AGE-RELATED DIFFERENCES IN MOTOR ADAPTATION: INVESTIGATING HABITUAL MOVEMENT PATTERNS AND PERFORMANCE IN OLDER ADULTS

Abstract

With aging comes physiological changes in the brain, affecting key regions involved in motor adaptation, including the cerebellum, basal ganglia, and hippocampus. These changes diminish the brain's capacity for flexible motor learning, leading to difficulties in adapting motor behavior to changing environments. We hypothesized that older adults rely more on habitual movement patterns, thereby exhibiting slower motor adaptation rates and increased motor errors. To test this hypothesis, we conducted an experiment where both older and younger participants were tasked with lifting a symmetrical object with a hidden asymmetric mass (i.e., one side is heavier than the other), that switches from side to side, aiming to keep it level. To achieve task success requires generating a compensatory torque at lift onset that is equal and opposite to the object’s torque. During the experimental block, the object's mass distribution alternated between sides to assess participants' task performance across successive trials, requiring generalizing and matching the object’s torque in multiple directions. In contrast to our hypotheses, our results indicate suboptimal generalization by both older and younger adults. Neither group adapted optimally to the desired level of task proficiency, failing to generate sufficient compensatory torque by the end of experimental block. Given this mutual inability to reach optimal performance, we cannot definitively assert that older adults exhibit slower motor adaptation compared to their younger counterparts. Nonetheless, we observed habitual tendencies for the older adults in how they controlled and adjusted their movements, which supports the idea of older adults relying on established motor patterns.