Neural Correlates Of Abnormal Self-concept Of Depressed Patients:Evidence From The MRI Study

Self-concept (or self-schemate, self_perception, self_structure) is a generalization of the self, is the individual’s viewpoint about himself or herself, is a core idea which is used to explain the emotional disturbance or other behavioral and psychological problems. Self-concept is strong correlation with the formation of depression. Numerous studies have confirmed that the depression often originated infrom self-concept, consolidated on self-concept. There are a lot of behavior researches about abnormal self-concept of depressed patients, but few researches on the neuroimaging at home. The results about neural mechanism of abnormal self-concept in depressed patients are inconsistencies and contradictions, the situation needs to be further discussed. There are a lot of fMRI studies about abnormal self-concept of depressed patients which focus on brain function, but this abnormal brain structure of self-concept in depressed patients has been little investigated. We hope to find the characteristics of abnormal self-concept in depressed patients from the perspectives of brain function and structure, in order to explain the characteristic of cognition of depressed patients, and provide biological targets about the treatment of depressed patients.This study included two experiments. The first experiment used the self-referential task with fMRI to explore the abnormalities of brain function in the self-concept of the depressed patients. The experiment required subjects judged two different judgment conditions:self-referential processing and other-referential processing. Behavior results reported that, the reaction time (RT) during participants processed negative words was longer than positive words, the RT of depressed patients was significantly longer controls; Controls were described themselves about more positive words and fewer negative words, but depressed patients had not significant difference, this indicated that depressed patient have negative self-concept. FMRI results showed that, depressed patients showed significantly bigger activated in the left ventromedial prefrontal cortex (VMPFC) and right posterior cingulate cortex (PCC), and significantly smaller activated in bilateral dorsomedial prefrontal cortex (DMPFC) and right angular relative to controls in self-referential condition; Patients showed significantly smaller activation in bilateral DMPFC and left insula relative to controls in other-referential condition. In addition, relative to controls, depressed patients significantly greater activated in left VMPFC and right precuneus, and more smaller activated in bilateral DMPFC and bilateral angular when processing of positive words in the self-referential condition; patients significantly greater activated in PCC, and significantly smaller activated in bilateral DMPFC. This suggested that activation of cortical midline structure (CMS) might be related to abnormal self-concept in depressed patients.The second experiment mainly was exploring the characteristic of brain structure about self-concept of depressed patients. Firstly, we compared the difference between depressed patients and controls in brain gray matter volume (GMV). Then, we used voxel-based morphometry to explore the correlation between Tennessee Self-Concept Questionnaire scores and the GMV of brain structure of the patients or controls. Behaviors results showed: depressed patients’ scores in physiological self, psychological self, family self-concept, social self-concept, self identity, self satisfaction, self-action and total self-concept were lower than controls. This suggests that, self-concept of depressed patients in these dimensions was more negative relative to controls. MRI results revealed: depressed patients revealed that the GMV of left precuneus and lingual gyrus were bigger, and the GMV of superior frontal gyrus was atrophy relative to controls, there were positive correlation about family self-concept and the GMV of left superior parietal gyrus, right PCC and right inferior frontal gyrus in controls; scores of self-action were higher, the GMV of right PCC was bigger; in moral-ethical self-concept dimension, controls were higher scores, the GMV of right inferior parietal gyrus was smaller; in self identity dimension, patients were higher scores, the GMV of right inferior parietal gyrus was bigger; the scores of personal self-concept were higher in patients, the GMV of right inferior parietal gyrus was larger; in total self-concept, patients were higher scores, the GMV of right inferior parietal gyrus were bigger. Structure results showed that the abnormal self-concept of patients may be associated with the changes of GMV.Above all, we think, self-concept of depressed patients is abnormal. Patients displayed the structure and function of CMS differing from controls in the MRI neuroimaging. For the realistic significance, this research had provided a constructive suggestion for prevention, diagnosis, treatment, recoverment of depressed patients, for the therapeutic intervention of depressed patients provide biological targets.