Frontal and temporal lobe sources from mismatch negativity (MMN) in schizophrenia: an ERP and MR anatomical imaging study

Abstract

BACKGROUND: MMN is an electrophysiological measure of automatic auditory change detection. A smaller MMN in patients with schizophrenia1,2 may reflect altered frontal activity3. METHODS: Following our report on the coordinates for frontal and temporal lobe dipole-loci contributing to normal MMN4, we replicated this result using brain electrical source analysis (BESA) and MR-images of the brain in 14 healthy subjects (34.8 years) and compared it with 17 patients (32 years) 15 years after the onset of schizophrenia. RESULTS: For MMN associated with a frequency deviant tone, asymmetric loci in the superior-temporal and left anterior-cingulate gyri were replicated, while that in the right inferior-frontal gyrus moved to the mid-frontal border (residual variance [RV] < 1%). Patients showed a modest MMN reduction, a weaker left temporal lobe source but essentially similar loci (RVf1%). Discrete changes in the locus of left temporal and cingulate sources were illustrated by plotting volumes around the group solution for individual’s data to 2% RV, with the radius illustrating the standard deviation of the distance to the better solutions for other subjects’ loci (also using a 2% RV criterion). The left temporal lobe source was marginally more medial in patients (5 mm, p < 0.01), while the left cingulate was more rostral (10 mm, p < 0.0001). CONCLUSION: The data show a degree of compensation of function despite altered source locations in the left hemisphere.