The Neural Basis Of Neuroticism Personality Trait And Its Influence Factors

In the personality,the neuroticism is a stable personality trait reflects individual difference in the emotion.High scorer on the neuroticism are characterized by frequent experience of “negative emotionality” such as anxiety,depression,and hostility.Neuroticism was thought to be a personality risk factor for negative emotion and emotional disorder.High neuroticism individuals have higher risk for emotional disorder,such as anxiety and depression.In general,neuroticism is a stable personality trait with special genes,however,the environment(family environment and the life events)also play an important role in the development of neuroticism.Thus,study the neural basis of neuroticism and found its core brain structure and function,and found the neural basis of the relationship between the neuroticism and negative emotion(for example depression mood),and found the neural basis of the influence of the environment factor on the neuroticism personality trait are help to understanding the neural basis of the neuroticism and the influence of the neuroticism on the negative emotion,and also help to the future intervention and treatment of the clinical depression and personality disorder and promote wellbeing of individuals.Recently,with the rapid development of functional magnetic resonance imaging,especial the development of the resting-state imaging and brain structure imaging,more and more researchers begin to study the brain mechanism of the cognitive ability,behavior and personality strait.So far,because of the difference of subjects group,sample size and research methods,the results of the neural basis of neuroticism is inconsistence and unclear.Although neuroticism was thought to be one of the most important personality risk factor for the depression,the neural basis of the relationship between neuroticism and depression is unclear.Previous studies mainly focus on the influence of environment on the neuroticism personality trait behavior,however,the neural mechanism of the environment and neuroticism is unclear.Thus,the present study used three studies including seven experiments to investigate the neural basis of neuroticism and its influence factors and found the core neural basis of the neuroticism personality trait,the neural basis between the neuroticism and negative mood,and the neural basis between the environment and neuroticism.It can be help to provide important biological marker for the future treatment of personality disorder and emotional disorder.In the first study,we used three experiments from brain structure magnetic resonance imaging and resting-state functional magnetic resonance imaging to investigate the brain mechanism of neuroticism,and the neural basis of the relationship between the neuroticism and negative emotion.Experiment 1 collect brain structure magnetic resonance imaging of university students(n=359)to investigate the individual difference in neuroticism and its association with structural features of the brain.Experiment 1 used voxel-based morphometry(VBM)on structural magnetic resonance images to identify the relationship between neuroticism and the volume of brain regions on the whole-brain level.The results of this experiment found that neuroticism scores were negatively associated with the gray matter volume of anterior cingulate gyrus(ACC)and positively associated with the gray matter volume of the medial prefrontal gyrus(m PFC).In addition,we also found a similar result in another university students sample(n=198).The results may be suggested that higher neuroticism individuals with smaller gray matter volume of ACC and bigger gray matter volume of m PFC may associated with more negative self-reference,more negative cognitive coping style and weaker emotional regulation ability.Experiment 2 from resting-state functional magnetic resonance imaging to investigate the individual difference in neuroticism and its association with functional connectivity of the brain.In this experiment,we choose the results of the experiment 1 including ACC and m PFC as the region of interest(ROI)to investigate the functional connectivity of the neuroticism on the whole-brain level.The results of this experiment found that neuroticism scores were positively associated with the strength of the connectivity between ACC-thalamus,the strength of the connectivity between ACC-amygdala,and the strength of connectivity between m PFC-PCC.That functional connectivity between prefrontal regions and brain regions of the limbic system are associated with the emotional processing,emotion regulation and stress coping.Experiment 3 use longitudinal study method and the mediation analysis to investigate the neural basis of the relationship between neuroticism and depression mood.In the experiment 3,we collect the behavior and brain imaging of 342 subjects in the first time,and then collect the behavior data of the 172 subjects after 6 months to investigate the neural mechanism between the neuroticism and depression mood.The behavioral results found that neuroticism scores were positively associated with the scores of the depression mood at the 2 times.The magnetic resonance imaging results found that the volume of the m PFC and the strength of the m PFC-PCC also associated with the scores of the depression mood at the 2 times.In addition,the results of the mediation analysis found