Savings in sensorimotor learning during balance-challenged walking but not reaching

Safe and successful motor performance relies on the ability to adapt to physiological and environmental change and retain what is learned. An open question is what factors maximize this retention? One overlooked factor is the degree to which balance is challenged during learning. We propose that the greater need for control and/or perceived threat of falling or injury associated with balance-challenging tasks increases the value assigned to maintaining a learned visuomotor mapping (i.e., the new relationship between visual input and motor output). And we propose that a greater-valued mapping is a more retainable mapping, as it serves to benefit future motor performance. Thus, we tested the hypothesis that challenging balance enhances motor memory, reflected by greater recall and faster relearning (i.e., savings). Four groups of participants adapted to a novel visuomotor mapping induced by prism lenses while performing a reaching or walking task, with and without an additional balance challenge. We found that challenging balance did not disrupt visuomotor adaptation during reaching or walking. We then probed recall and savings by having participants repeat the adaptation protocol 1 wk later. For reaching, we found evidence of initial recall, though neither group demonstrated savings upon reexposure to the prisms. In contrast, both walking groups demonstrated significant initial recall and savings. In addition, we found that challenging balance significantly enhanced savings during walking. Taken together, our results demonstrate the robustness of motor memories formed during walking and highlight the potential influence of balance control on sensorimotor learning.NEW & NOTEWORTHY Most everyday tasks challenge our balance. Yet, this aspect of daily motor behavior is often overlooked in adaptation paradigms. Here, we show that challenging balance does not impair sensorimotor adaptation during precision reaching and walking tasks. Furthermore, we show that challenging balance enhances savings of a learned visuomotor mapping during walking. These results provide evidence for the potential performance benefits associated with learning during unconstrained, naturalistic behaviors.