Tactile perception in the lower limbs is essential for maintaining balance and co-ordinating movement. Unlike the upper limbs, where movement errors are often tolerable, failures in posture control can result in instability or falls—particularly in older adults. This cumulative dissertation investigates how lower-limb somatosensory perception adapts to postural and sensorimotor demands, guided by models of predictive coding and reliability-based sensory integration.
Three experimental studies examined changes in vibrotactile perception during (1) quiet stance under stable and unstable conditions in young and older adults, (2) temporally predictable and unpredictable visual perturbations, and (3) goal-directed leg movements involving distinct functional roles of each leg. Across all studies, tactile perception dynamically modulated depending on postural state, task phase, and limb function.
Instability and postural load led to reduced perception, while balance-threatening or feedback-critical phases triggered transient enhancement. Older adults showed elevated baseline thresholds at rest but preserved modulation across postural conditions, suggesting intact compensatory reweighting. This indicates that while sensory degradation occurs with age, adaptive mechanisms remain functionally effective.
These findings support a dynamic model of lower-limb tactile perception, shaped by posture, timing, and behavioral relevance. They also emphasize the functional distinctiveness of the lower limbs, where sensorimotor demands are more tightly coupled to stability and whole-body control than in the upper limbs.
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