The influence of age and task demands on the ability to utilize proprioceptive feedback in right hand dominant individuals.

Diane Adamo
University of Michigan

*Susan Brown
University of Michigan

     Full text: Not available
     Last modified: February 26, 2007

Abstract
Proprioceptive feedback arising from muscle, joint, and cutaneous receptors is critical for the control of coordinated limb movement, postural stability, and the learning and adaptation of goal-directed functional activity. Previously, we have shown that the ability to utilize somatosensory feedback for upper limb position matching tasks declines with age (Adamo et al., in press). Based on our knowledge of cortical plasticity, it is known that motor training can improve upper limb function in neurological populations but to what extent task-specific activity preserves proprioceptive function in the elderly is not known. The purpose of this study was to examine the influence of age and task demands on the ability to utilize proprioceptive feedback in older adults and determine if performing tasks specific to the upper limbs contributes to these differences.
Twelve young (22-30 yrs) and 30 older (>70yrs) adults participated in the study with the elderly classified into two groups according to the frequency and duration of daily upper limb activities (upper limb specific: n=13, non-specific: n=17). Participants performed proprioceptively-guided, 40 deg wrist extension movements in the absence of vision. The reference position was generated by passive displacement of the wrist and participants then matched the reference position with the same (ipsilateral remembered) or opposite (contralateral concurrent and contralateral remembered) wrist. Matching movements were made by the both the right dominant and left non-dominant limb.
The ability to reproduce limb position using only proprioceptive information was significantly reduced in elderly compared to young individuals (p<.001). Position matching errors were 21% greater in older adults who showed less upper limb usage in everyday tasks compared to individuals who used their upper limbs to a greater extent (p=.02). These differences were most pronounced in matching tasks which required interhemispheric transfer of the reference position. (p=.05). In all groups, matching errors were greater in the right than left hand (p=.01) and when matching was performed by the opposite than with the same hand (p=.01).
This study shows that preferential upper limb use in older adults enhances proprioceptive ability through recurrent activation of sensorimotor pathways. This may also involve a facilitation in activity-dependent,interhemispheric transfer of movement-related somatosensory information, particularly in bilateral tasks.

Supported by University of Michigan Institute of Gerontology National Institute on Aging T32 training grant (AG00114) to DA, and a National Institute on Aging R03 grant (AG 025120-01) to SB.