim of this study was to investigate the interhemispheric functional connectivity (FC) of PAC and SAC in patients with AHs using functional magnetic resonance imaging (fMRI) data.
Methods:
Fourteen patients with schizophrenia with AHs, 13 patients with schizophrenia without AHs (non-AHs) and 16 normal controls were scanned while passively listening to semantically neutral words and at rest. Regions of interest were defined for each subject over PAC and SAC in both hemispheres. For the stimulus data, the stimulus effects were identified and regressed out of these time courses to estimate a ‘rest-like’ FC.
Results:
The interhemispheric FC was significantly reduced for the AHs group both for stimulus and resting-state data, while the non-AHs and controls had similar connectivity values.
Conclusions:
Interhemispheric connectivity between the auditory cortices permits the association of basic auditory information with higher order language processing as the left and right auditory cortices are primarily responsible for different linguistic functions. Without efficient integration of auditory and linguistic experiences, errors in the interpretation of auditory phenomenon may occur; thus, this failure to integrate may result in the experience of AHs.
