Different mechanisms of white matter growth, specifically, an increase in axonal diameter in males and a growth in myelin content in females, are implicated from magnetization-transfer ratio analysis (Perrin et al. 2009). Indeed, higher levels of lutenizing hormone is associated with greater white matter content (Peper et al. 2008), and increasing testosterone levels may influence axonal diameter in males (Perrin et al. 2008). Together, these findings suggest a role for sex hormones in developmental trajectories of cortical and white matter maturation.
