Abstract
Postural control and spatial orientation rely on multisensory integration and reweighting. Aging entails sensorimotor declines, and it is marked by an upweighting of visual cues (visual dependence), leading to alterations in how older adults perceive and interact with their environment, which can increase fall risk.
We investigated how changes in the integration of plantar cutaneous afferents affect spatial orientation in aging. 33 young adults (29.2±4.9) and 42 older adults (75.9±5) were tested on the rod and frame test (RFT) to assess their visual dependence (error with respect with gravity in degrees). Tests were repeated while sitting and standing barefoot. Participants’ plantar quotient, which indicates the contribution of plantar cutaneous afferents to postural control, was determined based on postural stability measures while standing on a firm versus compliant surface.
There was a general trend of decreased visual dependence when standing compared to sitting, with large variability, especially among older adults (young adults: range -1.58° to 2.15°, standard deviation 0.68°; older adults: range -3.86° to 2.84°, standard deviation 1.51°, see Figure 1a). This variability in older adults was associated with their plantar quotient: the more individuals were able to exploit plantar cutaneous cues, the more their visual dependence decreased while standing r= -0.314, p<0.01.
This study suggests that plantar sensitivity modulates sensory reweighting for spatial orientation. Further research on the mechanisms underlying these effects could provide insights that may be used in clinical practice for fall risk prevention to promote sensorimotor adaptation in older adults.
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