The human brain is organized into circuits that develop from childhood
through adulthood to support executive function — critical behaviors like
self-control, decision making, and complex thought. These circuits are anchored
by white matter pathways which coordinate the brain activity necessary for
cognition. However, little research exists to explain how white matter matures
to support activity that allows for improved executive function during
adolescence — a period of rapid brain development.
Researchers from the Lifespan Brain Institute of the Perelman School of
Medicine at the University of Pennsylvania and Children’s Hospital of
Philadelphia applied tools from network science to identify how anatomical
connections in the brain develop to support neural activity underlying these
key areas. The findings were published in the Proceedings of the National Academy of
Sciences.
“By charting
brain development across childhood and adolescence, we can better understand
how the brain supports executive function and self-control in both healthy kids
and those with different mental health experiences,” said the study’s senior
author Theodore Satterthwaite, MD, an assistant professor of Psychiatry at
Penn. “Since abnormalities in developing brain connectivity and deficits in
executive function are often linked to the emergence of mental illness during
youth, our findings may help identify biomarkers of brain development that
predict cognitive and clinical outcomes later in life.”
In this study,
the researchers mapped structure-function coupling — the degree to which a
brain region’s pattern of anatomical connections supports synchronized neural
activity. This could be thought of like a highway, where the anatomical
connections are the road and the functional connections are the traffic flowing
along those roads. Researchers mapped and analyzed multi-modal neuroimaging
data from 727 participants ages 8 to 23 years, and three major findings
emerged.
First, the team
found that regional variability in structure-function coupling was inversely
related to the complexity of the function a given brain area is responsible
for. Higher structure-function coupling was found in parts of the brain that
are specialized for processing simple sensory information, like the visual
system. In contrast, there was lower structure-function coupling in complex
parts of the brain that are responsible for executive function and
self-control, which require more abstract and flexible processing.
Results showed
that structure-function coupling also aligned with known patterns of brain
expansion over the course of primate evolution. Previous work comparing human,
ape, and monkey brains has showed that sensory areas like the visual system are
highly conserved across primate species and have not expanded much during
recent evolution. In contrast, association areas of the brain, such as the
prefrontal cortex, have expanded dramatically over the course of primate
evolution. This expansion may have allowed for the emergence of uniquely
complex human cognitive abilities. The team found that the brain areas which
expanded rapidly during evolution had lower structure-function coupling, while
simple sensory areas that have been conserved in recent evolution had higher
structure-function coupling.
Researchers also
found that structure-function coupling increased throughout childhood and
adolescence in complex frontal brain regions. These are the same regions that
tend to have lower baseline structure-function coupling, are expanded compared
to monkeys, and are responsible for self-control. The prolonged development of
structure-function coupling in these regions may allow for improved executive
function and self-control that develops into adulthood. Indeed, the team found
that higher structure-function coupling in the lateral prefrontal cortex — a
complex brain area which plays important roles in self-control — was associated
with better executive function.
“These results
suggest that executive functions like impulse control — which can be
particularly challenging for children and adolescents — rely in part on the
prolonged development of structure-function coupling in complex brain areas
like the prefrontal cortex,” explained lead author Graham Baum, PhD, a
postdoctoral fellow at Harvard University, who was a Penn neuroscience PhD
student during the time of the research. “This has important implications for
understanding how brain circuits become specialized during development to
support flexible and appropriate goal-oriented behavior.”
Journal article: https://www.pnas.org/content/117/1/771
No comments:
Post a Comment