> Surely a BCI can upload itself to a brain-simulator and live there. I'm not sure. I have a strong suspicion that we can make a useful brain-computer interfa

> Surely a BCI can upload itself to a brain-simulator and live there. I'm not sure. I have a strong suspicion that we can make a useful brain-computer interface, without any idea how the brain really works. And I kind of expect that's how it will go. I think this because, in a technical sense, we already have brain-computer interfaces. Cochlear implants. They are used to restore hearing. The auditory nerve and cochlea are, anatomically speaking, actually part of the brain. A long, extremely thin wire probe is inserted into the cochlea and auditory nerve. The probe has electrical contacts which are driven by the cochlear implant speech processor. The probes themselves are interesting in their own right; early ones only had a few electrical contacts, while modern ones have dozens or hundreds of electrodes spaced out along the length, each of which can be individually controlled, providing an almost infinite variety of possible inputs which the brain can distinguish. So here's the wild bit. We have only a vague idea how auditory signals are encoded by the cochlea and sent down the auditory nerve. This was even more true when cochlear implants were first devised, in the 1970s. It turns out that doesn't matter. If you start applying varying voltages at different electrodes along the probe, that correspond with activation of various frequency bands at varying intensities, in the vaguest mimicry of auditory nerve signalling, the brain pretty quickly figures it out. A person who previously had natural hearing and lost it can learn to understand speech this way sometimes in a matter of days. People who were born profoundly deaf and were not implanted in infancy often regret the decision to be implanted and usually do not learn to decode sound in a useful way. Children who are implanted in infancy usually do. As an aside, the accounts given by people who have had this generally unpleasant experience, suddenly given an extra sense but with no neural structures developed life-long to process it, are both fascinating and harrowing.