A Functional MRI Study On Difference Of Brain Functional Connectivity Between N-back Task And Resting-State In Patients With Paranoid Schizophrenia

Various social problems resulted from schizophrenia are prominent currently.The role of functional magnetic resonance imaging (fMRI) in pathogenesis ofschizophrenia is emphasized increasingly. The opinion that the patients withschizophrenia have abnormalities in prefrontal cortex and wide disrupted functionalintegration appears inconsistent in recent study with fMRI. The aim of our study is toinvestigate the relationship between brain activation and behavior performance anddiscrepancy of functional connectivity between resting state and task performing inpatients with paranoid schizophrenia. The main contributions of dissertation are asfollows:1. We investigated the correlations between activation and behavior performancefor paranoid schizophrenic patients with digital 2-back working memory task firsttime and explore the pathogenesis of schizophrenia according to brain domaindetection.2. Based on seed voxels method, we examined the differences of functionalconnectivity for paranoid schizophrenic patients compared to normal subjects inresting state and digital 2-back working memory task first time.3. It is the first time to found that the paranoid schizophrenic patients present awide conversion deficit of functional connectivity and entirely disrupted functionalintegration. SectionⅠFunctional MRI Study of Brain Activity of Normal Subjects withDigital 2-back TaskObjective: To explore the locations of activation and deactivation of fMRI innormal subjects with digital 2-back working memory task. Materials and Methods:The digital 2-back working memory task was executed in nine normal subjectsduring fMRI scan. The fMRI data were processed with statistical parametricmapping 2(SPM2) and the behavior performance data were analyzed with SPSS 13.0.Results: The main brain regions of activation included bilateral dorsolateralprefrontal cortex (DLPFC) (Brodmann area, BA 9/46), bilateral posterior parietalcortex (PPC)(BA 7/40), bilateral ventrolateral prefrontal cortex (VLPFC)(BA45/47), bilateral medial premotor areas (MPMA) (BA 6/8), bilateral supplementarymotor area (SMA), bilateral prefrontal cortex(PFC)(BA 10) and posterior lobes ofbilateral cerebellar hemisphere. The main cerebral areas of task induced deactivationincluded bilateral posterior cingulate cortex(PCC)/cuneus/precuneus/ paracentralgyri/parahippocampal gyri(BA29/30/31),bilateral anterior cingulatecortex(ACC)(BA 9/10/32), left middle and superior temporal gyri and uncusgyrus(BA21/34/38). Conclusion: The results are consistent with the view thattask-related activation network and task-related deactivation network are intrinsicanticorrelated functional networks in human brain. SectionⅡFunctional MRI Study on Brain Activity of Paranoid SchizophrenicPatients with Digital 2-back TaskObjective: To investigate the differences of activation or deactivation betweenparanoid schizophrenic patients and normal subjects with digital 2-back workingmemory task and its correlation to behavior performance. Materials and Methods:Nine patients with paranoid schizophrenia and nine normal subjects receivedfunctional MR examinations with digital 2-back working memory task. The fMRIdata were processed with SPM2 and the behavior performance data were analyzedwith SPSS13.0. Results: The activation and deactivation were all decreased inschizophrenia patients compared to normal subjects. The reaction time was longerin patients with schizophrenia than in normal subjects. The accuracy decreased inschizophrenic subjects compared to normal ones (P=0.01). The accuracy positivelycorrelated to the activation regions and slightly negatively correlated to thedeactivation regions which showed discrepancy in resting state and task performing.Conclusion: The results indicate that the poor performance contributes tohypoactivation for patients. The decreased TID in schizophrenic patients may reflectdisabilities of suppressing emotional awareness during working memory task anddeficit of attention conversion between resting state and task performing. The resultssupport the hypothesis that cognitive deficit is the core characteristic forschizophrenia. SectionⅢFunctional Connectivity Analysis for Paranoid SchizophrenicPatients in Resting State and Digital 2-back TaskObjective: To examine the differences of functional connectivity for paranoidschizophrenic patients compared to normal subjects in resting state and digital 2-backworking memory task and search for whether paranoid schizophrenic patients existwide functional disintegration. Materials and Methods: Nine patients withparanoid schizophrenia and nine normal subjects received functional MRexaminations in resting state and digital 2-back working memory task. The fMRI datawere processed with the software of AFNI and Matlab. Based on seed voxels method,we analyzed the time course correlation between DMPFC(6, 66, 15) and the otherbrain areas and the cross-correlogram were output. The correlation betweendifferences of functional connectivity and behavior performance were also analyzed.Results: A widely abnormal functional connectivity network occurred in limbicsystem which included the brain areas around lateral fissure, paracentral lobule,anterior nuclei of thalamus and in prefrontal and parietal cortex—thalamuscerebellum circuit. Conclusion: The results indicate that the paranoid schizophrenicpatients present a wide conversion deficit of functional connectivity and entirelydisrupted functional integration.