Blind vision
| Classification according to ICD-10 | |
|---|---|
| H47.6 | Affections of the visual cortex |
| ICD-10 online (WHO version 2019) | |
Blind See (English: Blind Sight ) denotes a remainder function of visual information processing in parts of the visual field , due to a cortical blindness are blind. The affected persons have no conscious visual impressions in these visual field areas , since the intactness of the primary visual cortex is obviously a prerequisite for this. Nevertheless, they can react sensibly to presented visual stimuli and, for example, indicate their location or name their color.
Since the normal (cortical) information transfer path from the eye to the brain via the (primary) visual pathway is interrupted, the neuronal basis is assumed to be information transfer via still intact subcortical connections that run from the lateral geniculate body in the thalamus to the secondary visual cortex .
The term blindsight was coined by Larry Weiskrantz and especially popular through the work of P. Stoerig on the German patient FS.
More attempts
Similar results could also be achieved in healthy test persons by blocking the visual center via transcranial magnetic stimulation (TMS). Here, too, the test subjects consciously saw nothing, but were mostly able to guess the color displayed to them intuitively. The test subjects denied having noticed the information. Obviously, visual information is processed even without conscious perception .
In 1997, Sahraie and Weiskrantz used functional MRI examinations to show that the phenomenon of blind vision activates anatomical structures other than the visual cortex. This is the superior colliculus of the midbrain to which retinal fibers, which are particularly sensitive to object movements, pull. Further research by Morris, DeGelder, Weiskrantz and Dolan in 2001 showed that people with a lesion of the visual cortex that led to hemianopia can process certain emotional contents of faces that are presented in the area of the visual field in which they are consciously presented not perceive anything anymore. It has been suggested that this too happens through the activation of visual centers in the superior colliculus, which in turn project onto the limbic system , especially the amygdala , which is important for the perception and processing of emotions.
literature
- P. Stoerig: Blind vision . In: H.-O. Karnath, P. Thier (Ed.): Cognitive Neurosciences . 2nd Edition. Springer Verlag, Heidelberg 2003, 2006, pp. 97-103.
- P. Stoerig, A. Cowey: Blindsight in man and monkey. In: Brain . Volume 120, No. 3, 1997, pp. 535-559, doi: 10.1093 / brain / 120.3.535 .
- Lawrence Weiskrantz : Blindsight. A case study and implications (= Oxford Psychology Series . Volume 12 ). Clarendon Press, Oxford et al. a. 1986, ISBN 0-19-852192-8 .
- Mike Wendt: General Psychology - Perception . Hogrefe, Göttingen [a. a.], 2014, ISBN 978-3-8017-2288-3 , p. 99 f. (Bachelor's degree in psychology)
Web links
- Java applet on the cortical blindness (English)
Individual evidence
- ↑ A. Sahraie, L. Weiskrantz, JL Barbur, A. Simmons, SCR Williams, MJ Brammer: Pattern of neuronal activity associated with conscious and unconscious processing of visual signals. In: Proceedings of the National Academy of Sciences . Volume 94, No. 17, August 1997, pp. 9406-9411, pnas.org
- ↑ JS Morris, B. DeGelder, L. Weiskrantz, RJ Dolan: Differential extrageniculostriate and amygdala responses to presentation of emotional faces in cortically blind field. In: Brain. Volume 124, No. 6, June 2001, pp. 1241-1252, doi: 10.1093 / brain / 124.6.1241 .
