Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rat Whisking May Provide Insight Into Debilitating Eye Disorder

03.02.2005


A rat’s whiskers Credit: Samar B. Metha, UCSD


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 environment is a positive feedback loop. It helps rats keep their whiskers on an object, enabling them to gather an uninterrupted stream of sensory information.

Nguyen commented that positive feedback loops make engineers “squeamish” because, if uncontrolled, they can create a vicious cycle. For example, in a furnace controlled by positive feedback, rather than negative feedback, the warmer a room became the more the thermostat would signal the furnace to turn on.

This type of vicious cycle appears to occur in blepharospasm. Normally, the blinking reflex protects the eye from bright light and other environmental hazards, but in blepharospasm this blinking response gets out of control. The resulting muscle spasms can be so intense that the eyelids remain forcefully closed for several hours at a time.

“The human eyeblink reflex circuit appears to share a common anatomy and physiology with the neural circuit that controls rat whiskers,” said Kleinfeld. “Actually, it isn’t unusual to see the repetition of neural circuits with the same design principles in different systems.”

As with blinking in humans, rat whisking does not normally turn into a vicious cycle. However, certain chemicals that interfere with normal communication between nerve cells can cause unintentional whisking in rats. By studying what mechanisms usually keep rat whisker movements in check, researchers can develop a better understanding of what causes the eyeblink reflex to go awry.

“Until now, treatment for blepharospasm has been mostly trial and error,” said Nguyen. “Our findings should permit a more principled approach to the development of new medications and therapies.”

The researchers also said their findings underscore the importance of basic scientific research. Nguyen called the connection to blepharospasm a “serendipitous” outcome of their work. Kleinfeld added that their finding is just one example that shows the growing trend to fund research on diseases at the expense of basic science may be unwise and counterproductive.

“We need to understand how a system works when it is normal in order to understand what goes wrong when it is broken,” he said.

Their research was supported by grants from the National Institutes of Health and the Human Frontiers Scientific Program.

Sherry Seethaler | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>