Learning the spatial features of a locomotor task is slowed after stroke

Abstract

Tyrell CM, Helm E, Reisman DS. Learning the spatial features of a locomotor task is slowed after stroke. J Neurophysiol 112: 480 -489, 2014. First published April 30, 2014 doi:10.1152/jn.00486.2013The capacity for humans to learn a new walking pattern has been explored with a split-belt treadmill during single sessions of adaptation, but the split-belt treadmill can also be used to study longer-term motor learning. Although the literature provides some information about motor learning after stroke, existing studies have primarily involved the upper extremity and the results are mixed. The purpose of this study was to characterize learning of a novel locomotor task in stroke survivors. We hypothesized that the presence of neurological dysfunction from stroke would result in slower learning of a locomotor task and decreased retention of what was learned and that these deficits would be related to level of sensorimotor impairment. Sixteen participants with stroke and sixteen neurologically intact participants walked on a split-belt treadmill for 15 min on 5 consecutive days and during a retention test.Step length and limb phase were measured to capture learning of the spatial and temporal aspects of walking. Learning the spatial pattern of split-belt treadmill walking was slowed after stroke compared with neurologically intact subjects, whereas there were no differences between these two groups in learning the temporal pattern. During the retention test, poststroke participants demonstrated equal retention of the split-belt treadmill walking pattern compared with those who were neurologically intact. The results suggest that although stroke survivors are slower to learn a new spatial pattern of gait, if given sufficient time they are able to do so to the same extent as those who are neurologically intact. stroke; locomotion; learning; adaptation MOTOR LEARNING is traditionally defined as a persistent change in a movement that occurs over long-term practice and experience and that results in stable performance (Schmidt 1988;Schmidt and Wrisberg 2000). The process of learning begins with exposure to the task, followed by consolidation, which is a set of processes that involve changes in the central nervous system leading to a long-term memory that is resistant to disruption or interference by other motor activity (Krakauer and Shadmehr 2006;Stickgold and Walker 2007). These processes ultimately lead to the ability to recall the newly learned motor skill in the appropriate context or environment.The capacity for humans to learn a new walking pattern has been explored with a split-belt treadmill (Malone et al. 2011) and a rotating treadmill (Earhart et al. 2001). During walking on a rotating treadmill, subjects adapt their walking pattern while walking in place on the perimeter of a rotating disk. After ϳ30 min of exposure, when the subjects are blindfolded and asked to walk under normal conditions they demonstrate an involuntary and significant curvature of their walking trajectory. The split-belt treadmill is a trea...

The influence of high intensity exercise and the Val66Met polymorphism on circulating BDNF and locomotor learning

“…Spatial and temporal parameters of gait have been found to respond differently during split-belt walking (Malone & Bastian, 2010; Malone, Vasudevan, & Bastian, 2011; Tyrell, Helm, & Reisman, 2014). Therefore, both spatial (step length) and temporal (limb phasing) variables were evaluated.…”

“…Step length was labeled as Left or Right based on leading leg. Stride by stride symmetry data for step length was calculated as: $$\frac{false(boldnormal\mathrm{Step}boldnormal\mathrm{Length}boldnormalofboldnormal\mathrm{Leg}boldnormalonboldnormal\mathrm{Slow}boldnormal\mathrm{Belt}-boldnormal\mathrm{Symmetrical}boldnormal\mathrm{Step}boldnormal\mathrm{Length}false)}{boldnormal\mathrm{Symmetrical}boldnormal\mathrm{Step}boldnormal\mathrm{Length}}$$Where symmetrical step length = (Left step length + Right step length)/2 (Tyrell et al, 2014; Tyrell, Helm, & Reisman, 2015). …”

Locomotor adaptation is influenced by the interaction between perturbation and baseline asymmetry after stroke

“…Previous studies have found that spatial and temporal variables respond differently to split-belt walking (Malone and Bastian, 2010; Malone et al, 2011; Malone et al, 2012a; Tyrell et al, 2014). We therefore evaluated a spatial (step length) and temporal (limb phasing) variable in this study.…”

“…Limb phase was a measure of the time lag between contralateral peak flexion and ipsilateral peak extension, and was calculated as described in our previous work (Tyrell et al, 2014). In order to evaluate the specific characteristics of adaptation in our participants, we calculated the following measures for each variable (Malone et al, 2011):…”

Gait asymmetry during early split-belt walking is related to perception of belt speed difference

“…The time course of this adaptation process has been studied in detail in recent years (Bruijn et al 2012;Finley et al 2014;Malone and Bastian 2010;Tyrell et al 2014;Vasudevan et al 2011). Using a split-belt condition, the Bastian group found that intralimb parameters (such as limb excursion; i.e., the distance the foot travels along the belt during the stance phase, previously termed stride length; Hoogkamer et al 2014a) adjust rapidly and thus can be considered as feedback-controlled parameters (rather than feedforward; Morton and Bastian 2006;Reisman et al 2005).…”