that the gray matter volume of the m PFC was partly mediation the relationship between neuroticism and depression mood at the first time.The mediation results may be suggested that neuroticism influence the gray matter volume of m PFC which play an import role in the negative emotion processing,negative self-reference,negative response style and emotion regulation,and then influence the depression mood.In another word,the m PFC may be the core neural basis of the relationship between neuroticism and depression mood.In the second study,we used task-state magnetic resonance imaging to investigate the brain mechanism of neuroticism in the emotion processing.In the experiment 4,we used a well-characterized perceptual face processing task and collect 164 subjects’ task-state magnetic resonance imaging to investigate the difference between the higher neuroticism individuals and lower neuroticism individuals in the negative emotion processing.The results of this experiment found that higher neuroticism scores group showed increased activation in the superior prefrontal cortex and decreased activation in the m PFC than the low neuroticism scores group in the processing of the negative emotion.The changed neural mechanism of the higher neuroticism individuals in negative emotion processing may be associated with its more negative mood and weaker emotional regulation ability.Experiment 5 used a cognitive reappraisal task and collect 160 subjects’ task-state magnetic resonance imaging to explore the brain mechanism of neuroticism in the emotion regulation.The behavioral results found that the score of neuroticisms was negative associated with individual’s cognitive reappraisal ability.The functional magnetic resonance imaging results found that the scores of neuroticisms were negatively associated with the strength of the activation of the m PFC,inferior frontal gyrus and middle frontal gyrus.In addition,the PPI analysis results found that the score of neuroticisms was negative associated with the strength of the connectivity between m PFC-amygdala.The results of this study may be suggested that the changed of m PFC and the connectivity between the m PFC-amygdala may contribute to the higher neuroticism personality trait.In the third study,we used the mediation analysis method to investigate the neural mechanism of the influence of the family environment and life events on the neuroticism.Experiment 6 investigate the neural mechanism of the influence of the family socioeconomic status and parenting behavior on neuroticism.The behavioral results found that family income was negatively correlated with the scores of the depression-related personality trait(N3)and parental education level was negatively correlated with the scores of the anxiety-related personality trait(N1).In addition,the results of this study found that the parenting behavior especially the emotional warmth of parents were negatively correlated with the scores of the neuroticism.The mediation analysis results found that the gray matter volume of the m PFC partly mediated the relationship between the parental emotion warmth and neuroticism.This results may suggested that the positive parenting behavior especially the parental emotional warmth influence the development of the brain structure and function of the m PFC,and then influence the neuroticism.Experiment 7 investigate the neural mechanism of the influence of the life events on the neuroticism.The behavioral results found that life events were positively associated with the scores of the neuroticism.The mediation analysis results found that the gray matter volume of the ACC partly mediated the relationship between the life events and neuroticism.The results may be suggested that the negative life events may influence the development of the brain structure,and then influence the neuroticism.Taken together,this study found that neuroticism personality trait was associated with the gray matter volume of the m PFC and ACC,and the strength of the connectivity between m PFC-PCC,the strength of the connectivity between ACC-thalamus,the strength of the connectivity between ACC-amygdala.Higher neuroticism individuals with smaller volume of ACC and bigger volume of m PFC,and stronger connectivity of ACC-thalamus,ACC-amygdala and m PFC-PCC may be associated with its negative self-reference,negative stress coping style and weaker emotional regulation ability.The changed of the core neural basis of the higher neuroticism individuals may contribute to the weaker activity of the m PFC and the connectivity of m PFC –amygdala in the emotion processing.Neuroticism through influence the volume of the m PFC,and then influence the depression mood.Moreover,the environment through influence the volume of the m PFC and ACC,and then influence the neuroticism.In general,this study was help to the understanding of the core brain mechanism of the neuroticism,the relationship between the neuroticism personality trait and depression mood and the influence of the family environment on the brain mechanism of neuroticism.In addition,finding the core brain structure and functional connectivity of the neuroticism and its influence are help to find the biological marker for the future intervention and treatment of the clinical depression and personality disorder.Moreover,this study also can help to the future healthy personality cultivation and promote the wellbeing of individuals.