Blindsight 176997 221969498 2008-06-26T22:36:44Z DOI bot 6652755 Citation maintenance. Formatted: doi, pmid. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{otheruses1|the neurological phenomenon}} '''Blindsight''' is a phenomenon in which people who are perceptually [[blind]] in a certain area of their visual field demonstrate some response to visual stimuli, without any qualitative experience ('[[qualia]]'). In Type 1 blindsight subjects have no awareness whatsoever of any stimuli, but yet are able to predict, at levels significantly above chance, aspects of a visual stimulus, such as location, or type of movement, often in a forced-response or guessing situation. Type 2 blindsight is when subjects have some awareness of, for example, movement within the blind area, but no visual percept, or quale. This may be caused by, for example, the person being aware of their eyes' tracking motion which will function normally. Blindsight is caused by injury to the part of the [[brain]] responsible for vision. == Technical details == Visual processing in the brain goes through a series of stages. Destruction of the first visual cortical area, [[visual cortex|primary visual cortex]] (or V1 or striate cortex) leads to [[blindness]] in the part of the visual field that corresponds to the damaged cortical representation. The area of blindness - known as a [[scotoma]] - is in the visual field opposite the damaged hemisphere and can vary from a small area up to the entire hemifield. Although individuals with damage to V1 are not consciously aware of stimuli presented in their blind field, [[Lawrence Weiskrantz]] and colleagues showed in the early 1970s that if forced to guess about whether a stimulus is present in their blind field, some observers do better than chance. This ability to detect stimuli that the observer is not conscious of can extend to discrimination of the type of stimulus (for example, whether an 'X' or 'O' has been presented in the blind field). This general phenomenon has been dubbed "blindsight". It is unsurprising from a neurological viewpoint that damage to V1 leads to reports of blindness. Visual processing occurs in the brain in a [[hierarchy|hierarchical]] series of stages (with much crosstalk and feedback between areas). As V1 is the first cortical area in this hierarchy, any damage to V1 severely limits visual information passing from the [[retina]], via the [[Lateral geniculate nucleus|LGN]] and then V1, to higher cortical areas. However, the route from the retina through V1 is not the only visual pathway into the cortex, though it is by far the largest; it is commonly thought that the residual performance of people exhibiting blindsight is due to preserved pathways into the [[Visual cortex|extrastriate cortex]] that bypass V1. What is surprising is that activity in these extrastriate areas is apparently insufficient to support visual [[consciousness|awareness]] in the absence of V1. Blindsight may be thought of as a converse of the form of [[anosognosia]] known as ''[[Anton's syndrome]]'', in which there is full [[cortical blindness]] along with the [[confabulation]] of visual experience. Notable medical fiction authors including [[Robin Cook (novelist)|Robin Cook]] write extensively on this condition <cite: Blindsight>. Other medical fiction authors include [[Tess Gerritsen]]; Brett Chatz; [[Patricia Cornwell]] and [[Michael Palmer (novelist)|Michael Palmer]].{{Clarifyme|date=March 2008}}<!--are you just saying that they are medical fiction authors, or are you saying they wrote about blindsight? If it's the latter, that should be stated explicitly.-->{{Specify|date=October 2007}}<!--where, in which books did these people write about blindsight?--> ==References== * {{cite journal | author=Danckert, J. & Rossetti, Y.| title= Blindsight in action: what can the different sub-types of blindsight tell us about the control of visually guided actions? | journal=Neurosci Biobehav Rev | year=2005 | volume=29 | issue=7 | pages=1035&ndash;1046 | url= | doi=10.1016/j.neubiorev.2005.02.001}} * {{cite journal | author=Stoerig, P. & Cowey, A.| title=Blindsight in man and monkey | journal=Brain | year=1997 | volume=120 | issue= | pages=535&ndash;559 | url= | doi=10.1093/brain/120.3.535| pmid=9126063}} * {{cite book | first=L | last=Weiskrantz | year=1986 | title=Blindsight: A case study and its implications | chapter= | editor= | others= | pages= | publisher=Oxford, Oxford University Press | id=ISBN 0-19-852192-8 | url= | authorlink= }} * {{cite journal |author=Leh, S.E., Mullen, K.T., and Ptito, A.| title=Absence of S-cone input in human blindsight. | journal=European Journal of Neuroscience | year=2006 | volume=24| issue=10|pages= 2954–60| url= |doi=10.1111/j.1460-9568.2006.05178.x}} * {{cite journal |author=Leh, S.E., Johansen-Berg, H. and Ptito,A.| title=Unconscious vision: New insights into the neuronal correlate of blindsight using Diffusion Tractography. | journal=Brain | year=2006 | volume=129| issue=Pt7|pages=1822–32| url= |doi=10.1093/brain/awl111| pmid=16714319}} * {{cite journal |author=Ptito, A. and Leh, S.E.| title=Brain Mechanisms of Blindsight. | journal=Article invitée; Neuroscientist | year=2007 | volume=13| issue=5|pages=506–18| url=| doi=10.1177/1073858407300598| pmid=17901259}} ==External links== * [http://www.scholarpedia.org/article/Blindsight Blindsight at Scholarpedia] [[Category:Neurology]] [[Category:Neuroscience]] [[Category:Vision]] [[de:Rindenblindheit]] [[fi:Sokeanäkö]] [[it:Blindsight]] [[nl:Blindzien]] [[pl:Zespół widzenia mimo ślepoty]]