Different evolutionary origins for the reach and the grasp: an explanation for dual visuomotor channels in primate parietofrontal cortex
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Date
2013
Authors
Karl, Jenni M.
Whishaw, Ian Q.
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers Media
Abstract
The Dual Visuomotor Channel Theory proposes that manual prehension consists of two
temporally integrated movements, each subserved by distinct visuomotor pathways in
occipitoparietofrontal cortex. The Reach is mediated by a dorsomedial pathway and transports
the hand in relation to the target’s extrinsic properties (i.e., location and orientation).
The Grasp is mediated by a dorsolateral pathway and opens, preshapes, and closes the
hand in relation to the target’s intrinsic properties (i.e., size and shape). Here, neuropsychological,
developmental, and comparative evidence is reviewed to show that the Reach
and the Grasp have different evolutionary origins. First, the removal or degradation of
vision causes prehension to decompose into its constituent Reach and Grasp components,
which are then executed in sequence or isolation. Similar decomposition occurs
in optic ataxic patients following cortical injury to the Reach and the Grasp pathways and
after corticospinal tract lesions in non-human primates. Second, early non-visual PreReach
and PreGrasp movements develop into mature Reach and Grasp movements but are only
integrated under visual control after a prolonged developmental period. Third, comparative
studies reveal many similarities between stepping movements and the Reach and
between food handling movements and the Grasp, suggesting that the Reach and the
Grasp are derived from different evolutionary antecedents. The evidence is discussed in
relation to the ideas that dual visuomotor channels in primate parietofrontal cortex emerged
as a result of distinct evolutionary origins for the Reach and the Grasp; that foveated vision
in primates serves to integrate the Reach and the Grasp into a single prehensile act; and,
that flexible recombination of discrete Reach and Grasp movements under various forms
of sensory and cognitive control can produce adaptive behavior
Description
Sherpa Romeo green journal; open access
Keywords
Prehension , Reach , Grasp , Jeannerod , Dual visuomotor channels , Parietofrontal cortex , Visually guided grasping , Haptically guided grasping , Evolutionary origins , Visual control , Visual occlusion
Citation
Karl, J. M., & Whishaw, I. Q. (2013). Different evolutionary origins for the reach and the grasp: An explanation for dual visuomotor channels in primate parietofrontal cortex. Frontiers in Neurology, 4:208. doi:10.3389/fneur.2013.00208