Visual control of trunk translation and orientation during locomotion

Abstract

Previous studies have suggested distinct control of gait characteristics in the anterior–posterior (AP) and medial–lateral (ML) directions in response to visual input. Responses were larger to a ML visual stimulus, suggesting that vision plays a larger role in stabilizing gait in the ML direction. Here, we investigated responses of the trunk during locomotion to determine whether a similar direction dependence is observed. We hypothesized that translation of the trunk would show a similar ML dependence on vision, but that angular deviations of the trunk would show equivalent responses in all directions. Subjects stood or walked on a treadmill at 5 km/h while viewing a virtual wall of white triangles that moved in either the AP or ML direction according to a broadband input stimulus. Frequency response functions between the visual scene motion and trunk kinematics revealed that trunk translation gain was larger across all frequencies during walking compared with standing. Trunk orientation responses were not different from standing at very low frequencies; however, at high frequencies, trunk orientation gain was much higher during walking. Larger gains in response to ML visual scene motion were found for all trunk movements. Higher gains in the ML direction while walking suggest that visual feedback may contribute more to the stability of trunk movements in the ML direction. Vision modified trunk movement behavior on both a slow (translation) and fast (orientation) time scale suggesting a priority for minimizing angular deviations of the trunk. Overall, trunk responses to visual input were consistent with the theme that control of locomotion requires higher-level sensory input to maintain stability in the ML direction.

Control of human gait stability through foot placement

“…It might use sensory information from three modalities: the proprioceptive, visual and vestibular systems. Studies using visual perturbations of gait have shown compensatory trunk movements [ 60 ] and changes in foot placement [ 61 ] and, with continuous unpredictable visual perturbations, variability of both trunk movement and foot placement increased [ 62 ]. Vestibular stimulation [ 63 – 67 ] and proprioceptive stimulation through the vibration of trunk or neck muscles [ 68 ] lead to ample deviations of heading.…”

“…Empirical data indeed support that sensory weighting is different in walking than in standing. For example, vibration of the leg muscles had much more pronounced effects in standing than in walking [ 68 ], while effects of visual perturbations were larger in walking than in standing [ 60 ]. Moreover, the importance of visual perturbations in walking appears to be directionally specific with larger effects of ML perturbations than those of AP perturbations [ 60 , 61 ].…”

Vestibular Dysfunction after Subconcussive Head Impact

“…The current system setup has been described in detail in a previous aticle. 22 Trunk orientation was represented to the subject as the position of a moving cursor within a bull's-eye target on a 68.58 cm (27-inch) wide screen TV (ViewSonic VA2703, ViewSonic,Walnut, CA) mounted at standing eye level. Trunk orientation relative to vertical here is defined as AP and medial-lateral (ML) angular displacement of the segment defined by the naval marker to the midpoint of the acromion process markers.…”

“…[13][14][15] We also investigated the control of balance during walking using visual feedback of the trunk while walking on a treadmill. 22 Our hypothesis is that these techniques are more sensitive to the subtle, transient effects of mild head impact with regard to the processing of vestibular information and postural stability under static and dynamic conditions.…”

Neural Control of Balance During Walking

“…More recently, interest in the role of the visual system for balance control is expanding from standing to walking (Logan et al, 2010 ). While responses of the upper body seem to be somewhat similar between standing and walking at low frequencies, gains are higher during walking at high frequencies (Anson et al, 2014 ). This is no doubt due to the nature of the gait cycle, which has a strong modulating effect on balance responses in the lower body (Logan et al, 2014 ; Qiao et al, 2018 ).…”