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The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF
Patient DF, who developed visual form agnosia following carbon monoxide poisoning, is still able to use vision to adjust the configuration of her grasping hand to the geometry of a goal object. This striking dissociation between perception and action in DF provided a key piece of evidence for the fo...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4259122/ https://www.ncbi.nlm.nih.gov/pubmed/25538675 http://dx.doi.org/10.3389/fneur.2014.00255 |
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author | Whitwell, Robert L. Milner, A. David Goodale, Melvyn A. |
author_facet | Whitwell, Robert L. Milner, A. David Goodale, Melvyn A. |
author_sort | Whitwell, Robert L. |
collection | PubMed |
description | Patient DF, who developed visual form agnosia following carbon monoxide poisoning, is still able to use vision to adjust the configuration of her grasping hand to the geometry of a goal object. This striking dissociation between perception and action in DF provided a key piece of evidence for the formulation of Goodale and Milner’s Two Visual Systems Hypothesis (TVSH). According to the TVSH, the ventral stream plays a critical role in constructing our visual percepts, whereas the dorsal stream mediates the visual control of action, such as visually guided grasping. In this review, we discuss recent studies of DF that provide new insights into the functional organization of the dorsal and ventral streams. We confirm recent evidence that DF has dorsal as well as ventral brain damage – and that her dorsal-stream lesions and surrounding atrophy have increased in size since her first published brain scan. We argue that the damage to DF’s dorsal stream explains her deficits in directing actions at targets in the periphery. We then focus on DF’s ability to accurately adjust her in-flight hand aperture to changes in the width of goal objects (grip scaling) whose dimensions she cannot explicitly report. An examination of several studies of DF’s grip scaling under natural conditions reveals a modest though significant deficit. Importantly, however, she continues to show a robust dissociation between form vision for perception and form vision-for-action. We also review recent studies that explore the role of online visual feedback and terminal haptic feedback in the programming and control of her grasping. These studies make it clear that DF is no more reliant on visual or haptic feedback than are neurologically intact individuals. In short, we argue that her ability to grasp objects depends on visual feedforward processing carried out by visuomotor networks in her dorsal stream that function in the much the same way as they do in neurologically intact individuals. |
format | Online Article Text |
id | pubmed-4259122 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-42591222014-12-23 The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF Whitwell, Robert L. Milner, A. David Goodale, Melvyn A. Front Neurol Neuroscience Patient DF, who developed visual form agnosia following carbon monoxide poisoning, is still able to use vision to adjust the configuration of her grasping hand to the geometry of a goal object. This striking dissociation between perception and action in DF provided a key piece of evidence for the formulation of Goodale and Milner’s Two Visual Systems Hypothesis (TVSH). According to the TVSH, the ventral stream plays a critical role in constructing our visual percepts, whereas the dorsal stream mediates the visual control of action, such as visually guided grasping. In this review, we discuss recent studies of DF that provide new insights into the functional organization of the dorsal and ventral streams. We confirm recent evidence that DF has dorsal as well as ventral brain damage – and that her dorsal-stream lesions and surrounding atrophy have increased in size since her first published brain scan. We argue that the damage to DF’s dorsal stream explains her deficits in directing actions at targets in the periphery. We then focus on DF’s ability to accurately adjust her in-flight hand aperture to changes in the width of goal objects (grip scaling) whose dimensions she cannot explicitly report. An examination of several studies of DF’s grip scaling under natural conditions reveals a modest though significant deficit. Importantly, however, she continues to show a robust dissociation between form vision for perception and form vision-for-action. We also review recent studies that explore the role of online visual feedback and terminal haptic feedback in the programming and control of her grasping. These studies make it clear that DF is no more reliant on visual or haptic feedback than are neurologically intact individuals. In short, we argue that her ability to grasp objects depends on visual feedforward processing carried out by visuomotor networks in her dorsal stream that function in the much the same way as they do in neurologically intact individuals. Frontiers Media S.A. 2014-12-08 /pmc/articles/PMC4259122/ /pubmed/25538675 http://dx.doi.org/10.3389/fneur.2014.00255 Text en Copyright © 2014 Whitwell, Milner and Goodale. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Neuroscience Whitwell, Robert L. Milner, A. David Goodale, Melvyn A. The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF |
title | The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF |
title_full | The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF |
title_fullStr | The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF |
title_full_unstemmed | The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF |
title_short | The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF |
title_sort | two visual systems hypothesis: new challenges and insights from visual form agnosic patient df |
topic | Neuroscience |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4259122/ https://www.ncbi.nlm.nih.gov/pubmed/25538675 http://dx.doi.org/10.3389/fneur.2014.00255 |
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