Sex modulated the relationship between trait approach motivation and decision-making.

It has been observed that one's Behavioral Approach System (BAS) can have an effect on decision-making under uncertainty, although the results have been mixed. To discern the underlying neural substrates, we hypothesize that sex may explain the conflicting results. To test this idea, a large sample of participants was studied using resting state fMRI, utilizing fractional Amplitude of Low Frequency Fluctuations (fALFF) and Resting-State Functional Connectivity (rsFC) techniques. The results of the Iowa Gambling Task (IGT) revealed an interaction between sex and BAS, particularly in the last 60 trials (decision-making under risk). Males with high BAS showed poorer performance than those with low BAS. fALFF analysis showed a significant interaction between BAS group and sex in the left superior occipital gyrus, as well as the functional connectivity between this region and the left ventrolateral prefrontal cortex. Additionally, this functional connectivity was further positively correlated with male performance in the IGT, particularly in the decision-making under risk stage. Furthermore, it was found that the functional connectivity between left ventrolateral prefrontal cortex and left superior occipital gyrus could mediate the relationship between BAS and decision-making in males, particularly in the decision-making under risk stage. These results suggest possible sex-based differences in decision-making, providing an explanation for the inconsistent results found in prior research. Since the research was carried out exclusively with Chinese university students, it is essential to conduct further studies to investigate whether the findings can be generalized.