The Washington Post
Childhood: 2 to 10 years
Starting at about 18 months to two years, the brain shifts toward learning, which involves both strengthening important connections and decreasing ones that aren’t being used. To help the brain prioritize certain experiences, more inhibitory connections, which act as brakes for information processing, develop across brain circuits.
To decrease connections, babies lose about half of those synapses they had just formed in a process known as synaptic pruning. To strengthen connections, myelination, the process by which neuronal connections are wrapped and insulated with the fatty protein, myelin rapidly increases throughout childhood and beyond.
This increased signal-to-noise ratio for information that corresponds with children’s experiences is especially important as they learn to process emotions, interact in social settings, and develop more complex communication skills.
Because there is so much connection building and strengthening during childhood, the brain is particularly sensitive to interactions with caregivers and others in their environment. Stress stemming from trauma or neglect in this period can therefore have deeply profound effects on the rest of a child’s brain development over life.