Volumetric abnormalities in connectivity-based subregions of the thalamus in patients with chronic schizophrenia

Objective: The thalamus, which consists of multiple subnuclei, has been of particular interest in the study of schizophrenia. This study aimed to identify abnormalities in the connectivity-based subregions of the thalamus in patients with schizophrenia. Methods: Thalamic volume was measured by a manual tracing on superimposed images of T1-weighted and diffusion tensor images in 30 patients with schizophrenia and 22 normal volunteers. Cortical regional volumes automatically measured by a surface-based approach and thalamic subregional volumes measured by a connectivity-based technique were compared between the two groups and their correlations between the connected regions were calculated in each group. Results: Volume reduction was observed in the bilateral orbitofrontal cortices and the left cingulate gyrus on the cortical side, whereas in subregions connected to the right orbitofrontal cortex and bilateral parietal cortices on the thalamic side. Significant volumetric correlations were identified between the right dorsal prefrontal cortex and its related thalamic subregion and between the left parietal cortex and its related thalamic subregion only in the normal group. Conclusions: Our results suggest that patients with schizophrenia have a structural deficit in the corticothalamic systems, especially in the orbitofrontal-thalamic system. Our findings may present evidence of corticothalamic connection problems in schizophrenia.