The Information Transmission Characteristic Of The Limbic System During Identification Of Positive Emotions In Patients With Depressed Patients: A MEG Study

Objective:The loss of pleasure is existing both major depression disorder and bipolar disorder,which is closely related to abnormal processing of positive emotional,however,the neural basis and the characteristics of information transmission have not been fully elucidated.In this study,positive emotion recognition task was used to explore the characteristics of the neural basis,and whether the information interaction characteristics of the related core regions before and after antidepressant therapy were state,further,whether these information transmission features are specificity of disease in unipolar depression and bipolar depression.Methods:The depressive episode patients from Nanjing Brain Hospital were covered by the DSM-IV-TR criteria of MDD and BD,who were well matched with the healthy controls'age,education,sex and the resident location.During the follow-up,parts of patients experienced mania and hypomania and were modified diagnosis as bipolar affective disorder according to DSM-IV-TR criteria.All the participants were estimated by the Hamilton depression scale 17-items(HAMD₁₇)and Bech-Rafaelsdn mania rating scale?BRMS?and scanned by the magnetoencephalograph?MEG?during the recognition of facial emotion task.The MEG data were preprocessed by the Filedtrip?/fieldtrip.fcdonders.nl?,the whole brain was divided into 90 regions using automated anatomical labeling template?AALs?via graph theoretical analysis.By using the coherence method,the functional connections of any two brain regions in 90 brain regions were calculated,and the Fisher Z transformation was performed to obtain the functional connectivity matrix of the whole brain.Then,the betweenness centerality and clustering coefficient index of graph theoretical analysis were calculated for the functional connection matrix of each subject.Discussion from the following aspects:1)To compare the difference of betweeness centrality of whole network nodes between patients with depression and healthy subjects,in processing of information transmission and integration of positive emotions,while exploring its correlation with the severity of the disease,permutation test was performed to compare values of betweeness centrality of two groups and Pearson correlation was also conducted for correlation with the total score and factor scores of HAMD17 items.Further,to explore the possible abnormal electrophysiological mechanisms of positive emotional processing in patients with depression.2)To provide the brain imaging markers for the treatment effect of clinical depression in acute stage.The differences between the interactions between the core regions of the limbic system in patients with depression before and after antidepressant therapy and those in normal subjects were compared in a longitudinal manner.The ANOVA was performed to investigate the aberrant effective connections of limbic circuits in three groups,and then the differences before and after treatment were found,and and further explore whether the abnormal happy facial emotion processing is state abnormality or trait defect.3)From the perspective of clinical differential diagnosis,we keep going on to explore the positive emotion recognition of unipolar depression and bipolar disorder with depressive episode.The differences in the integration and transmission of emotional information in the local brain regions of the whole brain network,in order to investigate whether the difference of information transmission was disease-specific,and find the biological markers for early identification of unipolar and developing bipolar disorder and the electrophysiological basis for later dysphoria.All the results obtained from statistical analysis were based on false discovery rate?FDR?method.Multiple comparisons correction was performed to obtain the brain area with significant difference?p<0.05?after FDR correction.Results1)To explore the correlation information transmission disorder and severity of the disease in patients with depressionCompared with the controls,during 0-600ms,depressed group showed decreased betweeness centrality in the right super frontal orbital gyrus?p=0.00038?,left middle orbital frontal gyrus?p=0.00016?,right middle orbital frontal gyrus?p=0.00023?,the right amygdala?p=0.00043?,which were corrected by false discovery rate.Among them,in depressed group,the betweenness centrality of right super frontal orbital cortex and the total HAMD17 score?r=-0.4810,p=0.004?and the anxiety/somatization factor?r=-0.3828,p=0.026?were negatively correlated,and the betweenness centrality of the right middle orbital frontal gyrus was negatively correlated with the total HAMD17 score?r=-0.7491,p<0.0001?and anxiety/somatization factor?r=-0.4309,p=0.011?2)The aberrant interaction of limbic system in recognition to positive emotions among depressed patients before and after antidepressant treatment were state?1?Among the above three groups,significant differences of effective connections were found in the connections of OFC to AMYG?p=0.030?,Hipp to AMYG?p=0.025?,Insu to AMYG?p=0.047?,and AMYG to Hipp?p=0.002,FDR correction?.?2?Compared with the healthy control group,the depressed patients before antidepressants treatment displayed higher activity in effective connections from OFC to AMYG?p=0.040?,lower activity in effective connections from the ACC to the Hipp?p=0.042?,and lower activity in effective connections from AMYG to Hipp?p=0.001?,and vise versa?p=0.026?.?3?After antidepressants treatment,the activity of effective connections from the OFC to the AMYG significantly reduced?p=0.013?,and the activity of connections from AMYG to Hipp significantly increased?p=0.006?,and vise versa?p=0.026?,while the activity of effective connections both from AMYG to Insula and from Insula to AMYG significantly reduced?p=0.036,p=0.015?.?4?Depressed patients after treatment showed no significant difference compared with the healthy control group.3)To explore information transmission characteristic during positive emotion recognition between unipolar depressive episode and developing bipolar disorder with depressive episodeThe enhanced clustering coefficient?Cp?in the left dorsolateral superior frontal gyrus?SFGdor?,right medial superior frontal gyrus?SFGmed?,left middle Occipital gyrus?MOG?and right paracentral lobule?PCL?in BD when compared to UD group.In addition,we also explored to analyze the topological properties of the abnormal areas,comparing the total score of HAMD₁₇,the age of the first onset,the total course of disease,ect,to elucidate their relationships with clinical indicators,with the pearson correlation analysis.Firstly,in UD group,there was a negative correlation between the Cp of right SFGmed and the total score of HAMD₁₇?p=0.036,r=-0.342?;the Cp value of right PCL was a negative correlation with total course of disease?p=0.002,r=-0.478?.In BD group,there was a negative correlation between the Cp of left SFGdor and the age of the first onset?p=0.005,r=-0.584?,positive correlation with duration of current episode?p=0.034,r=0.464?;what's more,the Cp of right PCL was a negative correlation with the age of the first onset?p=0.012,r=-0.538?.Conclusions:In patients with depression,the aberrant processing of positive emotions involved in multiple regions of the whole brain,in which the limbic system of information transmission disorders play an important role,may be the neuropathological basis of positive emotion processing abnormalities.The interaction between the core regions of the limbic system was weakened and improved with the relief of symptoms after antidepressant treatment,which suggested that the information transmission characteristics of abnormal processing of positive emotion were state.Furthermore,the abnormalities of positive emotional information transmission in patients with unipolar depression and bipolar depression were trait of disease.