Sleep in early life may play crucial role in brain d...( y focused specifically on the impact of...)

If this is shown to be the case, sleep could prove an important part of the strategy for preparing for such challenges as exams. "The fact that sleep provoked slightly more plasticity than double the amount of exposure to experience [when cats remained awake in a lit room] suggests that if you reviewed your notes thoroughly until you were tired and then slept, you'd achieve as much plasticity, or 'learning,' in the brain as if you'd pulled an all-nighter repeating your review of the material," says Stryker.

Significantly, the researchers determined that the amount of plasticity in the brain depended on the amount of sleep known as non-rapid eye movement, a deep, quiet, slumber marked by large, slow brain waves. This is the sleep that a person falls into when he or she first goes to sleep and which accounts for half of sleep in animals of this age. Non-REM sleep alternates with periods of rapid eye movement, or so-called "dream" sleep, a period marked by rapidly changing brain waves and rapid bursts of eye movement.

This discovery offers direction for examining the two major hypotheses for how sleep impacts plasticity. One theory is that patterned neuronal activity following a period of environmental stimulation is replayed during non-REM sleep, strengthening neuronal connection changes. The alternative theory, which could also work in conjunction with the first, is that powerful growth factors, such as neurotrophins, which are known to be necessary for cortical plasticity, are released during non-REM sleep.

"Right now we don't know if these neurotrophins are released during sleep. We do know that other growth factors are released during
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Contact: Jennifer O'Brien
jobrien@pubaff.ucsf.edu
415-476-8432
University of California - San Francisco
25-Apr-2001