[Show abstract][Hide abstract] ABSTRACT: Human altruistic cooperativeness, one of the most important components of our highly organized society, is along with a greatly enlarged brain relative to body size a spectacular outlier in the animal world. The "social-brain hypothesis" suggests that human brain expansion reflects an increased necessity for information processing to create social reciprocity and cooperation in our complex society. The present study showed that the young adult females (n = 66) showed greater Cooperativeness as well as larger relative global and regional gray matter volumes (GMVs) than the matched males (n = 89), particularly in the social-brain regions including bilateral posterior inferior frontal and left anterior medial prefrontal cortices. Moreover, in females, higher cooperativeness was tightly coupled with the larger relative total GMV and more specifically with the regional GMV in most of the regions revealing larger in female sex-dimorphism. The global and most of regional correlations between GMV and Cooperativeness were significantly specific to female. These results suggest that sexually dimorphic factors may affect the neurodevelopment of these "social-brain" regions, leading to higher cooperativeness in females. The present findings may also have an implication for the pathophysiology of autism; characterized by severe dysfunction in social reciprocity, abnormalities in social-brain, and disproportionately low probability in females.
[Show abstract][Hide abstract] ABSTRACT: The behavioral inhibition system (BIS) and the behavioral activation system (BAS) are two fundamental motivational systems which are not only responsible for affective states, behavior and personality, but also related to predispositions for various forms of psychopathology. A wide range of previous studies revealed sex differences in both BIS/BAS and affective disorders (e.g., anxiety disorder) and externalizing disorders (e.g., addictive and impulsive behaviors), and a close link might exist between them. It remains to be clarified, however, whether the relationships between neuroanatomical characteristics and BIS/BAS exhibit sex differences. To investigate, voxel-based morphometry (VBM) was used to examine sex differences in the correlations between regional gray matter volume (rGMV) and scores on the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scale in a large sample of healthy young adults (n=353). Results showed that females displayed a negative correlation between BIS sensitivity and rGMV in the parahippocampal gyrus (PHG), as well as positive correlations between BAS sensitivity and rGMV in the ventromedial prefrontal cortex (vmPFC) and inferior parietal lobule (IPL), whereas males showed the opposite pattern. These findings suggest that the brain regions associated with processing of negative emotions (PHG) and reward-related information (vmPFC and IPL) may contribute to sex-related differences in rGMV correlates of BIS and BAS, respectively. The present findings demonstrated the evidence of sex-linked neuroanatomical background of BIS and BAS among non-clinical subjects and might encourage future research into the gender-specific relationships between BIS/BAS and related affective disorders and externalizing disorders.
Behavioural Brain Research 08/2014; 274. DOI:10.1016/j.bbr.2014.08.041 · 3.39 Impact Factor
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