G. Pfurtscheller et al., ON THE EXISTENCE OF DIFFERENT TYPES OF CENTRAL BETA-RHYTHMS BELOW 30 HZ, Electroencephalography and clinical neurophysiology, 102(4), 1997, pp. 316-325
EEGs were recorded from sensorimotor areas of 12 subjects performing u
nilateral self-paced brisk and slow finger movements. Two different be
ta components were found below 30 Hz: (i) One component, at about twic
e the frequency of the mu rhythm, showed desynchronization in parallel
with the mu rhythm starting at about 2 s prior to movement. Measureme
nts of bicoherence have shown that this beta component can be non-line
arly related to the arch-shaped mu rhythm. (ii) Another beta component
started to desynchronize about 1 s prior to movement, recovered very
fast and displayed a pronounced post-movement beta synchronization (PM
BS) within the first second after movement-offset. This PMBS was found
in the frequency band between 12 and 26 Hz. The average percentage po
wer increase at contralateral sensorimotor area was 232% (SD = 82%) fo
r brisk and 265% (SD = 102%) for slow movements. The PMBS was of contr
alateral dominance and is interpreted as a correlate of active inhibit
ion or idling of the primary motor area following movement execution.
(C) 1997 Elsevier Science Ireland Ltd.