title: Desynchronization does not contribute to intracortical inhibition and facilitation: a paired-pulse paradigm study combined with TST.
abstract: The paired-pulse (PP) transcranial magnetic stimulation (TMS) paradigms allow the exploration of the motor cortex physiology. The triple stimulation technique (TST) improves conventional TMS by reducing effects of desynchronization of motor neuron discharges allowing a precise evaluation of the corticospinal conduction. The objective of our study was to explore PP TMS paradigms combined with the TST to study whether the desynchronization contributes to these phenomena and whether the combined TMS-TST protocol could improve the consistency of responses. We investigated the PP paradigms of short intracortical inhibition (SICI) with 2 ms interstimulus interval (ISI) and of intracortical facilitation (ICF) with 10 ms ISI in 22 healthy subjects applying either conventional TMS alone or combined with the TST protocol. The results of the PP paradigms combined with the TST of SICI and ICF do not differ from those with conventional TMS. However, combining the PP paradigm with the TST reduces their variability. These results speak against a contribution of the desynchronization of motor neuron discharges to the PP paradigms of SICI and ICF. Combining the PP TMS paradigm with the TST may improve their consistency, but the interindividual variability remains such that it precludes their utility for clinical practice.NEW & NOTEWORTHYCombining the triple stimulation technique with the paired-pulse stimulation paradigm improves the consistency of short intracortical inhibition and facilitation and could be useful in research, but the interindividual variability precludes their utility for clinical practice. Our findings do not suggest that desynchronization of descending discharges following transcranial magnetic stimulation contributes to short intracortical inhibition or intracortical facilitation.
authors.affiliation: Neurology Service, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.|Faculté de Biologie et de Médecine, Doctoral School, Université de Lausanne, Lausanne, Switzerland; and.
authors.forename: L
authors.initials: L
authors.lastname: Caranzano
authors.affiliation: Neurology Service, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: M A
authors.identifier: 0000-0002-0789-5308
authors.initials: MA
authors.lastname: Stephan
authors.affiliation: Division of Geriatrics, Department of Internal Medicine, Rehabilitation, and Geriatrics, University Hospitals and University of Geneva, Geneva, Switzerland.
authors.forename: F R
authors.initials: FR
authors.lastname: Herrmann
authors.affiliation: Neurology Service, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; David.Benninger@chuv.ch.
authors.forename: D H
authors.identifier: 0000-0002-1049-9533
authors.initials: DH
authors.lastname: Benninger
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: corticospinal excitability; motor-evoked potential; spinal motor neurons; transcranial magnetic stimulation; triple stimulation technique