The intensity of the moment helps to burn emotional memories into brain circuits. The memories are encoded into a part of the brain that operates outside conscious control, and they seem to take on a life of their own, sometimes intruding on the mind when they are not wanted. When emotional memories are reactivated, touched off perhaps by a smell, a taste, a snatch of music, the sight of an old friend or some other signal that a person may not even be consciously aware of, they can evoke the same powerful emotions that helped form them. Many addiction researchers believe memories of being high on drugs fall into this category of emotional memories, and contribute to craving, compulsion and relapse. Although a relapse can occur for no apparent reason, many addicts say that cravings are brought on by cues or reminders of past drug use, like seeing a needle or crack pipe or visiting a place where they used to get high.
Stress can also rekindle cravings.
So, in many people, can just one hit of an addicting drug, even after a long abstinence. Last month, Pollock invited 15 researchers to the National Institutes of Health in Bethesda, Md., to discuss the possible role of emotional memory in addiction. I only care about compulsion. Much of the interest in emotional memory stems from studies by Dr. Joseph LeDoux, a researcher at New York University. The human amygdala works in much the same way.