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Bilateral motor unit synchronization of leg muscles during a simple dynamic balance task
Author(s) -
Boonstra Tjeerd W.,
Daffertshofer Andreas,
Roerdink Melvyn,
Flipse Ivo,
Groenewoud Karin,
Beek Peter J.
Publication year - 2009
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2008.06584.x
Subject(s) - synchronization (alternating current) , context (archaeology) , motor unit , task (project management) , neuroscience , balance (ability) , computer science , electromyography , motor coordination , degrees of freedom (physics and chemistry) , coherence (philosophical gambling strategy) , motor control , communication , control theory (sociology) , psychology , physical medicine and rehabilitation , biology , artificial intelligence , mathematics , physics , control (management) , medicine , engineering , computer network , paleontology , channel (broadcasting) , statistics , systems engineering , quantum mechanics
To handle the rich repertoire of behavioural goals, the CNS has to control the many degrees of freedom of the musculoskeletal system in a flexible manner. This problem can be drastically simplified if muscle synergies serve as the to‐be‐controlled building blocks of motor performance, instead of the individual degrees of freedom. Muscle synergies have been identified as coherent activation patterns of a group of muscles in space or time, but the neural mechanisms underlying their formation remain largely unknown. Here we evaluated the hypothesis that synergies are reflected in common input to different contributing muscles, and investigated modulations in motor unit (MU) synchronization of homologous muscles during a rhythmic balance task. If common input is related to muscle synergies, the resultant MU synchronization should not be static but task dependent and, in the present context, vary in time. Coherence between surface electromyographic signals of bilateral leg muscles revealed MU synchronization in two distinct frequency bands. MU synchronization was not constant but modulated within a movement cycle, and its time course resembled the activation patterns of the muscles. These results are congruent with a linkage between MU synchronization and muscle synergies, and suggest that MU synchronization provides an expedient method for studying synergy‐related neural mechanisms.