Brain Network Mechanism Of Working Memory Dysfunction Based On Independent Component Analysis Using Temporal Lobe Epilepsy

ObjectiveWorking memory(WM)is the basis of advanced cognitive function,and most neurological and mental diseases exist working memory disorder.Therefore,the study of the mechanism of WM disorder is of great significance and value.Based on the method of independent component analysis(ICA),this paper studies the brain regions and brain network mechanism of working memory impairment in patients with temporal lobe epilepsy,and provides reference for the prediction and treatment of working memory disorder.MethodsWe selected 12 TLE without working memory disorder patients(TLE group)and13 TLE with work memory impairment patients(WM group)and 20 gender-matched healthy controls.All subjects performed a high-resolution anatomical image and a resting-state functional MRI scan using a Siemens 3.0 T magnetic resonance scanner.The pre-processing of fMRI data is carried out by DPARSFA V2.2 tool.The group-level independent component analysis software was used to analyze the pre-processed data.The network components and time series of the resting state networks(RSNs)of interest of the three groups were calculated,and the RSNs were saved as templates.The union template of each RSN was obtained through SPM8 of MATLAB 2009 a.After that,the brain regions where the difference between the groups of functional connections in the network were obtained on the basis of theses templates,and REST software was used to extract the mean z value of each brain area with significant difference in functional connection between groups.Correlation analysis between functional connection strength and working memory performance(RT and ACC)was performed using SPSS1.8.Results1?The difference of brain network activation between temporal lobe epilepsy with WM group and CON group:aDMN: Compared with CON group,the activation intensity of the right medial frontal gyrus,left insula,left medial frontal gyrus,and right thalamus was weakenedin WM group,and the activation in the left inferior frontal gyrus and right frontal gyrus was enhanced(Two-sample t-test,P<0.05,uncorrected).pDMN: Compared with the CON group,the activation intensity of the posterior cingulate cortex,right putamen,right inferior temporal gyrus and right lingual gyrus was weakened in the temporal lobe epilepsy with working memory disorder,and the activation in the left inferior temporal gyrus was enhanced(Two-sample t-test,P<0.05,uncorrected).LCEN: Compared with CON group,the activation intensity of the left inferior temporal gyrus,left inferior frontal gyrus and left precuneus was weakened(Two-sample t-test,P<0.05,uncorrected),and there was no significant enhancement of brain activation in WM group(Two-sample t-test,P>0.05,uncorrected).RCEN: Compared with the CON group,the activation intensity of the left cerebellum posterior lobe,right anterior cingulate cortex and right medial cingulate gyrus was weakened in the temporal lobe epilepsy with working memory disorder group(Two-sample t-test,P<0.05,uncorrected),and there was no significant enhancement of brain activation in WM group(Two-sample t-test,P>0.05,uncorrected).2?Comparison of intra-network connection strength among the three groups: In WM group,compared with CON and TLE group,the connection intensity of the right medial frontal gyrus(MNI: 12,45,27)and left middle temporal gyrus(MNI:-45,-81,15)in DMN were enhanced,the connection intensity of PCC(MNI: 0,-60,12)in DMN was weakened(Two-sample t-test,P<0.05,uncorrected),the connection intensity of right inferior frontal gyrus(MNI: 48,18,6)in CEN was weakened(Two-sample t-test,P<0.05,uncorrected),the connection strength in SN was not significantly enhanced or weakened(Two-sample t-test,P>0.05,uncorrected).There was no significant difference in the intra-network connection of the vision network among three groups(Two-sample t-test,P>0.05,uncorrected).3 ? The results of the Pearson correlation analysis between intra-network connection strength and reaction time: WM group: The connection intensity of PCC in pDMN was negatively correlated with the reaction time(RT)(Pearson correlation analysis,R=-3.29,P=0.04).There was no significant correlation between theconnection intensity of right medial frontal gyrus and left middle temporal gyrus in DMN and the reaction time(RT)(P>0.05).There was no significant correlation between the connection intensity of right inferior frontal gyrus in CEN and the RT(P>0.05).TLE group: There was no significant correlation between the connection intensity of the PCC,right medial frontal gyrus and left middle temporal gyrus in DMN and the reaction time(RT)(Pearson correlation analysis,P>0.05).There was no significant correlation between the connection intensity of right inferior frontal gyrus in CEN and the RT(Pearson correlation analysis,P>0.05).CON group: The connection intensity of left middle temporal gyrus in pDMN was negatively correlated with the reaction time(RT)(Pearson correlation analysis,R=0.398,P=0.0037).There was no significant correlation between the connection intensity of the PCC and right medial frontal gyrus in DMN and the RT(P>0.05).There was no significant correlation between the connection intensity of right inferior frontal gyrus in CEN and the RT(P>0.05).ConclusionThe posterior cingulate is an important brain area related to working memory.The declined intra-network connection strength of the posterior cingulate cortex(MNI: 0,-60,12)in DMN is one of the brain network mechanisms of working memory impairment,which affects the response time of working memory in patients with temporal lobe epilepsy.