Blindsight
From Psy3242
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== '''History''' == | == '''History''' == | ||
| - | The history of blindsight stems from a focus on animal research and neuroanatomy, especially in the contrast of human and other primate visual cortex functions. One of the first hypotheses of residual vision in monkeys was made in 1886 by David Ferrier, who removed his subjects' entire visual cortexes and observed the 'blind' monkeys navigating around obstacles. More than a century and numerous studies later, the general consensus has been drawn that monkeys lacking a primary visual cortex can discriminate shapes, show sharp sensitivity to the detection of movement and contrast, and have measurable acuity. However, these abilities are discernibly reduced from normal functioning. | + | The history of blindsight stems from a focus on animal research and neuroanatomy, especially in the contrast of human and other primate visual cortex functions. One of the first hypotheses of residual vision in monkeys was made in 1886 by David Ferrier, who removed his subjects' entire visual cortexes and observed the 'blind' monkeys navigating around obstacles. More than a century and numerous studies later, the general consensus has been drawn that monkeys lacking a primary visual cortex can discriminate shapes, show sharp sensitivity to the detection of movement and contrast, and have measurable acuity. However, these abilities are discernibly reduced from normal functioning. In contrast to primates, evidence on the lack of V1 or damage to the area in human brains remained inconclusive until more recently. |
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| + | == The Case of DB == | ||
Revision as of 03:57, 25 April 2008
Definition
Blindsight is defined by the Oxford Concise Dictionary as "a condition in which the sufferer responds to visual stimuli without consciously perceiving them". Human patients with such a condition often have lost V1 functioning and claim they are blind. In primates and humans, the retina relays its major neural output to the thalamus and then to visual cortex (V1, or striate cortex). When the strait cortex is completely removed or blocked in the brain of a monkey, the animal can still discriminate between certain visual stimuli, though its overall capacity for normal functioning has changed. This is because the output from the eye also reaches various other brain regions in the midbrain and thalamus that often remain intact and undamaged when V1 is completely removed.
History
The history of blindsight stems from a focus on animal research and neuroanatomy, especially in the contrast of human and other primate visual cortex functions. One of the first hypotheses of residual vision in monkeys was made in 1886 by David Ferrier, who removed his subjects' entire visual cortexes and observed the 'blind' monkeys navigating around obstacles. More than a century and numerous studies later, the general consensus has been drawn that monkeys lacking a primary visual cortex can discriminate shapes, show sharp sensitivity to the detection of movement and contrast, and have measurable acuity. However, these abilities are discernibly reduced from normal functioning. In contrast to primates, evidence on the lack of V1 or damage to the area in human brains remained inconclusive until more recently.
