What Is the Definition of the Myelination Process?

How the Myelination Process Relates to Your Tween's Impulse Control

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What is the definition of myelination? This process takes place when a substance called myelin, which is made up of fatty lipids and proteins, accumulates around nerve cells, or neurons. Improve your understanding of what myelin is and how it may affect tweens with this review.

What Is Myelin's Function?

Also known as myelin sheath, myelin forms around the long shaft or elongated fibers known as axons that are a part of neurons.

Think of axons as wires of sorts that send electrical signals to the various parts of the body. With this in mind, it's not surprising that myelin has been compared to the insulation on electrical wires. However, not all axons have myelin coating.

Myelin is comprised of glial support cells (sometimes called neuroglia or nervous system cells) that protect axons, which connect to other cells of the body such as fellow neurons, muscle cells, and organs at sites known as synapses. Myelin enables nerve cells to transmit information faster and allows for more complex brain processes. The reason brain matter looks white is reported because of the numerous amount of myelinated nerve cells.

The myelination process is vitally important to healthy central nervous system functioning. Myelination also occurs in the peripheral nervous system. Myelin can be divided into points called nodes or myelin sheath gaps.


When Myelin Suffers Damage

When this fatty substance is damaged it can lead to potentially devastating disorders such as multiple sclerosis. When MS occurs, it's believed that the immune system malfunctions and launches an attack on the myelin sheath, resulting in lesions. Problems with myelin have also been linked to fibromyalgia, adrenoleukodystrophy (ALD), Krabbe diseaseCharcot-Marie-Tooth disease (CMT)Guillain-Barré Syndrome, small fiber neuropathy and chronic inflammatory demyelinating polyneuropathy.

All of these medical conditions involve the nerves, and the people who have them typically suffer pain, muscle weakness, numbness, and sensory changes as a result. Some of these conditions can even be deadly. Guillain-Barré, for example, can prevent the individuals afflicted from breathing on their own.

If you or a loved one are displaying any signs of the above disorders, don't delay getting medical help. While sometimes nerve damage occurs gradually over a long period of time, other times its effects can be felt quickly. In either case, it's important to seek health care as soon as possible before the disease progresses. Obtaining medical help can also help individuals with such diseases manage their symptoms and get the support they need.

How Myelination Affects Tweens

Myelination begins in utero, when a fetus is about 16 weeks, and continues into adulthood. During the tween years, myelination is particularly occurring in the frontal lobe of the brain, the section of the brain that begins just behind the forehead.

Myelination of the frontal lobe aids tweens' cognitive development.

In particular, it enables them to have better "executive functioning," which includes planning, reasoning and decision-making skills. It also helps tweens inhibit their impulses more efficiently and to demonstrate greater self-discipline.

That said, many tweens and teens will continue to have impulse control problems, as the frontal lobe doesn't reach maturity until about the age of 25. 


Berger, Kathleen. The Developing Person Through the Lifespan. 2008. 7th Edition. New York: Worth.

Sowell, Elizabeth R., Peterson, Bradley S., Thompson, Paul M., Welcome, Suzanne E., Henkenius, Amy L., and Toga, Arthur W. "Mapping Cortical Change Across the Human Life Span." Nature Neuroscience. 2003: 6, 309-315.

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