Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why our shifty eyes don't drive us crazy

10.11.2006
Pitt, NIH researchers discover circuit underlying visual stability

Our eyes are constantly making saccades, or little jumps. Yet the world appears to us as a smooth whole. Somehow, the brain's visual system "knows" where the eyes are about to move and is able to adjust for that movement. In a paper published online this week in Nature, researchers at the University of Pittsburgh and the National Eye Institute (NEI) for the first time provide a circuit-level explanation as to why.

"This is a classic problem in neuroscience," says Marc Sommer, assistant professor of neuroscience at Pitt, who coauthored the paper with Robert Wurtz, senior investigator at NEI, one of the National Institutes of Health. "People have been searching for a circuit to accomplish this stability for the last 50 years, and we think we've made good progress with this study."

In 1950, Nobel laureate Roger Sperry hypothesized that when the brain commands the eyes to move, it also sends a corollary discharge, or internal copy, of that command to the visual system. Sommer and Wurtz showed in a 2002 Science paper that a pathway from brainstem to frontal cortex conveys a corollary discharge signal in the brains of monkeys. They suggested that this pathway might cause visual neurons of the cortex to suddenly shift their receptive field--their window on the world--just before a saccade. Such neurons with shifting receptive fields had been discovered by Pitt Professor of Neuroscience Carol Colby and colleagues in 1992.

In their current paper, which will be published in the Nov. 16 print edition of Nature, Sommer and Wurtz completed the circuit. They showed that the receptive fields in cortex are shifted because of the corollary discharge from the brainstem. To do this, they exploited the fact that the signals are relayed via the thalamus, a crucial intermediary. By knocking out the relay neurons, they interrupted the pathway. They found that receptive field shifts were curtailed by more than half.

A similar circuit is likely to exist in human brains, the researchers say. With this study, Sommer and Wurtz also provide a framework for studying corollary discharge in other sensory systems, such as hearing: Even when you move your head around, you still hear sounds around you as coming from the same place.

In future studies, Sommer and his graduate students at Pitt will perform the first direct test of the visual stability hypothesis. To determine whether shifting receptive fields are responsible for visual stability, the shifts will be disrupted in monkeys trained to detect visual motion. The monkeys could then report whether their world appears to be moving around abnormally as eye movements are made.

Karen Hoffmann | EurekAlert!
Further information:
http://www.pitt.edu

More articles from Studies and Analyses:

nachricht Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena

nachricht Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>