Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Findings Help Explain the Dynamics Between The Dominant and Non-Dominant Arm

19.03.2003


The phrase, “the right hand doesn’t know what the left hand is doing,” has its roots in a passage of the Bible (Matthew 6:3). If there is truth to this old saying, the reasons may have as much to do with the way the brain obtains information from the arms as it does from the observations of ancient scribes.



Background

Most individuals are either left- or right-handed. How the skills they have learned from the dominant arm (or hand) are transferred to the non-dominant arm have long intrigued physiologists and neurologists.


The transfer of a skill learned in one hand to the other hand has been used as evidence for the role of the brain’s hemispheres in controlling that skill. The movement of knowledge from the dominant to the nondominant arm (D ->ND) has been interpreted as confirmation of the brain’s ability to encode an experience in the dominant hemisphere with the dominant hand and to influence the performance of the nondominant hand. Many researchers believe that this process is accomplished either through connections across both hemispheres or through the same side of the brain. Other scientists believe that transfer in the opposite direction reflects a dominance of the right hemisphere (in right-handers) for some aspects of motor control, so both directions of transfer can be explained with a single model.

Little is known about the involvement of the body’s subcortical structures (such as the cerebellum, and spinal cord) in this process. While it is possible to get some indication of the role of the cerebral hemispheres through the study of subjects with a sectioned corpus callosum, this has rarely been pursued in the case of motor learning and transfer. Accordingly, a team of researchers wondered whether learning a force field with one arm generalizes to the other arm.

Previous observations have found that since learning generalizes in a muscle-like, intrinsic coordinate system for the trained arm, there was little expectation that there would be generalization to the contralateral arm. The scientists found the very surprising result that there was not only strong generalization, but also that it seemed to be with respect to an extrinsic coordinate. To investigate the neural basis of this generalization, they examined an individual who had undergone a complete section of the corpus callosum. Their results provide a significant challenge to current models of how the brain learns reaching movements.

The authors of “Learned Dynamics of Reaching Movements Generalize From Dominant to Nondominant Arm,” are Sarah E. Criscimagna-Hemminger, Opher Donchin, and Reza Shadmehr, from the Laboratory for Computational Motor Control, Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD; and Michael S. Gazzaniga, at the Center for Cognitive Neuroscience, Dartmouth College, Hanover, NH. Their findings appear in the January 2003 edition of the Journal of Neurophysiology.

Methodology

Quantifying inter-arm generalization allowed testing of the sensitivity of these elements to the other arm. Two possible coordinate systems were considered: (1) an intrinsic (joint) representation should generalize with mirror symmetry reflecting the joint’s symmetry and (2) an extrinsic representation, which should preserve the task’s structure in extrinsic coordinates. Both coordinate systems of generalization were compared with a naïve control group.

The researchers tested transfer in right-handed subjects both from dominant to nondominant arm (D ->ND) and vice versa (ND ->D). This led to a 2 × 3 experimental design matrix: transfer direction (D ->ND/ND ->D) by coordinate system (extrinsic, intrinsic, control). Generalization occurred only from dominant to nondominant arm and only in extrinsic coordinates. To assess the dependence of generalization on callosal inter-hemispheric communication, the researchers tested commissurotomy (brain surgery) patient JW. JW showed generalization from dominant to nondominant arm in extrinsic coordinates.

Results

This study produced three main findings.

  • First, learning to compensate for dynamics of reaching movements in right-handed individuals generalizes from dominant arm to the nondominant arm (D ->ND) but not vice versa.

  • Second, D ->ND generalization in the workspace that we tested (near the midline) is in an extrinsic, Cartesian-like coordinate system.

  • Third, generalization of this motor skill does not depend on transfer of information between the hemispheres via the corpus callosum.

Conclusions

The results suggest that when the dominant right arm is used in learning dynamics, the information could be represented in the left hemisphere with neural elements tuned to both the right arm and the left arm. In contrast, learning with the nondominant arm seems to rely on the elements in the nondominant hemisphere tuned only to movements of that arm.


Source: January 2003 edition of the Journal of Neurophysiology.

The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.

Donna Krupa | APS
Further information:
http://www.the-aps.org/press_room/journal/pr3-17-3.htm

More articles from Studies and Analyses:

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>