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Researchers tested how the vestibular system controls balance by applying electrical stimulation at varying intensities and frequencies to 10 healthy adults. They found that the ability to discriminate balance disturbances improved more than expected at higher stimulation levels, deviating from Weber's law, which predicts that sensory discrimination worsens proportionally with stimulus intensity. This deviation occurred because both the balance-correcting response and its variability changed in specific ways: the corrective response decreased more gradually than predicted, while variability increased initially then plateaued at higher stimulation levels.
Why it matters
These findings reveal fundamental properties of how the nervous system controls posture and could lead to improved diagnostic tools for assessing vestibular disorders. Understanding these deviations from Weber's law may help clinicians better identify and characterize balance impairments in patients with vestibular dysfunction.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Standing balance relies on the continuous detection of body motion across a wide range of amplitudes and frequencies. According to Weber’s law, sensory discrimination should degrade in proportion to stimulus amplitude, yet vestibular self-motion perception deviates from this prediction. Whether this deviation extends to the vestibular control of posture remains unknown. To test this hypothesis, we delivered amplitude-increasing electrical vestibular stimulation (EVS, 0-2 mA) at four frequencies (0.1, 0.2, 0.5, and 1 Hz) to 10 healthy young adults, and quantified balance discrimination thresholds (DTs) from the gain and inter-trial variability of the lateral ground reaction force, using signal detection theory. Balance control DTs increased sublinearly with EVS amplitude at all frequencies, deviating from Weber’s law. Both balance-correcting response gain and variability accounted for this deviation: gain decreased more slowly than the strictly inverse relationship that would have alone produced strict adherence to Weber’s law, while variability exhibited an initial increase followed by saturation at higher EVS amplitudes, a signal-dependent structure necessary to reproduce the observed DT pattern. EVS frequency modulated the shape of this deviation but affected neither overall DT nor the signal-to-noise ratio of the balance-correcting response, which instead remained similar across frequencies. This study revealed a particular property of postural control discrimination by extending the psychophysical and neural deviations from Weber’s law previously reported for vestibular perception. Overall, these results provide a better understanding of the balance control discrimination process and provide potential additional assessment criteria for vestibular impairments.