Why it matters: Previous work in animals and humans has shown that groups of muscles tend to be co-activated as a unit, in predicable patterns, or synergies, across a wide range of movements.
These synergies are thought to represent the fundamental building blocks from which the brain constructs complex movements. The new findings support this concept and also suggest new approaches to the rehabilitation of stroke patients. Stroke is a leading cause of long-term disability in the US, with about 700,000 new or recurrent cases each year.
How they did it: The researchers, led by Emilio Bizzi, an MIT Institute Professor and a member of the McGovern Institute for Brain Research and the Department of Brain and Cognitive Sciences, used electromyographic (EMG) recording to measure activity in arm and shoulder muscles of 8 stroke patients as they performed a variety of reaching movements. The patients had stroke damage in one cortical hemisphere only, so one arm was impaired while the other was largely unaffected. The researchers used computational methods to identify groups of muscles whose activation was correlated across movements. In 7 out of 8 patients, these correlations, or synergies, were largely identical between the affected and unaffected arms, even though the actual movements were very different between the two arms. The results support the view that the synergies are encoded in the brainstem or spinal cord, areas that were unaffected in these patients. “We show that descending neural signals from the motor cortex select, activate and combine a small number of muscle synergies that are specified by networks in the spinal cord or brainstem,” Bizzi explains, “and different movements emerge as these synergies are recruited to various degrees.”
Next steps: The findings suggest a new approach to the rehabilitation of stroke patients. By identifying synergies whose activations are affected following a stroke, it may be possible to develop focused rehabilitation methods that specifically train the impaired synergies. As a first step toward this goal, the researchers plan to monitor a group of stroke patients as they undergo rehabilitation therapy, to determine whether the post-stroke improvements in motor function can be explained as changes in the activation pattern of specific synergies.
Source: Cheung VC, Piron L, Agostini M, Silvoni S, Turolla A, Bizzi E. (2009). Stability of muscle synergies for voluntary actions after cortical stroke in humans. Proc Natl Acad Sci (USA). Oct 19 2009.
Funding: McGovern Institute for Brain Research at MIT and the Italian Ministry of Health
Jen Hirsch | Newswise Science News
Malaria Already Endemic in the Mediterranean by the Roman Period
27.07.2017 | Universität Zürich
Serious children’s infections also spreading in Switzerland
26.07.2017 | Universitätsspital Bern
Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.
Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
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...
26.07.2017 | Event News
21.07.2017 | Event News
19.07.2017 | Event News
27.07.2017 | Life Sciences
27.07.2017 | Life Sciences
27.07.2017 | Health and Medicine