The Neural Basis Of Extraversion Of Personality Trait And Its Influence Factors

Personality is a stable,enduring and distinctive behavioral pattern that reveals in the interaction between an individual and his/her environment.A person with the personality trait of extraversion is often optimistic and is more likely to enjoy social relationship and experience more positive emotions.Extraversion is a dimension of personality that is related to positive emotions like self-wellbeing.Generally speaking,extraversion is a relatively stable personality trait that is based on heredity.Moreover,environmental factors,such as family and narrative of life events,also contribute to the formation and development of extraversion.Therefore,it plays a fundamental role to interpret the neural basis of extraversion and how familial and genetic factors affect extraversion,which will further promote other studies related to intervening treatments,cultivating of healthy personality,elevation of self-wellbeing,etc.In this dissertation,three studies have been conducted in order to explore the genetic,neural,and familial basis of personality.The pilot study was to examine the correlation of brain structure and extraversion of personality and the stability of this correlation.337 subjects,all of which are college students,took part in this study.Data concerning extraversion were collected by using NEO-PI-R;grey matter volumes of each subject were calculated by using T1 structure images collected from resting-state functional magnetic resonance imaging.According to the multiple linear regression analysis of extraversion scores and volumes of grey matter,it was found that there is a positive correlation between the aggregate score of extraversion and grey matter volume of bilateral caudate nucleus,and that there is a negative correlation between the aggregate score of extraversion and grey matter volume of left inferior frontal gyrus and left parietal lobe.Two years later,118 of the 337 subjects were retested using the same questionnaire and the same method of MRI scanning and calculation.This time,it was found that extraversion is positively correlated with grey matter volumes of bilateral caudate nucleus,cerebellum,and middle frontal gyrus,and negatively correlated with grey matter volumes of left inferior frontal gyrus and left parietal lobe.According to the overlay analysis of the results of the two studies,it can be confirmed that the correlation of bilateral caudate nucleus and extraversion aggregate sore is replicable.The second study was to investigate the influences of family environment on extraversion and to examine whether these influences can be reflected in the neural system.Family factors in this study include parenting pattern,presence of a single child,family income and socioeconomic status during childhood.Bilateral caudate nucleus is chosen as ROI to study the neural mechanism of how familial factors influence the trait of extraversion.After the analysis of correlation,it was found that only socioeconomic status during childhood has a significant correlation with extraversion.The results of mediation analysis showed that the mediating effect of the volume of left caudate nucleus in the relationship between “socioeconomic status during childhood” and extraversion is validated.In the last study,genetic information was analyzed with neural structure and personality traits to explore how genes affect extraversion of personality via neural system.Polygenic Score was adopted as the indicator of genes,and bilateral caudate nucleus was also used as ROI to study the neural mechanism of how hereditary factors influence extraversion.Correlation analysis showed that Polygenic Score has the significant positive influence on extraversion occurs when the PRSe5 threshold is 0.5.Mediation analysis also confirmed the validity of left caudate nucleus in the relationship between PRSe5 and extraversion.To conclude,this series of studies can give better knowledge of extraversion,the mechanism of how extraversion influences self-wellbeing and the neural mechanism of extraversion.Moreover,the location of the key region of extraversion also provides a biological marker of prediction and intervention of emotional dysfunctions and an evidence on cultivating of wholesome personality,elevating of self-wellbeing and,promotion of individual lives.