1. Neuroscience
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Human blindsight is mediated by an intact geniculo-extrastriate pathway

  1. Sara Ajina
  2. Franco Pestilli
  3. Ariel Rokem
  4. Christopher Kennard
  5. Holly Bridge  Is a corresponding author
  1. University of Oxford, United Kingdom
  2. Indiana University, United States
  3. Stanford University, United States
Research Article
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Cite this article as: eLife 2015;4:e08935 doi: 10.7554/eLife.08935

Abstract

Although damage to the primary visual cortex (V1) causes hemianopia, many patients retain some residual vision; known as blindsight. We show that blindsight may be facilitated by an intact white-matter pathway between the lateral geniculate nucleus and motion area hMT+. Visual psychophysics, diffusion-weighted magnetic resonance imaging and fibre tractography were applied in 17 patients with V1 damage acquired during adulthood and 9 age-matched controls. Individuals with V1 damage were subdivided into blindsight positive (preserved residual vision) and negative (no residual vision) according to psychophysical performance. All blindsight positive individuals showed intact geniculo-hMT+ pathways, while this pathway was significantly impaired or not measurable in blindsight negative individuals. Two white matter pathways previously implicated in blindsight; (i) superior colliculus to hMT+ and (ii) between hMT+ in each hemisphere were not consistently present in blindsight positive cases. Understanding the visual pathways crucial for residual vision may direct future rehabilitation strategies for hemianopia patients.

Article and author information

Author details

  1. Sara Ajina

    Oxford Centre for Functional MRI of the Brain, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  2. Franco Pestilli

    Department of Psychological and Brain Sciences, Programs in Neuroscience and Cognitive Science, Indiana University Network Science Institute, Indiana University, Bloomington, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Ariel Rokem

    Department of Psychology, Stanford University, Stanford, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Christopher Kennard

    Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Holly Bridge

    Oxford Centre for Functional MRI of the Brain, University of Oxford, Oxford, United Kingdom
    For correspondence
    holly.bridge@ndcn.ox.ac.uk
    Competing interests
    The authors declare that no competing interests exist.

Ethics

Human subjects: Ethical approval was provided by the Oxfordshire Research Ethics Committee B (Ref B08/H0605/156). All participants gave informed, written consent.

Reviewing Editor

  1. Emery N Brown, Massachusetts Institute of Technology, United States

Publication history

  1. Received: May 22, 2015
  2. Accepted: October 20, 2015
  3. Accepted Manuscript published: October 20, 2015 (version 1)
  4. Version of Record published: November 11, 2015 (version 2)

Copyright

© 2015, Ajina et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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