Age-related deficits in motor learning are associated with altered motor exploration strategies

How is motor learning affected by aging? Although several experimental paradigms have been used to address this question, there has been limited focus on the early phase of motor learning, which involves motor exploration and the need to coordinate multiple degrees of freedom in the body. Here, we examined motor learning in a body-machine interface where we measured both age-related differences in task performance as well as the coordination strategies underlying this performance. Participants (N = 65; age range 18-72 years) wore wireless inertial measurement units on the upper body, and learned to control a cursor on a screen, which was controlled by motions of the trunk. Results showed that, consistent with prior studies, there was an age-related effect on movement time, with middle-aged and older adults taking longer to perform the task than young adults. However, we also found that these changes were associated with limited exploration in older adults. Moreover, when considering data across a majority of the lifespan (including children), longer movement times were associated with greater inefficiency of the coordination pattern, producing more task-irrelevant motion. These results suggest exploration behaviors during motor learning are affected with aging, and highlight the need for different practice strategies with aging.