Synaptic pruning.
Synaptic pruning is the process of eliminating neurons and synapses that are not profitable for the well-function and efficiency of neuronal transmissions. Since the beginning of the brain development until the baby is born, and after, up to 2 years of age, new neurons and synapses are created in an exponential way. This pruning starts early from 2 years of old until 10 years of old or later.