The ability to modulate peripersonal and extrapersonal reach space via tool use among the elderly

Functional decrements associated with increasing aging may restrict daily activities and require use of tools (e.g., canes and walkers) for postural control and locomotion. Therefore, we examined older adults' ability to plan reach movements with their arm and tools of 20 and 40 cm in length. Twenty-seven participants between the ages of 55 and 92 years were divided into two groups, <75 and >76 years. The task required participants to estimate reach via use of motor imagery in regard to seven targets randomly presented in peripersonal and extrapersonal space. Each condition consisted of a block of 21 trials for the ARM and TOOL and a "switch-block" of 7 trials with the opposite condition. The procedure was repeated for both tool lengths and presented in counterbalanced order. Analysis of variance (ANOVA) results revealed a significant difference in the switch-blocks, suggesting that participants were more accurate when they switched from ARM to TOOL (extension) in comparison to TOOL to ARM (retraction). In addition, a correlation analysis indicated a negative relationship for accuracy in the 40 cm tool condition and age. In view of the total sample, two findings warrant further consideration. For both tool lengths, retraction from TOOL to ARM was more difficult than extension from ARM to TOOL. And specifically to the 40 cm tool, accuracy decreased as age increased. In addition to gaining information about aging of the neuro-cognitive processes associated with spatial representation, these outcomes may have implications for physical safety and rehabilitation with older persons.