EEG Data

Data Types for EEG in Matlab

The structure holding continuous (i.e., not epoched) EEG signals is denoted by cnt. The following list shows its typical fields.

cnt	Structure of continuous signals
.x	The EEG signals as 2-D array of size [T nChannels] with time along the first and channels along the second dimension.
.fs	The sampling rate, unit [samples per second].
.clab	Channel labels, stored as strings in a cell array.
.title	Title of the data set (string), used by some visualization functions. (This field should not be obligatory, but some functions may try access this field, without prior checking its existance. If so the function should be corrected.)

The structure holding epoched EEG signals (i.e., a series of short-time windows of equal length) is denoted by epo. (This structure is not resticted to time domain signals, although it is suggested by some notions, e.g. the fi eld .t).

epo	Structure of epoched signals.
.x	The EEG epochs as 3-D array of size [T nChannels nEpochs] with time along the rst, channels along the second, and epochs along the third dimension. (Thus, an epoch structure holding only one epoch is a special case of continuous signal structure.)
.t	Time line, vector of length T, i.e., the size of the rst dimension of epo.x. In the frequency domain, this eld holds the frequencies.
.y	Class labels of the epochs as 2-D array of size [nClasses nEpochs]. The i-th row indicates class membership with class i (0 means no member-ship, 1 means membership), see Sec. A.1.
.className	Cell array of strings defining names of the classes.
.fs	The sampling rate, unit [samples per second].
.clab	Channel labels, stored as strings in a cell array.
.title	Title of the data set (string), used by some visualization functions. (This field should not be obligatory, but some functions may try access this field, without prior checking its existance. If so the function should be corrected.)
.file	The file name (string) of the data set (with absolute path). When the data set is a concatenation of several files, this field is a cell array of strings. (This eld is only use by some special functions.)