Development Changes And Sex Differences In Responding To Negative Emotion Of Different Intensity During Adolescents: ERP Correlates

The adolescent undergoes dramatic physiological and psychological changes. Hormone changes in this period result in changes in the height, the reproductive system and other secondary sex characteristics. Meanwhile, the development of teenager is also undergoing the redistribution of brain function which occurred from low-level subcortical structures to prefrontal cortex and other senior brain area. This kind of redistribution provides better self-control over emotional behavior. Moreover, the redistribution may be modulated by changes of gender special hormone.The previous research claimed that related brain regions for emotional processing during the adolescence period are still in developing, and they reflected the development immaturity during the childhood and the adolescence period. Thus, compared with adults, individuals who have immaturity brain may appear different responses model to different strength negative emotional stimuli. Bottom-up processing of subcortical region and inefficient top-down control system of prefrontal regions may result in the incongruousness between emotional processing system and control system in the adolescent stage, which caused emotional disorders'increase in the adolescence period. Development research on emotional processing and emotional regulation and emotional processing model basing on neurobiology can enhance the knowledge of abnormal emotion regulation and emotional disorder which individuals are suffer from in the childhood and the adolescence period. Therefore, research on neural mechanisms of different strength negative emotional stimuli for brain development individual, may be benefit to prevention of emotional disorder for adolescent. Due to the crucial evolutional meaning of negative attentional bias to terrified and threatening stimuli, the sensitivity of teenagers to negative emotional stimuli is of great significance for the development of the teenager. However, fewer researches have examined teenagers undergoing important development period of brain.In experiment one, employing the double choose implicit oddball paradigm and ERP with high temporal resolution, we aimed to investigate the processing of different negative strength emotional stimuli and its time course for teenagers and adults, and found differences of negative emotional processing between teenagers and adults. Emotional stimuli strength is divided into three conditions: extreme negative (HN), medium negative (MN), Neutral. The data showed that although there were no differences in explicit behavioral responses for adolescence to different strength negative emotional stimuli under the implicit task, there appeared separations from the ERP results, which showed separating ERP components such as P2, N2, P3 in different conditions. This significant separation appeared in the frontal-central scalp electrodes, but not in the back scalp electrodes. Moreover, the ERP amplitudes of teenagers were bigger than that of adults. The decrease of amplitudes with the age growth was consistent with cortical efficiency improvement. Compared with adults, the negative emotional effects of teenagers appeared later. Especially speaking, the effects appeared N2 stage for teenagers, but it appeared earlier P2 stage for adults. However, the negative emotional effects of teenagers lasted longer than that of adults, which reflected by the fact that the sensitivity to extreme negative emotional stimuli still exist in P3. The results demonstrated the sensitivity of teenagers to extreme negative stimuli, and inadequate sensitivity to the medium negative stimuli. The results also showed immature emotion regulation ability of teenagers.In experiment two, bounded by the maturation of puberty, we aimed to investigate neural mechanisms of negative emotional valance effects of pre-adolescence and adolescent, and understand the changing trend of sensitivity of different gender to negative emotional due to maturation, and provide electrophysiological evidence for teenager's emotional development research. Using the same paradigm and technical means as experiment one, we manipulate the emotional negative intensity. By Physical Development Scale, participants were divided into two different age groups:pre-adolescence and adolescent. Negative emotional valance effects of different gender in pre-adolescence and adolescent were examined in the second experiment. ERP results showed that there were significant interaction between valence of P2, N2, age and gender. In the N2 stage, Males in pre-adolescence group were sensitive to HN, but females in this group did not appeare emotional effect. In the stage of P2 and N2, females in adolescence group were sensitive to HN and MN. In the Late P3 and SNW stage, there were no significant interaction between valence, age and gender. They were all sensitive to HN. Therefore, female's sensitivity to negative emotions improves gradually due to maturation, while males do not be affected by maturation, which are reflected by no change before and after puberty. At the late top-down processing stage, regardless of gender, both groups showed immature prefrontal cortex function was and insufficient emotional adjustment ability, which demonstrated negative emotional processing capacity of individual in childhood and adolescences stage is still under development.As for future research, it is necessary to investigate neural mechanisms of adolescent from the emotional inhibitory control, selective attention perspective. Meanwhile, it is necessary to develop the pathology of brain development individual, conduct targeted prevention and control, and attract the education system and the judiciary's concern.