Augmenting cognitive load during split-belt walking increases the generalization of motor memories across walking contexts

Cognitive load plays a role on the movement recalibration induced by sensorimotor adaptation, but little is known about its impact on the generalization of movements from trained to untrained situations. We hypothesized that altering cognitive load by distracting subjects during sensorimotor adaptation would facilitate the generalization of recalibrated movements beyond the training condition. We reasoned that awareness of the novel condition inducing adaptation could be used to consciously contextualize movements to that particular situation. To test this hypothesis, young adults adapted their gait on a split-belt treadmill (moving their legs at different speeds) while they observed visual information that either distracted them or made them aware of the speed difference between their feet. We assessed the adaptation and aftereffects of spatial and temporal gait features known to adapt and generalize differently when walking on the treadmill or overground. We found similar adaptation and aftereffects on the treadmill across all groups. In contrast, both groups with altered cognitive load (i.e., distraction and awareness groups) generalized their movements from the treadmill to overground more than controls, who walked without altered cognitive load. Of note, this effect was only observed in temporal gait features, which are less susceptible to online motor adjustments, and were eliminated upon experiencing large errors by briefly removing the split perturbation during adaptation (i.e., catch trial). Taken together, increasing cognitive demands during sensorimotor adaptation facilitates the generalization of movement recalibration, but this cognitive-mediated effect cannot eliminate the specificity of actions due to context-specific errors.