Many physiological disorders such as Amyotrophic Lateral Sclerosis (ALS) or injuries such as high-level spinal cord injury can disrupt the communication path between the brain and the body. People with severe motor disabilities may lose all voluntary muscle control, including eye movements. These people are forced to accept a reduced quality of life, resulting in dependence on caretakers and escalating social costs [VAU03]. Most of the existing assistive technology devices for these patients are not possible because these devices are dependant on motor activities from specific parts of the body. Alternative control paradigms for these individuals are thus desirable.
Over the last two decades, brain-computer interface (BCI) has emerged as a new frontier in assistive technology (AT) since it could provide an alternative communication channel between a user’s brain and the outside world [WOL02]. Other terms that are also used in the literature for referring to a BCI system include: brain interface (BI), direct brain interface (DBI), and brain machine interface (BMI).
A BCI system allows individuals with motor disabilities to control objects in their environments (such as a light switch in their room or television, wheelchairs, neural prosthesis and computers) using their brain signals only.This could be accomplished by measuring specific features of the user’s brain activity that relate to his/her intent to perform the control. This specific type of brain activity is termed a “neurological phenomenon”. As an example, when a particular movement such as right index finger flexion is performed, specific neurological phenomena that correspond to that movement are generated. The corresponding neurological phenomena are then translated into signals that are eventually used to control devices [MAS07].
Figure 1 shows a traditional BCI system in which a person controls a device in an operating environment (e.g., a powered wheelchair in a house) through a series of functional components (revised from [FAT06]). In this context, the user’s brain activity is used to generate IC commands that operate the BCI system. The user monitors the state of the device to determine the result of his/her control efforts.