No abstract

Our understanding of age-related declines in upper limb proprioceptive abilities is limited. Furthermore, the extent to which physical activity might ameliorate age-related changes in proprioception is not known. Upper limb proprioceptive acuity was examined in young and older (active and sedentary) right-handed adults using a wrist-position-matching task that varied in terms of processing demands. Older individuals were also classified according to their participation in tasks specific to the upper limb. Errors were greater for older than younger individuals. Older sedentary adults showed greater errors and performed movements less smoothly than older active adults. The nonspecific group showed greater errors and longer movement times than the upper-limb-specific group. In older adults, decreased ability to perceive limb position may be related to a sedentary lifestyle and declines associated with memory and transfer of proprioceptive information. Performing tasks specific to the upper limbs may reduce age-related declines in proprioception.

Accurate path integration (PI) requires the integration of visual, proprioceptive, and vestibular self-motion cues and age effects associated with alterations in processing information from these systems may contribute to declines in PI abilities. The present study investigated age-related differences in PI in conditions that varied as a function of available sources of sensory information. Twenty-two healthy, young (23.8 ± 3.0 years) and 16 older (70.1 ± 6.4 years) adults participated in distance reproduction and triangle completion tasks (TCTs) performed in a virtual environment (VE) and two “real world” conditions: guided walking and wheelchair propulsion. For walking and wheelchair propulsion conditions, participants wore a blindfold and wore noise-blocking headphones and were guided through the workspace by the experimenter. For the VE condition, participants viewed self-motion information on a computer monitor and used a joystick to navigate through the environment. For TCTs, older compared to younger individuals showed greater errors in rotation estimations performed in the wheelchair condition, and for rotation and distance estimations in the VE condition. Distance reproduction tasks (DRTs), in contrast, did not show any age effects. These findings demonstrate that age differences in PI vary as a function of the available sources of information and by the complexity of outbound pathway.

Although upper limb movements are known to be slower and more variable in elderly persons, the extent to which these changes are associated with deficits in movement-related sensory feedback is poorly understood, despite the importance of proprioception in the control of skilled movement. Age-related changes were examined with 22 participants (10 of M age 27 years and 12 of M age 75 years) in performance of an elbow position-matching task which varied in terms of interhemispheric transfer and/or the need to retrieve memory-based proprioceptive information. Matching errors were significantly greater, and movements more prolonged, and irregular in their time course in the elderly group than in the young group. Impaired performance in conditions requiring interhemispheric transfer and retrieval of memory-based proprioceptive information reflected the importance of cognitive processing during complex sensorimotor tasks. This novel matching paradigm provided a sensitive means of manipulating the demands of the task and may be an effective method for as sessing both cognitive and sensorimotor declines associated with aging.