Thursday, July 26, 2007

A device that could win a Nobel?

In my readings in the neuroscience literature, I've yet to find any account of how information is sent from the eyes to the brain--what form the nerve signals take. Visual images are complex, so it would follow that the system has to be pretty complex, and it would be a real interesting topic. Knowing how the nerve impulses go would tell us something about the brain: it would tell us that its set up to process information in that particular format. It seems to me like that would be a huge step in finding out how the brain works.

Since this doesn't get talked about at all, as far as I've seen, one of two things must be true: the research has been done and has been ignored (in which case a lot of scientists are being stupid), or the research hasn't been done. I don't think scientists would ignore something as big as this, so I can only guess the research hasn't been done. On the other hand, it would seem in principle simple to do: put a sheep eyeball with intact optic nerve into an apparatus with chemicals able to keep it functioning in the short term, a small video screen, and sensor able to give a very precise account of what's happening at the end of the optic nerve. I can only assume, then, that the technical aspects of building such a device would be too difficult, and therefore no such device has been built. If someone did figure out how to build the thing, though, the hard part of the research would be over, they'd be able to gather some amazing data, publish it, and be a real contender for the Nobel.

All of the above is definite half-assed speculation territory for me. I'd love to have someone who really knows what they're talking about shed some light on this one. But if the above is correct, might it suggest we should start giving scientists engineering training in the interest of being able to develop better experimental apparatuses? Or perhaps, at least, having scientists work closer with engineers?

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The Vicar said...

Oliver Sacks mentions some stuff about sight in An Anthropologist On Mars. I'm working from memory, and am not a doctor anyway, but the impression I received was: all the data received by the eyes travels out through the optic nerve. (From an evolutionary standpoint, this is why the eyes are so near the brain; transmitting that much data is difficult, so the transit has to be short.) The brain then has several subsystems that chop the input up into objects and process color, etc. The case being discussed in the book was that of a man who had brain damage in the higher-level parts of this process and lost the ability to see colors. (And also saw different grays than one would assume from normal vision.) References were made to other cases from medical history leading to the same conclusion.

In other words: it's too late to win a Nobel Prize for that.

BlackSun said...

Read Marvin Minsky's The Emotion Machine. It has been documented that the visual cortex receives only about 20% of its input from the optic nerve, and 80% from other parts of the brain.

So our visual perception seems to be created only partially from the light that hits our eyes. The rest is a model created internally by comparing what we are "seeing" with previously recognized objects and scenes.