Research at the LNCD focuses on brain mechanisms that support the transition to adult-level cognitive control of behavior. During adolescence, cognition begins to appear mature while, at the same time, important changes such as synaptic pruning and myelination are occurring in the brain, increasing the efficiency of local and distributed brain function. This is also a period where major psychiatric disorders first emerge, emphasizing the importance of understanding the mechanisms underlying the shift towards adult-level behavior.
Cognitive development and brain maturation have been considered independent areas of research thus far. We are interested in understanding the link between these two processes to better understand the constraints of maturation. We focus on “maturation” to emphasize the stage of development when stabilization occurs. Dr. Luna, the LNCD director, has demonstrated that while adolescents can show adult-level cognitive control of behavior, their brain function shows increased recruitment of the prefrontal executive regions and a lack of participation of regions evident in adults that are believed to assist in increasing efficient control of behavior and in establishing a response set. Specifically, Dr. Luna has conducted fMRI studies while subjects performed response inhibition and working memory tasks that required an eye movement response and has found that while adolescents rely heavily on prefrontal cortex, adults recruit regions such as the cerebellum and hippocampus, which are not primarily for the specific tasks, but may play a role in supporting mature performance. The traditional view of the brain basis of cognitive development proposes that late maturation of prefrontal cortex, relative to the rest of the brain, accounts for the transition to adult-level behavior. Based on her findings, Dr. Luna proposes that what supports cognitive maturation is the emergence of more efficient collaborative brain function that recruits regions that enhance cognitive control of behavior. Recent findings regarding brain maturation support this theory indicating that prefrontal cortex is not the last region to develop, but instead it is the association heteromodal cortex that develops last. Dr. Luna’s behavioral studies also support this theory, indicating that what characterizes the transition to mature behavior is the enhancement of existing abilities, not the appearance of new ones.
Current new directions for this research include characterizing developmental changes in reward processing, the emergence of functional networks, and the effects of affect on cognitive development using fMRI and DTI.