lsky, 1994). Stress stimulates the release of glucocorticoids, which at chronically high levels can decrease the ability of neurons to take up glucose and function properly for the formation and recall of memory. In working with rats, Michela Gallagher (1999) has found that implicit memories of fearful experiences are strengthened when noradrenaline a neurotransmitter associated with alertness and stress is released in the amygdala. He has also found that under extreme stress rats release a naturally occurring opium-like substance called endogenous opiates that weaken memory storage. This finding suggests a fascinating possibility. If an incident is so distressing that the brain makes opiates to dull the pain, the opiates may interfere with the memory storing process. Gallagher has also found using a drug called nalaxone to block endogenous opiates at the time of consolidation does enhance memory recall in rats.These studies suggest there may be a biological mechanism through which memories are suppressed in humans, but there arises the question of how these memories are retrieved. Some researchers have speculated that a memory can be stored weakly in the explicit system because endogenous opiates interfered with its consolidation- so weakly the person has no conscious memory of the original wrenching event. That same event, though, might also be captured by the implicit system through a characteristic, physical sensation, or gesture. Perhaps later the implicit system may provide clues, such as physical sensations, that help stir the recall of the weak explicit memory (Kandel, 1994). The fact that many people who say they were abused as children often describe their memories coming back as bodily sensations relates well with this theory. Some survivors of abuse describe their recovered memories as qualitatively different from other memories. They feel as if they are actually experiencing the event, with all its textures, smells, and phy...
