Effect of visual transition on postural control in young adults within the moving room

Abstract

The relationship between sensory information and motor action can be examined through the moving room paradigm. Monocular vision combined with increased distance from the front wall of the moving room reduces the coupling between visual information and motor response (Moraes et al., 2009, Neuroscience Letters, 460, 209-213), suggesting a diminished contribution of visual information to postural control. It is important to note, however, that in Moraes et al.'s study the monocular or binocular condition was set before each trial. Therefore, participants could adjust the weight of the different sensory systems in an anticipatory manner (i.e., feedforward control). Nevertheless, in daily situations the weight adjustment of sensory information is a dynamical process and occurs during movement execution. Then, the unexpected change in visual condition within the moving room allows the investigation of the dynamical process related to sensory information re-weighting in an on-line manner. The main purpose of the present study will be, therefore, to examine the effect of visual transition in the coupling between perception and action within the moving room. Participants will wear a liquid crystal lenses goggles, which allow the transition of the lenses from opaque to transparent and vice-versa independently while participants stand still within the moving room. Participants will be invited to stand as still as possible within the moving room during five minutes for each trial. The lenses status will be changed every one minute (no vision-binocular vision, no vision-monocular vision, binocular vision-monocular vision, and vice-versa for all three situations) in an unexpected way for the participant. The following selected variables will be used to analyze the relationship between sensory stimulus (i.e., moving room movement) and motor response: gain, relative phase, stimulus frequency sway amplitude, and variability. It will be also calculated the transient gain (i.e., cycle-to-cycle) in order to obtain the necessary time to achieve the stabilization of the visual information contribution to postural control. (AU)