Direct brain-computer communication through EEG signals

Automatic systems capable of understanding different facets of human communication will be at the heart of human-computer interfaces (HCI) in the near future. An HCI which is built on the guiding principle: "think and make it happen without any physical effort" is called a brain-computer interface (BCI). Indeed, the "think" part of this principle involves the human brain, "make it happen" implies that an executor is needed (here: a computer) and "without any physical effort" means that a direct interface between the brain and the computer is required. To make the computer understand what the brain intends to communicate necessitates monitoring the brain activity. Among the possible brain monitoring methods, the scalp recorded electroencephalogram (EEG) constitutes an adequate alternative because of its good time resolution, relative simplicity and noninvasiveness when compared to other methods such as: functional magnetic resonance imaging, positron emission tomography, magnetoencephalography and electrocorticogram. Furthermore, there is clear evidence that observable changes in EEG result from performing given mental activities [1]. In the following, an EEG based BCI will be simply called a BCI. Current BCIs use the following EEG signals: