New visuomotor maps are immediately available to the opposite limb
Journal of Neurophysiology. 2014-06-01; 111(11): 2232-2243
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1. J Neurophysiol. 2014 Jun 1;111(11):2232-43. doi: 10.1152/jn.00042.2014. Epub 2014
New visuomotor maps are immediately available to the opposite limb.
Carroll TJ(1), Poh E(2), de Rugy A(3).
(1)Centre for Sensorimotor Neuroscience, School of Human Movement Studies,
University of Queensland, Brisbane, Queensland, Australia; and
(2)Centre for Sensorimotor Neuroscience, School of Human Movement Studies,
University of Queensland, Brisbane, Queensland, Australia; and.
(3)Centre for Sensorimotor Neuroscience, School of Human Movement Studies,
University of Queensland, Brisbane, Queensland, Australia; and Institut de
Neurosciences Cognitives et Intégratives d’Aquitaine, Centre National de la
Recherche Scientifique Unité Mixte de Recherche 5287, Université Bordeaux
Segalen, Bordeaux, France.
Humans can learn to make accurate movements when the required map between vision
and motor commands changes, but can visuomotor maps obtained through experience
with one limb benefit the other? Complete transfer would require new maps to be
both fully compatible and accessible between limbs. However, when this question
is addressed by providing subjects with rotated visual feedback during reaching,
transfer is rarely apparent in the first few trials with the unpracticed limb and
is sometimes absent altogether. Partial transfer might be explained by limited
accessibility to remapped brain circuits, since critical visuomotor
transformations mediating unilateral movements appear to be lateralized.
Alternatively, if adaptation involves movement representations associated with
both extrinsic (i.e., direction of motion in space) and intrinsic (i.e., joint or
muscle based) frames of reference, new visuomotor maps might be incompatible with
opposite limb use when visual distortions have opposite effects for the two limbs
in intrinsic coordinates. Here we addressed this issue when subjects performed an
isometric aiming task with the index finger. We manipulated the alignment of
visuomotor distortion for the two hands in different reference frames by altering
body posture relative to the orientation of the finger and the visual display.
There was strong, immediate transfer of adaptation between limbs only when
visuomotor distortion had identical effects in eye- and joint-based coordinates
bilaterally. This implies that new visuomotor maps are encoded in neural circuits
associated with both intrinsic and extrinsic movement representations and are
available to both limbs.
Copyright © 2014 the American Physiological Society.
PMID: 24598522 [Indexed for MEDLINE]