MEG insight into the spectral dynamics underlying steady isometric muscle contraction

Mathieu Bourguignon, Harri Piitulainen, Eero Smeds, Guangyu Zhou, Veikko Jousmäki, Riitta Hari

Research output: Contribution to journalArticleScientificpeer-review

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To gain fundamental knowledge on how the brain controls motor actions, we studied in detail the interplay between MEG signals from the primary sensorimotor (SM1) cortex and the contraction force of 17 healthy adult humans (7 females, 10 males). SM1 activity was coherent at ∼20 Hz with surface electromyogram (as already extensively reported) but also with contraction force. In both cases, the effective coupling was dominant in the efferent direction. Across subjects, the level of ∼20 Hz coherence between cortex and periphery positively correlated with the “burstiness” of ∼20 Hz SM1 (Pearson r ≈ 0.65) and peripheral fluctuations (r ≈ 0.9). Thus, ∼20 Hz coherence between cortex and periphery is tightly linked to the presence of ∼20 Hz bursts in SM1 and peripheral activity. However, the very high correlation with peripheral fluctuations suggests that the periphery is the limiting factor. At frequencies <3 Hz, both SM1 signals and ∼20 Hz SM1 envelope were coherent with both force and its absolute change rate. The effective coupling dominated in the efferent direction between (1) force and the ∼20 Hz SM1 envelope and (2) the absolute change rate of the force and SM1 signals. Together, our data favor the view that ∼20 Hz coherence between cortex and periphery during isometric contraction builds on the presence of ∼20 Hz SM1 oscillations and needs not rely on feedback from the periphery. They also suggest that effective cortical proprioceptive processing operates at <3 Hz frequencies, even during steady isometric contractions.
Original languageEnglish
Pages (from-to)10421–10437
Number of pages17
Issue number43
Early online date26 Sep 2017
Publication statusPublished - 25 Oct 2017
MoE publication typeA1 Journal article-refereed


  • cortex–muscle coherence
  • coticokinematic coherence
  • isometric contraction
  • magnetoencephalography
  • MEG
  • motor control
  • primary sensorimotor cortex

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