TY - JOUR
T1 - Limited control strategies with the loss of vestibular function
AU - Creath, Rob
AU - Kiemel, Tim
AU - Horak, Fay
AU - Jeka, John J.
N1 - Funding Information:
Acknowledgements We are deeply indebted to Bob Peterka for providing assessment of bilateral vestibular loss individuals. Support for this research was provided by NIH grant RO1AG06457 and NIDCD grant DC-01849 (Fay Horak, PI).
PY - 2002
Y1 - 2002
N2 - When subjects stand on an unstable or compliant support surface, rather than a stable one, vestibular information becomes more important for the control of posture. We investigated how subjects with bilateral vestibular loss (BVL) controlled their upright posture, with and without light-touch contact at the fingertip, while standing on a support surface, sinusoidally rotating at different frequencies. Subjects stood with eyes closed on a platform that rotated ±1.2° around an axis directly beneath the midline of the ankle for frequencies ranging from 0.01 to 0.4 Hz for two sensory conditions: (1) with light, nonsupportive touch (less than 1 N vertical force) on a stationary surface; or (2) with the fingertip held in a position directly above the contact surface (no contact). Gain, phase, and variability of the center of mass (CoM) and the finger were analyzed to compare BVL subjects with healthy controls in the no-touch and light-touch conditions. Three important results were observed: First, CoM gain and variability of BVL subjects was distinctly higher than control subjects with no-touch contact, particularly at the higher platform frequencies. Second, with light-touch contact, BVL and control subjects showed equivalent gain, variability, and phase. Third, multiple relationships between the finger and the CoM were observed in control subjects, whereas BVL subjects implemented a single finger/CoM control scheme. The results are explained in terms of three interacting factors: the transfer function of the vestibular system, a sensory reweighting mechanism, and the inertial properties of the body. Moreover, multiple control strategies observed in control subjects suggest a more flexible control system than that of individuals with severely diminished vestibular function.
AB - When subjects stand on an unstable or compliant support surface, rather than a stable one, vestibular information becomes more important for the control of posture. We investigated how subjects with bilateral vestibular loss (BVL) controlled their upright posture, with and without light-touch contact at the fingertip, while standing on a support surface, sinusoidally rotating at different frequencies. Subjects stood with eyes closed on a platform that rotated ±1.2° around an axis directly beneath the midline of the ankle for frequencies ranging from 0.01 to 0.4 Hz for two sensory conditions: (1) with light, nonsupportive touch (less than 1 N vertical force) on a stationary surface; or (2) with the fingertip held in a position directly above the contact surface (no contact). Gain, phase, and variability of the center of mass (CoM) and the finger were analyzed to compare BVL subjects with healthy controls in the no-touch and light-touch conditions. Three important results were observed: First, CoM gain and variability of BVL subjects was distinctly higher than control subjects with no-touch contact, particularly at the higher platform frequencies. Second, with light-touch contact, BVL and control subjects showed equivalent gain, variability, and phase. Third, multiple relationships between the finger and the CoM were observed in control subjects, whereas BVL subjects implemented a single finger/CoM control scheme. The results are explained in terms of three interacting factors: the transfer function of the vestibular system, a sensory reweighting mechanism, and the inertial properties of the body. Moreover, multiple control strategies observed in control subjects suggest a more flexible control system than that of individuals with severely diminished vestibular function.
KW - Human
KW - Light touch
KW - Multisensory
KW - Posture
KW - Vestibular
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U2 - 10.1007/s00221-002-1110-0
DO - 10.1007/s00221-002-1110-0
M3 - Article
C2 - 12136382
AN - SCOPUS:0036326791
SN - 0014-4819
VL - 145
SP - 323
EP - 333
JO - Experimental Brain Research
JF - Experimental Brain Research
IS - 3
ER -