Variable errors suppress implicit motor adaptation among older adults

Abstract

Age-related changes in motor control networks manifest in a highly task-dependent manner. Although older adults can display enhanced implicit sensorimotor adaptation, this effect is inconsistent across perturbation types (e.g., visuomotor vs. force-field perturbations). Because these perturbations induce different errors to drive learning, their distinct effects on learning suggest that specific properties of the error signal modulate the extent of adaptation among older adults. Here, we investigated whether age-related hyper-adaptation is modulated by error variability. More specifically, we manipulated the consistency of error direction during an error-clamp visuomotor adaptation task in both younger and older adults. While consistent errors elicited enhanced implicit adaptation in older adults relative to younger controls, variable errors did not. These findings reveal that error consistency is a critical prerequisite for age-related enhancements in implicit motor learning. Rather than exhibiting unconstrained hyper-adaptation, older adults maintain an adaptive error-sensitivity mechanism that prevents hyper-recruitment of implicit systems in noisy motor environments.