Physionet Motor Imagery dataset.

Physionet MI dataset: https://physionet.org/pn4/eegmmidb/

This data set consists of over 1500 one- and two-minute EEG recordings,
obtained from 109 volunteers [2]_.

Subjects performed different motor/imagery tasks while 64-channel EEG were
recorded using the BCI2000 system (http://www.bci2000.org) [1]_.
Each subject performed 14 experimental runs: two one-minute baseline runs
(one with eyes open, one with eyes closed), and three two-minute runs of
each of the four following tasks:

1. A target appears on either the left or the right side of the screen.
   The subject opens and closes the corresponding fist until the target
   disappears. Then the subject relaxes.

2. A target appears on either the left or the right side of the screen.
   The subject imagines opening and closing the corresponding fist until
   the target disappears. Then the subject relaxes.

3. A target appears on either the top or the bottom of the screen.
   The subject opens and closes either both fists (if the target is on top)
   or both feet (if the target is on the bottom) until the target
   disappears. Then the subject relaxes.

4. A target appears on either the top or the bottom of the screen.
   The subject imagines opening and closing either both fists
   (if the target is on top) or both feet (if the target is on the bottom)
   until the target disappears. Then the subject relaxes.

References

[1] Schalk, G., McFarland, D.J., Hinterberger, T., Birbaumer, N. and Wolpaw, J.R., 2004. BCI2000: a general-purpose brain-computer interface (BCI) system. IEEE Transactions on biomedical engineering, 51(6), pp.1034-1043.

[2] Goldberger, A.L., Amaral, L.A., Glass, L., Hausdorff, J.M., Ivanov, P.C., Mark, R.G., Mietus, J.E., Moody, G.B., Peng, C.K., Stanley, H.E. and PhysioBank, P., PhysioNet: components of a new research resource for complex physiologic signals Circulation 2000 Volume 101 Issue 23 pp. E215–E220.