Reflections on blindsight: neuroimaging and behavioural explorations clarify a case of reversed localisation in the blind field of a patient with hemianopia
- PMID: 20565174
- DOI: 10.1037/a0017426
Reflections on blindsight: neuroimaging and behavioural explorations clarify a case of reversed localisation in the blind field of a patient with hemianopia
Abstract
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.
(PsycINFO Database Record (c) 2010 APA, all rights reserved).
Similar articles
-
Cortical activation in hemianopia after stroke.Neurosci Lett. 2007 Oct 9;426(1):34-8. doi: 10.1016/j.neulet.2007.08.028. Epub 2007 Aug 19. Neurosci Lett. 2007. PMID: 17881128
-
Is V1 necessary for conscious vision in areas of relative cortical blindness?Neuroimage. 2001 Apr;13(4):654-61. doi: 10.1006/nimg.2000.0720. Neuroimage. 2001. PMID: 11305894
-
Bandpass characteristics of high-frequency sensitivity and visual experience in blindsight.Conscious Cogn. 2010 Mar;19(1):144-51. doi: 10.1016/j.concog.2010.01.005. Epub 2010 Feb 2. Conscious Cogn. 2010. PMID: 20129798
-
Neural substrates of blindsight after hemispherectomy.Neuroscientist. 2007 Oct;13(5):506-18. doi: 10.1177/1073858407300598. Neuroscientist. 2007. PMID: 17901259 Review.
-
Blindsight, conscious vision, and the role of primary visual cortex.Prog Brain Res. 2006;155:217-34. doi: 10.1016/S0079-6123(06)55012-5. Prog Brain Res. 2006. PMID: 17027389 Review.
Cited by
-
Functional outcomes following lesions in visual cortex: Implications for plasticity of high-level vision.Neuropsychologia. 2017 Oct;105:197-214. doi: 10.1016/j.neuropsychologia.2017.06.030. Epub 2017 Jun 29. Neuropsychologia. 2017. PMID: 28668576 Free PMC article. Review.
-
Psychophysical and neuroimaging responses to moving stimuli in a patient with the Riddoch phenomenon due to bilateral visual cortex lesions.Neuropsychologia. 2019 May;128:150-165. doi: 10.1016/j.neuropsychologia.2018.05.008. Epub 2018 May 9. Neuropsychologia. 2019. PMID: 29753019 Free PMC article.
Publication types
MeSH terms
LinkOut - more resources
Full Text Sources