Posted on: March 4, 2009
To Sleep, Perchance to Remember
By Mirielle Cailles
CTW Features
According to a new study, the old wives' tale that sleep helps solidify memories is no longer a myth. Researchers at the University of Pennsylvania, Philadelphia, have discovered how cellular changes in the sleeping brain help promote the formation of memories.
This is the first real direct insight into how the brain, on a cellular level, changes the strength of its connections during sleep, says lead researcher Marcos Frank, PhD., Assistant Professor of Neuroscience, at UPenn.
"We find that the biochemical changes are simply not happening in the neurons of animals that are awake," he says. "And when the animal goes to sleep it's like you've thrown a switch, and all of a sudden, everything is turned on that's necessary for making synaptic changes that form the basis of memory formation. It's very striking."
Using an experimental model to mimic the machinery of memory, the team used visual stimulation to study an animal's brain with and without sleep. The study found that during wakefulness the brain triggers its neural networks, intra- and intercellular communication pathways engage, setting a series of enzymes into action within the reorganizing neurons during sleep.
"To our amazement, we found that these enzymes never really turned on until the animal had a chance to sleep," Frank explains, "As soon as the animal had a chance to sleep, we saw all the machinery of memory start to engage."
Though this study did not examine recalling memories, it does give a broader understanding of why humans need sleep and why they are so affected by the lack of sleep.
How and even where humans store long-lasting memories still remains a mystery, but Frank says, "We do know that changes in cortical connections is at the heart of the mystery. By understanding that in animal models, it will bring us close to understanding how it works in humans."