title: Stochastic order parameter equation of isometric force production revealed by drift-diffusion estimates.
abstract: We address two questions that are central to understanding human motor control variability: what kind of dynamical components contribute to motor control variability (i.e., deterministic and/or random ones), and how are those components structured? To this end, we derive a stochastic order parameter equation for isometric force production from experimental data using drift-diffusion estimates. We show that the force variability increases with the required force output because of a decrease of deterministic stability and an accompanying increase of noise intensity. A structural analysis reveals that the deterministic component consists of a linear control loop, while the random component involves a noise source that scales with force output. In addition, we present evidence for the existence of a subject-independent overall noise level of human isometric force production.
authors.affiliation: Institute for Theoretical Physics, University of Münster, Wilhelm-Klemm-Strasse 48149 Münster, Germany.
authors.forename: T D
authors.initials: TD
authors.lastname: Frank
authors.forename: R
authors.initials: R
authors.lastname: Friedrich
authors.forename: P J
authors.initials: PJ
authors.lastname: Beek
mesh_terms: D000328:Adult; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012680:Sensitivity and Specificity; D013269:Stochastic Processes; D013314:Stress, Mechanical