An FMRI Study Of Central Executive Function In Working Memory In First-episode Schizophrenia Patients

Objects:We want to explore:(1) differences of central executive function in working memory between healthy controls and first-episode medication-naive schizophrenia patients while performing neuropsycholo-gical tests,(2) and differences of activation between them while the perform of a working memory task with different memory loads and its relationships with loads, and (3) dysfunction and neurobiology in schizop-hrenia related with central executive function of working memory.Materials:We used Stop Signal Task, Paced Auditory Series Addition Task Running Memory Task, Trial Making Test, Stroop Task, and Wiscon-sin Card Sorting Test to assess the central executive function of healthy controls (n=28) and first-episode medication-naive schizophrenia patients (n=48). Psychopathological status of the patients was assessed by the Positive and Negative Syndrome Scale (PANSS). Using event-related functional MRI, we scanned the brain responses of healthy controls (n=24) and first-episode medication-naive schizophrenia patients (n=36) during performance of a revised-version of the Sternberg item recognition paradi-gm (R-SIRP). Preprocessing and statistical analysis of the fMRI data were performed using SPM.Results:For neuropsychological tests, compared with control group, first-episode schizophrenia patients showed significantly worse in almost of the test scores (P<0.05), except the errors number in TMT and percenta-ge of correct responses in SST (P>0.05). For fMRI, schizophrenia patients were generally load-dependently slower and less accurate than healthy controls (P<0.05). Patients showed significantly less activation of left dorsolateral prefrontal cortex (DLPFC, BA9/46) with moderate and high cognitive loads, and more activation in left precuneus (BA7) and less activation left cuneus (BA18) with all cognitive loads. Defining left DLP-FC and precuneus as the region of interest (ROI) respectively, we extracted and calculated the percent signal change differences per subject and load at the ROI. We found that both groups’percent signal change in DLPFC was increasing with increasing load. But for precuneus, healthy controls show-ed a deactivation pattern, the percent signal change was increasing with increasing load. While patients showed an activation pattern, the percent signal change was declining with increasing load.Conclusions:(1) First-episode medication-naive schizophrenia patie-nts showed generally functional deficit in sub-features of central executive function in working memory.(2) Patients also showed abnormal activation pattern of brain network during the R-SIRP, especially in left DLPFC, precuneus and cuneus cortex.(3) The deficits of central executive function in working memory in First-episode medication-naive schizophrenia patients may be related with patients’ dysfunctions in perceptual organization, failure to deactivate default mode network in rest state, and ineffectively chunking items in high memory loads.