The challenge of initiating movements to proprioceptive targets in older adults


As people age, distinct changes occur across sensory systems. Specifically, the availability and reliability of sensory inputs decrease with age, prompting older adults to adopt behavior modifications to maintain comparable movement outcomes. Older adults have been observed to exhibit varying motor planning and execution strategies (e.g., Chaput & Proteau , 1996), specifically attributed to their ability to use proprioceptive feedback (e.g., Helsen et al., 2016). However, these studies solely employ visual targets, which may not reflect sensory specific motor processes (Bernier et al., 2007). To better understand the use of vision and proprioception for the preparation and control of aiming movements, the current study employed visual, proprioceptive, and visuo-proprioceptive targets. Younger and older adults were seated in a dark room while aiming with their right hand towards a brief visual and/or proprioceptive target. The proprioceptive target was provided to one of three fingers on the contralateral hand. In terms of endpoint precision, younger adults outperformed the older adults, and the visuo-proprioceptive targets yielded the best performance for both age groups. Additionally, younger adults completed movements faster than older adults. Critically, older adults exhibited longer reaction times compared to younger adults, including an age group by target modality interaction. Further analysis revealed that this outcome was especially the case for the proprioceptive targets. The result that older adults experienced greater temporal costs than younger adults when initiating movements to proprioceptive targets may indicate that, as people age, reliance on proprioceptive feedback is down regulated for the identification of a target location.

Acknowledgments: Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Foundation for Innovation (CFI), University of Toronto (UofT).