Physicists at the University of California, San Diego have discovered a neural circuit in rats that could provide a powerful model for understanding a neurological condition known as blepharospasm--uncontrolled eye blinking that affects 50,000 people in the U.S. and leaves some patients functionally blind.

In the February 3 issue of the journal Neuron, the researchers, Quoc-Thang Nguyen and David Kleinfeld, describe the brain circuit, which coordinates sensory inputs and muscle activity in rats' whiskers. It is the first discovery of a reflex circuit that functions to boost the amount of incoming sensory information. Because the neural wiring of the rat whiskers appears to be identical to the circuit that controls eyeblinking in humans, the UCSD scientists believe it could be used for pioneering new treatments for blepharospasm.

"We have been studying the rat whisker system as an example to help us understand how sensory systems control where the sensors are in space and how the sensors are moved," said Nguyen, an assistant project scientist in UCSD's physics department. "Our study is the first to find a neural circuit responsible for keeping sensors on an object during active touch."

"We hope that this finding will help push the field from a focus biased by anatomy to a focus centered on functionality of neural circuits," added David Kleinfeld, a professor of physics at UCSD. "Also, this circuit could serve as a model system to deepen our understanding of a pathology in the human eyeblink circuit."

The only neural circuits controlling reflexes that had been identified prior to the UCSD physicists' discovery were negative feedback loops, in which sensory input leads to motor output that withdraws sensors from the source of a stimulus. For example, such a reflex occurs if you accidentally touch a hot stove.

On the other hand, the newly discovered reflex circuit that controls rats' whiskers as rats explore their environm
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Contact: Sherry Seethaler
sseethaler@ucsd.edu
858-534-4656
University of California - San Diego
2-Feb-2005

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