Cerebral Contribution to the Execution, But Not Recalibration, of Motor Commands in a Novel Walking Environment

Abstract

Human movements are flexible as they continuously adapt to changes in the environment. The recalibration of corrective responses to sustained perturbations (e.g., constant force) altering one's movement contributes to this flexibility. We asked whether the recalibration of corrective actions involve cerebral structures using stroke as a disease model. We characterized changes in muscle activity in stroke survivors and control subjects before, during, and after walking on a split-belt treadmill moving the legs at different speeds. The recalibration of corrective muscle activity was comparable between stroke survivors and control subjects, which was unexpected given the known deficits in feedback responses poststroke. Also, the intact recalibration in stroke survivors contrasted their limited ability to adjust their muscle activity during steady-state split-belt walking. Our results suggest that the recalibration and execution of motor commands are partially dissociable: cerebral lesions interfere with the execution, but not the recalibration, of motor commands on novel movement demands.

Motorized Shoes Induce Robust Sensorimotor Adaptation in Walking

“…split condition) without showing any significant after-effects (Long et al, 2015;Gonzalez-Rubio et al, 2019). A recent study has also shown that changes in motor patterns during steady state splitbelt walking and post-adaptation are not related and might be mediated by different neural substrates (de Kam et al, 2020). Taken together our findings further support the idea that gait adjustments during and after split-belt walking are governed by different mechanisms.…”

The Effect of Split-Belt Treadmill Interventions on Step Length Asymmetry in Individuals Poststroke: A Systematic Review With Meta-Analysis

“…Four articles presented duplicate datasets to other included articles and, therefore, were excluded from the meta-analysis. [27][28][29][30] Individual and pooled Hedge's g effect sizes were calculated using RStudio (Package: meta, RStudio Inc). A random effects model was chosen due to the distribution of the included studies' methods.…”

“…Out of these 20 studies, 9 calculated the fast belt speed as the fastest comfortable walking speed and the slow belt speed as half of that speed, 7,9,11,13,16,[23][24][25][26] 6 calculated the slow belt speed as the participant's self-selected speed and the fast belt as twice the self-selected speed, 8,10,22,27,28,30 3 studies had the fast belt move at 1.0 m/s and the slow belt move at 0.5 m/s, 12,14,17 and 2 studies calculated each participant's self-selected speed and the fast belt was 133% of that speed and the slow belt was 66% of that speed. 18,29 One study 25 had a group complete the training at 3 different speed ratios, 1.5:1, 2:1, and 2.5:1. Last, one study controlled the ratio of the belt speeds based on the degree of the patient's asymmetry and it changed on a step-by-step basis.…”

“…Seven of these studies had individuals walk only with their nonparetic side on the fast belt and their paretic side on the slow belt. 8,14,17,24,25,29,38 The other 7 studies utilized a repeated measures design where participants walked in 2 conditions, one with their nonparetic side on the fast belt and another with their paretic side on the fast belt. 7,9,10,12,15,28,30 Limb placement strategy can vary depending on the objective of the study.…”

“…Seven of the 21 studies [12][13][14][23][24][25][26] did not include sufficient data for effect size calculations. Four of the 21 studies [27][28][29][30] had duplicate datasets and were excluded from the metaanalysis portion of the study. Individual effect sizes were calculated from 10 of the 21 studies.…”