Differential integration of visual and kinaesthetic signals to upright stance

Abstract

The present experiment was designed to assess the effect of active (deliberate) maintenance of a small forward (FL) or backward body lean (BL) (about 2° ankle flexion) with respect to the spontaneous direction of balance (or neutral posture, N) on postural balance. We questioned whether BL and FL stances, which impose a volitional proprioceptive control of the body-on-support angle, could efficiently reduce mediolateral displacements of the centre of pressure (CoP) induced by the visual motion of a room and darkness. Subjects (n = 15) were asked to stand upright quietly feet together while confronted to a large visual scene rolling to 10° on either side in peripheral vision (and surrounding vertical visual references in central vision) at 0.05 Hz. CoP displacements were recorded using a force platform. Analysis of medio-lateral CoP root-mean square showed that the effect of the moving room depends on the subject's postural stability performance in the eyes open N stance condition. Two significant postural behaviours emerged. (1) The most stable subjects (G1) were not affected by the conditions of altered vision, but swayed more in BL stance than in the N stance. (2) The unstable subjects (G2) exhibited (i) larger CoP displacements in altered visual conditions and a greater coupling of the CoP with the motion of the visual scene, (ii) enhanced visual dependency with postural leaning, and (iii) decreased CoP displacements when leaning forward in the eyes open motionless scene. Interestingly, the visual quotient positively correlated with the proprioceptive quotient, indicating that the more the subjects relied heavily on the visual frame of reference (FOR) the more they were influenced by body leaning. This result suggested hence a lesser ability to use efficiently body-ground proprioceptive cues. On the whole, the present findings indicate that body leaning could provide a useful mean to assess the subject's ability to use body-ground proprioceptive cues not only to improve postural stability during eyes opening (especially during forward leaning), but also as a mean to disclose subjects' visual dependency and their associated difficulties to shift from visual to proprioceptive-based FOR.

Individuals with Autism: Analysis of the First Interaction with Nao Robot Based on Their Proprioceptive and Kinematic Profiles

“…We computed the Root Mean Square (RMS) of the CoP in both mediolateral and anteroposterior directions as an indicator of the individual's stability. Indeed, the RMS provides the information about the variability of the CoP in space [15]. We computed the Fast Fourier Transform (FFT) of the CoP and the correlation with a 0.25Hz sinus so as to evaluate coupling between the postural response and the moving visual stimulus.…”

Proprioceptive and Kinematic Profiles for Customized Human‐ Robot Interaction for People Suffering from Autism

“…We designed a sensorimotor experimental setup to assess the sensory integration of each participant. The setup has been used in several studies [36,37]. It evaluates (1) the effect of a moving virtual visual room on postural control and (2) one's capability to use proprioceptive information to reduce visual dependency [36,37].…”

“…The setup has been used in several studies [36,37]. It evaluates (1) the effect of a moving virtual visual room on postural control and (2) one's capability to use proprioceptive information to reduce visual dependency [36,37]. It has been shown that the integration of proprioceptive cues differs among individuals in unstable posture [38][39][40].…”

Social Personalized Human-Machine Interaction for People with Autism

“…First, we used the Sensory Profile (SP) and the Adolescents/Adults Sensory Profiles (AASP) developed by Dunn [11], [12] to assess Movement, Visual, Touch, and Auditory processing. Second, we designed an experimental setup to assess the effect of a moving virtual visual scene (VVS) on postural control, and the individual's capability to use proprioceptive inputs provided in dynamics of balance to reduce visual dependency [13].…”