A process account of the uncontrolled manifold structure of joint space variance in pointing movements

• DOI: 10.1007/s00422-019-00794-w
• Publication Date: 2019-02-15T09:45:23Z
• Authors: Valère Martin; Hendrik Reimann; Gregor Schöner
• Keywords: Manifold (fluid mechanics); Complex system

In many situations, the human movement system has more degrees of freedom than needed to achieve a given task. Martin et al. (Neural Comput 21(5):1371–1414, 2009) accounted for signatures such redundancy like self-motion and motor equivalence in process model which neural oscillator generated timed end-effector virtual trajectories that dynamics transformed into joint while decoupling task-relevant task-irrelevant combinations angles. Neural control muscle activation biomechanical arm were taken account. The did not address main signature redundancy, however, UCM structure variance: Many experimental studies have shown across repetitions, variance configuration is structured. Combinations angles affect task variables (lying uncontrolled manifold, UCM) are much variable do not. This finding been robust systems, age, tasks often preserved clinical populations as well. Here, we provide an account by adding four types noise sources 2009). Comparing pointing movements systematically examining role each source mechanism, identify three causes effect, all which, argue, contribute: (1) commands subspaces together with "neural" at level these commands; (2) "muscle noise" combined imperfect limb; (3) back-coupling sensed configurations then yield within UCM.