Development of Brain Structures, Connections, and Functions
Joan Stiles and Terry Jernigan present a comprehensive and lucid review of the basics of brain development from biological, neuroimaging, and neuropsychological perspectives. The authors remind us of the terms “experience expectant” development and “experience dependent” learning as central constructs underlying individual variation in development and the potential for improving experience during critical periods of development. This theme pervades the issue, highlighting the importance of environmental experience during critical periods of development.
Jay Giedd, Michael Stockman, Catherine Weddle, Maria Liverpool, Aaron Alexander-Bloch, Gregory Wallace, Nancy Lee, Francois Lalonde, and Rhoshel Lenroot relate findings from longitudinal studies of children and adolescents supportive of extensive post-natal morphological changes in the developing brain. A pattern that has emerged from studies using structural imaging, sleep electrophysiology, and positron emission tomography has been confirmed with longitudinal investigation providing evidence for growth of cortical gray matter volume until about age 5 to 10 years, followed by an inexorable decline through to old age. White matter volume increases throughout adolescence, and possibly much longer, and provides the essential infrastructure for communication across long distances in the brain. Twin studies provide evidence for genetic factors contributing to a significant portion of brain growth variance.
Alecia Vogel, Johathan Power, Steven Petersen, and Bradley Schlaggar describe methods and findings based on noninvasive, in vivo neuroimaging approaches to identify and track functional connectivity in the developing brain. One general principle these authors identified is a developmental difference between children and adults in their basic organization of brain networks. Whereas networks of adults are distributed throughout the brain, those of children are organized by anatomical proximity.
Margaret Sheridan, Stacy Drury, Kate McLaughlin, and Alisa Almas remind us of the importance that early childhood experiences and nurturing contribute to cognitive and emotional development in the context of neurobiological development. They recount that the experience of children previously institutionalized in foster or adoptive care can determine adult outcome, especially in cases where environmental, nutritional, or emotional input was tenuous during development. The end result we observe with adult neuropsychological testing can be determined in large part by early childhood experience—or lack thereof.
Florence Roussotte, Linsay Soderberg, and Elzabeth Sowell review neuroimaging findings on prenatal exposure to alcohol, cocaine, and methamphetamine. Each agent affects different constellations of brain systems, and the extent of effect depends on timing of prenatal exposure. Knowledge about these potentially hidden effects could explicate some behavioral, cognitive, and motor deficits that manifest during development and young adulthood.
Sunita Bava and Susan Tapert show that the brain continues structural development throughout adolescence, a time when youth test the waters of life and characteristically engage in risky behavior. Along with this remarkable plasticity is vulnerability to environmental teratogens, including legal and illicit substances of abuse—alcohol, marijuana, cocaine, and other psychoactive agents. Whether neurofunctional changes that occur with alcohol and drug abuse and dependence in youth are reversible remains unknown.
This work was supported by grants from the NIAAA (AA010723, AA017168, AA017923) and NIA (AG017919).
The author is the editor-in-chief of the journal.