Muscle ‘synergies’ may be key to stroke treatment

	Tweet

What’s new: Researchers at MIT and San Camillo Hospital in Venice, Italy, have shown that motor impairments in stroke patients can be understood as impairments in specific combinations of muscle activity, known as synergies.

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 United States, 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 eight 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 seven out of eight 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 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: Chung VC, Piron L, Agostini M, Silvoni S, Turolla A, Bizzi E. (2009). Stability of muscle synergies for voluntary actions after cortical stroke in humans. Proceedings of the National Academy of Science (USA). Oct 19 2009.

Funding: McGovern Institute for Brain Research at MIT and the Italian Ministry of Health Grant.

Contact: Jen Hirsch

617-253-1682
Massachusetts Institute of Technology

RELATED STORIES:
Women Need Clot-Busting Therapy After Stroke   Blood sugar control impacts stroke risk   Patients Reaching Hospital within ‘Golden Hour’ More Likely to Get Stroke Drug   After stroke, admission to designated stroke center hospitals associated with reduced risk of death   Stroke victims recover much better after temporary stent procedure   New Procedure Offers Hope to Patients at High Risk for Recurrent Stroke   Cholesterol Drugs can Reduce Stroke Risk, but Aren’t for Everyone   Keep a Cool Head on Hot, Humid Days to Avoid Heat Stroke   Migraine Raises Risk of Most Common Form of Stroke   Using CT, radiologists can pinpoint cause of some strokes   Controlling Cholesterol, Blood Pressure Adds Up to Prevent Stroke   Risk model based on Get with the Guidelines analysis can help

Comments

[ + Post Your Own ]

Now you're in the public comment zone. What follows is not Armenian Medical Network's stuff; it comes from other people and we don't vouch for it. A reminder: By using this Web site you agree to accept our Terms of Service. Click here to read the Rules of Engagement.

I wonder what the pre-motor cortex does that may explain these synergies and if the pre-motor cortex is destroyed then these synergoes do not appear. This sounds like Sherringtonian reflexology which I thought was no longer accepted.

posted by dean reinke on 10/21/2009 at 6:31 am -08:00