Influence of switching rule on motor learning

Humans and animals can flexibly switch rules to generate appropriate motor commands; for example, actions can be flexibly produced toward a sensory stimulus (e.g., pro-saccade or pro-reaching) or away from a sensory stimulus (e.g., anti-saccade or anti-reaching). Distinct neural activities are related to pro- and anti-movement actions; however, the effects of switching rules on motor learning are unclear. Here, we study the effect of switching rules on motor learning using pro- and anti-arm-reaching movements and a visuomotor rotation task. Although previous results support the perfect availability of learning effects under the same required movements, we show that the learning effects trained in pro-reaching movements are partially rather than perfectly available in anti-reaching movements even under the same required movement direction between those two conditions. The partial transfer is independent of the difference in the visual cue, the cognitive demand, and the actual movement direction between the pro- and anti-reaching movements. We further demonstrate that the availability of learning effects trained with pro-reaching movements is partial not only in anti-reaching movements but in reaching movements with other rules and the availability of learning effects trained with anti-reaching movements is also partial in pro-reaching movements. We thus conclude that the switching rule causes the availability of learning effects to be partial rather than perfect even under same planned movements.\n\nNew & Noteworthy\n\nMost motor learning experiments supported the involvement of planned movement directions in motor learning; the learning effects trained in a movement direction can be available at movement directions close to the trained one. Here, we show that the availability of motor learning effects is partial rather than perfect even under the same planned movements when rule is switched, which indicates that sports training and rehabilitation should include various situations under the same required motions.