The Journal of Neuroscience, August 19, 2009, 29(33):10396-10404; doi:10.1523/JNEUROSCI.1294-09.2009
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Behavioral/Systems/Cognitive
Dual Adaptation Supports a Parallel Architecture of Motor Memory
Jeong-Yoon Lee1 and
Nicolas Schweighofer2
Departments of 1Computer Science and 2Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California 90089
Correspondence should be addressed to Nicolas Schweighofer, Department of Biokinesiology and Physical Therapy, University of Southern California, CHP 155, 1540 Alcazar Street, Los Angeles, CA 90089. Email: schweigh{at}usc.edu
Although our understanding of the mechanisms underlying motor adaptation has greatly benefited from previous computational models, the architecture of motor memory is still uncertain. On one hand, two-state models that contain both a fast-learning–fast-forgetting process and a slow-learning–slow-forgetting process explain a wide range of data on motor adaptation, but cannot differentiate whether the fast and slow processes are arranged serially or in parallel and cannot account for learning multiple tasks simultaneously. On the other hand, multiple parallel-state models learn multiple tasks simultaneously but cannot account for a number of motor adaptation data. Here, we investigated the architecture of human motor memory by systematically testing possible architectures via a combination of simulations and a dual visuomotor adaptation experimental paradigm. We found that only one parsimonious model can account for both previous motor adaptation data and our dual-task adaptation data: a fast process that contains a single state is arranged in parallel with a slow process that contains multiple states switched via contextual cues. Our result suggests that during motor adaptation, fast and slow processes are updated simultaneously from the same motor learning errors.
Received March 11, 2009;
revised June 4, 2009;
accepted July 10, 2009.
Correspondence should be addressed to Nicolas Schweighofer, Department of Biokinesiology and Physical Therapy, University of Southern California, CHP 155, 1540 Alcazar Street, Los Angeles, CA 90089. Email: schweigh{at}usc.edu