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Interactions between vestibular and proprioceptive inputs triggering and modulating human balance-correcting
1Department of ORL, University HNO-Klinik, Basel, Switzerland. allum@ubaclu.unibas.ch
Experimental Brain Research
|September 24, 1998
Summary
Balance corrections rely on proprioceptive and vestibular inputs, with trunk and leg proprioception crucial for timing. Vestibular loss alters muscle responses, but sensory switching is not a compensatory mechanism.
Area of Science:
- Neuroscience
- Biomechanics
- Human Physiology
Background:
- Balance control involves complex interactions between proprioceptive and vestibular sensory systems.
- The adaptability of these sensory systems in modulating muscle synergies for balance corrections is not fully understood.
- Potential mechanisms include sensory information switching or fixed sensory-muscle interactions.
Purpose of the Study:
- To investigate how proprioceptive and vestibular inputs interact to generate balance corrections.
- To determine if sensory systems can switch inputs based on availability or if interactions are fixed.
- To compare balance responses in healthy individuals and those with vestibular loss.
Main Methods:
- Examined balance corrections using controlled proprioceptive stimuli (surface rotation/translation) under eyes-open/closed conditions.
- Manipulated ankle, knee, and trunk proprioceptive inputs (nulled, normal, enhanced; locked/flexed knee; flexed/extended trunk).
- Compared responses in normal subjects and subjects with bilateral peripheral vestibular loss, analyzing muscle activation timing and amplitude.
Main Results:
- Identified three types of proprioceptive and vestibulospinal interactions in triceps surae, quadriceps, and paraspinal muscles.
- Ankle proprioception did not trigger balance corrections; trunk inputs appear critical for initiating responses.
- Vestibular loss altered muscle response amplitudes and timing, particularly in paraspinals, but did not lead to sensory switching for compensation.
Conclusions:
- Trunk and upper-leg proprioception are key for the timing of automatic balance corrections.
- Vestibular input preferentially modulates these corrections, but this modulation is not replaced by other sensory systems upon vestibular loss.
- The findings challenge the concept of flexible sensory switching for balance control, suggesting more fixed interactions.