title: Low-Frequency Repetitive Transcranial Magnetic Stimulation Targeted to Premotor Cortex Followed by Primary Motor Cortex Modulates Excitability Differently Than Premotor Cortex or Primary Motor Cortex Stimulation Alone.
abstract: OBJECTIVE
  The excitability of primary motor cortex (M1) can be modulated by applying low-frequency repetitive transcranial magnetic stimulation (rTMS) over M1 or premotor cortex (PMC). A comparison of inhibitory effect between the two locations has been reported with inconsistent results. This study compared the response secondary to rTMS applied over M1, PMC, and a combined PMC + M1 stimulation approach which first targets stimulation over PMC then M1.
  
  
  METHODS
  Ten healthy participants were recruited for a randomized, cross-over design with a one-week washout between visits. Each visit consisted of a pretest, an rTMS intervention, and a post-test. Outcome measures included short interval intracortical inhibition (SICI), intracortical facilitation (ICF), and cortical silent period (CSP). Participants received one of the three interventions in random order at each visit including: 1-Hz rTMS at 90% of resting motor threshold to: M1 (1200 pulses), PMC (1200 pulses), and PMC + M1 (600 pulses each, 1200 total).
  
  
  RESULTS
  PMC + M1 stimulation resulted in significantly greater inhibition than the other locations for ICF (P = 0.005) and CSP (P < 0.001); for SICI, increased inhibition (group effect) was not observed after any of the three interventions, and there was no significant difference between the three interventions.
  
  
  CONCLUSIONS
  The results indicate that PMC + M1 stimulation may modulate brain excitability differently from PMC or M1 alone. CSP was the assessment measure most sensitive to changes in inhibition and was able to distinguish between different inhibitory protocols. This work presents a novel procedure that may have positive implications for therapeutic interventions.
authors: Programs in Physical Therapy and Rehabilitation Science, Department of Physical Medicine and Rehabilitation, School of Medicine, University of Minnesota, Minneapolis, MN, USA.
authors: Mo
authors: M
authors: Chen
authors: Programs in Physical Therapy and Rehabilitation Science, Department of Physical Medicine and Rehabilitation, School of Medicine, University of Minnesota, Minneapolis, MN, USA.|Department of Psychiatry and Behavioral Sciences of the University of Texas Medical School at Houston, Houston, TX, USA.
authors: Huiqiong
authors: H
authors: Deng
authors: Programs in Physical Therapy and Rehabilitation Science, Department of Physical Medicine and Rehabilitation, School of Medicine, University of Minnesota, Minneapolis, MN, USA.
authors: Rebekah L
authors: RL
authors: Schmidt
authors: Programs in Physical Therapy and Rehabilitation Science, Department of Physical Medicine and Rehabilitation, School of Medicine, University of Minnesota, Minneapolis, MN, USA.
authors: Teresa J
authors: TJ
authors: Kimberley
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D018709:Statistics, Nonparametric; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Brain excitability; neuromodulation; premotor cortex; primary motor cortex; repetitive transcranial magnetic stimulation