Implicit sensorimotor adaptation is preserved in Parkinson's Disease

Abstract

Our ability to enact successful goal-directed actions involves multiple learning processes. Among these processes, implicit motor adaptation ensures that the sensorimotor system remains finely tuned in response to changes in the body and environment. Whether Parkinsons Disease (PD) impacts implicit motor adaptation remains a contentious area of research: whereas multiple reports show impaired performance in this population, many others show intact performance. While there are a range of methodological differences across studies, one critical issue is that performance in many of the studies may reflect a combination of implicit adaptation and strategic re-aiming. Here, we revisited this controversy using a visuomotor task designed to isolate implicit adaptation. In two experiments, we found that adaptation in response to a wide range of visual perturbations (3{degrees} - 45{degrees}) was similar in PD and matched control participants. Moreover, in a meta-analysis of previously published work, we found that the mean effect size contrasting PD and controls across 16 experiments was not significant. Together, these analyses indicate that implicit adaptation is preserved in PD, offering a fresh perspective on the role of the basal ganglia in sensorimotor learning. Significance statementAmong multiple motor learning processes, implicit adaptation ensures that our motor system remains exquisitely calibrated. Whether Parkinsons disease affects implicit motor adaptation has been a point of controversy. We revisited this issue using a visuomotor task designed to isolate implicit adaptation and found that individuals with PD and matched controls showed indistinguishable performance. A meta-analysis based on data from 16 previous experiments yielded a similar null result, strongly supporting the notion that implicit adaptation is preserved in PD.