Movement-related slow potentials during motor imagery and motor suppression in humans.

Electro-encephalograms (EEGs) associated with motor imagery and motor suppression were recorded from motor-related frontal regions in humans. A negative potential was observed both during motor imagery and during NO-GO responses, as well as in movement trials. The negative potentials observed in the motor imagery trials had a similar pattern to those observed in the movement trials, although the potentials were different from those during NO-GO responses. The peak amplitude of the negative potential recorded at FCz was significantly larger than those recorded at F3, F4, C3 and C4 in the imagery task. The peak amplitude of the negative component in movement trials was larger than that in the imagery trials of all recording positions. By contrast, during the GO/NO-GO task, the peak amplitude during NO-GO responses was larger than that during the GO responses at every position. It appears, therefore, that motor imagery and motor suppression are associated with their own specific internal processes which are reflected by specific EEG patterns in motor-related frontal areas.