Why is "blindsight" blind? A new perspective on primary visual cortex, recurrent activity and visual awareness

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Silvanto, Juha
dc.date.accessioned 2017-05-11T09:15:00Z
dc.date.available 2017-05-11T09:15:00Z
dc.date.issued 2015
dc.identifier.citation Silvanto , J 2015 , ' Why is "blindsight" blind? A new perspective on primary visual cortex, recurrent activity and visual awareness ' CONSCIOUSNESS AND COGNITION , vol 32 , no. March , pp. 15-32 . DOI: 10.1016/j.concog.2014.08.001 en
dc.identifier.issn 1053-8100
dc.identifier.other PURE UUID: f1b07f5c-8e06-4105-8cf2-5d2a5e913bea
dc.identifier.other PURE ITEMURL: https://research.aalto.fi/en/publications/why-is-blindsight-blind-a-new-perspective-on-primary-visual-cortex-recurrent-activity-and-visual-awareness(f1b07f5c-8e06-4105-8cf2-5d2a5e913bea).html
dc.identifier.other PURE FILEURL: https://research.aalto.fi/files/11717286/1_s2.0_S1053810014001329_main.pdf
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/25961
dc.description.abstract The neuropsychological phenomenon of blindsight has been taken to suggest that the primary visual cortex (V1) plays a unique role in visual awareness, and that extrastriate activation needs to be fed back to V1 in order for the content of that activation to be consciously perceived. The aim of this review is to evaluate this theoretical framework and to revisit its key tenets. Firstly, is blindsight truly a dissociation of awareness and visual detection? Secondly, is there sufficient evidence to rule out the possibility that the loss of awareness resulting from a V1 lesion simply reflects reduced extrastriate responsiveness, rather than a unique role of V1 in conscious experience? Evaluation of these arguments and the empirical evidence leads to the conclusion that the loss of phenomenal awareness in blindsight may not be due to feedback activity in V1 being the hallmark awareness. On the basis of existing literature, an alternative explanation of blindsight is proposed. In this view, visual awareness is a “global” cognitive function as its hallmark is the availability of information to a large number of perceptual and cognitive systems; this requires inter-areal long-range synchronous oscillatory activity. For these oscillations to arise, a specific temporal profile of neuronal activity is required, which is established through recurrent feedback activity involving V1 and the extrastriate cortex. When V1 is lesioned, the loss of recurrent activity prevents inter-areal networks on the basis of oscillatory activity. However, as limited amount of input can reach extrastriate cortex and some extrastriate neuronal selectivity is preserved, computations involving comparison of neural firing rates within a cortical area remain possible. This enables “local” read-out from specific brain regions, allowing for the detection and discrimination of basic visual attributes. Thus blindsight is blind due to lack of “global” long-range synchrony, and it functions via “local” neural readout from extrastriate areas. en
dc.format.extent 15-32
dc.format.mimetype application/pdf
dc.language.iso en en
dc.relation.ispartofseries CONSCIOUSNESS AND COGNITION en
dc.relation.ispartofseries Volume 32, issue March en
dc.rights openAccess en
dc.title Why is "blindsight" blind? A new perspective on primary visual cortex, recurrent activity and visual awareness en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department O.V.Lounasmaa-laboratorio
dc.contributor.department Department of Neuroscience and Biomedical Engineering en
dc.subject.keyword Blindsight
dc.subject.keyword Feedback
dc.subject.keyword Inter-areal synchrony
dc.subject.keyword Oscillatory activity
dc.subject.keyword Primary visual cortex (V1)
dc.subject.keyword Transcranial magnetic stimulation
dc.identifier.urn URN:NBN:fi:aalto-201705114336
dc.identifier.doi 10.1016/j.concog.2014.08.001
dc.type.version publishedVersion


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