How providing more or less time to solve a cognitive task interferes with upright stance control; a posturographic analysis on healthy young adults

Abstract

Contrasted postural effects have been reported in dual-task protocols associating balance control and cognitive task that could be explained by the nature and the relative difficulty of the cognitive task and the biomechanical significance of the force platform data. To better assess their respective role, eleven healthy young adults were required to stand upright quietly on a force platform while concomitantly solving mental-calculation or mental-navigation cognitive tasks. Various levels of difficulty were applied by adjusting the velocity rate at which the instructions were provided to the subject according to his/her maximal capacities measured beforehand. A condition without any concomitant cognitive task was added to constitute a baseline behavior. Two basic components, the horizontal center-of-gravity movements and the horizontal difference between center-of-gravity and center-of-pressures were computed from the complex center-of-pressure recorded movements. It was hypothesized that increasing the delay should infer less interaction between postural control and task solution. The results indicate that both mental-calculation and mental-navigation tasks induce reduced amplitudes for the center-of-pressure minus center-of-gravity movements, only along the mediolateral axis, whereas center-of-gravity movements were not affected, suggesting that different circuits are involved in the central nervous system to control these two movements. Moreover, increasing the delays task does not infer any effect for both movements. Since center-of-pressure minus center-of-gravity expresses the horizontal acceleration communicated to the center-of-gravity, one may assume that the control of the latter should be facilitated in dual-tasks conditions, inferring reduced center-of-gravity movements, which is not seen in our results. This lack of effect should be thus interpreted as a modification in the control of these center-of-gravity movements. Taken together, these results emphasized how undisturbed upright stance control can be impacted by mental tasks requiring attention, whatever their nature (calculation or navigation) and their relative difficulty. Depending on the provided instructions, i.e. focusing our attention on body movements or on the opposite diverting this attention toward other objectives, the evaluation of upright stance control capacities might be drastically altered.

Incongruity of Geometric and Spectral Markers in the Assessment of Body Sway

“…On a different vein, it has been suggested that sway may not be a reliable marker of functional balance performance (20), and it seems that traditional measures of postural sway are not always able to differentiate between healthy subjects and patients with movement disorders (21,22). These uncertainties are partly dependent on technical or practical reasons, such as the recording apparatus, the duration of the acquisition period (23,24), the frequency of sampling of the CoP excursions, the filtering procedures, and other confounding subject-related circumstances such as fatigue (25), not to speak of the instruction given to the participants and the ample interindividual variability (17,(26)(27)(28)(29)(30)(31)(32)(33)(34).…”

The Effectiveness of Diverse Designs of Chinese Stem-Deriving Instruction for Chinese Children With Dyslexia

“…According to cognitive load theory, to facilitate learning, instructional methodologies should attempt to eliminate, to the greatest degree possible, working memory demands (e.g., Rougier & Bonnet, 2016). However, when selecting the extending characters for CSDI, the working memory loads of different domains may increase according to their frequency or level of difficulty, which may lead to controversy regarding CSDI’s effectiveness, especially for those with dyslexia who are already experiencing limited working memory.…”