Getting the Brain's Attention

Abstract
Researchers dissecting the role of the neurotransmitter dopamine in the brain are finding that rather than signaling pleasure as previously thought, it may act to highlight significant stimuli. New data indicate that dopamine is released within the brain not only in response to events the organism finds rewarding, but also in response to those that predict rewards, and to stimuli that are simply startling. By underscoring such events, say these researchers, the dopamine signal helps the animal learn to recognize them--and in some cases, to repeat them.