Human brain connectivity during single and paired pulse transcranial magnetic stimulation

Florinda Ferreri, Patrizio Pasqualetti, Sara Määttä, David Ponzo, Fabio Ferrarelli, Giulio Tononi, Esa Mervaala, Carlo Miniussi, Paolo Maria Rossini

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: Intracortical inhibition (SICI) and facilitation (ICF) in the human motor cortex can be measured using a paired pulse transcranial magnetic stimulation (ppTMS) protocol. Recently, a technical device has been introduced, which allows recording electroencephalographic (EEG) responses to TMS of a given scalp site. The latency, amplitude and scalp topography of such responses are considered a reflection of cortico-cortical connectivity and functional state. The aim of the present study is to better characterize the neuronal circuits underlying motor cortex connectivity as well as the mechanisms regulating its balance between inhibition and facilitation by means of EEG navigated-ppTMS coregistration. Methods: Sub-threshold and supra-threshold single and ppTMS of the left primary motor cortex were carried out during a multi-channel EEG recording on 8 healthy volunteers; the between-pulse intervals used in the paired pulse trials were 3 (for SICI) and 11. ms (for ICF). Motor evoked potentials (MEPs) from the opposite hand were simultaneously recorded. Results: Single and ppTMS induced EEG responses characterized by a sequence of negative deflections peaking at approximately 7, 18, 44, 100 and 280. ms alternated with positive peaks at approximately 13, 30, 60 and 190. ms post-TMS. Moreover, ppTMS modulated both EEG evoked activity and MEPs. Amplitude variability of EEG responses was correlated with - and therefore might partially explain - amplitude variability of MEPs. Interpretation: EEG-ppTMS is a promising tool to better characterize the neuronal circuits underlying cortical effective connectivity as well as the mechanisms regulating the balance between inhibition and facilitation within the human cortices and the corticospinal pathway.

Original languageEnglish
Pages (from-to)90-102
Number of pages13
JournalNeuroImage
Volume54
Issue number1
DOIs
Publication statusPublished - Jan 1 2011

Keywords

  • Cortical effective connectivity
  • EEG
  • Motor cortex
  • Navigated transcranial magnetic stimulation
  • SICI/ICF

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Neurology

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