14.5: Brain Maturation

Learning Objectives

1. Describe the processes of synaptogenesis and synaptic pruning.
2. Explain how myelination and prefrontal cortex development influence behavior and learning.
3. Identify the functions of the left and right hemispheres of the brain and describe the role of the corpus callosum in coordinating tasks between them.
4. Recognize how children’s drawings reflect changes in brain development and visual-motor integration.

Brain Development

The brain is about 75 percent of its adult weight by two years of age. By the time a child reaches the age of five, their brain is approximately 90% of its adult size. However, growth is not just about size—it’s about the connections forming within the brain. Neurons, the brain’s nerve cells, communicate through synapses, and during early childhood, the brain creates trillions of these connections. This process, known as synaptogenesis, allows children to process information more efficiently and supports their ability to learn new skills. This surplus of connections provides children with the flexibility to adapt to different environments and experiences.

Figure \(\PageIndex{1}\). The number of new synapses related to sensory function, language skills, and higher-order cognition across development. Synapse formation related to sensory functioning is thought to peak first, followed by language skills, and lastly, higher-order cognitive functions. Syanpse Formation Across Development © by the National Library of Medicine is licensed CC BY-NC-SA.

However, not all of these connections are necessary, which leads to the next important process- synaptic pruning. Synaptic pruning eliminates weaker or unused synapses, strengthening the connections that are most frequently used. Therefore, the process of synaptic pruning is heavily influenced by experience (Greenough et. al, 1987). By removing excess connections, the brain becomes more efficient at both cognitive and motor functions (Tierney & Nelson, 2009). The timing of pruning varies across brain regions. The visual and auditory cortices undergo pruning earlier, while areas related to higher-order thinking, such as the prefrontal cortex, continue to undergo pruning well into adolescence (Huttenlocher, 1990).

The Prefrontal Cortex and Myelination

Myelination and the development of dendrites continue to occur in the cortex. As it does, we see a corresponding change in the child’s abilities. Significant growth in the prefrontal cortex (the area of the brain behind the forehead that helps us to think, strategize, and control emotion), and white matter (which consists of myelinated nerve fibers) makes it increasingly possible to control emotional outbursts and to understand how to play games (Pujol et. al, 2006; Giedd et. al, 1999).

Consider 4- or 5-year-old children and how they might approach a game of soccer. Chances are, every move would be a response to the commands of a coach standing nearby, calling out, “Run this way! Now, stop. Look at the ball. Kick the ball!” And when the child is not being told what to do, he or she is likely to be looking at the clover on the ground or a dog on the other side of the fence! Understanding the game, thinking ahead, coordinating movement, and handling losing improve with practice and myelination.⁷

Growth in the Hemispheres and Corpus Callosum

Between the ages of three and six, the left hemisphere of the brain undergoes dramatic growth. This side of the brain or hemisphere is typically involved in language skills (Friederici, 2012). The right hemisphere continues to grow throughout early childhood and is engaged in tasks that require spatial skills, such as recognizing shapes and patterns, as well as creativity. The corpus callosum, which connects the two hemispheres of the brain, undergoes a growth spurt between the ages of three and six, resulting in improved coordination between tasks performed by the right and left hemispheres. This is referred to as brain lateralization. Hand preference also becomes more pronounced in early childhood as a result of lateralization, and is usually established by the age of four or five (Michel et al., 2013).

Visual Pathways

Children’s drawings are representative of the development of visual pathways; as children’s brains mature, the images in their drawings change. Early scribbles and dots illustrate the use of simple motor skills. No real connection is made between an image being visualized and what is created on paper.

At the age of 3, the child begins to draw wispy creatures with heads and little other detail. Gradually, pictures start to have more detail and incorporate more parts of the body. Arm buds develop into arms, and faces acquire noses, lips, and eventually eyelashes.

Figure \(\PageIndex{2}\): Early scribbles. Image by Wikimedia is licensed CC BY-SA 3.0.

Figure \(\PageIndex{3}\): Creatures with heads. Image by torange.biz is licensed CC-BY 4.0.

Figure \(\PageIndex{4}\): A detailed face. Image by torange.biz is licensed CC-BY 4.0.

References, Contributors and Attributions

7. Lifespan Development - Module 5: Early Childhood by Lumen Learning references Psyc 200 Lifespan Psychology by Laura Overstreet, licensed under CC BY 4.0

Friederici, A. D. (2012). The cortical language circuit: From auditory perception to sentence comprehension. Trends in Cognitive Sciences, 16(5), 262–268. https://doi.org/10.1016/j.tics.2012.04.001

Giedd, J. N., Blumenthal, J., Jeffries, N. O., Castellanos, F. X., Liu, H., Zijdenbos, A., ... & Rapoport, J. L. (1999). Brain development during childhood and adolescence: A longitudinal MRI study. Nature Neuroscience, 2(10), 861–863. https://doi.org/10.1038/13158

Greenough, W. T., Black, J. E., & Wallace, C. S. (1987). Experience and brain development. Child Development, 58(3), 539–559. https://doi.org/10.2307/1130197

Huttenlocher, P. R. (1990). Morphometric study of human cerebral cortex development. Neuropsychologia, 28(6), 517–527. https://doi.org/10.1016/0028-3932(90)90031-I

Michel, G. F., Babik, I., Nelson, E. L., Campbell, J. M., & Marcinowski, E. C. (2013). How the development of handedness could contribute to the development of language. Developmental Psychobiology, 55(6), 608–620. https://doi.org/10.1002/dev.21119

Pujol, J., Soriano-Mas, C., Ortiz, H., Sebastián-Gallés, N., Losilla, J. M., & Deus, J. (2006). Myelination of language-related areas in the developing brain. Neurology, 66(3), 339–343. https://doi.org/10.1212/01.wnl.0000194501.15226.9a

Tierney, A. L., & Nelson, C. A. (2009). Brain development and the role of experience in the early years. Zero to Three, 30(2), 9–13.