TY - JOUR T1 - Challenges and New Approaches to Proving the Existence of Muscle Synergies of Neural Origin A1 - Kutch, Jason J. A1 - Valero-Cuevas, Francisco J. Y1 - 2012/05/03 N2 - Author Summary How the brain and spinal cord control the body is a fundamental question of critical scientific and clinical importance. The preferred experimental approach to answer this question has been to infer the neural control strategy by analyzing recordings of muscle activity and limb mechanics collected while animals and people use their limbs. This has led to a popular, but not yet proven, hypothesis that the brain and spinal cord simplify the control of the numerous muscles by grouping them into few functional units called neural synergies. Our detailed experiments and simulations challenge the utility of this approach and the validity of its interpretation. We point out that mechanical constraints can also explain those experimental recordings. In particular, the anatomy of the limb combined with the type of tasks studied and analysis used, suffice to give the appearance of neural synergies. To be clear, we do not disprove the neural synergy hypothesis. Rather, in the tradition of scientific debate, by showing an alternative explanation to the available data we challenge the community and ourselves to design novel experiments and analyses to conclusively test that hypothesis by ruling out the confounds we point out. JF - PLOS Computational Biology JA - PLOS Computational Biology VL - 8 IS - 5 UR - https://doi.org/10.1371/journal.pcbi.1002434 SP - e1002434 EP - PB - Public Library of Science M3 - doi:10.1371/journal.pcbi.1002434 ER -