Additional information on the EEG data which is put available on the BIOMED website 

(pdf version of this text, data and matlab files)

Matlab code

function eegplot(S,meas,sens,linestyle)

%EEGPLOT    plots a multi-channel data set

%   eegplot(S,meas,sens,linestyle)

%   S is a matrix with m rows (channels) and n coloms (timesamples)

%   meas is the montage used (optional)

%   sens is the y-axes scale (optional)

%   linestyle (optional)

meas19chch: longitudinal montage used to review epileptic events. This data structure can be fed into eegplot.

elpos19chch : A two-column matrix containing theta and phi in radials. The standard electrode positions on a spherical head model of the 19 electrodes. This information is necessary when performing EEG source localization.

% |           |z

% |           |   

% |           | th /

% |           |-->/

% |           |  /

% |           | /          y

% |           |/-----------

% |           /\

% |          /  \

% |         /`-->\

% |        / phi  \

% |       /

% |      /x

The rows represent the following electrodes:

'Fp1'    'Fp2'    'F3'    'F4'    'C3'    'C4'    'P3'    'P4'    'O1'    'O2'    'F7'   'F8'    'T3'    'T4'    'T5'    'T6'    'Fz'    'Cz'    'Pz'

Matlab code on ICA and EEG source localization can be found on the open source package EEGLAB: http://sccn.ucsd.edu/eeglab/

Interictal EEG

Raw data stored with an average reference i.e. sum of all channels equals zero for each time sample.

Sample frequency 256 Hz

spike1.mat : Is a 19 x 1281 matrix. The rows represent the 19 channels (see above for order); the columns represent the time samples.  

>>eegplot(sig_av,meas19chch)

Two epileptic transients can be observed, one at 1.6 s on channels T3-T5 and T5-O1, both peaks are pointing to each other, and one at 2.5 s at channels F8-T4 and T4-T6.

spike2.mat: Is a 19 x 1281 matrix as above.

>>eegplot(sig_av,meas19chch)

At 1.8 s an eye-blink or eye-movement artifacts occurs mainly on channels Fp2-F4, Fp1-F3, Fp2-F8 and Fp1-F7. These are channels in the vicinity of the eyes. Epileptic transients are noticed at 2.5s and 4.4s on the channels Fp1-F7 and T5-O1. We also observe runs of high frequency activity mainly on channels T4-T6 and F8-T4. This signal  may be due to muscle activity or due to 50 Hz power line disturbance.

Ictal EEG 

Matlab code:

function eegplotavr(S,meas,sens,linestyle)

%EEGPLOTAVR   plots a multi-channel data set in an average reference montage

%   eegplotavr(S,meas,sens,linestyle)

%   S is a matrix with m rows (channels) and n coloms (timesamples)

%   meas is the montage used (optional)

%   sens is the y-axes scale (optional)

%   linestyle (optional)

meas21avr: average reference montage used to review epileptic seizures. This data structure can be fed into eegplotavr.

sig_ictal.mat: Is a 21 x 2500 matrix. The rows represent the 21 channels; the columns represent the time samples. The sampling frequency is 250 Hz.

>>eegplotavr(sig_ictal,meas21avr,100)

Epileptic seizure activity can be observed on channels T2, F8, T4 and T6. At 2.5 s, 3.4 s, 6 s, 7.6 s eye blinks occur. Muscle artifacts can be observed between 0 s - 3.9 s on channels F7, T3, T5, C3, T1 and between 5 s - 10 s on channels F8, T4, F4, C4 and P4.