Motor memory is encoded as a gain-field combination of intrinsic and extrinsic action representations
Actions can be planned in either an intrinsic (body-based) reference frame or an extrinsic (world-based) frame, and understanding how the internal representations associated with these frames contribute to the learning of motor actions is a key issue in motor control. We studied the internal represe...
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Published in | The Journal of neuroscience Vol. 32; no. 43; pp. 14951 - 14965 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
Society for Neuroscience
24.10.2012
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Subjects | |
Online Access | Get full text |
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Summary: | Actions can be planned in either an intrinsic (body-based) reference frame or an extrinsic (world-based) frame, and understanding how the internal representations associated with these frames contribute to the learning of motor actions is a key issue in motor control. We studied the internal representation of this learning in human subjects by analyzing generalization patterns across an array of different movement directions and workspaces after training a visuomotor rotation in a single movement direction in one workspace. This provided a dense sampling of the generalization function across intrinsic and extrinsic reference frames, which allowed us to dissociate intrinsic and extrinsic representations and determine the manner in which they contributed to the motor memory for a trained action. A first experiment showed that the generalization pattern reflected a memory that was intermediate between intrinsic and extrinsic representations. A second experiment showed that this intermediate representation could not arise from separate intrinsic and extrinsic learning. Instead, we find that the representation of learning is based on a gain-field combination of local representations in intrinsic and extrinsic coordinates. This gain-field representation generalizes between actions by effectively computing similarity based on the (Mahalanobis) distance across intrinsic and extrinsic coordinates and is in line with neural recordings showing mixed intrinsic-extrinsic representations in motor and parietal cortices. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Author contributions: J.B.B. and M.A.S. designed research; J.B.B. performed research; J.B.B. and M.A.S. contributed unpublished reagents/analytic tools; J.B.B., D.Z.P., and M.A.S. analyzed data; J.B.B., D.Z.P., and M.A.S. wrote the paper. |
ISSN: | 0270-6474 1529-2401 1529-2401 |
DOI: | 10.1523/jneurosci.1928-12.2012 |