of the muscle leads to shifts of ? with no major change in the shape of the F(L) dependence. The magnitude of λ may be viewed as a referent length (referent coordinate [RC]) for the muscle, which it would reach in the absence of external resistance. The idea of control with RCs has been generalized
Mark L. Latash
Mark L. Latash
Living systems may be defined as systems able to organize new, biology-specific, laws of physics and modify their parameters for specific tasks. Examples include the force-length muscle dependence mediated by the stretch reflex, and the control of movements with modification of the spatial referent coordinates for salient performance variables. Low-dimensional sets of referent coordinates at a task level are transformed to higher-dimensional sets at lower hierarchical levels in a way that ensures stability of performance. Stability of actions can be controlled independently of the actions (e.g., anticipatory synergy adjustments). Unintentional actions reflect relaxation processes leading to drifts of corresponding referent coordinates in the absence of changes in external load. Implications of this general framework for movement disorders, motor development, motor skill acquisition, and even philosophy are discussed.
Satyajit Ambike, Daniela Mattos, Vladimir Zatsiorsky and Mark Latash
human motor actions (reviewed in Latash, 2016 ). According to this approach, force production in isometric conditions is associated with setting a referent coordinate (RC) for the effector and a magnitude of apparent stiffness ( k , which is a reflection of shifts in spatial RCs for the participating
Arturo Forner-Cordero, Virgínia H. Quadrado, Sitsofe A. Tsagbey and Bouwien C.M. Smits-Engelsman
predictability of the forces. Nevertheless, there could be alternative interpretations such as learning a desired timing for the trajectory of the referent coordinate for the hand. It is possible to see learning in the movement as the change of equilibrium positions of agonist antagonist groups of muscles. This