Sleep in early life may play crucial role in brain d...( esting synaptic connections are strengt...)

But while these findings together provide strong, suggestive evidence that synaptic circuits are modified during sleep the current study provides the first direct evidence that sleep and sleep loss modify experience-dependent changes in synaptic plasticity.

"The significance of our study is that we examined a system in which we know a great deal about the neural inputs and the outputs - we know how information gets into the visual cortex from the two eyes, how it changes during normal development, and we know a lot about what goes on in the circuitry to cause plasticity in this system, and to cause the loss of response to the eye after monocular deprivation," says Stryker.

"Among other things, now we can begin to examine to what extent the mechanisms inherent in sleep are distinct from those governing cortical plasticity during wakefulness. We should also gain general insights into plasticity."

To tease out the impact of sleep on plasticity during early brain development, the researchers established a model in which they measured in cats the response of neurons of the visual cortex to an environmental challenge -vision blocked in one eye for six hours. The visual deprivation initiates a rapid remodeling of neural circuitry known as ocular dominance plasticity. The researchers then examined the impact of sleep on the long-term effects of those changes by using brain imaging and making electrical recordings from brain cells.

First, in one set of cats they took a measurement of the brain change, or plasticity, immediately following the period of visual deprivation. Then, in the other three sets of cats, they examined the relative effects of sleep or lack of sleep on the initial plasticity. This is where the provocativ
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Contact: Jennifer O'Brien
jobrien@pubaff.ucsf.edu
415-476-8432
University of California - San Francisco
25-Apr-2001