An emerging theme from longitudinal studies is that in neuroimaging, as in life, the journey is often as important as the destination. This is exemplified in MRI studies where developmental trajectories of morphometry (i.e. size by age curves) show discriminating features not found with static measures for predicting cognitive parameters (Shaw et al., 2006), separating clinical groups (Shaw et al., 2007), and predicting good and bad outcomes (Mackie et al., 2007). Understanding the sexual dimorphism of developmental brain trajectories may also clarify some of the allometric issues previously discussed.
