Myelination of the peripheral nervous system begins about 24 weeks after conception.  However, myelination is most intense after birth and begins at the spinal cord, gradually progressing to include the hindbrain, midbrain, and forebrain. Myelination affects sensory cortices prior to motor cortices.

Trends in Myelination

Multiple sclerosis is an autoimmune condition in which the cells of the immune system attack the myelin sheath insulating some axons, forming patchy scars. The symptoms of multiple sclerosis vary depending on the areas of the brain affected, but the most common systems are typically pain, blurry vision, and tingling or numbness. Treatment focuses on managing symptoms, usually by implementing immunosuppressive drugs into the treatment plan.

Multiple Sclerosis

The main mechanism driving synapse rearrangement are similar to those driving plasticity: Experience. Synapses that are more frequently stimulated by our experiences  may acquire more neurotrophic factors that allow them to survive. These synapses may also undergo more myelination in order to conduct impulses more rapidly in the brain. 

Brandeis University

The process of neural pruning continues beyond early childhood, extending through adolescence and into adulthood in certain brain regions. This selective reduction of synapses occurs in various areas of the brain at different times, with the prefrontal cortex being one of the last to fully mature through this process.

Timeline of Neural Pruning

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Mechanisms of Synapse Rearrangement

A 16-year-old demonstrates remarkable ability in learning complex new physical skills but often struggles with weighing future consequences and making well-thought-out plans. Which statement best applies the principles of neural development to explain this common adolescent behavioral pattern?

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