Dynamic Reweighting of Three Modalities for Sensor Fusion

Sungjae Hwang,John J Jeka,Peter Agada,Tim Kiemel,Maurice J Chacron

doi:10.1371/journal.pone.0088132

Sungjae Hwang, John J Jeka + Show 3 more

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https://doi.org/10.1371/journal.pone.0088132

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Journal: PloS one	Publication Date: Jan 31, 2014
Citations: 120	License type: CC BY 4.0

Affiliation: Temple University, University of Maryland, College Park

Abstract

We simultaneously perturbed visual, vestibular and proprioceptive modalities to understand how sensory feedback is re-weighted so that overall feedback remains suited to stabilizing upright stance. Ten healthy young subjects received an 80 Hz vibratory stimulus to their bilateral Achilles tendons (stimulus turns on-off at 0.28 Hz), a ±1 mA binaural monopolar galvanic vestibular stimulus at 0.36 Hz, and a visual stimulus at 0.2 Hz during standing. The visual stimulus was presented at different amplitudes (0.2, 0.8 deg rotation about ankle axis) to measure: the change in gain (weighting) to vision, an intramodal effect; and a change in gain to vibration and galvanic vestibular stimulation, both intermodal effects. The results showed a clear intramodal visual effect, indicating a de-emphasis on vision when the amplitude of visual stimulus increased. At the same time, an intermodal visual-proprioceptive reweighting effect was observed with the addition of vibration, which is thought to change proprioceptive inputs at the ankles, forcing the nervous system to rely more on vision and vestibular modalities. Similar intermodal effects for visual-vestibular reweighting were observed, suggesting that vestibular information is not a “fixed” reference, but is dynamically adjusted in the sensor fusion process. This is the first time, to our knowledge, that the interplay between the three primary modalities for postural control has been clearly delineated, illustrating a central process that fuses these modalities for accurate estimates of self-motion.

Highlights

Control of human upright stance during standing requires sensory input from multiple sources to detect center of gravity of gravity excursions and to generate appropriate muscle responses for upright stance control
Numerous studies have demonstrated that the integration of sensory information appears to be dynamically regulated to adapt to changing environmental conditions and the available sensory information, a process referred to as ‘‘sensory reweighting’’ [1,16,17,18,19,20,21,22,23]
This is the first time, to our knowledge, that the interplay between the three primary modalities for postural control has been clearly delineated, illustrating a central process that fuses these modalities for accurate estimates of self-motion

Summary

Introduction

Control of human upright stance during standing requires sensory input from multiple sources to detect center of gravity of gravity excursions and to generate appropriate muscle responses for upright stance control. During eyes-closed stance on a fixed, level surface, the primary sensory source for information about body orientation in space is proprioceptive, but under conditions where the platform moves, the primary source of sensory information shifts from proprioceptive to vestibular [16,23]. Most of these previous studies stimulated an individual sensory system or the combined influence of two sensory systems. This is the first time, to our knowledge, that the interplay between the three primary modalities for postural control has been clearly delineated, illustrating a central process that fuses these modalities for accurate estimates of self-motion

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Conclusion