Chemical May Help Solve the Mysteries of Memory
Scientists are closing in on the mystery of human memory, how images are stored permanently and what determines which thoughts are remembered and which are quickly and forever forgotten.
Dr. Robert Rose, a professor of psychiatry at the University of Chicago, is studying a chemical he thinks will help explain the complex process of information storage and retrieval in the brain.
Stress-Related Hormone
He has strong evidence to indicate that the substance, a stress-related hormone, may play a vital role in signaling the brain that something is worth remembering. This, he said, is very different from the chemicals--called neurotransmitters--that do the actual storing.
But right now, what Rose is struggling for is an appropriate metaphor.
“The computer model doesn’t really do it with memory,” he said. “It might be easier to explain in terms of a radio.
“You might say the neurotransmitters are more like the radio waves, the actual representation of what’s going on, and the hormone is a neuromodulator, more like tuning the dial on the radio.”
After a pause, Rose adds, “Well, that’s close, but not exactly it.”
Released During Stress
What this particular neuromodulator is exactly is adrenocorticotropic hormone, or ACTH. Produced by the pituitary gland at the base of the brain, ACTH is released into the blood during times of stress and helps activate the production of adrenaline.
ACTH is also found throughout the brain during times of stress, Rose said, but appears to be produced where it is found and not by the pituitary gland. This finding has led Rose and other researchers to speculate that ACTH and other hormones somehow “tune” the brain in to experiences associated with important emotional states, initiating the remembering process.
“They’re the ones who tell the neurons, ‘Hey, this is important, you better remember it,’ ” he said.
“In 90% or 95% of the time, most of what you’re going to experience you’re going to forget,” Rose said, “But if somebody’s coming at you with a knife, it’s not going to be forgotten.”
Rose and his colleagues recently completed studies that seem to support this theory. Human subjects were given ACTH shortly after a learning task, and depending on the level of hormone already in their blood, adding more either facilitated or interfered with remembering.
Can Block Memory Too
The fact that too much ACTH blocks memory formation is consistent with other findings on stress, Rose said, and confirms a common observation from school days: “Certainly, it helps to be a little bit anxious about a test, but you don’t want to be too stressed out or you can’t remember anything.”
