Editing Blindsight (section)

==== "TN" ====
A potential weak point of case studies like the ones above is that the participants were not completely blind, and therefore it is not out of the question that their existing vision could have assisted them in some way.<ref name=":9">{{Cite book |last1=Milner |first1=David |url=https://academic.oup.com/book/4415 |title=The Visual Brain in Action |last2=Goodale |first2=Mel |date=2006-10-12 |publisher=Oxford University Press |isbn=978-0-19-852472-4 |pages=71 |doi=10.1093/acprof:oso/9780198524724.001.0001}}</ref> So a particularly noteworthy patient is a man known as “TN”, who suffered two [[Stroke|strokes]] at age 52 that resulted in the destruction of the [[Visual cortex#Primary visual cortex (V1)|primary visual cortex]] (V1) in both [[Cerebral hemisphere|hemispheres]] of the brain, and hence complete loss of (conscious) sight.<ref name=":7">{{Cite journal |last1=Pegna |first1=Alan J. |last2=Khateb |first2=Asaid |last3=Lazeyras |first3=Francois |last4=Seghier |first4=Mohamed L. |date=2005 |title=Discriminating emotional faces without primary visual cortices involves the right amygdala |url=https://www.nature.com/articles/nn1364 |journal=Nature Neuroscience |language=en |volume=8 |issue=1 |pages=24–25 |doi=10.1038/nn1364 |pmid=15592466 |issn=1546-1726}}</ref> In one famous case, researchers persuaded TN to walk down an obstacle-filled hallway, without his cane or any prior knowledge of the layout. He was able to navigate the full length of the hallway without hitting a single object, at one point even hugging the wall to get past a trashcan<ref>{{cite journal |display-authors=6 |vauthors=de Gelder B, Tamietto M, van Boxtel G, Goebel R, Sahraie A, van den Stock J, Stienen BM, Weiskrantz L, Pegna A |date=December 2008 |title=Intact navigation skills after bilateral loss of striate cortex |journal=Current Biology |volume=18 |issue=24 |pages=R1128-9 |bibcode=2008CBio...18R1128D |doi=10.1016/j.cub.2008.11.002 |pmid=19108766 |doi-access=free}}</ref><ref>{{Cite journal |last1=Ajina |first1=Sara |last2=Bridge |first2=Holly |date=2017-10-01 |title=Blindsight and Unconscious Vision: What They Teach Us about the Human Visual System |journal=The Neuroscientist |language=EN |volume=23 |issue=5 |pages=529–541 |doi=10.1177/1073858416673817 |issn=1073-8584 |pmc=5493986 |pmid=27777337}}</ref>. 

TN has taken part in a number of other experiments looking at blindsight. In one early study, he was shown images of expressive faces<ref name=":7" />. While he could not guess the gender or shape accurately, he correctly guessed what emotion was shown at an above chance level. [[Neuroimaging|Brain imaging]] showed significant activity in the right [[amygdala]], particularly in response to fearful faces, suggesting that the brain can unconsciously process expressions of emotion<ref name=":7" />.

Similarly, another experiment investigated the brain’s sensitivity to looming stimuli, which often indicate an incoming collision<ref name=":8">{{Cite journal |last1=Hervais-Adelman |first1=Alexis |last2=Legrand |first2=Lore B. |last3=Zhan |first3=Minye |last4=Tamietto |first4=Marco |last5=de Gelder |first5=Beatrice |last6=Pegna |first6=Alan J. |date=2015-10-22 |title=Looming sensitive cortical regions without V1 input: evidence from a patient with bilateral cortical blindness |journal=Frontiers in Integrative Neuroscience |volume=9 |page=51 |doi=10.3389/fnint.2015.00051 |doi-access=free |issn=1662-5145 |pmc=4614319 |pmid=26557059}}</ref>. This sensitivity can involve heightened [[attention]] capture, but is also thought to operate on a [[subconscious]] level, and has been observed in monkeys and infants<ref>{{Cite journal |last1=Ball |first1=William |last2=Tronick |first2=Edward |date=1971-02-26 |title=Infant Responses to Impending Collision: Optical and Real |url=https://www.science.org/doi/10.1126/science.171.3973.818 |journal=Science |volume=171 |issue=3973 |pages=818–820 |doi=10.1126/science.171.3973.818|pmid=5541165 |bibcode=1971Sci...171..818B }}</ref><ref>{{Cite journal |last1=King |first1=Sheila M. |last2=Cowey |first2=Alan |date=1992-11-01 |title=Defensive responses to looming visual stimuli in monkeys with unilateral striate cortex ablation |url=https://linkinghub.elsevier.com/retrieve/pii/002839329290053O |journal=Neuropsychologia |volume=30 |issue=11 |pages=1017–1024 |doi=10.1016/0028-3932(92)90053-O |pmid=1470337 |issn=0028-3932}}</ref>. In the experiment<ref name=":8" />, both TN and a group of [[Control group|control]] participants were shown a series of moving red dots, some of which made looming motions. An [[Functional magnetic resonance imaging|fMRI]] scan of the control group showed that the movement of the dots produced normal activation in the [[Visual cortex#Middle temporal visual area (V5)|middle temporal visual area]] (V5), known for its role in motion processing. In TN, activation was found in response to both general motion and to looming in particular; notably, however, this occurred primarily in areas of the brain not associated with motion processing in healthy individuals. Given that the specific V5 areas activated in the control participants were mostly [[Lesion|lesioned]] in TN, this unusual activation seems to be a result of [[Neuroplasticity|cortical plasticity]]<ref name=":8" />.