New Insights on Brain Development Sequence through Adolescence
Published:08 May2023 Source:University of Pennsylvania School of Medicine
Brain development does not occur uniformly across the brain, but follows a newly identified developmental sequence, according to a new Penn Medicine study. Brain regions that support cognitive, social, and emotional functions appear to remain malleable -- or capable of changing, adapting, and remodeling -- longer than other brain regions, rendering youth sensitive to socioeconomic environments through adolescence.Researchers charted how developmental processes unfold across the human brain from the ages of 8 to 23 years old through magnetic resonance imaging (MRI). The findings indicate a new approach to understanding the order in which individual brain regions show reductions in plasticity during development.
The findings reveal that reductions in brain plasticity occur earliest in "sensory-motor" regions, occur later in "associative" regions. To address this challenge, the researchers focused on comparing insights from previous rodent studies to youth MRI imaging insights. Prior research examining how neural circuits behave when they are plastic uncovered that brain plasticity is linked to a unique pattern of "intrinsic" brain activity. Intrinsic activity is the neural activity occurring in a part of the brain when it is at rest, or not being engaged by external stimuli or a mental task. When a brain region is less developed and more plastic, there tends to be more intrinsic activity within the region, and that activity also tends to be more synchronized. This is because more neurons in the region are active, and they tend to be active at the same time. As a result, measurements of brain activity waves show an increase in amplitude(or height).
The authors studied relationships between youths' socioeconomic environments and the same functional marker of plasticity. They found that the effects of the environment on the brain were not uniform across regions nor static across development. Rather, the effects of the environment on the brain changed as the identified developmental sequence progressed.Critically, youths' socioeconomic environments generally had a larger impact on brain development in the late-maturing associative brain regions, and the impact was found to be largest in adolescence.