Blindsight

Cortical blindness or even "blind sight" ( engl. Blindsight ) is a form of blindness, in which not the eye is diseased, but the primary visual cortex in the brain. The two terms are not exactly synonymous, since the cortical blindness mainly describes that no optical impression reaches the conscience, while the term "blind vision" mainly describes that the so- blind still is and sometimes talks as if he could see. Here to stay more than ten different nerve pathways through which the eyes usually transmit their signals to the visual cortex intact. Therefore, in cortical blindness a transfer of Sehreizen carried to the brain, but these are not transferred into the consciousness.

Attempts

Experiments with light flashes have shown that cattle often blind though the flashes of light can not perceive consciously but might say, for example, intuitively, the direction from which came the flashes of light, without knowing why they could say that. Ultimately, the images are thus unconsciously perceived.

Even in healthy subjects could be achieved by a blockage of the visual cortex via transcranial magnetic stimulation ( TMS) similar results. Again, the subjects saw nothing but the color of them shown were mostly accurate intuitive guess. The subjects denied having seen the information.

One of the most commonly voiced objections to the astonishing at first sight phenomenon of blindsight is that sufferers simply lying. However, can be at all the people who pretend to be blindsichtig, find the same brain injuries or diseases objectively.

Interpretation

The result of experiments shows that, while within the visual cortex awareness is generated, but also without the conscious perception is a process the information instead.

1997 Sahraie and Weiskrantz have shown by functional MRI studies have shown that the phenomenon of cortical blindness other anatomical structures as the visual cortex are activated, namely the superior colliculus in the brainstem, the processed fibers from the retina, which extend from nerve cells in the retina, the are particularly sensitive to moving objects. Further studies of Morris, DeGelder, Weiskrantz and Dolan in 2001 have shown that people with a lesion in the visual cortex, which has led to a hemianopia, can process certain emotional content of faces that are presented in the visual field, they deliberately do not longer perceive. It has been shown that this is achieved by the activation of the visual centers of the superior colliculus, the project itself in the limbic system, amygdala, and in particular which has an important meaning for the emotions.