Brain-computer interfaces provide a direct communication and control channel for sending messages and instructions from brain to external computers or other electronic devices.Using the non-muscular channel

subjects with severe neuromuscular dysfunction can directly express their thought and manipulate the external devices without using human language and actions.This will greatly enhance the ability of these subjects to manage external event and will improve their living quality.Brain-computer interface technology is an interdisciplinary technology integrating neurology

signal collection

signal processing

pattern recognition and more other relevant techniques.In the present paper

we review the development

the rationale and the methodology of BCI's technology and the major limitations in the BCI's implementation and applications

and then discuss some vital aspects that may be conducted in the future investigations.