Synapses are connections between neurons, the cells that control brain functioning. Baby brains go crazy with these connections, making many more than adult brains need. This way, the brain is able to learn what the most useful and efficient connections are, rather than having to have this information programmed into genes. If a synapse doesn't get used, it gets pruned away. By the time a child is 10, the number of synapses in his brain has been cut by half.
Because of this, what people learn in early childhood is incredibly important. If a child doesn't learn to talk, which has happened in some cases of severe neglect, it's likely they'll never be able to, because the synapses that would have enabled communication were never used and therefore destroyed. On the other hand, if the pruning process doesn't stop naturally, as it normally does, even essential connections can get the ax. Researchers at Stanford University recently discovered that certain degenerative diseases, including glaucoma, get their start when the brain continues to destroy synapses.
