| Reflections on blindsight: neuroimaging and behavioural explorations clarify a case of reversed localisation in the blind field of a patient with hemianopia. | |
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MedLine Citation:
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PMID: 20565174 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Blindsight refers to residual visual abilities of patients with primary visual cortex lesions. Most of this research uses single case studies, most famously patient GY. We examined a patient (DC) after surgical resection of V1 who demonstrated robust but reversed blind field target localisation, mislocalising midline blind field targets to the periphery and vice versa. This pattern was reliable across multiple sessions and was not because of extraocular light scatter. We then used functional magnetic resonance imaging to examine neural responses to blind field motion stimuli with no evidence of motion-selective activation in DC's extrastriate cortex in the damaged hemisphere, in stark contrast to GY who showed robust bilateral activation in response to blind field stimuli. This suggests that DC's blind field performance may not represent true blindsight. Follow-up testing with the target--background contrast reversed (i.e., black targets/white background), eliminated DC's reversed localisation, strongly suggesting that she was employing an unusual decision criterion based on intraocular light scatter. DC's failure to demonstrate true blindsight may be related to the age at which she acquired her lesion--much later in life than GY. |
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Authors:
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James Danckert; Jody C Culham |
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Publication Detail:
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Type: Case Reports; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Canadian journal of experimental psychology = Revue canadienne de psychologie expérimentale Volume: 64 ISSN: 1878-7290 ISO Abbreviation: Can J Exp Psychol Publication Date: 2010 Jun |
Date Detail:
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Created Date: 2010-06-22 Completed Date: 2010-09-22 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9315513 Medline TA: Can J Exp Psychol Country: Canada |
Other Details:
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Languages: eng Pagination: 86-101 Citation Subset: IM |
Copyright Information:
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(PsycINFO Database Record (c) 2010 APA, all rights reserved). |
Affiliation:
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Department of Psychology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada. jdancker@watarts.uwaterloo.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Blindness, Cortical
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complications,
physiopathology* Brain Mapping Female Hemianopsia / complications, physiopathology* Humans Magnetic Resonance Imaging Middle Aged Photic Stimulation Reaction Time Visual Cortex / physiopathology, surgery* Visual Fields / physiology* Visual Perception / physiology |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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