Publication Date:
2010-06-25
Description:
Injury to the primary visual cortex (V1) leads to the loss of visual experience. Nonetheless, careful testing shows that certain visually guided behaviours can persist even in the absence of visual awareness. The neural circuits supporting this phenomenon, which is often termed blindsight, remain uncertain. Here we demonstrate that the thalamic lateral geniculate nucleus (LGN) has a causal role in V1-independent processing of visual information. By comparing functional magnetic resonance imaging (fMRI) and behavioural measures with and without temporary LGN inactivation, we assessed the contribution of the LGN to visual functions of macaque monkeys (Macaca mulatta) with chronic V1 lesions. Before LGN inactivation, high-contrast stimuli presented to the lesion-affected visual field (scotoma) produced significant V1-independent fMRI activation in the extrastriate cortical areas V2, V3, V4, V5/middle temporal (MT), fundus of the superior temporal sulcus (FST) and lateral intraparietal area (LIP) and the animals correctly located the stimuli in a detection task. However, following reversible inactivation of the LGN in the V1-lesioned hemisphere, fMRI responses and behavioural detection were abolished. These results demonstrate that direct LGN projections to the extrastriate cortex have a critical functional contribution to blindsight. They suggest a viable pathway to mediate fast detection during normal vision.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904843/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904843/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schmid, Michael C -- Mrowka, Sylwia W -- Turchi, Janita -- Saunders, Richard C -- Wilke, Melanie -- Peters, Andrew J -- Ye, Frank Q -- Leopold, David A -- Z01 MH002838-05/Intramural NIH HHS/ -- England -- Nature. 2010 Jul 15;466(7304):373-7. doi: 10.1038/nature09179. Epub 2010 Jun 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Neuropsychology, National Institute of Mental Health (NIMH), 49 Convent Drive, Bethesda, Maryland 20892, USA. schmidmicha@gmail.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20574422" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Female
;
Geniculate Bodies/*physiology/physiopathology
;
Macaca mulatta/*physiology
;
Male
;
Models, Neurological
;
Photic Stimulation
;
Visual Cortex/physiology/physiopathology
;
Visual Pathways/*physiology/physiopathology
;
Visual Perception/*physiology
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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