Brain activity related to abandonment of motor intention in point-to-point finger movement

We investigated brain potentials related to the abandonment of the motor intention prior to the initiation of a point-to-point finger reaching movement. The starting time of the movement was indicated with the clock making one revolution for 4 s. The time at which the clock hand passed the 3 o'clock position was defined as a go timing. In the go trials, a subject was instructed to start the movement at the timing. In a series of trials, a task, we designated pre-stop task, with a stop signal indicated unexpectedly before the timing of the go-signal was conducted. In the pre-stop task, the subject abandoned the motor intention immediately after the stop-signal, and all subjects were able to inhibit finger movement. Cerebral potentials from the scalp were recorded using a 20-channel electroencephalography (EEG) system. In the go task, typical movement-related cortical potentials were observed. On the other hand, a positive potential distributed at the midline fronto-cental scalp about 400ms after the go-signal was observed only in the pre-stop task. This result suggests that the positive component observed in the pre-stop task is associated with the abandonment of the motor intention.