Document Detail

Nonvisual learning of intrinsic object properties in a reaching task dissociates grasp from reach.
MedLine Citation:
PMID:  23288327     Owner:  NLM     Status:  MEDLINE    
The Dual Visuomotor Channel theory proposes that skilled reaching is composed of a Reach that directs the hand in relation to the extrinsic properties of an object (e.g., location) and a Grasp that opens and closes the hand in relation to the intrinsic properties of an object (e.g., size). While Reach and Grasp movements are often guided by vision, they can also be performed without vision when reaching for a body part or an object on one's own body. Memory of a recently touched but unseen object can also be used to guide Reach and Grasp movements although the touch-response memory durations described are extremely brief (Karl et al. in Exp Brain Res 219:59-74, 2012a). The purpose of the present study was to determine whether repeated nonvisual reaching for a consistent object could calibrate Reach and Grasp movements in a way similar to those guided by vision. The nonvision group wore vision-occluding goggles and reached for fifty consecutive trials for a round donut ball placed on a pedestal. The control group performed the same task with vision. Frame-by-frame video analysis and linear kinematics revealed that nonvision participants consistently used an elevated Reach trajectory, in which the hand, rather than being directed toward the target in the horizontal plane, was first elevated above the target before being lowered to touch and locate it. First contact was established with the dorsal surface of the target, and thus, adjustments in contact locations were often required for purchase. Although nonvision participants initially used an open and extended hand during transport, with practice they began to scale digit aperture to object size with an accuracy and temporal relation similar to vision participants. The different ways in which the Reach and Grasp movements respond to nonvisual learning are discussed in relation to support for the dual channel theory of reaching and to the idea that the Reach and Grasp channels may be differentially dependent on online visual guidance.
Jenni M Karl; Leandra R Schneider; Ian Q Whishaw
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2013-01-04
Journal Detail:
Title:  Experimental brain research     Volume:  225     ISSN:  1432-1106     ISO Abbreviation:  Exp Brain Res     Publication Date:  2013 Apr 
Date Detail:
Created Date:  2013-03-12     Completed Date:  2013-08-26     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  465-77     Citation Subset:  IM    
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MeSH Terms
Biomechanical Phenomena / physiology
Hand Strength / physiology*
Learning / physiology*
Movement / physiology*
Photic Stimulation
Psychomotor Performance / physiology*
Touch / physiology

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