A common term in science fiction, a neural interface is the next generation in human-computer interfaces, allowing a human nervous system to directly link up to the computer, usually via a link into the spinal cord or via external electrodes. The idea of the neural interface was original produced in cyberpunk novels such as Neuromancer. The idea of the impications of neural interfaces, and the effects on human individuality and conciousness are explored in depth by authors such a Greg Egan. Several films have also been produced dealing with the issue, the most famous being The Matrix, but also including Ghost in The Shell, as well as various poor virtual reality B-movies.
In real life neural interface research is being funded, mainly to enable paraplegics to control wheelchairs using their brain. Unfortunately the major problem with the totally immersive idea of a neural interface popularised in sci-fi is effectively the bandwidth capacity of the human brain: in order to create a high bandwidth interface a large nerve bundle would have to be converted to the interface, such as the optic nerve and electrodes certainly wouldn't work. Alternative ideas involve inserting the interface directly into the brain, but that is limited by our understanding of the brain structure. Also, the neural interace is currently limited by the fact it can only recieve signals from the brain, sending signals to the brain is significantly more difficult, as recieving signals is a matter of measuring voltages, whereas a return signal has to generate these in a controlled way. Finally we have no way of knowing how the brain would respond to the new signals: whether it would adapt so we could percieve them, the currently held view, or whether it would be to drastic a sensory change.
Despite these problems current research has shown that it is possible to create a limited,one-way neural interface, so it is still a viable possibility, and a cool one at that.