| ObjectiveWorking memory is one of the most important memory forms in human life and plays an important role in many advanced cognitive activities.Working memory impairment is common in many neurological or mental patients,especially in patients with temporal lobe epilepsy.As the first sub-time process of time separation of working memory,coding period can not be ignored in the brain network mechanism of working memory.In this paper,the patients with temporal lobe epilepsy were taken as the experimental subjects,and the brain network during the coding period of working memory was studied by means of functional magnetic resonance imaging(fMRI).MethodWe recruited 37 TLE patients as the experimental group and 20 healthy subjects as the control group.Visual working memory delayed sample matching paradigm(delayed matching-to-sample task,DMS)was used to perform working memory tasks,and Siemens 3.0T nuclear magnetic resonance scanner was used to collect data.According to the performance of paradigm behavior:(ACC)and reaction time(RT),the experimental group was divided into normal temporal lobe epilepsy group(TLE group,n=17)and abnormal temporal lobe epilepsy group(WM group,n=20).The task state data were preprocessed,modeled and statistically analyzed by SPM12 on the platform of Matlab 2013a,and the activated brain regions,inactivated brain regions and different brain regions of each group during the coding period were obtained.The resting(ROIs),data of different brain regions among groups were extracted as regions of interest by REST software.Based on MATLAB 2013a platform,DPARSF V4.5(Data process assistant for rest-state fMRI was used for pre-processing.The functional connection method based on region of interest was used to calculate the functional connections with statistical differences among groups.Finally,we use SPSS software to analyze the Pearson correlation between functional links and behavioral performance with statistical differences.Result1.Behavioral performance of three groups of subjects.The average values of ACC in CON group,TLE group and WM group were 0.98±0.11,0.96±0.33,0.90±0.84 and 771.11±82.17ms,841.10±143.87ms and 1120.93±213.88ms,respectively.There was a significant difference in behavior between the WM group and the other two groups,but there was no statistical difference between the CON group and the TLE group.That is,compared with the other two groups,ACC was significantly decreased and RT was significantly prolonged in WM group.2.Results of intra-group analysis of task-activated brain regions.During the coding period,the brain regions of CON subjects were mainly activated in bilateral fusiform gyrus,bilateral middle occipital gyrus,left inferior occipital gyrus,left superior parietal gyrus,bilateral middle frontal gyrus,bilateral caudate nucleus and left triangular inferior frontal gyrus.The main activated brain regions in TLE group were bilateral fusiform gyrus,bilateral supplementary motor area,bilateral middle frontal gyrus,bilateral inferior parietal gyrus and left triangular inferior frontal gyrus.The main activated brain regions in WM group were bilateral fusiform gyrus,bilateral middle frontal gyrus,bilateral supplementary motor area,bilateral superior parietal gyrus and left caudate nucleus.The main inactivated brain regions of the three groups were all related to the main brain regions of the default network,such as medial superior frontal gyrus,angular gyrus,middle temporal gyrus and so on.3.Task state activates the difference between groups of brain regions.Compared with Con group,the activation of left middle frontal gyrus decreased in TLE group,increased in right middle frontal gyrus and left posterior cingulate gyrus,no activation in WM group,increased activation in bilateral middle frontal gyrus,left medial superior frontal gyrus,bilateral wedge anterior lobe,bilateral angular gyrus,right posterior central gyrus,left anterior cingulate,right posterior cingulate,left inferior occipital gyrus,left superior occipital gyrus and right superior temporal gyrus.Compared with TLE group,there was no activation of weakening brain areas in WM group,but increased activation in left middle frontal gyrus,bilateral caudate nucleus,right superior parietal gyrus,left inferior parietal gyrus,left superior marginal gyrus,right anterior cuneate lobe,bilateral taloid fissure and right lingual gyrus(double sample t test,P<0.001,Uncorrected).4.Calculation results of functional connection based on region of interest.Compared with CON group,the functional connections between right superior parietal gyrus and right middle frontal gyrus,left anterior cingulate gyrus,right postcentral gyrus and left superior occipital gyrus,right superior marginal gyrus and left caudate nucleus,and bilateral Talar fissure were weakened in TLE group,while the functional connections between left superior marginal gyrus and left angular gyrus,bilateral middle frontal gyrus and right precuneus and right cerebellum were enhanced in TLE group.In WM group,there was no weakened functional connection,but the functional connection between right angular gyrus and right superior temporal gyrus,right superior marginal gyrus and right postcentral gyrus,right middle frontal gyrus and right lingual gyrus was enhanced.Compared with TLE group,there was no weakened functional connection between left angular gyrus and right superior temporal gyrus,right angular gyrus and right superior temporal gyrus,right superior parietal gyrus,right middle frontal gyrus and right lingual gyrus,right superior parietal gyrus,left superior occipital gyrus,left anterior cingulate and left superior occipital gyrus,right anterior cingulate gyrus and right superior parietal gyrus(double sample t test,P<0.001 uncorr correction).5.Correlation Analysis between functional connection strength and Behavioral Science.Correlation analysis between functional connection strength and ACC:the Z value of functional connection between the left corner gyrus and the left superior marginal gyrus was negatively correlated with ACC at p<0.05.The functional connection strength of the left corner gyrus and the left marginal superior gyrus were negatively correlated with ACC(r=0.310,P<0.019).The Z value of functional connection between right angular gyrus and right superior temporal gyrus was negatively correlated with ACC.The Z value of the functional connection between the right middle frontal gyrus and the right lingual gyrus was negatively correlated with the accuracy at the level of P<0.05.The Z value of functional connection between left angular gyrus and right superior temporal gyrus was negatively correlated with ACC.Correlation analysis between functional connection strength and RT:the Z value of functional connection between right middle frontal gyrus and right lingual gyrus was positively correlated with RT.Conclusion1.Some TLE patients showed behavioral abnormalities in working memory,that is,the accuracy decreased and the reaction time prolonged.2.The task positive network during WM coding period was concentrated in the frontal-parietal-occipital network,especially in the middle frontal gyrus,parietal cortex and fusiform gyrus.3.The inactivation of brain regions related to the DMN network plays an important role in the WM coding process.4.The resting state network between frontal,parietal and occipital lobes is an important neural basis for WM processing.5.The inhibition in insular lobe,hippocampus and other local brain regions is related to the task performance of WM coding in patients with TLE.6.The functional connections between parietal cortex and frontal-occipital cortex are closely related to the task performance of WM in patients with TLE. |
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