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 Physicists discover that lithium oxide on tokamak walls can improve plasma performance
22.05.2017 | DOE/Princeton Plasma Physics Laboratory

nachricht Experts explain origins of topographic relief on Earth, Mars and Titan
22.05.2017 | City College of New York

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: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>