The authors investigated adaptation of goal-directed forearm movements to an unknown external viscous force assisting forearm flexion in 6 patients with cerebellar dysfunction and in 6 control participants. Motor performance was generally degraded in cerebellar patients and was markedly reduced under the force condition in both groups. However, patients and controls were able to adapt to the novel force within 8 trials. Only the healthy controls were able to improve motor performance when readapting to a null-force condition. The results indicate that cerebellar patients' motor control system has imprecise estimations of actual limb dynamics at its disposal. Force adaptation may have been preserved because single-joint movements were performed, whereas the negative viscous force alone and no interaction forces had to be compensated.
Bibliographical noteFunding Information:
This work was supported by Grants Ka 417/18-2 of the Deutsche Forschungsgemeinschaft (German Science Foundation) to K.-T. Kalveram and J. Konczak. We thank Charlotte Hanisch and Sven Bestmann for invaluable help with the data acquisition and analysis. We are indebted to each participating patient and control participant who invested considerable time and effort into this experiment.
- Inverse dynamic models
- Motor control
- Motor learning