Multisensory control of human upright stance

Area of Science:

• Neuroscience
• Biomechanics
• Systems Biology

Background:

• Posture control integrates multiple sensory inputs, including vestibular, proprioceptive, and somatosensory information.
• The precise mechanisms of sensory interaction and re-weighting in response to altered sensory availability are not fully understood.

Purpose of the Study:

• To investigate how individuals with and without vestibular loss control posture under various sensory conditions.
• To model the sensor fusion and re-weighting strategies employed in postural control.

Main Methods:

• Postural responses to platform tilts and external torques were measured in humans during stance perturbations.
• Experiments included conditions with intact and removed proprioceptive feedback (body-sway referenced).
• An inverted pendulum model incorporating sensor fusion and non-linear thresholds was developed and compared to experimental data.

Main Results:

• Postural responses varied with stimulus frequency, amplitude, and the availability of vestibular and proprioceptive cues.
• A non-linear relationship between stimulus amplitude and response gain was observed.
• Model simulations accurately replicated experimental findings, particularly demonstrating context-specific sensory re-weighting in normal subjects.

Conclusions:

• The human postural control system dynamically re-weights sensory inputs based on availability and task demands.
• Plantar somatosensory feedback plays a crucial role in maintaining stability when vestibular or ankle proprioception is compromised.
• Computational models can effectively capture the complex sensor fusion and adaptation strategies underlying posture control.