Using a Split-belt Treadmill to Evaluate Generalization of Human Locomotor Adaptation

Abstract

Understanding the mechanisms underlying locomotor learning helps researchers and clinicians optimize gait retraining as part of motor rehabilitation. However, studying human locomotor learning can be challenging. During infancy and childhood, the neuromuscular system is quite immature, and it is unlikely that locomotor learning during early stages of development is governed by the same mechanisms as in adulthood. By the time humans reach maturity, they are so proficient at walking that it is difficult to come up with a sufficiently novel task to study de novo locomotor learning. The split-belt treadmill, which has two belts that can drive each leg at a different speed, enables the study of both short- (i.e., immediate) and long-term (i.e., over minutes-days; a form of motor learning) gait modifications in response to a novel change in the walking environment. Individuals can easily be screened for previous exposure to the split-belt treadmill, thus ensuring that all experimental participants have no (or equivalent) prior experience. This paper describes a typical split-belt treadmill adaptation protocol that incorporates testing methods to quantify locomotor learning and generalization of this learning to other walking contexts. A discussion of important considerations for designing split-belt treadmill experiments follows, including factors like treadmill belt speeds, rest breaks, and distractors. Additionally, potential but understudied confounding variables (e.g., arm movements, prior experience) are considered in the discussion.

A single exercise bout and locomotor learning after stroke: physiological, behavioural, and computational outcomes

“…In both experimental sessions, subjects walked on a split‐belt treadmill on which belts could move at either the same (tied‐belt mode) or different (split‐belt mode) speed (Vasudevan et al . ). At the beginning of experimental session 1, all subjects walked for 1 min while both belts moved at half the speed of the fast‐comfortable treadmill walking speed (i.e.…”

“…, ; Malone & Bastian, ; Helm & Reisman, ; Vasudevan et al . ). Both neurologically intact and impaired adults are capable of learning this task (Reisman et al .…”

“…Recovery of walking is feasible (Jorgensen et al 1995) and is very important to stroke survivors (Bohannon et al 1988), and therefore considerable effort is spent on relearning to walk during rehabilitation after stroke. Among the various forms of learning , sensorimotor adaptation of walking has been extensively investigated using a novel locomotor task, split-belt treadmill walking (Reisman et al 2005(Reisman et al , 2010aMalone & Bastian, 2010;Vasudevan et al 2017). Both neurologically intact and impaired adults are capable of learning this task (Reisman et al 2005(Reisman et al , 2009(Reisman et al , 2010b(Reisman et al , 2013Vasudevan & Bastian, 2010), yet those with stroke require more time (i.e.…”

The Posterior Parietal Cortex Is Involved in Gait Adaptation: A Bilateral Transcranial Direct Current Stimulation Study

“…Last, subjects underwent a 5-min after-effect period where the belts were re-tied at 0.5 m/s. A 3:1 speed ratio and 15 min period of split-belt walking are commonly utilized in the literature, including a previous study of the effects of tDCS on gait adaptation (Jayaram et al, 2012;Vasudevan et al, 2017;Yokoyama et al, 2018). Data were collected during the baseline, split-belt walking, and after-effect period phases.…”

Effects of sensory manipulations on locomotor adaptation to split-belt treadmill walking in healthy younger and older adults

“…Split-belt treadmill walking protocols are commonly used to assess locomotor adaptation. These protocols involve walking on a treadmill with two parallel, independently controlled belts, with one foot on each belt ( Dietz et al, 1994 , Reisman et al, 2005 , Vasudevan et al, 2017 ). Initially, both belts move at the same speed (“tied-belt”), allowing individuals to rely on a feedforward control model in a predictable and somewhat normal movement environment.…”