| Objective:Cerebral small vascular disease(CSVD),which causes one fifth of stroke in the world,is the main cause of cognitive impairment and dementia.As one of the main cognitive functions,working memory(WM)causes behavioral errors when working memory is impaired.It still needs a lot of research to understand the relationship between neural network structure and information processing process in working memory.At present,the onset and clinical manifestations of working memory disorder are more subtle than other types of cognitive dysfunction.Foreign research on working memory brain motor system has achieved considerable scale and results,while domestic research in this direction is relatively lacking,and the research scope is limited and not deep enough.Based on the study of theta oscillation of EEG,this paper further analyzes the EEG signals of patients with cerebrovascular disease and normal subjects in working memory,compares the functional connection strength and information flow of the two groups of subjects,so as to analyze the EEG signals of each subject in the process of working memory individually and understand how the different regions of brain are in the functional circuit The purpose of information transmission is to provide new ideas and techniques for the early clinical detection of working memory disorders,and to support the analysis of WM brain network in CSVD patients.Methods:A total of 78 patients with cerebrovascular disease and 49 control subjects were enrolled.The 25 channel EEG and working memory behavioral data of the two groups were recorded under the visual object working memory task(load 4).The response time and accuracy of working memory behavior were analyzed.2770 experimental results of working memory subjects were analyzed,EEG data were processed,the characteristic frequency band of working memory was explored,and the spatial distribution of energy in the characteristic frequency band was drawn.The directed transform function(DTF)is calculated,and the causal network is constructed.Based on the multivariate frequency domain Granger causal analysis,the DTF matrix between 25 channels is obtained,and the Weighted Causal flow of each group is calculated.ROC curve is used to analyze theta oscillation and prediction value of DTF value of Fz channel to CSVD.Result:1.Baseline data: a total of 78 CSVD patients,49 control subjects,1636 experiments in CSVD group and 1134 experiments in normal control group were included.There was significant difference in age and education years(P < 0.05),but no significant difference in gender(P > 0.05).MMSE and Mo CA scores of CSVD group decreased significantly(P < 0.01).2.Behavioral results of working memory: there was a significant difference between CSVD group and control group,which showed that the response time was prolonged and the accuracy was decreased(P < 0.001),suggesting that CSVD patients had significant working memory disorders.3.Energy density of 25 channel EEG: calculate the energy density of 25 channel EEG in the whole frequency band of two groups of subjects: the energy density value of theta frequency band is significantly higher than that of delta,alpha,beta and gamma frequency bands(LSD-t test,P < 0.001),theta frequency band(4-8Hz)is the characteristic frequency band,and the average energy density of frontal area in the whole frequency band is the highest,with Fz channel being the most significant,suggesting that The frontal area is the characteristic brain area of working memory,the Fz channel is the characteristic channel of visual object working memory,and the energy density of EEG in theta band in CSVD group is lower than that in control group(P < 0.001).4.Time-frequency distribution of Fz channel: the time-frequency distribution of the two groups of subjects in the characteristic channel(Fz channel)shows that the energy density of EEG is mostly concentrated in the 3s delay period in time,which indicates that the key memory period of visual object working memory is 3s delay period;and the energy density of EEG in theta band in the 3s delay period of Fz channel in CSVD group is lower than that in the control group.5.Causal connection: the DTF value of theta frequency band is the largest in Fz channel,indicating that Fz channel has strong causal connection;the average weighted causal flow is significantly higher in frontal area than other brain areas,and the causal flow in parietal and occipital areas is significantly lower than other brain areas,indicating that frontal area is the causal source of information interaction,and the parietal and occipital areas are the causal sink.Conclusion:1.CSVD patients have behavioral disorders of working memory.The characteristic frequency band of visual object working memory is theta frequency band,the characteristic channel is Fz channel,the characteristic brain area is frontal area,the causal connection of visual object working memory is the strongest in Fz channel,the average weighted causal flow indicates that frontal area is the causal source of information interaction,and the top area and occipital area are the causal sink;2.When theta band energy is lower than 0.505 μ V2 / Hz,it is highly suspected that the subjects have working memory disorder.Next,the functional connection strength of EEG signal of the subjects is analyzed.When the DTF value of Fz channel of the subjects is lower than 0.04,it can be further confirmed that the subjects have working memory disorder;3.Individualized analysis of EEG signals of each subject in the process of working memory,which will lay a foundation for the future research on the mechanism of CSVD cognitive impairment,have a certain guiding role in the early clinical detection of patients with working memory impairment,and provide new ideas for the analysis of WM brain network of CSVD patients. |
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