| Temporal lobe epilepsy(TLE)is the most common form of focal epilepsy in adults,and about 40% of TLE is refractory epilepsy.TLE is a progressive disease whose clinical,cognitive and imaging characteristics change over time.Although there have been a few reports on the mechanism of TLE disease progression in previous studies,the disease progression mechanism of epilepsy has not been well explained,especially the mechanism of epilepsy development after a long duration of disease remains unclear.In recent years,resting functional magnetic resonance imaging(f MRI)technology has been widely used in the field of neuropsychiatric diseases.Recent f MRI studies have shown that brain functional connectivity is not fixed,but a dynamic and complex system.The use of a combination of static and dynamic tests can capture changes in brain functional connectivity more fully.Objective: This study uses multi-scale brain network analysis methods such as static and dynamic functional network connectivity,graph theory methods,time-varying networks,etc.,from the large-scale functional networks of patients with TLE in different disease processes,brain functional network topological properties and time-varying networks,etc.,To conduct in-depth research on the static and dynamic brain function network mechanisms related to TLE disease progression.Methods: This study included 19 TLE patients with a disease duration of less than or equal to 5 years(TLE-SD group),24 TLE patients with a disease duration of more than 5 years(TLE-LD group),and 21 matched gender,age and education level Healthy control group(HCs group).Demographic and clinical data were assessed for all subjects.Resting state f MRI and attention network test(ANT)were performed.The main research contents include the following three aspects:1.Changes in static and dynamic functional network connectivity related to TLE disease progression and their effects on attentional function in TLE patients:(1)Group independent component analysis(GICA)was used to determine the target resting-state network(RSN),and a comparison of static functional network connectivity(s FNC)between TLE groups was conducted.(2)Dynamic functional network connectivity(d FNC),temporal characteristics and temporal variability parameters of different states were obtained by using sliding window correlation and K-means clustering analysis,and then compared between groups.(3)Correlation analysis with attention function.2.Study on the mechanism of the whole brain functional network related to disease progression in TLE patients based on graph theory:(1)constructing the whole brain functional network.(2)The topological properties of the functional brain networks of the three groups of subjects were calculated by the graph theory method,and the hub nodes were determined.(3)Comparison of global attributes and hub node attributes between groups.(4)Correlation analysis with attention function.3.Study on the mechanism of time-varying networks related to disease progression in TLE patients based on graph theory:(1)A time-varying network of dynamic brain connectivity patterns of all subjects was constructed by using the sliding window method.(2)Calculate the variance of the dynamic network topology attribute based on graph theory as the temporal variability indicator.(3)Comparison of temporal variability of global and node topological attributes between groups was conducted.(4)Correlation analysis with attention function.Results: 1.TLE patients with disease progression related changes in static and dynamic function network connectivity and its influence on attention function:(1)no significant between-group differences were found in terms of the alerting efficiency,orienting efficiency,or executive control efficiency.However,there were significant between-group differences in response time(RT)of the seven prompt conditions,TLE-SD group and TLE-LD group were significantly longer than the HCs group.(2)There were specific s FNC changes in TLE-SD patients,and the connectivity between dorsal attention network(DAN),sensorimotor network(SMN)and visual network(VN)increased,while the connectivity between inferior-posterior default mode network(ip DMN)and VN decreased.(3)TLE-SD patients showed more and inconsistent abnormal functional connectivity between networks in d FNC.(4)The temporal characteristic of the TLE patients and temporal variability in specificity,change in d FNC strong connectivity state,TLE-SD patients spend the longest fraction of spent time and the mean dwell time,two groups of the temporal variability in TLE patients were significantly higher than that of HCs group.And the auditory network(AN)-left fronto-parietal network(l FPN)connectivity are negatively correlated with orienting efficiency.(5)Only differences in static and dynamic RSN connectivity were found between TLE-SD patients and HCS group,while no significant differences were detected between TLE-LD patients and HCS group.2.Based on graph theory of TLE disease progression in patients with whole brain function network related mechanism research:(1)Small-world attributes can be observed in the brain function network of TLE patients and healthy controls.Compared with TLE-LD and HCs groups,The TLE-SD group showed a decline in the function integration of the whole brain network,an increase in functional separation,and a decline in information processing capabilities(the characteristic path length and the normalized characteristic path length increased,the normalized clustering coefficient decreased,and the global efficiency and local efficiency decreased).(2)The distribution pattern of hub nodes in TLE-SD patients was changed.Compared with the TLE-LD and HCs groups,the TLE-SD group has the ventrolateral area of the left middle frontal gyrus,the left central anterior gyrus(upper limb area),the head of the left upper lobule,and the tail.The nodal value of the brain areas such as the lateral and parietal inner area,the caudal side of the right upper upper lobule,and the right lateral occipital cortex are significantly increased.(3)TLE-SD patients have a significant increase in the middle of the right upper frontal gyrus and the head of the left upper upper lobule.The node efficiency is significantly lower than that of TLE-LD patients,and the node efficiency in the middle of the right upper frontal gyrus is significantly lower than that of the HCs group.(4)The node network attributes of the left upper lobe are positively correlated with the execution control efficiency,and negatively correlated with the orientation efficiency.(5)Only the comparison between TLE-SD patients and HCs group found significant differences in global and node network attributes,and no significant difference was detected between TLE-LD patients and HCs group.3.Study on the mechanism of time-varying network associated with disease progression in TLE patients based on graph theory:(1)The temporal variability of the characteristic path length in TLE-SD patients was significantly higher than that of TLE-LD patients and HCs group.(2)The temporal variability of the node efficiency in brain areas such as the right inferior frontal gyrus,right cingulate gyrus,bilateral basal ganglia and bilateral thalamus showed significant changes.The TLE-SD patients were significantly higher than the TLE-LD patients and the HCs group.(3)The temporal variability of node efficiency in the ventral region of the right inferior frontal gyrus is negatively correlated with alertness efficiency,and the temporal variability of node efficiency in the right basal ganglia dorsal-caudal region is positively correlated with executive control efficiency.Conclusion: 1.Patients with TLE have abnormal static and dynamic brain functional network connectivity,and this abnormality may lead to functional reorganization and compensatory remodeling with the prolongation of disease duration.2.The network topology of patients with TLE is damaged;some hub nodes are damaged and overloaded;the stability of the whole brain network function integration is reduced,and the information transmission or processing capacity and efficiency of some brain regions are disordered;as the duration of the disease is prolonged,there is a compensatory reorganization,and the brain function network dynamic reconfiguration occurred,and the redistribution began to be normalized.The whole brain information integration and abnormal regulation and its dynamic reconstruction may be the neuroimaging mechanism related to the disease progression of TLE patients.3.The stability of the connectivity between the auditory network and the left frontal-parietal network decreases,which may lead to the impairment of orienting function;The left parietal lobule may play an important role in the impairment of orienting and executive control function in TLE patients.The research on the whole brain time-varying network shows that the variability of the dynamic network topology properties may be an important indicator for the study of attention dysfunction in TLE patients. |
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