Total Recall

T oday, human-computer interfaces (HCIs) are rather physical in nature. The communication of information from and to computers is limited to the capabilities of individual input and output devices. With a typing speed of less than 50 words per minute and a reading rate of less than 300 words per minute, my transmission rate to and from my laptop is far lower than the communication bandwidth of most computer-to-computer interfaces. Advanced HCI approaches, such as speech recognition, are clearly widening this communication bottleneck. A direct link to the brain, however, would avoid most physiological activities. Ignoring all the required processing tasks for a moment, in the future we might end up at the speed of thinking when communicating with computers. In addition to a more efficient way of communication, such brain-computer interfaces will introduce completely new possibilities. For instance, they will support people with physical disabilities so that they can control prostheses and other interfaces mentally. BCIs also offer promising new approaches in neurological rehabilitation and even computer games. Futurists predict that, by the mid-21st century, it will be possible to download human brain content onto a supercomputer. Replicating and changing consciousness can be implied from such capabilities—total recall becomes reality. BCI technology is truly both an exciting and challenging topic. On the way to digital immortality and mental control, there are still many hurdles to overcome. How can brain signals be sensed both noninvasively and efficiently? How can researchers process and interpret these signals? In the five articles in this special issue, leading scientists shed some light on the state of the art in brain-computer interfaces.