Time-frequency analysis of short-lasting modulation of EEG induced by intracortical and transcallosal paired TMS over motor areas

Paolo Manganotti, Emanuela Formaggio, Silvia Francesca Storti, Daniele de Massari, Alessandro Zamboni, Alessandra Bertoldo, Antonio Fiaschi, Gianna Maria Toffolo

Research output: Contribution to journalArticlepeer-review


Dynamic changes in spontaneous electroencephalogram (EEG) rhythms can be seen to occur with a high rate of variability. An innovative method to study brain function is by triggering oscillatory brain activity with transcranial magnetic stimulation (TMS). EEG-TMS coregistration was performed on five healthy subjects during a 1-day experimental session that involved four steps: baseline acquisition, unconditioned single-pulse TMS, intracortical inhibition (ICI, 3 ms) paired-pulse TMS, and transcallosal stimulation over left and right primary motor cortex (M1). A time-frequency analysis based on the wavelet method was used to characterize rapid modifications of oscillatory EEG rhythms induced by TMS. Single, paired, and transcallosal TMS applied on the sensorimotor areas induced rapid desynchronization over the frontal and central-parietal electrodes mainly in the alpha and beta bands, followed by a rebound of synchronization, and rapid synchronization of delta and theta activity. Wavelet analysis after a perturbation approach is a novel way to investigate modulation of oscillatory brain activity. The main findings are consistent with the concept that the human motor system may be based on networklike oscillatory cortical activity and might be modulated by single, paired, and transcallosal magnetic pulses applied to M1, suggesting a phenomenon of fast brain activity resetting and triggering of slow activity.

Original languageEnglish
Pages (from-to)2475-2484
Number of pages10
JournalJournal of Neurophysiology
Issue number9
Publication statusPublished - May 1 2012


  • Paired pulse
  • Single pulse
  • Transcallosal stimulation

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)


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