Firefox

In 1977, Craig Thomas published his novel, "Firefox". It also became a movie, staring Clint Eastwood. In it the pilot can control the weapon systems of a MiG-31, code-named Firefox, by thought.
What about these visions? At present, even the most sophisticated EEG-based BCIs are not able to decipher more than 25 bits of information per minute (more). This can enable a completely paralysed person to use for example a mental typewriter (more) at a speed of two words per minute. It can also be used to perform routine tasks in the household. But it is many thousands of times too slow to control even simple movement (more). Thus: To bring powerful BCIs into existence, one has to either improve EEG-technology or use different modes of communication.
Apart from the speed of communication, the second big problem of BCI-research is the signal itself, as neither brainwaves nor individual firing rates of nerve cells were made to drive a prosthesis (more).

definitions / components / history of BCIs
what's a BCI / what is it for / types of BCI / problems
definitions > problems
This is a major theoretical problem...

The whole concept of BCIs rests on the assumption that you can learn to control the electrical activity of your brain, which is not what learning is normally about. Can you control your brain enough to use sampled nerve cell activity, either EEG-based or recorded by electrodes, as a new output channel for performing complex tasks? Noone knows. Another, more technical problem with the signals are artifacts which can result from muscle activation and eye movement.

Learn about definitions of BCI, how to build your own one, and what the history of BCIs was like.