Motion state-dependent motor learning based on explicit visual feedback has limited spatiotemporal properties compared to adaptation to physical perturbation.

We recently showed that subjects can learn motion state-dependent changes to motor output (temporal force patterns) based on explicit visual feedback of the equivalent force-field (i.e., without the physical perturbation). Here, we examined the spatiotemporal properties of this learning compared to learning based on physical perturbations. There were two human subject groups and two experimental paradigms. One group (n=40) experienced physical perturbations (i.e., a velocity-dependent force-field, vFF) while the second (n=40) was given explicit visual feedback (EVF) of the force-velocity relationship. In the latter, subjects moved in force channels and we provided visual feedback of the lateral force exerted during the movement, as well as the required force pattern based on movement velocity. In the first paradigm (spatial generalization), following vFF or EVF training, generalization of learning was tested by requiring subjects to move to 14 untrained target locations (0o to ±135o around the trained location). In the second paradigm (temporal stability), following training we examined the decay of learning over 8 delay periods (0 to 90 seconds). Results showed that learning based on EVF did not generalize to untrained directions while the generalization for the vFF was significant for targets £ 45o away. In addition, the decay of learning for the EVF group was significantly faster than the FF group (a time constant of 2.72 + 1.74 seconds vs 12.53 + 11.83 seconds). Collectively, our results suggest that recalibrating motor output based on explicit motion state information, in contrast to physical disturbances, utilizes learning mechanisms with limited spatiotemporal properties.