查看文章

We studied the effect of stimulus predictability on the alpha and beta changes observed in central regions during stimulus-induced movement paradigms. Six young volunteers were instructed to extend briskly their dominant wrist as soon as possible after hearing a 2000 Hz sound. Two sequences of stimuli were presented to each subject, the first rhythmic at 1/6 s and the second with random intervals between 5 and 13s. A time-frequency analysis of nonphase-locked activity in the 7–37 Hz range was performed on stimulus-centred EEG sweeps using wavelet filters and Gabor transforms. During the sequence of predictable rhythmic stimuli, stimulus-induced movements were accompanied by a decrease in beta activity that began contralaterally about 1 s prior to the stimulus and extended to both sides later on. This decrease was followed by a rebound after the end of the movement. In the alpha band, the decrease …