Evaluation of Brain Neural Networks in Patients with Schizophrenia

Purpose: The purpose of this study is to clarify the relationship between the disruption of neural networks in the brain and the pathogenesis of schizophrenia and verified its clinical significance. Materials and Methods: Using resting-state functional magnetic resonance imaging (rs-fMRI) we compared functional connectivity between patients with schizophrenia and healthy controls. The association between the severity of clinical symptoms assessed by rating scale and degree of functional connectivity in the patient group was also examined. This rs-fMRI study examined resting-state connectivity in 48 schizophrenia patients and 48 healthy controls. The schizophrenia group was assessed for symptoms using the Positive and Negative Symptom Scale. Using a five-factor model, factor scores were calculated for positive, negative, and disorganized symptoms, depression, and excitement. Using the image analysis program CONN toolbox, the connectivity of the brain functional network at rest was evaluated using region of interest (ROI) -to-ROI analysis. Results: Compared with the healthy control group, connectivity was increased in the schizophrenia group at two clusters: the bilateral thalamus and bilateral middle temporal gyrus (cluster 1) and the bilateral thalamus and bilateral superior temporal gyrus (cluster 2). However, connectivity decreased in the bilateral thalamus and bilateral superior temporal gyrus. In the schizophrenia group, positive symptoms such as hallucination and delusion indicated a positive association between symptom severity and connectivity of the left amygdala/left nucleus accumbens and left supramarginal gyrus or bilateral amygdala/bilateral nucleus accumbens and left fusiform gyrus. No brain regions were significantly associated with negative symptoms such as blunted affect and passive apathetic social withdrawal. Symptom severity of disorganized symptoms was positively associated with connectivity of the bilateral angular gyrus, supramarginal gyrus, left middle temporal gyrus, bilateral supramarginal gyrus, left parahippocampal gyrus, left orbital gyrus, and right middle temporal gyrus. Conclusions: We found increased thalamus-temporal connectivity and decreased thalamus-temporal lobe hemispheric connectivity in patients with schizophrenia. The results suggest that the abnormal connectivity between thalamus and temporal lobe is associated with the development of schizophrenia. Furthermore, temporal lobe and limbic system functions may be involved in the development of the core symptoms of schizophrenia, such as positive and disorganized symptoms.