Prosthetic synaesthesia and cortical implants.

The human brain is a remarkably complex and flexible organ, with as many possible failure modes and glitches as there are emergent and surprising properties. Take something away, and sometimes you can coax another part of the brain to take up the slack in some other way. Case in point, artist Neil Harbisson. Harbisson was born with a condition called achromatopsia, which is the name for a group of disorders which collectively result in the same phenomenon - he cannot see colors, only shades of greyscale. Sometimes it's a neurological dysfunction, sometimes it's a defect in the retina, and sometimes it's due to some other combination of factors. In a decade-long experiment, Harbisson developed a prosthesis which incorporates a high resolution camera, a small radio scanner, and a microprocessor which converts patterns of color and RF emissions into patterns of sound. Over time, he's trained his brain to interpret those patterns of sound into a form that he can use to create his art. Some might say that he's trained himself to have a form of synaesthesia, or a state in which sensory modes are combined in unusual ways (such as seeing geometric or colored patterns when hearing certain sounds, or tasting phantom flavors when touching things with different textures). Recently, to increase the resolution of the new sensory input he had a new version implanted into his skull. The implant is much more sensitive, and its placement in his skull will give him much depth of sensation. Of what use might this be to someone who isn't an artist? Ask someone who has a magnet implanted in their finger how useful it is when debugging power supplies. It's interesting to trace the evolution of brain implants. Sure, a lot of us would love to have datajacks, interfaces connected directly to our nervous systems that would hypothetically let us control communications devices and computers. There's some evidence that some aspects of such an interface are easier than previously thought, thanks to the nervous system's marvelous ability adapt to new forms of input, but there are other considerations that have to be taken into account. Chief among them are the fact that neurons that have been injured somehow (say, someone's poked a very tiny, very thin wire into them) will develop scarring and push the wires out. However, techniques to mitigate this are being worked on, and a significant amount of progress has been made toward interfacing with living neural networks. In testing right now, for example, are prosthetic versions of the hippocampus, the part of the mammalian brain which controls the storage and recall of long term memory. Deep brain stimulation units, which generate minute pulses of electricity and pump them through slender wires into the brains of patients are used to treat Parkinson's Disease, certain forms of obsessive-compulsive disorder, Alzheimer's Disease, and certain forms of clinical depression that neither therapy nor drugs have any effect upon. There are other problems that we have to solve before cerebral implants are more common. For starters, the brain is exceptionally delicate for all of its power. Once you get the skull open and part the meninges the brain has a consistancy very similar to that of toothpaste. Think about that for a minute. Better yet, go to the bathroom and squeeze a little toothpaste onto your fingertip, and play with it a little. The cranial vault is not someplace one trespasses without extreme care. The blood-brain barrier protects the interior of the brain from the rest of the body; that's correct, I said the rest of the body. Biochemistry is an amazingly weird and responsive thing. The brain has a system of biochemistry all its own, and if the blood-brain barrier didn't isolate the brain from the rest of the body and enforce a strict set of exceptions and modulating factors, something as commonplace as a rise in blood glucose after dinner might wreak havoc with the bra