What is Myelination?
Myelination is the process of forming a myelin sheath around nerve fibers (axons), dramatically increasing the speed and efficiency of neural signal transmission. It is a key mechanism of brain development and learning.
How it works
Myelin is a fatty substance produced by oligodendrocytes (in the brain) and Schwann cells (in the peripheral nervous system) that wraps around axons in segments. Myelinated axons conduct signals up to 100 times faster than unmyelinated ones. Myelination continues into the mid-20s, with the prefrontal cortex among the last regions to fully myelinate—explaining why executive function and impulse control mature late. Recent research shows that myelination is activity-dependent: neural circuits that are frequently used become more heavily myelinated, a form of plasticity that optimizes frequently used pathways.
Applied example
The fact that the prefrontal cortex is not fully myelinated until the mid-20s explains why teenagers can understand the risks of dangerous behavior (knowledge) but struggle to inhibit impulsive actions in the heat of the moment (executive control): the neural hardware for impulse control is literally not yet fully wired.
Why it matters
Myelination is the physical infrastructure of cognitive development, and its activity-dependent nature means that practice and experience physically optimize the brain’s communication pathways.
