Proprioceptively guided reaching movements in 3D space: effects of age, task complexity and handedness.

Aging is associated with impaired upper limb proprioceptive acuity, as reflected by decreased position matching accuracy with increasing task complexity and movement extent. Most studies have primarily used single-joint or planar paradigms to examine age-related changes in proprioception. It is unclear whether these changes can be generalized to more complex multi-joint movements, where additional sensory feedback may affect performance. Since age-related declines in cognitive function may impair the ability to integrate multiple sources of sensory feedback, deficits in position matching ability in older adults may persist when tasks are performed in three-dimensional space. The accuracy with which young and older participants reproduced remembered reference hand positions was assessed under different experimental conditions. Participants matched target locations located directly to the front or 45° to the side relative to the midline using the preferred and non-preferred arms. Either the same (i.e., ipsilateral matching) or the opposite (i.e., contralateral matching) arm was used to reproduce the target location. No differences in matching accuracy were found between young and older participants when matching ipsilaterally. When matching contralaterally, accuracy was worse in older participants for target locations located to the side, which may reflect age-related changes in the perception of peripersonal space. In contrast to previous studies, accuracy did not differ between the preferred and non-preferred arms in either group. These results extend previous findings demonstrating age-related impairments in proprioceptively guided arm movements when interhemispheric transfer is required.