Wednesday, February 18, 2009

Oliver Sacks

Oliver Sacks became a household name after his bestseller Awakenings (and the subsequent movie),and is the author of one of our TED Book Club selections, Musicology.

Sacks walked gingerly on stage, sat down, and embarked on a story. It was the story of Rosalee, a lady in her 90's, who had lost her sight and who was having recurrent hallucinations. Rosalee, and her attendants, worried that she might be going mad. Rosalee described seeing people in European dress, a man with huge teeth, children in pink and blue clothes, often walking down stairs. The visions were detailed, vivid, but silent.

Sacks was called out to speak with her and diagnose her; he was quickly able to determine that she was sane, lucid, and intelligent, but suffering from Charles Bonnet syndrome. This syndrome affects upwards of 10% of the visually impaired. Particularly prevalent are faces, often with deformities, and, surprisingly, cartoons. There is a particular portion of the brain which recognizes faces, and another which handles cartoons. Apparently, in the absence of real visual stimulation, those parts of the brain start to react anyway, and present an image, or hallucination. Since this takes place in the visual cortex, outside the area which adds sound, or emotion to a visual, these hallucinations appear like silent movies, with no emotional baggage attached.

As Sacks puts it, "the theatre of the mind is generated by the machinery of the brain." What a lovely expression. And what a lovely way to introduce the subject, by telling us the story of Rosalee.

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