Experience affects brain development in two major ways. Activation of synaptic connections strengthens the connections but lack of activation causes these connections to die off. The atrophy (or dying off) of unused connections is known as pruning. In short, the brain has a “use it or lose it” policy. For example, a baby is born with the capacity to recognize all sounds of all languages on earth. With exposure to the child’s native language, however, the synapses activated by those sounds are strengthened, but the neural networks related to other sounds weaken. Eventually the child’s brain has been wired to respond only to its own native language. Although a strong capacity to learn new languages is retained throughout childhood, receptivity to new languages decreases with age.