Feedforward and Feedback Control Share an Internal Model of the Arm's Dynamics

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
Rodrigo S MaedaJ Andrew Pruszynski


Recent work has shown that, when countering external forces, the nervous system adjusts not only predictive (i.e., feedforward) control of reaching but also reflex (i.e., feedback) responses to mechanical perturbations. Here we show that altering the physical properties of the arm (i.e., intersegmental dynamics) causes the nervous system to adjust feedforward control and that this learning transfers to feedback responses even though the latter were never directly trained. Forty-five human participants (30 females) performed a single-joint elbow reaching task and countered mechanical perturbations that created pure elbow motion. In our first experiment, we altered intersegmental dynamics by asking participants to generate pure elbow movements when the shoulder joint was either free to rotate or locked by the robotic manipulandum. With the shoulder unlocked, we found robust activation of shoulder flexor muscles for pure elbow flexion trials, as required to counter the interaction torques that arise at the shoulder because of forearm rotation. After locking the shoulder joint, which cancels these interaction torques, we found a substantial reduction in shoulder muscle activity over many trials. In our second experiment, we tested ...Continue Reading


Feb 7, 2019·Journal of Neurophysiology·Xiao ZhouSteven M Chase
Aug 29, 2019·Journal of Neurophysiology·Alexander MathisSamuel D McDougle
Feb 27, 2020·Journal of Neurophysiology·Rodrigo S MaedaJ Andrew Pruszynski
Nov 28, 2019·The European Journal of Neuroscience·Luis Augusto TeixeiraDaniel Boari Coelho

Related Concepts

Reflex, Tendon
Elbow Joint Structure
Entire Nervous System
Entire Elbow Region
Joint Structure of Shoulder Region
Entire Glenohumeral Joint

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