Presentation Title

The Temporal Structure of Postural Control Variability During Standing is Affected by Suprathreshold Mechanical Stimulation

Advisor Information

Nicholas Stergiou

Location

Dr. C.C. and Mabel L. Criss Library

Presentation Type

Poster

Start Date

7-3-2014 1:00 PM

End Date

7-3-2014 4:00 PM

Abstract

Variability is inherent in the maintenance of human posture and is reflective of the contribution of different sensory systems as postural sway. Changes in the structure of postural sway variability under different task and sensory conditions are essential in understanding their role in the organization of human motor output. To address this issue, we used suprathreshold mechanical stimulation (sMVS) to perturb the vestibular system. We hypothesized that the structure of postural sway variability would become predictable when sensory information from other sources became less reliable. Eight healthy young adults (24.7±5 years) were instructed to maintain their balance while standing on the Smart Balance Master (NeuroCom, Clackamas, OR, USA). There were total six sensory challenging conditions: 1) normal, 2) vision-blocked, 3) visual sway-reference, 4) surface sway-reference, 5) visionblocked, surface sway-reference, and 6) visual and surface sway reference condition. In general, conditions 5 and 6 were used to indirectly detect the participant’s ability to use inputs from the vestibular system to maintain balance. The suprathreshold mechanical vestibular stimulation (sMVS) contained two vibrating elements, called tactors (Engineering Acoustics, FL, USA.), were placed on the mastoid process on each side to perturb the vestibular feedback signals. Our results supported the hypothesis that structure of postural sway variability became predictable if sensory information became less reliable. Our study also found that unilateral vestibular stimulation made postural sway to become more rigid than bilateral stimulation. This is probably because postural control is a bilateral coordination task requiring dynamic input from bilateral sources.

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Mar 7th, 1:00 PM Mar 7th, 4:00 PM

The Temporal Structure of Postural Control Variability During Standing is Affected by Suprathreshold Mechanical Stimulation

Dr. C.C. and Mabel L. Criss Library

Variability is inherent in the maintenance of human posture and is reflective of the contribution of different sensory systems as postural sway. Changes in the structure of postural sway variability under different task and sensory conditions are essential in understanding their role in the organization of human motor output. To address this issue, we used suprathreshold mechanical stimulation (sMVS) to perturb the vestibular system. We hypothesized that the structure of postural sway variability would become predictable when sensory information from other sources became less reliable. Eight healthy young adults (24.7±5 years) were instructed to maintain their balance while standing on the Smart Balance Master (NeuroCom, Clackamas, OR, USA). There were total six sensory challenging conditions: 1) normal, 2) vision-blocked, 3) visual sway-reference, 4) surface sway-reference, 5) visionblocked, surface sway-reference, and 6) visual and surface sway reference condition. In general, conditions 5 and 6 were used to indirectly detect the participant’s ability to use inputs from the vestibular system to maintain balance. The suprathreshold mechanical vestibular stimulation (sMVS) contained two vibrating elements, called tactors (Engineering Acoustics, FL, USA.), were placed on the mastoid process on each side to perturb the vestibular feedback signals. Our results supported the hypothesis that structure of postural sway variability became predictable if sensory information became less reliable. Our study also found that unilateral vestibular stimulation made postural sway to become more rigid than bilateral stimulation. This is probably because postural control is a bilateral coordination task requiring dynamic input from bilateral sources.