Sensorimotor System And Schizophrenia: The Functional Magnetic Resonance Imaging Study

Schizophrenia is a multidimensional psychotic syndrome and associates with substantial disability.Cognition deficits are considered to be the most important cause of the social function damage in patients.Most of the present studies employed top-down view,that is,the patient's knowledge and experience influence the low-level information processing process.Thus,most studies focused on the patient's frontal cortex;correspondingly,the low-level perception processing process get insufficient attention.Actually,a large number of studies,including neuropsychological assessment,steady-state visually evoked potential and functional magnetic resonance imaging,had found that the sensorimotor dysfunction was also a central feature of schizophrenia.In this study,schizophrenia patients were included as participants.Integrating information of the local neural activity and the whole brain network,the role of sensorimotor system in the pathophysiology of schizophrenia was investigated.The main works and findings in this thesis are introduced as follows:1.We investigated the local functional connectivity features of schizophrenia patients from the spatial dimensional aspect.A data-driven method,functional connectivity density mapping,was used to investigate the spontaneous local spatial coherence abnormalities in schizophrenia patients' whole brain.The schizophrenia patients exhibited increased local functional connectivity density(FCD)in frontal area while demonstrating decreased local functional connectivity density in the primary sensorimotor area and in the occipital lobe.The followed functional connectivity analysis illustrated decreased functional connectivity between visual areas and the primary sensorimotor area.these findings suggest disturbed integration in perception-motor processing,which may contribute to mapping the neural physiopathology associated with self-disorder in schizophrenia patients.2.We investigated the local functional connectivity features of schizophrenia patients by integrating the temporal and spatial information of the local region.In the current study,a voxelwise data-drive measure,named Four-dimensional(spatiotemporal)consistency of local neural activities(FOCA),was used to investifate abnormalities of local spontaneous brain activity in schizophrenia patients.Compared with the healthy controls,the patients exhibited altered local consistency in hippocampo-cerebello-cortical(occipital)circuit.These findings suggested that this circuit might play a role in the motor dysfunction in schizophrenia.3.The first two studies used data-driven method on resting-state functional magnetic resonance data and identifed the sensorimotor cortex's functional abnormality.In order to investigate the role of sensorimotor system when patients performing cognitive tasks,this study compared the functional connectivity pattern of sensorimotor system in schizophrenia patients and healthy controls during three cognition tasks.It was found that the functional connection between the somatosensory cortex and the visual cortex in schizophrenic patients was significantly lower than that in the healthy control group when performing the tasks.And this reduced functional connection had a significant correlation with the severity of symptoms in schizophrenic patients.This results indicated that the abnormalities of the senserimotor system still exist when schizophrenic patients performing cognitive tasks.4.The first three studies focused on the more low-level sensorimotor cortex.The function of the insula involves the filtering of the primary sensory information.This study used functional connectivity analysis to investigate the functional connection pattern of the insula in schizophrenic patients.It was found that the right dorsal anterior insula and right posterior insula of schizophrenia patients exhbited altered functional connection with the primary sensorimotor cortex.And these changes were related to the altered self-experience in patients.The results suggested that the insula,especially the right posterior insula,may play an important role in the pathophysiology of schizophrenia.5.The first four studies only examined schizophrenia patients.In order to identify the special role of sensorimotor cortex in schizophrenia,we compared the functional connectivity pattern of sensorimotor area in schizophrenia and depression patients.It was found that compared with healthy controls,the depression patients and schizophrenia patients exhibited decreased functional connectivity within sensorimotor systems,while there was none significant group differences between depression and schizophrenia patients.In addition,there changes were related to the severity of symptom in schizophrenia.The results suggested that the altered functional connectivity of sensorimotor system might be a common brain functional abnormality in mental diseases.In conclusion,we collected resting-state and task-related functional magnetic resonance imaging data.The data-driven and theory-driven analysis based on these data had identified that there was a significantly altered functional connection within sensorimotor system in schizophrenic patients.In addition,these abnormalities also existed in depressive patients.These results suggested that the sensorimotor system dysfunction exsited in mental illness patients,and this damage might be the basis of high-level cognitive processing.In the future,we should pay more attention to the sensorimotor system.