A functional neuroimaging study assessing gender differences in the neural mechanisms underlying the ability to resist impulsive desires.
Diekhof EK, Keil M, Obst KU, Henseler I, Dechent P, Falkai P, Gruber O.
Brain Res. 2012;1473:63-77.
Several structural and functional gender differences have been reported in the human reward system. This fMRI study assessed which neural processes enable men and women to successfully control their desire for immediate reward during a task aimed at achieving a higher-order goal (i.e., during a ‘desire-reason dilemma’). 32 volunteers (16 females), closely matched for age, personality characteristics and behavioral performance in self-control tasks, were first asked to perform an operant conditioning task, to establish stimulus-response-reward contingencies between specific color and immediate reward. Then they performed a second task with the same color stimuli as the previous one, but now subjects had to pursue a superordinate long-term goal, that consisted in collecting the two target colors defined at the beginning of each block. The results showed a significant reduction in the activation in the nucleus accumbens and in the ventral tegmental area during the ‘desire-reason dilemma’ and this was similar in female and male subjects. Instead, a significant interaction of ‘gender by context’ was observed in several other regions that are also part of the reward system: only men showed a significant decrease of activation in the right ventral pallidum, the pregenual and adjacent subgenual anterior cingulated cortex, the right putamen and the left posterior orbitofrontal cortex. Moreover, men showed a consistent increase in the connectivity between the right accumbens and the left anteroventral prefrontal cortex during the ‘desire-reason dilemma’, while women exhibited the expected negative functional interaction. Since these regions have been associated with action control in reward processing and representation of perceived pleasantness, one could therefore speculate that increased activation in these ‘impulsive’ brain regions in men may have interfered with the successful resolution of the ‘desire-reason dilemma’, which thus required a ‘male-specific’ compensatory down-regulation: as if men try to attenuate positive feelings elicited by predictors of immediate reward, to reduce the interference between long-term goal and immediate reward.