Longitudinal measures of monkey brain structure and activity through adolescence predict cognitive maturation.

In humans and other primates, adolescence is associated with improvement in cognitive abilities and with changes in brain structure and connectivity. However, how these changes affect neural activity underlying cognitive performance remains unknown. Here we conducted a multilevel, longitudinal study of monkey adolescent neurocognitive development by tracking behavior, neuronal activity and anatomical imaging measures. The trajectory of prefrontal neural activity accounted well for working memory improvements. Complex aspects of activity changed progressively during adolescence, but even simpler attributes, such as baseline rate and variability, had predictive power over behavior. Trajectories of neural activity and cognitive performance were well predicted by maturation of long-distance white matter tracts linking the frontal lobe with other brain areas but, surprisingly, not by decreases in brain volume and thickness, which underlie cognitive changes in humans. Our results link white matter maturation to neural activity changes in adolescent cognitive development.