Neuromagnetic study of movement-related changes in rhythmic brain activity.
Neuromagnetic fields from the left cerebral hemisphere of five healthy, right-handed subjects were investigated in a typical Bereitschaftspotential paradigm consisting of self-paced voluntary movement of the right index finger. To assess movement-related spectral changes of the spontaneous magnetoencephalogram. latency-dependent short-time spectra were obtained by Fourier analysis for each single trial. The number of trials in which the spectral estimate for a certain frequency and latency deviated from reference values was then transformed into a probabilistic relative power measure. A spectral power depression around 20 Hz was observed starting about 2.5 s before movement onset, followed by elevated power in the 20-35 Hz range starting about 500 ms after movement onset. Generally, the power increase differed from the prior depression in both spectrum and topography, suggesting different generating processes rather than just a 'rebound' effect of the idling rhythm generator. The time course and topography of spectral power changes are discussed in relation to the corresponding properties of the movement-related neuromagnetic fields (readiness field, motor field, and movement-evoked field I).
Feige
B
B
Department of Psychiatry, University of Freiburg, Germany. feige@ukl.uni.freiburg.de
Kristeva-Feige
R
R
Rossi
S
S
Pizzella
V
V
Rossini
P M
PM
D000328:Adult; D001921:Brain / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D010507:Periodicity; D011930:Reaction Time; D012016:Reference Values; D013997:Time Factors