Sleep deprivation may impair the memory for subsequent experiences by altering the function of the hippocampus, reports a paper in the March 2007 issue of Nature Neuroscience. Previous research has shown that sleep occurring after an experience can be critical to learning and memory but this new study shows why sleep before an experience is also critical, and that memory systems do not function normally without it.
Matthew Walker and colleagues deprived people of a night's sleep and then asked them to observe and remember a large set of picture slides for a subsequent recognition test. Brain activity was monitored with fMRI -- functional magnetic resonance imaging -- while subjects viewed the slides. Following a full night of sleep, the subjects were then queried about the slides on the next day. The researchers found that sleep-deprived subjects showed decreased activity in the hippocampus -- a brain region important for memory -- relative to control subjects who were not sleep-deprived while viewing the pictures; sleep-deprived people also had poorer subsequent recall abilities. The relationship of activation in other brain areas to activation in the hippocampus was also altered, suggesting that sleep deprivation alters memory-encoding strategies.
Matthew Walker (Harvard Medical School, Boston, MA, USA)
Abstract available online.
(C) Nature Neuroscience press release.
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