Mind over Computer 13
Brain Image of Fish Hunting Prey
widely distributed in the brain than was first thought. Conscious seeing is based in the visual cortex, but there are older pathways still active in the brain that facilitate this unconscious seeing.
The brain is very plastic. Lose your sight through damage to the eye or optic nerve, and the brain can repurpose the visual cortex to other uses such as processing sound or touch. Daniel Kish has developed this to such a high level that he can ride a bicycle despite being blind. He clicks his tongue against the roof of his mouth and uses echolocation to form an auditory model of the world around him. Using a similar approach, Amir Amedi from the Hebrew University of Jerusalem has built an audio imager that turns pictures of the world into musical sound patterns. CAT scans of people using this system show they use the visual cortex to convert these sound images into models of the world in similar parts of the brain to a sighted person.
We now know roughly what each part of the brain does, but we have no idea how it does it. The scale of an individual thought is too small to see in a brain scan. All we can do is observe large-scale electrical activity associated with those thoughts. A video, from a group at Tokyo University, shows an example of electrical activity filmed in real time as a fish hunts for its prey. Fish have transparent bodies and thin skulls facilitating this sort of imaging. Humans are much harder subjects to work with!
The most popular theory to explain how brains work is as some form of computer. Computers are easy to study because we manufacture them. They tend to crash quite frequently — usually at the most inconvenient
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