How the Brain Adapts

Researchers identify 'reset switch'

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WEDNESDAY, Oct. 29, 2003 (HealthDayNews) -- A "reset switch" that increases or decreases the sensitivity of brain cells to stimulation by their neighbors has been identified by Duke University Medical Center neurobiologists.

This action, called homeostatic plasticity, enables the brain to adapt to changes in the environment. It helps the brain avoid having its neurons swamped by increased activity of the neural pathway or from becoming too insensitive to detect triggering impulses from other neurons when there is low neural activity.

The Duke scientists, who used an array of analytical techniques in their study, say this homeostatic plasticity is distinct from more rapid changes in neural circuits that occur during the formation of memory.

The study appears in the Oct. 30 issue of Neuron.

The research offers long-sought clues to how neurons protect themselves during stroke, epilepsy, and spinal cord damage. The study may also help explain various brain changes that occur during early childhood and problems that occur later in life when people develop Alzheimer's or Parkinson's disease.

"Neurobiologists have understood that a neuron can increase only so much its firing rate in response to inputs from other neurons, and then it saturates. There had to be a way for a neuron to recalibrate -- to scale up or down to stay within an optimal dynamic firing frequency range," lead researcher Dr. Michael Ehlers, an assistant professor of neurobiology, says in a prepared statement.

"Consider when you're driving a car with a manual transmission. As you accelerate, you reach a point where the engine's RPMs are maximal and can go no higher. At that point, you need to switch gears to bring back your RPMs to an optimal range," Ehlers explains.

"What we have found is the molecular clutch that allows neurons to shift gears. This really is a profoundly important discovery. Imagine if your brain could operate only in 'second gear,'" he says.

More information

Here's where you can learn more about neurons.

SOURCE: Duke University news release, Oct. 29, 2003

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