Colzato, L.
Leiden University, Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden, The Netherlands
Animal studies point to a role of estrogen in explaining gender differences in striatal dopaminergic functioning, but evidence from human studies is still lacking. Given that dopamine is crucial for attentional flexibility, estrogen may have a specific impact on the inhibition of return (IOR) effect, which refers to the fact that people are slower to detect a target if it appears in a previously attended location. We compared performance on the IOR task with stimulus-onset asynchronies (SOAs) between attention cue and target of 150-1200 ms in young women across the three phases of their menstrual cycle (salivary estradiol and progesterone concentrations were assessed) and in young men, at different sessions separated by 10 days, according to the corresponding time interval in days between the different phases in women. First, women were higher magnitude of IOR in their follicular phase (FP), which is associated with higher estradiol levels dopamine turnover rates, than in their luteal or menstruation phase. Second, women showed higher magnitude of IOR than men only in the FP. Our results support the idea that striatal DA levels promote IOR, presumably by biasing the interplay between prefrontal and striatal networks towards greater cognitive flexibility. The variation of estrogen levels across the menstrual cycle may account for our observations of gender differences in IOR, suggesting that such differences are variable and state-dependent but not structural.