Ongoing cumulative effects of single TMS pulses on corticospinal excitability: An intra- and inter-block investigation

Maria Concetta Pellicciari, Carlo Miniussi, Clarissa Ferrari, Giacomo Koch, Marta Bortoletto

Research output: Contribution to journalArticlepeer-review


Objective: To evaluate the effects of several single TMS pulses, delivered at two different inter-trial intervals (ITIs), on corticospinal excitability. Methods: Twelve healthy volunteers participated in two experimental sessions, during which TMS pulses were delivered at random or at fixed ITIs. The TMS single pulse-induced modulation of corticospinal output (motor evoked potential amplitude - MEP) was evaluated on-line. Each session began with a baseline block, followed by 10 blocks, with 20 TMS pulses each. Intra- and inter-block effects were valuated using an ANOVA model, through nested random effect on subjects considering the subject-specific variability. Results: The delivery of successive TMS pulses significantly changed both intra-block and inter-block cortical excitability, as demonstrated by an increase in the amplitude of MEPs (p 2 =1) and nearly linear trend for intra-block levels (R 2 =0.97). The MEPs significantly increased when the TMS pulses were delivered at both random and fixed ITIs. Conclusions: Single TMS pulses induce cumulative changes in neural activity during the same stimulation, resulting in a motor cortical excitability increase. Significance: Particular attention should be taken when several single TMS pulses are delivered in research and clinical settings for diagnostic and therapeutic purposes.

Original languageEnglish
JournalClinical Neurophysiology
Publication statusAccepted/In press - 2015


  • Corticospinal excitability
  • Motor evoked potentials (MEP)
  • Random and fixed inter-trial interval
  • Single pulse
  • Transcranial magnetic stimulation (TMS)

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology
  • Physiology (medical)
  • Sensory Systems


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