Visuo-proprioceptive control of the hand in older adults

Abstract

To control hand movement, we have both vision and proprioception, or position sense. The brain is known to integrate these to reduce variance. Here we ask whether older adults integrate vision and proprioception in a way that minimizes variance as young adults do, and whether older subjects compensate for an imposed visuo-proprioceptive mismatch as young adults do. Ten healthy older adults (mean age 69) and 10 healthy younger adults (mean age 19) participated.Subjects were asked to estimate the position of visual, proprioceptive, and combined targets, with no direct vision of either hand. After a veridical baseline block, a spatial visuoproprioceptive misalignment was gradually imposed by shifting the visual component forward from the proprioceptive component without the subject's awareness. Older subjects were more variable than young subjects at estimating both visual and proprioceptive target positions (F 1,18 = 6.14, p = 0.023). Older subjects tended to rely more heavily on vision than proprioception compared to younger subjects. However, the weighting of vision vs. proprioception was correlated with minimum variance predictions for both older (r = 0.71, p = 0.021) and younger (r = 0.81, p = 0.0047) adults, suggesting that variance-minimizing mechanisms are present to some degree in older adults. Visual and proprioceptive realignment were similar for young and older subjects in the misalignment block, suggesting older subjects are able to realign as much as young subjects. These results suggest that intact multisensory processing in older adults should be explored as a potential means of mitigating degradation in individual sensory systems.

Conscious awareness of a visuo-proprioceptive mismatch: Effect on cross-sensory recalibration

“…However, eye movements were not recorded or enforced, and this was not intended to override subjects' instinctive saccades to target position. The red cross was included in this paradigm Bastian, 2011, 2012;Block et al, 2013;Munoz-Rubke et al, 2017;Liu et al, 2018;Block and Sexton, 2020;Mirdamadi et al, 2021) to discourage conscious strategies involving gaze, particularly on P targets. In other words, we wanted to avoid having some subjects fixate where they think the P target is, and others staring off into space on P targets.…”

Visuo-proprioceptive recalibration and the sensorimotor map

“…The RHI is associated with “visual capture”, where the visual signal is so much stronger than the proprioceptive signal that most recalibration is likely proprioceptive rather than visual. In contrast, our paradigm is associated with a slightly stronger weight of proprioception compared to vision, and greater visual recalibration than proprioceptive (Block and Sexton 2020; Liu et al 2018). Indeed, Kammers et al (2009) suggested that weighting of vision vs. proprioception in multisensory integration could explain their results, with perceptual judgments relying heavily on vision and ballistic movements relying on proprioception.…”

A Trajectory Model for Desktop-Scale Hand Redirection in Virtual Reality

“…The sense with the best reliability will be favored in this integration. This model of integration has been verified for the combination of vision and vestibular cues for the perception of displacement [28] and for the localization of body parts with vision and proprioception [4,10,5]. Vision is often more reliable than other senses and thus generally favored by the brain.…”