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Optic ataxia as a model to investigate the role of the posterior parietal cortex in visually guided action: Evidence from studies of patient M.H

Cavina-Pratesi, C.; Connolly, J.D.; Milner, A.D.

Optic ataxia as a model to investigate the role of the posterior parietal cortex in visually guided action: Evidence from studies of patient M.H Thumbnail


Authors

C. Cavina-Pratesi

J.D. Connolly

A.D. Milner



Abstract

Optic ataxia is a neuropsychological disorder that affects the ability to interact with objects presented in the visual modality following either unilateral or bilateral lesions of the posterior parietal cortex (PPC). Patients with optic ataxia fail to reach accurately for objects, particularly when they are presented in peripheral vision. The present review will focus on a series of experiments performed on patient M.H. Following a lesion restricted largely to the left PPC, he developed mis-reaching behavior when using his contralesional right arm for movements directed toward the contralesional (right) visual half-field. Given the clear-cut specificity of this patient's deficit, whereby reaching actions are essentially spared when executed toward his ipsilateral space or when using his left arm, M.H. provides a valuable “experiment of nature” for investigating the role of the PPC in performing different visually guided actions. In order to address this, we used kinematic measurement techniques to investigate M.H.'s reaching and grasping behavior in various tasks. Our experiments support the idea that optic ataxia is highly function-specific: it affects a specific sub-category of visually guided actions (reaching but not grasping), regardless of their specific end goal (both reaching toward an object and reaching to avoid an obstacle); and finally, is independent of the limb used to perform the action (whether the arm or the leg). Critically, these results are congruent with recent functional MRI experiments in neurologically intact subjects which suggest that the PPC is organized in a function-specific, rather than effector-specific, manner with different sub-portions of its mantle devoted to guiding actions according to their specific end-goal (reaching, grasping, or looking), rather than according to the effector used to perform them (leg, arm, hand, or eyes).

Citation

Cavina-Pratesi, C., Connolly, J., & Milner, A. (2013). Optic ataxia as a model to investigate the role of the posterior parietal cortex in visually guided action: Evidence from studies of patient M.H. Frontiers in Human Neuroscience, 7, Article 336. https://doi.org/10.3389/fnhum.2013.00336

Journal Article Type Article
Acceptance Date Jun 14, 2013
Online Publication Date Jul 16, 2013
Publication Date Jul 16, 2013
Deposit Date Jun 14, 2013
Publicly Available Date Jul 28, 2015
Journal Frontiers in Human Neuroscience
Electronic ISSN 1662-5161
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 7
Article Number 336
DOI https://doi.org/10.3389/fnhum.2013.00336
Keywords Optic ataxia, Posterior parietal cortex, Grasping, reaching, Hand, Arm, Leg.
Public URL https://durham-repository.worktribe.com/output/1454028

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Published Journal Article (2.4 Mb)
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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
© 2013 Cavina-Pratesi, Connolly and Milner. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.






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