R.Hari, and S. Salenius.
Collaborators:
Helsinki University Central Hospital
Department of Clinical Neurophysiology, University of Helsinki
Dept. of Physics, Univ. of Pittsburgh, USA
Dept. of Mathematics, Univ. of Pittsburgh, USA
Dept. of Mathematics, Boston Univ., USA
F.C. Donders Centre for Cogn. Neuroimaging, The Netherlands
Sobell Department of Neurophysiology, Institute of Neurology, Queen Square, London, UK
Department of Anatomy, University of Cambridge, Cambridge, United Kingdom
By recording simultaneously rhythmic brain activity and electromyographic activity of a cotnracting muscle, we showed in 1997 that "cortex speaks to the muscle" at about 20 Hz and that cortex always leads in time. This "cortex-muscle coherence" has now become rather popu lar worldwide. We have recently quantified cortex-muscle coherence in healthy subjects for example during bimanual movements. The rhythmic interaction may reveal interesting information in several motor disorders. We have also shown, both applying benzodiazepines and using modelling of oscillating neuronal networks, that the motor-cortex 20-Hz activity most likely reflects inhibitory phenomena.