% Apply filters:
    % High pass:
    [H_HP, G_HP] = butter(4, (2*1)/128, 'high');
    % Low pass:
    [H_LP, G_LP] = butter(4, (2*40)/128, 'low');
    
    for i = 1:size(eeg,1)
        data_filtered(i,:) = filtfilt(H_HP, G_HP, data_rerefed(i,:));
        data_filtered(i,:) = filtfilt(H_LP, G_LP, data_filtered(i,:));
    end
    
    eeg = data_filtered;