An ERP Study On The Characteristics Of Attention Bias Of Clinical Depression And Their Antidepressant Effects

Objectives : 1.According to the characteristics of event related potentials when executing cue-target paradigm to explore clinical depressions’ cognitive features of attention bias of negative emotional information. 2.Discussing antidepressants could correct the attention bias or not, and analyzing the psychological mechanism of these modifications.Methods:This study included two parts, one was an ERP study about the deference between depression group and control group, another was the comparison of depression before and after treatment. Selected clinical depressions were in accordance with international psychiatric diagnosis and classification standard(ICD-10)(depression group,20 cases), and following-up after SSRIs antidepressant treatment for 4 weeks, 16-case effective treated depressions were totally collected(treatment group,16 cases), 20-case control group were selected in terms of gender,age,and education years which matched with depression group(control group,20 cases). Using the Chinese facial affective picture system established by psychological research institutes in Chinese academy of sciences as stimulus materials,selected one of the common paradigms about attention bias—cue-target paradigm, as current experiment paradigm, the time interval between the clues and target was1000 ms. All subjects were required to press button when targets came as soon as possible, and recording the behavioral and electroencephalological data simultaneously. Count data was by Chi-square test, numerical variable data two groups’ comparing used t test and three groups’ used analysis of variance,comparing the difference of mean reaction time and accuracy between depression group with control one and the depression group before and after treatment under the condition of different clues(effective tasks, invalid tasks, neutral pictures, negativepictures). Basing on the formula to calculate the score of inhibition of return, then using t test compared their differences. Comparing the differences of corresponding components’ amplitude and latency after offline analysis by curry 7.0.7.Results:1. The deferences between depression group and control group.1.1 Behavioral outcomes:Compared to the control subjects, clinical depressions’ total mean reaction time was longer(p<0.01). The deference of control group between invalid task reaction time and effective one is positive, and the deference of depression group is negative. Both groups showed that the accuracy of effective tasks was higher than invalid one, and the neutral one was higher than negative one(p<0.05).1.2 Electroencephalological outcomes : N1 component, parietal lobe amplitude of depression group was larger than control group(p<0.01), and the latency of neutral pictures,negative pictures,parietal lobe,left and right cerebral hemisphere was longer than control group(p<0.01). P1 component, the latency of effective tasks, invalid tasks,neutral pictures, negative pictures and occipital lobe of depression group was longer than control group(p<0.05). N170 component, the amplitude of frontal lobe, parietal lobe and occipital lobe of depression group was larger than control group(p<0.05).The latency of neutral pictures,parietal lobe and right cerebral hemisphere of depression group was longer than control group(p<0.05). P300 component,the latency of left cerebral hemisphere of depression group was longer than control group(p<0.05).2. The comparison of depression before and after treatment2.1 Behavioral outcomes:After treatment, the reaction time of neutral and negative pictures was shorter than before(p<0.01). Before and after treatment, the deference of invalid tasks reaction time and effective one was both negative. Both two groups showed that the accuracy of effective tasks was higher than invalid ones, and the neutral pictures higher than negative ones(p<0.05).2.2 Electroencephalological outcomes:N1 component, after treatment, the amplitude of frontal lobe was lower than before(p<0.05). P1 component, after treatment, thelatencies of invalid tasks and middle cerebral hemisphere were longer than before(p<0.05). N170 component, after treatment, the amplitude of parietal lobe and middle cerebral hemisphere was lower than before(p<0.05). P300 component, after treatment,the latency of right cerebral hemisphere was shorter than before(p<0.05).Conclusions:1.Compared to control subjects, clinical depression’s speed of cognitive processing when executing cue-target paradigm is slower, can interpret the symptom characteristics of depression which are retardation of thinking and hypobulia.2.Normal person showed cuing effect to negative emotional pictures, clinical depression showed inhibition of return, prompt that clinical depression tended to be attracted by negative information. Both normal person and clinical depression show that there is lateralization in emotion process, the amplitude of left frontal lobe is larger, left cerebral hemisphere put more attention resource, that reflects cerebral hemisphere function is asymmetric.3. After SSRI antidepressants treatment, emotional cognitive processing mechanisms of clinical depression are partially corrected. After treatment, the amplitude of frontal lobe of N1 component is lower obviously, prompt that treated depression pay less attention resource when fulfill a task. After treatment, the latency of all components is inordinately cut down.