Wikipedia
Process of synapse elimination
Summary
Synaptic pruning is the process of synapse elimination or weakening. Though it occurs throughout the lifespan of a mammal, the most active period of synaptic pruning in the development of the nervous system occurs between early childhood and the onset of puberty in many mammals, including humans. Pruning starts near the time of birth and continues into one’s late 20s. During elimination of a synapse, the axon withdraws or dies off, and the dendrite decays and dies off. Synaptic pruning was traditionally considered to be complete by the time of sexual maturation, but magnetic resonance imaging studies have discounted this idea.