Sleep Affects Some Memories But Not All

The researchers found that the mice that were kept awake immediately after their learning session were unable to retain the memory of their environment, but had no trouble recognizing the audible cue that told them to look for the nearest exit. But the mice that were allowed to go to sleep immediately retained both types of memories.

Targeting Memory Loss

Loss of sleep more than five hours after their learning sessions had no effect on either group of mice. So the timing of the sleep deprivation was critical.

"One of the fundamental findings of modern neuropsychology is that there are specific memory systems for specific kinds of memory," Abel says. "So if you learn a motor skill, like playing the piano, or some complicated tennis stroke, that is mediated by a brain region called the stratum and the cerebellum, and if you learn a complicated thing about facts and events, that's mediated by the hippocampus. And if you learn an emotional response, to be afraid of some stimulus, that's mediated by another brain region called the amygdala."

So immediate sleep deprivation wiped out the memory in the hippocampus, but not in the amygdala, showing that lack of sleep had an impact on one type of memory, but not the other.

This type of research has implications far beyond the interest of a handful of scientists in the sleep habits of mice. Understanding how various types of memories are recorded, and the type of events or situations that can effect those specific areas of the brain, could prove invaluable in the development of drugs to help fight memory loss, and in our understanding of which memories are most vulnerable to the timing of sleep deprivation.

Lee Dye’s column appears weekly on A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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