Postural Mechanisms to Control Body Displacements in the Performance of Lateral Gaze Shifts

Abstract

Medialateral postural control mechanisms (bodyweight distribution and center of pressure location) have been studied in static conditions. Our objective was to determine how these mechanisms are adjusted to perform voluntary movements, in our case 80° lateral gaze shifts at 0.125 Hz and 0.25 Hz. In healthy, young adults, we expected body marker (neck, lower back) and center of pressure displacements to be significantly greater in gaze shift conditions than in the stationary gaze condition. To explain these changes in center of pressure displacement, the amplitude contribution of both mechanisms was expected to increase significantly. All these results were found accordingly. Unexpectedly, the active contribution of the bodyweight distribution mechanism was negatively related to body marker displacements in the gaze shift conditions (ns in stationary condition). Moreover, changes in the contribution of the mechanisms were statistically weaker in effect size than changes in body displacement. However, the participants were not unstable because they performed the visual tasks as requested. We propose that the strength of medialateral postural control mechanisms may not only be strengthened to control challenging ML stance conditions but also slightly weakened to allow the performance of adequate body motions in ongoing tasks.

Functional Synergy Between Postural and Visual Behaviors When Performing a Difficult Precise Visual Task in Upright Stance

“…This procedure (MLsway = detrend (MLsway); APsway = detrend(APsway)) led the principal component of displacement to be flat in each trial, reducing thereby the influence of change in body orientation on the characteristics of COP and head, neck, and lower-back body displacement. For control purposes, the mean position of the COP and markers (not detrended this time) was analyzed to check any change in body orientation between tasks (cf., Bonnet, Morio, Szaffarczyk, & Rougier, 2014;Tarantola, Nardone, Tacclini, & Schieppati, 1997).…”

Interest of active posturography to detect age-related and early Parkinson's disease-related impairments in mediolateral postural control

“…Bonnet et al 2014c). The confounding influence of body weight and height was then removed by application of the normalization procedure recommended by O'Malley (1996) and briefly explained by Bonnet et al (2014c).…”

“…Additionally, we computed cross-correlations for COP v vs. COP net and COP c vs. COP net as in all previous studies (Bonnet et al 2013;Lafond et al 2004;Rougier 2007Rougier , 2008Termoz et al 2008;Winter et al 1993Winter et al , 1996. In line with the study by Bonnet et al (2013Bonnet et al ( , 2014bBonnet et al ( , 2014c, we assumed that the degree of similarity between COP c (t) and COP v (t) on one hand and COP net (t) on the other hand could show the degree of active contribution of that mechanism to control COP net (t). We assumed that the higher the cross-correlation coefficient, the higher the active contribution of the postural mechanism to control of ML COP displacement.…”

Application of virtual reality head mounted display for investigation of movement: a novel effect of orientation of attention

“…Turning Changes in gaze are generated through a combination of eye, head, trunk and lower limb movements [15,33,34]. Furthermore, it has been observed that onset of saccades precede head movements in a well-characterised fashion [31].…”