Modular organisation of hand movements by the human central nervous system: a transcranial magnetic stimulation study

Previously, kinematic analyses have revealed that human grasping movements can be reduced to recombinations of a few motor synergies. It is, however, unclear whether this reflects a motor control strategy implemented by the central nervous system. To test this hypothesis directly, we mapped finger movements of 18 subjects by transcranial magnetic stimulation (TMS). Principal component (PC) analysis, a widely used mathematical decomposition algorithm, revealed that just 4 PCs (“modules“) were necessary to account for ˜90% of variance of the entire data set. Modules showed high intra-subject stability and partiall…