Effects Of Testosterone On Male Freshman’s Altruistic Punishment: An ERP Study

Objective：In order to observe the records of behavour and electroencephalography, wechoose Trust Game(TG) paradigm in ERP to detect the difference of feedback relatednegativity(FRN) which activated through different conditions of TG, and analyse theresults affected by the higher testosterone level(HTL) group and the lowerertestosterone level(LTL) group,Methods:100male students from a random sample of340male freshmen of DalianMedical University in2013were taken. Fifteen students were used as the highertestosterone level (HTL)group with the upper of limit the twenty-fifth testosterone level,and twelve students as lower limit of testosterone level(LTL) group in the bottom oftwenty-fifth percentile testosterone level. All participants were consisted of studentswere right-handed, healthy, same age, and no significant in intelligence.The stimuli performed by the software of E-prime1.0. The first experiment calledsingle Trust Game, the second experiment called repeated Trust Game. The former need10minutes, the latter need40minutes. The whole schedule was completed about1hour.Behavior data of two groups were compared by t-test, and ERP data were done by repeated-measures analyses of variance (ANOVA), reporting the consequence ofpost-hoc.Consequence:(1) No significant group differences were found in average number of trustinvestment. but the average number of punishment and punishment amount differencedstatistically. HTL group on penalties and punishment strength performance of the groupwere significantly higher than that of LTL group.(2) A negative component was found between200~400ms in both tasks. Asignificant group differences were found in prefrontal and central region(FZ,FCZ,CZ,C4,CPZ) from actual punish-or-not task. While under the symbolicpunish-or-not task, different serum testostetrone levels of FRN activation sites were nosignificant differences.(3) A diffenrence significantly between groups was found in actual punish-or-nottask, but symbolic punish-or-not task. The negative componet in actual punish-or-nottask performed much more negtive in HTL group, but not that obvious in LHL group.Meanwhile, there was a significant difference between these acticated areas in HTLgroup，and the location of this diffenence focus in prefrontal and central region.(4) In actual punish-or-not task, the main effect of lobe area were significant in thepeak of amplitude of FRN component, but hemisphere and groups. And there were nosignificant interaction effect between hemisphere and groups. The effect was significantbetween hemisphere and groups in spatial task, also between hemisphere, lobe area andgroups. Thinking about the actual-no-punish condition, FRN in LTL group were foundmore negtive in F3than in FC3. While under the actual-punish condition, FRN in LTLgroup were found more negtive in FCZ than in CZ. Thinking about the actual-punishcondition, FRN in HTL group were found more negtive in F3and FC3than in C3, samesutuation appeared in FZ and FCZ, considering CZ.Conclusion:(1) Testosterone promotes the altruistic punishment behavior. (2) High testosterone levels probably affect the prefrontal lope FRN by regulating5-HT1A receptor.