Age-related differences in proprioceptive asymmetries.

Age-related differences in proprioceptive asymmetries have received little attention. This study aimed to determine differences in asymmetry of the right/left upper limb proprioceptive systems between younger and older adults. Asymmetries were compared in two "eyes closed" experiments involving the same elbow joints. Position sense was tested in two matching conditions: ipsilateral remembered and contralateral concurrent. Movement sense was tested while reproducing with the opposite forearm the illusory movement elicited by distal tendon vibration applied to the reference forearm. Older adults exhibited a larger error when matching with the non-dominant than dominant forearm in the ipsilateral remembered condition and a disparate asymmetry in the contralateral condition when compared to younger adults. In addition, in older adults, the velocity of reproduced illusory movements was slower, and asymmetry in movement perception was not significant. The difference in proprioceptive asymmetry between younger and older adults might be attributed to a significant reduction of the sensory system gain affecting, more particularly, the left non-dominant arm sensory system via several physiological and neurophysiological mechanisms.