| Objective(1) To investigate whether patients with major depression show negative cognitive bias and the time characteristics identifying the valence of the emotional words presented in hemi-field.(2) To explore abnormal brain activities of patients with major depression(MDD).(3) Combining the behavioral and event-related potentials(ERPs) results,to explore the brain lateralization of emotional words procession.MethodsTwenty-five(13females) first-episode depression outpatients whose symptoms met the DSM-Ⅳcriteria for major depression were recruited and Twenty-five healthy participants(14females) matched with the patients took part in this study.They were asked to response to the valence of the emotional words presented in hemi-field while the ERPs were recorded during the subjects performing the task.The average reaction times were subjected to ANOVA with repeated measures.The ERPs waves under different conditions were overlapped and averaged separately and then the mean amplitudes of ERPs components were compared between depressed and control group.Results(1) Compared to control group(640ms),MDD(736ms) got longer reaction time(RT),(F(1,48)=8.087,P=0.007).For all subjects the RT was significantly longer to the positive words(694ms) than the negative(663ms) presented in the right hemi-field(F(1,48)=9.482, P=0.003).And the RT of the negative words(691ms) presented in the right hemi-field was longer than the RT(662ms) of the ones presented in the left hemi-field(F(1,48)=21.548,P＜0.001).RT of the positive words presented in the left hemi-field was longer than that presented in the right hemi-field(F(1,48)=6.296,P=0.095).(2)The analysis of P2 component showed that the mean amplitudes of positive words (5.76μv) were larger in the middle line(FZ,CZ,PZ)than the left area (F4,C4,P4)(4.77μv),P＜0.05.And the amplitudes induced by negative words were larger in the middle(FZ,CZ,PZ)(6.74μv) and right area(F4,C4,P4)(6.42μv) than the left hemisphere(F3,C3,P3)(5.18μv) P＜0.05.(3)In control group the amplitudes of N400 in the central(C3,CZ,C4)(5.28μv) and parietal area(P3,PZ,P4)(6.72μv) were larger than the frontal area(F3,FZ,F4)(2.24μv) (F(2,96)=6.600,P=0.007).(4)The analysis of Late positive component (LPC) showed that in MDD group the amplitudes of positive words were larger in central area(C3,CZ,C4)(4.99μv) than that in the frontal area(F3,FZ,F4)(3.10μv),P=0.007,but no significant differences were found in the control group.For the MDD,the amplitudes of negative words in central(C3,CZ,C4)(5.29μv) and parietal area(P3,PZ,P4)(4.50μv) were larger than the frontal area(F3,FZ,F4)(2.40μv), P＜0.05,while in the control group the amplitudes in the central area(C3,CZ,C4)(5.46μv) were larger than parietal area(P3,PZ,P4)(3.64μv),P=0.001.There were differences between two hemispheres. For the control group,the amplitudes of negative words in the middle lineFZ,CZ,PZ)(5.46μv) were larger than that in the right hemisphere (F4,C4,P4)(3.64μv);in MDD group,the amplitudes of the right hemisphere(F4,C4,P4)(4.50μv) and middle line(FZ,CZ,PZ) (5.28μv) were larger than that of the left hemisphere(F3,C3,P3) (2.40μv),P＜0.05.Conclusions(1) The behavioral results did not support that there is negative bias in MDD.(2)The ERPs data suggested that there were deficits of emotion procession of MDD emerging during the later stage.And MDD had functional brain abnormalities in the central and parietal area of the brain,as well as in left profronntal area.(3)Combining the behavior and ERPs results,the data supported the model of the brain lateralization of emotional processing that the left and right anterior regions are specialized for the expression and experience of positive and negative valence,respectively,whereas the right posterior parietal,temporal,and occipital regions are dominant for the perception of emotion. |
PDF Full Text Request