Transfer of Motor and Perceptual Learning in Parkinson’s Disease

Introduction: Patients with Parkinson’s disease (PD) show impairments of motor and perceptual learning; however, their abilities to apply and generalize skills learned in one condition to new situations (learning transfer) remain unclear. Herein, we investigated motor and perceptual learning transfer abilities and their underlying neural substrates in patients with PD. Materials and Methods: Forty‐four patients with PD and 42 healthy controls (NCs) were investigated. Motor learning transfer ability (MLTA) and perceptual learning transfer ability (PLTA) were assessed immediately after learning (i.e., in the early phase) and were defined, respectively, as the ability to adapt to angle changes in a reaching task with rotation perturbation and to adapt to domain changes during a categorization task. Additionally, late‐phase retention of motor learning and transfer performance were evaluated the day after the early‐phase assessment. Results: MLTA and PLTA in the early phase, as well as retention and transfer performance of motor learning in the late phase, were more impaired in patients with PD than in NCs. In the early phase, the MLTA score was significantly positively correlated with the PLTA score and the number of categories correctly answered in the Modified Card Sorting Test (MCST categories ) in patients with PD. In the late phase, the transfer performance of motor learning was significantly positively associated with the degree of motor learning retention. The MLTA score, PLTA score, and MCST categories value were all positively correlated with blood flow in the right inferior parietal lobule (IPL). Discussion: Dysfunction of the right IPL region in patients with PD may be associated with impairments in early‐phase motor and perceptual learning transfer, as well as poor MCST performance. Furthermore, late‐phase motor learning transfer performance may depend on long‐term (24 h) motor learning retention.