It’s a startling but true fact that brain damage that causes blindness can leave intact the brain’s ability to still process the visual information even though we can no longer “see”. Called “blind-sight”, neurologists have been mapping the different pathways in the brain that lead to sight. What they have discovered are several pathways: one that leads to visual awareness, the that leads visula processing.

Neurologists have known about this after studying stroke vicitms but they are moving closer to understanding the connections between these pathways in the brain. In a recent article in the journel Cell Biology neurologist Beatrice de Gelder and her team studied a patient who had suffered a stroke that lead to complete blindness. Damage to the primary visual cortex was confirmed through sophisticated brain imaging techniques. The part of the brain that processes visual stimulus however remained intact.

What they discovered was that despite being blind, the patient, known only as TN, was able to successfully navigate around obstacles in a hallway without awareness that he was doing so. Because sight is linked to awareness/consciousness, it raises several interesting questions: What does it mean to be aware? How much of the brain functions at levels that remain unaware to us? How much of our behavior is subconsciously directed?

You can watch the video of TN as he wends his way around obstacles in the hallways by following this link on NPR. To learn more about the phenonmenon of blindsight, watch this BBC video with neurologist Ramachandran on how \”blind-sight\” gives clues about the nature of consciousness.

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