Brain–Computer Interfaces - Index of

264 J. Mellinger and G. Schalk
Fig. 3 The BCI2000 parameter configuration dialog. The “Storage” tab is selected and reveals the
configuration details relating to data storage. Using the sliders on the right side, individual parameters
can be assigned user levels so that only a subset of them will be visible at lower user levels;
this is useful for clinical applications of BCI systems. “Save” and “Load” buttons provide storage
and retrieval of parameters, the “Configure” buttons allow to determine a subset of parameters to
store or retrieve. The “Help” button provides instant access to parameter documentation
In more detail, BCI experiments based on sensorimotor rhythms are supported
by two signal processing modules that extract spectral features, i.e., the
ARSignalProcessing module that uses an autoregressive spectral estimator, and
the FFTSignalProcessing module that uses short-term Discrete Fourier Transform
(DFT) to compute an amplitude spectrum. Typically, output of these Signal
Processing modules is used to control a cursor on a feedback screen; such feedback
is provided by the CursorTask User Application module (Fig. 4 left).
For presentation of visual or auditory stimuli, we provide a dedicated User
Application module. In conjunction with a corresponding Signal Processing module
that averages data across epochs, this module is used to classify evoked responses
in real time. The same Signal Processing module can be used in combination with
the P300 matrix speller application module (Fig. 4; right).