Berniker, M and Franklin, DW and Flanagan, JR and Wolpert, DM and Kording, K (2013) Motor learning of novel dynamics is not represented in a single global coordinate system: evaluation of mixed coordinate representations and local learning. J Neurophysiol.Full text not available from this repository.
Successful motor performance requires the ability to adapt motor commands to task dynamics. A central question in movement neuroscience is how these dynamics are represented. Although it is widely assumed that dynamics (e.g. force-fields) are represented in intrinsic, joint-based coordinates (Shadmehr and Mussa-Ivaldi 1994), recent evidence has questioned this proposal. Here we re-examine the representation of dynamics in two experiments. By testing generalization following changes in shoulder, elbow, or wrist configurations, the first experiment tested for extrinsic, intrinsic or object-centered representations. No single coordinate frame accounted for the pattern of generalization. Rather, generalization patterns were better accounted for both by a mixture of representations or by models that assumed local learning and graded, decaying generalization. A second experiment, in which we replicated the design of an influential study that had suggested encoding in intrinsic coordinates (Shadmehr & Mussa-Ivaldi, 1994), yielded similar results. That is, we could not find evidence that dynamics are represented in a single coordinate system. Taken together, our experiments suggest that internal models do not employ a single coordinate system when generalizing and may well be represented as a mixture of coordinate systems, as a single system with local learning, or both.
|Uncontrolled Keywords:||coordinate frames internal models intra-limb generalization motor adaptation motor control|
|Divisions:||Div F > Computational and Biological Learning|
|Depositing User:||Cron Job|
|Date Deposited:||30 Dec 2013 17:10|
|Last Modified:||06 Jan 2014 01:01|
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