Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How does the brain know what the right hand is doing?

23.03.2006
A new experiment has shed more light on the multi-decade debate about how the brain knows where limbs are without looking at them.

You don’t have to watch your legs and feet when you walk. Your brain knows where they are. For decades scientists have debated two options for how the brain achieves this:

(1) the outflow hypothesis says that the brain monitors signals it sends to the muscles telling them how strongly to contract, and uses this to predict where the limb has moved to;

(2) the inflow hypothesis suggests that the brain relies on information from sensors within tissues that say how far a limb has moved.

While there has been plenty of evidence that inflow plays a role, no one before has been able to show definitively that outflow is also important.

Now research just published in The Journal of Physiology provides evidence that outflow is involved. Working at the Prince of Wales Medical Research Institute in Sydney, the Australian research team asked subjects to sit at a bench and place their right hand through a screen so they couldn’t see it. The hand was clamped so that the researchers could move it, but the subjects could only push against a fixed plate. The researchers then moved the hand and the subjects had to say which way it was pointing. The researchers then asked the subjects to push against the plate, and say where they thought the hand had moved to. The researchers inflated a cuff around the arm, cutting off blood flow and temporarily paralysing and anaesthetising the arm. They then repeated the tests.

Before the cuff was inflated, the subjects accurately indicated where their hand was pointing, both when they were resting and when they were pushing against the plate. After the arm was paralysed and anaesthetised, the subjects were unable to detect when researchers moved their hand, but incorrectly thought that they were still able to move it themselves when they tried to push against the plate.

‘The fact that the person thought they had changed the position of their paralysed hand, even though they hadn’t, shows that the perception of limb position is at least partly driven by outflow commands going to the muscles. There were no incoming signals from receptors, so this cannot have been responsible for the illusion,’ says Dr Janet Taylor, one of the authors of the paper.

The experiment provides a new and intriguing illusion that sheds light on how we learn to move accurately, as well as indicating why some people who have had limbs amputated still feel as if they can move their ‘phantom’ limb.

Lucy Mansfield | alfa
Further information:
http://www.blackwellpublishing.com/tjp

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

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 >>>