Messages in the Brain

Every thought, memory, and movement begins as a tiny electrical signal traveling through the brain. The brain contains roughly eighty-six billion cells called neurons, each one shaped like a tree with many branching arms. A neuron receives signals through its branches, and when enough of them arrive, the cell fires a pulse of electricity down a long fiber toward its neighbors. But neurons do not actually touch. Between them lies a microscopic gap called a synapse. To cross it, the electrical signal triggers the release of chemical messengers that drift across the gap and pass the message along. This blend of electricity and chemistry lets billions of neurons coordinate in fractions of a second. What we experience as a single smooth thought is really a vast storm of these signals racing through an intricate web of connections, many of them strengthened or weakened by what we learn.