Seeing in the Dark

New Ideas / by Joe Kloc / January 14, 2009

A blind man shocks researchers with what he sees.

Illustration by Joe Kloc

Patient TN was, by his own account, completely blind. Two consecutive strokes had destroyed the visual cortex of his brain, and consequently, his ability to see.

It is not uncommon for stroke patients to suffer brain damage, but the case of TN — referenced by his initials, the general practice in such studies — was peculiar. His first stroke had injured only one hemisphere of his visual cortex. About five weeks later, a second stroke damaged the other hemisphere. An assessment of his brain function revealed that after two strokes, TN, in his 50s, was clinically blind.

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