Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.04.25.061382v1?rss=1 Authors: Coltman, S. K., Gribble, P. L. Abstract: We investigated whether task specific changes in the feedback stretch response were related to the proposed fast and slow processes of motor adaptation. Participants (n=35) grasped the handle of a robotic manipulandum and performed reaches to a visual target while the hand and arm were occluded. We measured movement kinematics and shoulder and elbow muscle activity with surface EMG electrodes. We tracked the feedback stretch response throughout a force field adaptation task. Using force channel trials we measured overall learning, which was later decomposed into a fast and slow process. We found that the long latency component of the feedback stretch response was upregulated in the early stages of learning, and the time course was correlated with the fast process of motor adaptation. While some propose that the fast process reflects an explicit strategy, we argue instead that it may be a proxy for the feedback controller. Copy rights belong to original authors. Visit the link for more info