The Transitional Age Brain: “The Best of Times and the Worst of Times”

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Key points

  • Over the past 2 decades, there have been substantial developments in the understanding of brain development.

  • Progress in neuroimaging has allowed us to better understand the nuances of the development of cortical, subcortical, and white matter structures.

  • Modern neuroscience, genomics, and epigenomic studies allow us a lens through which to develop an understanding of transitional age youth (TAY) behavior from a neurodevelopmental perspective.

  • Developing brain building health promotion and illness

Early brain development

With advances in both structural (MRI) and functional (fMRI) imaging techniques, along with creative experimental designs using fMRI, information about the development of the human brain has been rapidly expanding. Still, research in the field continues to rely on studies the using other mammalian species with the extrapolation of data to humans.1

Human brain development begins during the third week of gestation and continues to about the middle of the second decade, when the components involved

Brain patterning and plasticity

During the prenatal period, a basic structure of brain organization is developed. The core structures from the spinal cord to the neocortex and the major compartments within these structures are formed, and there is an initial partitioning of the neocortex into well-defined functional areas.19, 20, 21, 22, 23 This initial patterning is underdefined, malleable, and based largely on intrinsic signaling.24 Beginning in the late prenatal period, brain development is exquisitely responsive to

Gray and white matter maturation

Early MRI morphometry studies compared children and adults. In Jernigan and Tallal’s seminal study, gray matter volumes were shown to be considerably larger in school-aged children than in young adults.70, 71 And in Giedd’s landmark study, he showed that the volume of the cortical gray matter follow an inverted U shape, with peaks in late childhood and a surge just before puberty and occurring about 1 to 2 years earlier in girls.72, 73 In subsequent studies, Shaw and Raznahan have also reported

Transitional age brain mismatch hypothesis

In almost every measurable domain, adolescence is a developmental period of strength and resilience. Compared with young children, adolescents are stronger, bigger, and faster, and are achieving maturational improvements in reaction time, reasoning abilities, immune function, and capacity to withstand cold, heat, injury, and physical stress. Yet, despite these robust maturational improvements in many domains, overall morbidity and mortality rates increase by 200% over the same interval of time.

Emotion regulation and the brain

The neuropsychological processes important for emotion perception, allowing the generation of contextually appropriate, complex affective states, emotional experiences (feelings), and behaviors, include the identification of the emotional significance of an environmental stimulus, the production of an affective state and emotional behavior, and the regulation of the affective state and emotional behavior. Findings of neuroimaging studies indicate that specific neural regions may be important

Epigenetics, gene expression, and a period of vulnerability and opportunity

As discussed, epigenetic regulations can have powerful effects on the brain. The main factors that contribute to epigenetic changes in the adolescent brain are DNA methylation, histone modification, and microRNAs or noncoding RNAs. DNA methylation is generally associated with gene silencing as a methyl group binds to CpG islands blocking RNA polymerase, although recent evidence suggests that the effects of methylation could be more complicated.148, 149, 150 Histone modifications alter the

Summary

Over the past 2 decades, there have been substantial developments in the understanding of brain development. Progress in neuroimaging has allowed us to better understand the nuances of the development of cortical, subcortical, and white matter structures. Modern neuroscience, genomics, and epigenomic studies allow us a lens through which to develop an understanding of TAY behavior from a neurodevelopmental perspective. We now understand, to a greater degree, why adolescents have difficulty with

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