Current BCI technologies in brain engineering

Various neuroimaging modalities have appeared to acquire brain signals for developing a brain-computer interface (BCI). In this article, we review studies on different modalities including both invasive and non-invasive techniques for the implementation of BCIs, for brain signals detection, decoding, feature extraction, and classification. We discuss their advantages, disadvantages, and implementation issues to design of BCIs. Finally, we focus on fundamental principles, recent developments, and applications by using optical imaging as a promising modality for BCI applications.