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Bionic Brains
New Scientist is carrying this article summarizing new developments in prosthetic brain implants. Scientists have now created a microchip that correctly imitates the hippocampus when implanted in living rat brain tissue samples. The ultimate goal is to be able to replace this critical section of the brain when it is damaged or destroyed by illness or injury.
Most interesting to me was how the thing was developed:
In previous work, Berger’s team had recorded exactly what biological signals were being produced in the central part of the hippocampal circuit and had made a mathematical model to mimic its activity. They then programmed the model onto a microchip, roughly 2 millimetres square
This is very similar to how the original IBM PC clones were developed. Engineers would feed the original IBM BIOS chips a signal, read what came out, and then create from scratch (and without looking at the IBM chips) a "clone" that did the exact same thing. Strange how biology and technology can sometimes coincide.
It would be interesting to see how they work into effect Hebb's theory of synaptic plasticity let alone how it deals with stored synaptic changes in the hippocampus. Since some theories put forth state that the brain takes the opportunity to consolidate the synapses in the hippocampus to the cortex during sleep (part of the interleaving memory hypothesis) it will be fascinating to see how that comes into play.
The interleaving memory hypothesis states that memory is initially stored in synaptic changes in the hippocampus. And when certain aspects of these changes recurs, then the hippocampus also participates in changes on cortical activation that changes cortical synapses a little. The interleaving that is happening involves the addition of information to knowledge already at hand and just adds, or refines the existing representation so that the new information does not interfere with the old but enhances the existing explicit memories already stored in the cortical systems.
All in all, it will either help give strength to the theories or pave the way for new ones. Exciting times!
Posted by: Joshua on October 26, 2004 02:49 PM