Effects Of Testosterone On Working Memory Task: An ERP Study

Objective：In order to observe the mechanisms that affect testosterone on thespecialized functional areas of the brain, and different working memory tasks were thatresearched in ERP to suggest whether differences between verbal and spatial workingmemory were determined.Methods:100male students from a random sample of445freshmen of DalianMedical University were taken. Twelve students were used as the higher testosteronelevel (HTL)group with the upper of limit the twenty-fifth testosterone level, and twelvestudents as lower limit of testosterone level(LTL) group in the bottom of twenty-fifthpercentile testosterone level. All participants were consisted of students wereright-handed, healthy, same age, and no significant in intelligence.There were two types of tasks in this experiment, the stimuli performed by thesoftware of E-prime1.0. The first task stimulus contained letters, the second tasks forspatial matched. Two types of stimuli task were both150trial, and the target stimulusand non-target stimulus had same random probability (50%), in non-target stimulusthere were15interference trial (10%). The whole experiment was completed about30minutes, each of tasks need10min, and broken3min between two parts.Behavior data (exclude response time(RT), hit rate, omission rate, interferencetrial-RT) of two groups were compared by t-test, and ERP data were done by repeated-measures analyses of variance (ANOVA), reporting the consequence of post-hoc.Consequence:No significant group differences were found in RT, hit rate, omission rate,interference trial-RT in verbal task, and so was in RT, omission rate, interfering trial-RTin spatial task. HTL group had a significant higher hit rate than LTL group.An positive component was found between280~400ms in both tasks, morepositive in frontal area, central area, parietal area(F4,C4,P4,PZ) in LTH group from verbal task. Also there was found in spatial task which area in central frontalarea(FZ),central parietal area(PZ) in HTL group and in right frontal(F4),centralparietal(PZ) in LTL group.This positive component in spatial task performed larger between the groups in theparietal area after280~400ms stimulus onset in topographic map, and especially in HTLgroup. There was also a tendency of right hemisphere in LTL group.In verbal task, the main effect of lobe area were significant in the mean amplitudeof P300component from the PZ site of group average between280~400ms, and also inspatial task. And there were significant interaction effect between hemisphere andgroups in verbal task. The effect was significant between hemisphere and groups inspatial task, also between hemisphere, lobe area and groups.Conclusion:LTL group performed right hemisphere in a compensatory activation, and nosignificant in HTL group in verbal task.HTL group had a higher processing status in spatial task, especially in central areaand parietal area.