Static monocular visual cues can decrease the vestibular-evoked balance response at low frequencies

Publication date: March 2019

Source: Gait & Posture, Volume 69

Author(s): Jacob E. Kysar, Brian H. Dalton

Abstract

Background

The balance system continually integrates and processes diverse sensorimotor cues to maintain upright posture. Yet, little is known about how monocular visual cues may modulate the vestibular control of standing balance.

Research question

To determine how visual cues, specifically monocular vision, modulate the vestibular-evoked myogenic and whole-body balance response.

Methods

Seventeen (12 female) healthy subjects (age: 24.8 ± 5.3years) were exposed to a random, continuous electrical vestibular stimulation (EVS) signal (±3.5 mA, 0–20 Hz). Subjects stood quietly during four experimental (no vision, non-dominant eye, dominant eye, binocular) conditions. The EVS-medial-lateral ground reaction force (ML GRF) acting on the body and EVS-medial gastrocnemius electromyography (EMG, bilateral) responses were evaluated in the frequency (coherence) and time (cumulant density) domains.

Results

Coherence was increased for no vision compared to binocular, dominant eye, and non-dominant eye visual cues, respectively, with the most pronounced increases occurring at lower frequencies. For cumulant density, the EVS-ML GRF medium-latency peak amplitude was increased 45, 26 and 18% with no vision compared to binocular, dominant eye and non-dominant eye visual cues, respectively (p < .05). The EVS-EMG medium-latency peak amplitude during no vision was greater than binocular (p < .05) for both gastrocnemii, but binocular and dominant eye monocular vision was not different (p > .05). The EVS-ML GRF and EVS-EMG (right medial gastrocnemius) medium-latency peak amplitude was greater for non-dominant eye monocular vision compared to binocular vision (p < .05).

Significance

Monocular visual cues, at least for the dominant eye, can depress the vestibular-evoked balance response at low frequencies akin to binocular vision with limited differences exhibited between dominant and non-dominant eye.

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