Biomedical Engineering Reference
In-Depth Information
CHAPTER 8
Quantitative EEG-Based Brain-Computer
Interface
Bo Hong, Yijun Wang, Xiaorong Gao, and Shangkai Gao
The brain-computer interface (BCI) is a direct (nonmuscular) communication chan-
nel between the brain and the external world that makes possible the use of neural
prostheses and human augmentation. BCI interprets brain signals, such as neural
spikes and cortical and scalp EEGs in an online fashion. In this chapter, BCIs based
on two types of oscillatory EEG, the steady-state visual evoked potential from the
visual cortex and the sensorimotor rhythm from the sensorimotor cortex, are intro-
duced. Details of their physiological bases, principles of operation, and implemen-
tation approaches are provided as well.
For both of the BCI systems, the BCI code is embedded in an oscillatory signal,
either as its amplitude or its frequency. With the merits of robust signal transmis-
sion and easy signal processing, the oscillatory EEG-based BCI shows a promising
perspective for real applications as can be seen in the example systems described in
this chapter. Some challenging issues in real BCI application, such as subject vari-
ability in EEG signals, coadaptation in BCI operation, system calibration, effective
coding and decoding schemes, robust signal processing, and feature extraction, are
also discussed.
8.1
Introduction to the qEEG-Based Brain-Computer Interface
8.1.1 Quantitative EEG as a Noninvasive Link Between Brain and Computer
In the past 15 years, many research groups have explored the possibility of estab-
lishing a direct (nonmuscular) communication channel between the brain and the
external world, by interpreting brain signals, such as neural spikes and cortical and
scalp EEGs, in an online fashion [1-3]. This communication channel is now widely
known as the brain-computer interface. BCI research originally was aimed at being
the next generation of neural prostheses, to help people with disabilities, especially
locked-in patients, interact with their environment. Besides potential application in
clinics, BCI has been adopted as a new way of human-computer interaction as well,
which can provide healthy people with an augmentative means of operating a com-
puter when it is inconvenient for some reason to use the hands, or for computer
gaming.
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