Working Memory FMRI In Cognitive Impairment Of Medial Temporal Lobe Epilepsy

Objective:In this study,we observed the whole brain activation of m TLE and the normal control group in the performance of the working memory task(picture),and analyzed the differences between the activated brain regions of each group,and investigated its correlation with m TLE induced cognitive dysfunction and its possible neuropathological mechanism.Data and methods:80 cases of medial temporal lobe epilepsy(m TLE)and 50 cases of normal control group matched by gender,age and years of education were collected.Subjects with major depression were excluded by Beck Depression Inventory(BDI).According to the scores of mini-mental state examination scale(MMSE),the enrolled patients with medial temporal lobe epilepsy were divided m TLE without cognitive impairment(NCI-m TLE)and m TLE with cognitive impairment(CI-m TLE)groups.All subjects underwent structural and functional MRI scans.SPM 8.0 software was used to analyze and compare the activated brain areas of the three groups in different periods of the working memory task,that is coding and delay period,respectively.Results:No significant difference was seen in gender,age,years of education and BDI scores among the three groups,while the medical history of CI-m TLE group and nci-mtle group was statistically significant.MMSE scale score and behavioral test showed significant differences.On analysis by the LSD method(further-significant Difference,the Least significant Difference method),the results showed that NCIm TLE group and the control group was not significantly different.MMSE score and the result of behavior,CI-m TLE group and NCI-m TLE of MMSE score and the result of behavior(response speed and accuracy)Difference had statistical significance.1.Coding period: In control group,the brain was predominantly activated and elevated to distinguish the areas of visual task cortex,namely fusiform gyrus,middle occipital gyrus and posterior cerebellar lobe,while the default brain networks such as anterior cingulate gyrus,inferior parietal lobule,medial frontal lobe andsuparmarignal gyrus showed significantly decreased activation.On two groups comparision of m TLE with controls,respectively,no significant difference was seen between NCI-m TLE and control group,while CI-m TLE group compared with control group and NCI-m TLE group,showed some default brain network,such as inferior parietal lobule,angular gyrus compensatory activation and suparmarignal gyrus to rise,associated with visual brain areas,including the occipital lobe,occipital gyrus and other brain regions decompensated activated to reduce.2.Delayed period: In control group,the activation of some areas in the brain was diffusely increased,including bilateral cingulate gyrus and insula,and but the medial frontal lobe showed decreased activation.NCI-m TLE,meanwhile,was found in group and CI-m TLE group were prioritize for some brain regions activated to reduce,including some default activated significantly reduce brain networks,such as precuneus,inferior parietal lobule,cingulate cortex and medial frontal lobe,and on further comparison it was found that in patients with m TLE,CI-m TLE and NCI-m TLE group,these default brain net was characterized by increased compensatory activation.In addition,multiple compensatory activated brain regions are also seen,mainly in the bilateral inferior frontal gyrus,superior temporal gyrus,left insula,inferior parietal lobule and precentral gyrus.Also the areas of the lingual gyrus and other visual-related brain regions showed increased activation compensatory activation.Conclusion:In this study,Bold-f MRI technique was used to analyze and compare the whole brain activation of ci-mtle group,nci-mtle group and normal control group in different periods of working memory task.Results show that when CI-m TLE group compared to control,performance for decompensated activation reduce in multiple regions,and withn compared to NCI-m TLE group,multiple compensatory activated brain areas appear to increase,but the behavior test results(reaction speed and Zheng Chang Lv)are lower than the rest of the two groups.CI-m TLE more serious damage to the brain network.Long-term seizures may also cause network reconfiguration,revealing the m TLE causing nerve pathological mechanism of working memory related cognitive impairment.