September 2019
Volume 19, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2019
Primary Visual Cortex is Active in Response to Stimulation of Phenomenally Blind Areas of the Visual Field in Patients with Cortical Blindness
Author Affiliations & Notes
  • Colleen L Schneider
    Department of Brain and Cognitive Sciences, University of Rochester
    Medical Scientist Training Program, University of Rochester School of Medicine and Dentistry
    Department of Psychology, Carnegie Mellon University
  • Emily K Prentiss
    Department of Neurology, University of Rochester Medical Center
  • Ania Busza
    Department of Neurology, University of Rochester Medical Center
  • Kelly Matmati
    Department of Neurology, Rochester Regional Health
  • Nabil Matmati
    Department of Neurology, Rochester Regional Health
  • Zoe R Williams
    Department of Neurology, University of Rochester Medical Center
    Department of Ophthalmology, University of Rochester Medical Center
    Department of Neurosurgery, University of Rochester Medical Center
  • Bogachan Sahin
    Department of Neurology, University of Rochester Medical Center
  • Bradford Z Mahon
    Department of Psychology, Carnegie Mellon University
    Department of Neurology, University of Rochester Medical Center
    Department of Neurosurgery, University of Rochester Medical Center
    Center for Visual Science, University of Rochester
Journal of Vision September 2019, Vol.19, 34c. doi:https://doi.org/10.1167/19.10.34c
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      Colleen L Schneider, Emily K Prentiss, Ania Busza, Kelly Matmati, Nabil Matmati, Zoe R Williams, Bogachan Sahin, Bradford Z Mahon; Primary Visual Cortex is Active in Response to Stimulation of Phenomenally Blind Areas of the Visual Field in Patients with Cortical Blindness. Journal of Vision 2019;19(10):34c. doi: https://doi.org/10.1167/19.10.34c.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Geniculostriate pathway lesions disrupt vision in the contralesional visual hemifield. Loss of tissue may not be the only cause of cortical blindness from these lesions. Careful inspection of previous functional MRI (fMRI) studies of patients with visual field defects reveals numerous cases of blind areas of the visual field with a preserved V1 response to visual stimulation (‘blind voxels’). Here we describe the characteristics of blind voxels in stroke patients with homonymous visual field defects. We compared V1 activity (fMRI) with visual sensitivity (Humphrey perimetry) in 13 chronic stroke patients with cortical blindness. During fMRI, we presented 12 non-overlapping flickering wedges to map the retinotopic organization of visual cortex. The average number of blind voxels in V1 was significantly greater than zero (mean = 27.7, 95%, CI = 15.1–40.4 voxels) and was about one third of the average number of voxels activated for wedges presented in sighted areas of the visual field (‘sighted voxels’, mean = 96.7, 95%, CI = 81.3–112.2 voxels). These blind voxels were retinotopically organized. In 6 of the 13 patients we found that the number of blind voxels fell within the range of the number of sighted voxels. For example, in one subject, the number of voxels that responded to stimulation of a wedge presented in a blind area of the visual field ranged from 26–69 voxels, whereas this range was 20–274 voxels for wedges presented in sighted areas of the visual field. This observed dissociation between visual perception and V1 activity may be due to disordered information content in peri-lesional voxels such that the signal can no longer be read out as a visual percept. If the visual signal in blind voxels is merely disordered, it is possible that patients could recover some of their lost vision by learning a new read-out strategy.

Acknowledgement: F30EY027988 (CLS), R21NS076176 and R01NS089609 (BZM), Schmitt Program on Integrative Brain Research (BS and BZM), Research to Prevent Blindness to the Ophthalmology Department at the Flaum Eye Institute (ZRW), and P30EY001319 (BZM). 
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