title: Fast but fleeting: adaptive motor learning processes associated with aging and cognitive decline.
abstract: Motor learning has been shown to depend on multiple interacting learning processes. For example, learning to adapt when moving grasped objects with novel dynamics involves a fast process that adapts and decays quickly-and that has been linked to explicit memory-and a slower process that adapts and decays more gradually. Each process is characterized by a learning rate that controls how strongly motor memory is updated based on experienced errors and a retention factor determining the movement-to-movement decay in motor memory. Here we examined whether fast and slow motor learning processes involved in learning novel dynamics differ between younger and older adults. In addition, we investigated how age-related decline in explicit memory performance influences learning and retention parameters. Although the groups adapted equally well, they did so with markedly different underlying processes. Whereas the groups had similar fast processes, they had different slow processes. Specifically, the older adults exhibited decreased retention in their slow process compared with younger adults. Within the older group, who exhibited considerable variation in explicit memory performance, we found that poor explicit memory was associated with reduced retention in the fast process, as well as the slow process. These findings suggest that explicit memory resources are a determining factor in impairments in the both the fast and slow processes for motor learning but that aging effects on the slow process are independent of explicit memory declines.
authors.affiliation: Centre for Neuroscience Studies and Departments of Psychology and.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Trewartha
authors.affiliation: Centre for Neuroscience Studies and Departments of Psychology and Medicine, Queen's University, Kingston, Ontario, Canada, K7L 3N6, and.
authors.forename: Angeles
authors.identifier: http://orcid.org/0000-0002-5907-8924
authors.initials: A
authors.lastname: Garcia
authors.affiliation: Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, United Kingdom.
authors.forename: Daniel M
authors.identifier: http://orcid.org/0000-0003-2011-2790
authors.initials: DM
authors.lastname: Wolpert
authors.affiliation: Centre for Neuroscience Studies and Departments of Psychology and flanagan@queensu.ca.
authors.forename: J Randall
authors.identifier: http://orcid.org/0000-0003-2760-6005
authors.initials: JR
authors.lastname: Flanagan
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001245:Association Learning / Q000502:physiology*; D001696:Biomechanical Phenomena; D003072:Cognition Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D008960:Models, Psychological; D009043:Motor Activity / Q000502:physiology*; D009483:Neuropsychological Tests; D011930:Reaction Time; D013028:Space Perception / Q000502:physiology*; D055815:Young Adult
keywords: aging; explicit memory; human; motor control; motor learning; state-space model