Studies have reported sex differences in brain activation levels in the presence of equal cognitive ability (Bell, Willson, Wilman, Dave, & Silverstone, 2006). Some have suggested that, at least in adulthood, females tend to have more bilateral activity during tasks, and males more regional activation (Shaywitz et al., 1995). One study found that females had less relative activation for a given level of task performance than males, possibly indicating greater efficiency (Christova, Lewis, Tagaris, Uğurbil, & Georgopoulos, 2008). Although there has been very little investigation yet into sex differences in functional brain development during adolescence, one study looking at an interaction of sex and age during adolescence with regards to responses to viewing different types of faces found that females and males had similar responses to angry faces during childhood. However, females showed greater responses to angry faces after puberty, while males did not change. This pattern is possibly related to sex-related changes in HPA axis functioning, which is discussed in more detail below (Mcclure, 2004).
