Using virtual reality to induce cross-axis adaptation of postural control: Implications for rehabilitation

Abstract

Adaptation of sensorimotor processes has been studied for over a century. However, rigorous experimental approaches require controlling as many variables as possible to study the phenomenon, which limits generalizability. Conversely testing adaptation in an unconstrained ecologically valid situation makes it difficult to identify what parameters affect this process. This study utilizes virtual environments (VE) to create complex, but controlled environments to test visual, vestibular, and sensorimotor adaptation of whole-body posture. Findings show automatic postural processes can be adapted to unusual and discordant sensory environments, suggesting its lability would be advantageous when employing the kind of sensorimotor rehabilitation therapy VE affords.

No Evidence That Frontal Optical Flow Affects Perceived Locomotor Speed and Locomotor Biomechanics When Running on a Treadmill

“…This would also explain the lower impact of visual incongruences on balance and locomotor patterns while treadmill running, as shown in Experiment 2. Our results contradict previous studies on walking, which showed an influence of an artificial optical flow on postural stability [31][32][33][34] and on locomotor patterns. In particular, Pailhous et al [17] found that when walking overground, stride length decreases in presence of an artificial optical flow.…”

“…In this experiment, we tested if treadmill running is influenced by the presence and the manipulation of an optical flow. Studies show that the manipulation of the optical flow has a destabilizing effect on postural stability [31][32][33][34], and a significant influence on locomotor patterns when walking [15,17,21,22]. The results regarding modifications of gait parameters and their variability as an effect of a virtual optical flow are contradicting, suggesting a great influence of the specific setup, the walking mode (i.e., fixed speed vs. self-paced treadmill) and the time to adapt to the new environment.…”

Using virtual reality to augment perception, enhance sensorimotor adaptation, and change our minds

“…We were also interested in determining how VE immersion might affect other motor control processes such as head stabilization (Wright et al, 2013 ) and whole-body postural control (Wright, 2013 ). In one study, subjects were exposed to physical accelerations while viewing a directionally discordant visual scene.…”

“…In another study applying a similar experimental test protocol to investigate posture control, we paired visually-depicted translation in one direction with an orthogonally directed translation of the support surface. This cross-axis stimulation resulted in a postural response in standing humans that showed entrainment with both the visual and the support surface stimuli (Wright, 2013 ). These findings may not be unexpected, since studies pre-dating VR technology have shown that postural control can be entrained to a visual stimulus by simulating movement of the entire room, when the floor is kept stationary (Lishman and Lee, 1973 ).…”

“…To study postural adaptation in VE, we exposed subjects to cross-axis postural stimulation for an extended period of time. By looking for aftereffects, as is often done in prism-adaptation research, we wished to see if the postural response seen during discordant stimulation involved adaption or was simply a transient response that would disappear as soon as one of the stimuli was removed (Wright, 2013 ). The plasticity of the CNS, which allows discordance to be reduced by sensorimotor re-mapping, is present at birth and plays an essential role in shaping motor development through interaction with the environment (Held and Freedman, 1963 ).…”