Novel Mechanism for Long-Term Learning Identified by Carnegie Mellon R...( Mechanism Described in Jan. 4 Iss...),Health

Mechanism Described in Jan. 4 Issue of Science Explains How Neuronal

Connections Continue To Strengthen After Repeated Stimulation

PITTSBURGH, Jan. 3 /PRNewswire/ -- Practice makes perfect -- or at least that's what we're told as we struggle through endless rounds of multiplication tables, goal kicks and piano scales -- and it seems, based on the personal experience of many, to be true. That's why neuroscientists have been perplexed by data showing that at the level of individual synapses, or connections between neurons, increased, repetitive stimulation might actually reverse early gains in synaptic strength. Now, neuroscientists from Carnegie Mellon University and the Max Planck Institute have discovered the mechanism that resolves this apparent paradox. The findings are published in the Jan. 4 issue of Science.

(Logo: http://www.newscom.com/cgi-bin/prnh/20020422/CMULOGO)

The mechanism further explains how brain synapses strengthen in response to new experiences. Previous research by Carnegie Mellon researcher and lead author of the study Alison Barth has shown that there is a connection between synaptic plasticity, or changes, and learning and memory. However, little was known about the mechanisms that underlie learning that occurs over longer timeframes, with continuing training or practice.

Scientists have shown that N-methyl-D-aspartate (NMDA) receptors are required to initiate synaptic plasticity in this mechanism, a fact that holds true in many areas of the brain. Indeed, it is becoming increasingly clear that these receptors are required for the kind of synaptic strengthening that occurs during learning.

Barth and colleagues discovered that the NMDA receptors undergo a sort of Jekyll-and-Hyde transition after an initial phase of learning. Instead of helping synapses get stronger, they actually begin to weaken the synapses and i
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