3.2 Post-natal Brain Development

Viewing the shape of brain at birth, reveals an organ that externally looks smaller, but similar in shape to the adult brain. The internal structure, however, is still under construction. The number of synapses continues to dramatically increase after birth. This increase in synaptic growth, called synaptogenesis, results in an increase in synaptic density. There is a relatively rapid period of growth until around the age of two years. This process is strongly influenced by the experiences the individual has. The synapses that are used continue to grow and branch. Other synapses begin to die off. Figure 3.2 shows the changes in relative growth of white and grey matter. Areas related to vision matures rapidly, with rapid growth during infancy and full maturity by age 10. Other areas are much slower to mature. The frontal cortex is the last to fully mature.

The pruning process is shown in this clip that was constructed from MRI scans of healthy children and teens. The time-lapse animation compresses 15 years of brain development (ages 5-20) into just a few seconds. Red indicates more gray matter, blue less gray matter. The changes in color from yellow/red to blue show the pruning process. NIMH
Figure 3.2 Brain Maturation Developmental Changes in Gray matter ages 5-20. Brain Maturation. By: psupb Source: pressbooks CC-BY SA

Link to Learning

Interview with Dr. Jay Giedd on post-natal development and the interaction of growth and experience

Myelination and other glial development

Glial cells begin to form after most neurons are generated. Glial cells form throughout life. Myelin formation is an important part of learning. Myelinization within the brain is a slow process. It begins after birth and continues until around 18 years of age. Myelin develops in different parts of the brain at different rates. See Figure 3.3 for a visual representation of the pattern of maturation of myelin within the cortex. The frontal lobe is the last region of the brain to be fully myelinated.

3D visualization of the traced limbic tracts of representative subjects at following developing stages, at birth (0 month), early childhood (2 years old), childhood (6 years old), adolescence (13 years old), and young adulthood (22 years old).
Figure 3.3 3D Visualization of the Traced Limbic Tracts Development of the Limbic Tracts from Birth through 22 Years. 3D Visualization of the Traced Limbic Tracts By: Yu Q, Peng Y, Mishra V, Ouyang A, Li H, Zhang H, Chen M, Liu S and Huang H Source: pressbooks CC-BY SA

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An Introduction to the Science of Learning Copyright © 2020 by Victoria Kazmerski. All Rights Reserved.

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