The Functional Connectivity Within Frontoparietal Network Of Verbal-and Spatial-working Memory In Bipolar ? Depression:Based On MSI

Objective:We used the verbal-and spatial-working memory 2-back tasks which are the same in stimulus presentation and respond requirement to evaluate working memory functions of patients with bipolar ? depression(BD)and health controls(HC)Furthermore,we used magnetic source image(MSI)to explore the Gamma oscillation functional connectivity(FC)within left-and right-frontoparietal network(FPN)of patients and HC.We aim to find out the neural mechanism of impaired working memory in BD patientsMethods:According to diagnostic criteria of BD of the Diagnostic and Statistical Manual of Mental Disorders,Fifth Edition(DSM-5)and assessments,13 BD patients and 15 HC were recruited in the study.We used 2-back tasks and MSI to test working memory functions and get brain reactions of the participants.We set group(BD vs.HC)as between-subjects variable and task(Visual vs.Spatial)as within-subjects variable to apply mixed-design ANOVA on behavior data.We also compared the Gamma oscillation FC within FPN between BD patients and HC.Finally,we analyze the correlations between FC and task accuracyResults:(1)Both the verbal-and spatial-working memory tasks accuracy of BD patients were significantly worse than that of HC(F=5.254,p<0.001).And BD performed worse in spatial task than in visual task(F=6.898,p=0.014),The interaction was also significant(F=18.209,p<0.001)(2)During the visual working memory task,the FCs within left FPN did not show significant difference between BD patients and HC(p>0.05).However,the FCs of left MFG-IFG,IFG-IPL,IFG-precuneus,IPL-precuneus and IPL-pre-SMA were found significantly increased during the spatial working memory task in BD patients(t=-2.265,p=0.032;t=-2.089,p=0.047;t=-2.254,p=0.033;t=-2.540,p=0.017;t=-3.049,p=0.005).In terms of the right hemisphere,The FC between IFG and IPL was increased in BD patients(t=-2.556,p=0.017)?(3)we found a significant negative correlation between working memory tasks accuracy and FCs of the left IFG-IPL and IFG-precuneus in BD patients(r=-0.591,p=0.033;r=-0.614,p=0.026).Conclusion:(1)Bipolar ? depression' verbal-and spatial-working memory are impaired,and they perform worse in spatial working memory than in verbal working memory.(2)The abnormal FCs of left FPN during spatial working memory suggest that the IFG and IPL may be the key component of spatial working memory in bipolar ?depression,and the stronger the FCs,the lower accuracy of spatial working memory task.(3)The abnormal FCs of left FPN within bipolar ? depression patients may be risked factors such as inhibition,top-down attention regulation and interaction between brain networks.