The brain undergoes its greatest growth and development in the first years of life, with a second phase beginning in adolescence characterized by increased sexual differentiation as well as growth of white matter tracts and synaptic pruning in gray matter, leading to anatomical and functional maturation85. This second phase of development is most profound in regions of the brain involved in higher order cognitive functions (e.g., top-down control functions, such as inhibition and other aspects of executive function), as well as affective functions (e.g., emotional and reward processing; 86,87).
