WE analysed whether type of movement (brisk vs slow) and active muscle
force are encoded in the time course of mu-rhythm desynchronization d
uring self-paced finger movements. Ten subjects performed 100 brisk an
d slow extensions of the right index finger. The time course of mu-rhy
thm desynchronization in the contralateral sensorimotor area before mo
vement was identical for both types of movements. Brisk movements acco
mpanied by a stronger extensor muscle contraction were preceded by lar
ger desynchronization. The onset of mu-rhythm recovery was related to
the duration of the extensor EMG burst in both types of movement. The
results suggest that both amplitude and duration of the extensor muscl
e contraction are encoded in the time course of mu-rhythm desynchroniz
ation.