J Neurophysiol (December 1, 2002). 10.1152/jn.00281.2002
Submitted on 15 April 2002
Accepted on 16 August 2002
Movement Rate Effect on Activation and Functional Coupling of
Motor Cortical Areas
Keiichiro
Toma,
Tatsuya
Mima,
Takahiro
Matsuoka,
Christian
Gerloff,
Tatsuhito
Ohnishi,
Benjamin
Koshy,
Frank
Andres, and
Mark
Hallett
Human Motor Control Section, Medical Neurology Branch, National
Institute of Neurological Disorders and Stroke, National Institutes of
Health, Bethesda, Maryland 20892-1428
Toma, Keiichiro,
Tatsuya Mima,
Takahiro Matsuoka,
Christian Gerloff,
Tatsuhito Ohnishi,
Benjamin Koshy,
Frank Andres, and
Mark Hallett.
Movement Rate Effect on Activation and Functional Coupling of
Motor Cortical Areas. J. Neurophysiol. 88: 3377-3385, 2002. We investigated changes in the
activation and functional coupling of bilateral primary sensorimotor
(SM1) and supplementary motor (SMA) areas with different movement rates
in eight normal volunteers. An auditory-cued repetitive right-thumb
movement was performed at rates of 0.5, 0.75, 1, 2, 3, and 4 Hz. As a
control condition, subjects listened to pacing tones with no movements. Electroencephalogram (EEG) was recorded from 28 scalp electrodes and
electromyogram was obtained from the hand muscles. The event-related changes in EEG band-power (ERpow: activation of each area) and correlation (ERcor: functional coupling between each pair of cortical areas) were computed every 32 ms. Modulations of ERpow and ERcor were
inspected in alpha (8-12 Hz) and beta (16-20 Hz) bands. Motor cortical activation and coupling was greater for faster movements. With
increasing movement rate, the timing relationship between movement and
tone switched from synchronization (for 0.5-1 Hz) to syncopation (for
3-4 Hz). The results suggested that for slow repetitive movements
(0.5-1 Hz), each individual movement is separately controlled, and EEG
activation and coupling of the motor cortical areas were immediately
followed by transient deactivation and decoupling, having clear
temporal modulation locked to each movement. In contrast, for fast
repetitive movements (3-4 Hz), it appears that the rhythm is
controlled and the motor cortices showed sustained EEG activation and
continuous coupling.
