The Brain Structural Basis Of Reinforcement Sensitivity Personality And Its Gender Difference

Personality is a unique structure of each individual that is critical to the development of healthy social interactions and influences an individual’s emotions and motivation.Reinforcement Sensitivity Theory(RST)is a theory that blends trait theory and biologically oriented personality research to describe and explain individuals’ differences.Reinforcement Sensitivity Theory suggests that there are three conceptual neural systems that regulate individuals’ emotional responses and behavioral decisions to rewards,punishments,and conflicts: the Behavioral Approach System(BAS),the Behavioral Inhibition System(BIS)and Fight/Flight/Freeze system(FFS).Reinforcement sensitivity is closely related to various psychiatric disorders and has important implications for psychopathological research.Currently,the actual brain anatomy structure corresponding to the three conceptual neural systems is still unknown.Personality traits are influenced by various factors such as physiology and social upbringing styles.There are gender differences in personality: for example,women generally score higher on neuroticism than men.However,fewer studies have been conducted on gender differences in RST.Therefore,in order to investigate the brain structural basis of personality traits in RST and the gender differences of personality,this paper used the behavioral inhibition system/behavioral approach system scale(BIS/BAS Scale)and the voxel-based morphometry(VBM)to analyze two large scale healthy subjects’ personality scores and MRI data.The paper explored three aspects which include the gender differences in reinforcement sensitivity personality,the brain structures basis of RST and brain structural basis of gender differences in reinforcement sensitivity personality.To investigate the gender differences in reinforcement-sensitive personality and the correlations among the traits of reinforcement sensitivity personality,the t-test and correlation analysis were conducted on data from the BIS/BAS scale and other personality scales of 1854 subjects in the study 1.The results showed that the BIS and BAS-RR scores were significantly higher in females than in males.And the BAS-D and BAS-FS scores were significantly higher in males than in females.The BAS subscales were significantly inter-correlated.The BIS and BAS-RR were positively correlated.The BIS were negatively correlated with BAS-D and BAS-FS.Study 2preprocessed the structural brain MRI data from right-handed subjects in Study 1,having removed data with poor image quality and heterogeneity.Study 2 examined the correlation between BIS/BAS scale scores and brain gray matter volume(GMV)in1366 subjects using the VBM method,aiming to investigate the structural brain basis of reinforcement sensitivity personality.The results showed that the GMV of left middle frontal gyrus was positively correlated with BIS scores.The GMV of putamen,pallidum were positively correlated with BAS scores.In Study 3,based on Study 1 and Study 2,the gray matter images of 1366 subjects in Study 2 were analyzed.Sex and scale scores were recoded using multiple regression analysis to investigate the structural brain basis of gender differences in reinforcement sensitivity.The results revealed that there were significant gender differences in the correlation between GMV and BIS/BAS scale scores in structures such as cerebellum,supramarginal gyrus,parahippocampal gyrus,triangular part inferior frontal gyrus.The above results suggest that there are gender differences in reinforcement sensitivity.The social adaptation component of the behavioral approach systems and the behavioral inhibition are more active in females than in males.And the impulsivity component of the behavioral approach system is more active in males.In general,the relationship between the behavioral inhibition system and the behavioral approach system supports the joint subsystem hypothesis.The brain structural basis of the reinforcement sensitivity personality involve the brain regions such as frontal middle gyrus,the putamen and pallidum in the basal ganglia.The parahippocampal gyrus,supramarginal gyrus,cerebellum,triangular part inferior frontal gyrus play a key role in gender differences in reinforcement sensitivity.