Shadmehr R (1995), The equilibrium point hypothesis for control of posture, movement, and manipulation. In: Handbook of Brain Theory and Neural Networks, M. A. Arbib (ed), MIT Press, pp. 370-372.

Abstract  The equilibrium point hypothesis (EPH) provides a systems level description of how the nervous system controls the muscles so that a stable posture is maintained or a movement is produced. In the EPH framework, the controller is composed of muscles and the spinal-based reflexes, and the plant is the skeletal sytem. The controller is represented as a mapping which assigns a force to each state of teh plant, i.e., a force field. This mapping, which is meant to capture the mechanical behavior of the muscles and the effect of the spinal reflexes, is also dependent on a st of control inputs from supra-spinal centers. EPH predicts certain properties for the controller. For example, that the field will have an attractor, and movement is a result of supra-spinal input which causes a gradual shift of this attractor.