Accelerating locomotor savings in learning: compressing four training days to one

Abstract

Acquiring new movements requires the capacity of the nervous system to remember previously experienced motor patterns. The phenomenon of faster relearning after initial learning is termed "savings." Here we studied how savings of a novel walking pattern develops over several days of practice and how this process can be accelerated. We introduced participants to a split-belt treadmill adaptation paradigm for 30 min for 5 consecutive days. By training day 5, participants were able to produce near-perfect performance when switching between split and tied-belt environments. We found that this was due to their ability to shift specific elements of their stepping pattern to account for the split treadmill speeds from day to day. We also applied a state-space model to further characterize multiday locomotor savings. We then explored methods of achieving comparable savings with less total training time. We studied people training only on day 1, with either one extended split-belt exposure or alternating four times between split-belt and tied-belt conditions rapidly in succession. Both of these single-day training groups were tested again on day 5. Experiencing four abbreviated exposures on day 1 improved the performance on day 5 compared with one extended exposure on day 1. Moreover, this abbreviated group performed similarly to the group that trained for 4 consecutive days before testing on day 5, despite only having one-quarter of the total training time. These results demonstrate that we can leverage training structure to achieve a high degree of performance while minimizing training sessions. NEW & NOTEWORTHY Learning a new movement requires repetition. Here, we demonstrate how to more efficiently train an adapted walking pattern. By compressing split-belt treadmill training delivered over 4 days to four abbreviated bouts of training delivered on the first day of training, we were able to induce equivalent savings over a 5-day span. These results suggest that we can manipulate the delivery of training to most efficiently drive multiday learning of a novel walking pattern.

Motorized Shoes Induce Robust Sensorimotor Adaptation in Walking

“…Thus, perturbation size regulated the extent to which participants adapted in our temporal measure, as observed in other sensorimotor adaptation protocols of reaching (Morehead et al, 2015;Marinovic et al, 2017) or walking (Finley et al, 2015;Yokoyama et al, 2018). We did not find a direct relation between perturbation size and the reached steady state of StepPosition at an individual level, indicating that there are other factors, such as navigation strategies (Matthis et al, 2017) or practice (Day et al, 2018), influencing "where" people place their feet. Despite the subtle differences during adaptation, we saw similar after-effects between groups during early post-adaptation in all gait parameters.…”

“…For example, laboratory-based protocols challenge the study of extended practice, which is a critical aspect of motor learning (Ericsson and Pool, 2016;Haith and Krakauer, 2018). There are several efforts to investigate the effect of extended practice on motor behavior by bringing participants to the laboratory multiple times (Day et al, 2018;Leech et al, 2018;Hardwick et al, 2019). This research effort would be facilitated if individuals could practice outside the laboratory setting.…”

On Nonlinear Regression for Trends in Split-Belt Treadmill Training

“…In this study, the inferences are drawn on the common language parameters that were obtained from the estimated parameters of the exponential models fitted to the data. The finding that the participants took a smaller number of strides to complete 50% of the adaptation in session II compared to session I is inline with the past research [ 80 ]. However, the finding that the participants at the end of the adaptation phase in session II had higher asymmetry when compared to session I is in contrast with the previous research in which a similar trend was seen but the difference was not statistically significant [ 80 ].…”

Application of a novel force-field to manipulate the relationship between pelvis motion and step width in human walking

“…While intriguing, these potential indicators of adaptation should be interpreted cautiously due to limitations of our experimental and analytical design. For example, repeated exposure to a novel mechanical environment can influence the presence and magnitude of aftereffects in later bouts [26]. The present study involved multiple bouts of force-field Assistance or Perturbations, but with the underlying control equation presented in randomized order to reduce potential ordering effects.…”