EEG dataset for 22 channels

      This data set consists of EEG data from 4 subjects. The cue-based BCI paradigm consisted of four different motor imagery tasks, namely the imagination of movement of the left hand (class1), right hand (class 2), both feet (class 3), and tongue (class 4). Two sessions on different days were recorded for each subject. Each session is comprised of 6 runs separated by short breaks. One run consists of 48 trials (12 for each of the four possible classes), yielding a total of 288 trials per session. At the beginning of each session, a recording of approximately 5 minutes was performed to estimate the EOG influence. The recording was divided into 3 blocks: (1) two minutes with eyes open (looking at a fixation cross on the screen), (2) one minute with eyes closed, and (3) one minute with eye movements.
            The timing scheme of one session is illustrated in Figure 1 Note that due to technical problems the EOG block is shorter for subject A04T and contains only the eye movement condition. The subjects were sitting in a comfortable armchair in front of a computer screen. At the beginning of a trial (t = 0 s), a fixation cross appeared on the black screen. In addition, a short acoustic warning tone was presented. After two seconds (t = 2 s), a cue in the form of an arrow pointing either to the left, right, down or up (corresponding to one of the four classes left hand, right hand, foot or tongue) appeared and stayed on the screen for1.25 s.

                                            Figure 1 Timing scheme of one session.

                                          Figure 2 Timing scheme of the paradigm.

      This prompted the subjects to perform the desired motor imagery task. No feedback was provided. The subjects were ask to carry out the motor imagery task until the fixation cross disappeared from the screen at t = 6 s. A short break followed where the screen was black again. As shown in figure 2 Timing scheme of the paradigm.¹

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

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