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 Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center

nachricht A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country

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: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>