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

A process account of the uncontrolled manifold structure of joint space variance in pointing movements.
Biol Cybern. 2019 Feb 15;:
Authors: Martin V, Reimann H, Schöner G
Abstract
In many situations, the human movement system has more degrees of freedom than needed to achieve a given movement task. Martin et al. (Neural Comput 21(5):1371-1414, 2009) accounted for signatures of such redundancy like self-motion and motor equivalence in a process model in which a neural oscillator generated timed end-effector virtual trajectories that a neural dynamics transformed into joint virtual trajectories while decoupling task-relevant and task-irrelevant combinations of joint angles. Neural control of muscle activation and the biomechanical dynamics of the arm were taken into account. The model did not address the main signature of redundancy, however, the UCM structure of variance: Many experimental studies have shown that across repetitions, variance of joint configuration trajectories is structured. Combinations of joint angles that affect task variables (lying in the uncontrolled manifold, UCM) are much more variable than combinations of joint angles that do not. This finding has been robust across movement systems, age, and tasks and is often preserved in clinical populations as well. Here, we provide an account for the UCM structure of variance by adding four types of noise sources to the model of Martin et al. (Neural Comput 21(5):1371-1...

Source: Biological Cybernetics - February 15, 2019 Category: Science Authors: Martin V, Reimann H, Schöner G Tags: Biol Cybern Source Type: research