Changing brains: how longitudinal functional magnetic resonance imaging studies can inform us about cognitive and social-affective growth trajectories.

Brain imaging studies have demonstrated widespread changes in brain networks which support cognitive and social-affective development. These conclusions, however, are largely based on cross-sectional comparisons, which limits the possibility to investigate growth trajectories and detect individual changes. Understanding individual growth patterns is crucial if we want to ultimately understand how brain development is sensitive to environmental influences such as educational or psychological interventions or childhood maltreatment. Recently, longitudinal brain imaging studies in children and adolescents have taken the first steps into examining cognitive and social-affective brain functions longitudinally with several compelling findings. First, longitudinal measurements show that activations in some brain regions, such as the prefrontal, temporal, and parietal cortex, are relatively stable over time and can be used as predictors for cognitive functions, whereas activations in other brain regions, such as the amygdala and ventral striatum, are much more variable over time. Second, developmental studies reveal how these changes are related to age, puberty, and changes in performance. These findings have implications for understanding how environmental factors influence brain development. An important future direction will be to examine individual characteristics (e.g., genetic, temperamental, personality) which make individuals differentially susceptible to their environment.