Rat Whiskers Give Clues to Blinking Disorder

Discovery could bring treatments for serious eye condition

WEDNESDAY, Feb. 2, 2005 (HealthDayNews) -- A rat's whiskers may hold vital clues to a debilitating human disorder called blepharospasm, an eye condition characterized by uncontrolled blinking.

Physicists at the University of California, San Diego (UCSD) say they've identified a rat neural circuit that coordinates sensory input and muscle activity in the rodents' whiskers -- a circuit nearly identical to that which controls human blinking. Because it gives new insights into neural "positive feedback loops," the researchers believe the finding could yield new treatments for blepharospasm.

The study appears in the Feb. 3 issue of Neuron.

Up till now, scientists have found that most neural circuits controlling reflexes work via negative feedback -- meaning that as sensory input increases, circuits tell nerve sensors to withdraw from the source of stimulus.

However, in a positive feedback model such as that seen in rat whisker circuitry, increasing sensory input drives nervous activity to heightened activity. Experts believe this type of out-of-control dynamic may occur in blepharospasm as well.

"Until now, treatment for blepharospasm has been mostly trial-and-error," co-researcher Quoc-Thang Nguyen said in a prepared statement. "Our findings should permit a more principled approach to the development of new therapies and medications."

More than 50,000 Americans suffer from blepharospasm, which in extreme cases can cause blindness.

More information

The U.S. National Eye Institute has more about blepharospasm.

SOURCE: University of California, San Diego, news release, Feb. 2, 2005
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