An astonishing story from the New Scientist: an engineer at the University of Illinois has built a prototype retinal cell out of silicon. The idea is to replace damaged cells in human retinae with something that is a lot better than nothing. People have played around for years with the idea of implanted surrogate sensory organs which would transmit signals to the nerves behind.
What’s enchanting about this one is that it doesn’t supply electrical signals directly. It is of course electrical but the way it works is that light deforms a piezo-electric crystal which is turn squeezes out a drop of neurotransmitter onto the nerve cells behind, and this chemical stimulation causes the other end to send an electrical impulse. So it turns out that all the science ficiton had things the wrong way round.
All this puts me in mind of Dennett’s essay, referenced by HEB some time back, about the man who is slowly turned into a cyborg: at what point does he stop being himself?
The idea in Dennett’s essay is of course a whole lot older than that (says the Dick head), but it’s elegantly expressed.
1. Build a functional equivalent to a neuron
2. Replace a single neuron in your brain with with the result from 1. Are you still you?
3. Repeat until all neurons have been replaced
4. Still you?
It’s an interesting thought experiment for cognitive scientists and those who have a tendency to vitalism, but absolutely fascinating for theologians. What happens to your soul, and at what point? Is there a material difference to the experiment if you do it with a dog?
The first step is the one with the most questions begged, but it’s amenable to the same techniques as piss off the audiophiles: you build your device and test it against reality. When you can detect no difference between what it does and what reality does, you’re getting somewhere – and when the complex things you build from your device behave as real complex things made from the real building blocks, it’s very hard to argue against. That’s one of the things that IBM and The Ecole Polytechnique Fédérale de Lausanne are up to with their lake water cooled artificial neocorticular columns, so we might find more stuff out soon.
R