Data recording

      Twenty-two Ag/AgCl electrodes (with inter-electrode distances of 3.5 cm) were used to record the EEG; the montage is shown in Figure 9 left. All signals were recorded monopolarly with the left mastoid serving as reference and the right mastoid as ground. The signals were sampled with 250 Hz and band pass-filtered between 0.5 Hz and 100 Hz. The sensitivity of the amplifier was set to 100 μV. An additional 50 Hz notch filter was enabled to suppress line noise.
       In addition to the 22 EEG channels. They were band pass filtered between 0.5 Hz and 100 Hz (with the 50 Hz notch filter enabled), and the sensitivity of the amplifier was set to 1 mV. The EOG channels are provided for the subsequent application of artifact processing methods [1] and must not be used for classification. A visual inspection of all data sets was carried out by an expert and trials containing artifacts were marked.[1]



          Fig 1 Electrode montage for 22 channel using international 10-20 system.[1]

References:
[1] http://www.physionet.org/pn4/eegmmidb/

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