Effects of antiepileptic drugs on cortical excitability in humans: A TMS-EMG and TMS-EEG study

Hum Brain Mapp. 2019 Mar;40(4):1276-1289. doi: 10.1002/hbm.24448. Epub 2018 Dec 13.


Brain responses to transcranial magnetic stimulation (TMS) recorded by electroencephalography (EEG) are emergent noninvasive markers of neuronal excitability and effective connectivity in humans. However, the underlying physiology of these TMS-evoked EEG potentials (TEPs) is still heavily underexplored, impeding a broad application of TEPs to study pathology in neuropsychiatric disorders. Here we tested the effects of a single oral dose of three antiepileptic drugs with specific modes of action (carbamazepine, a voltage-gated sodium channel (VGSC) blocker; brivaracetam, a ligand to the presynaptic vesicle protein VSA2; tiagabine, a gamma-aminobutyric acid (GABA) reuptake inhibitor) on TEP amplitudes in 15 healthy adults in a double-blinded randomized placebo-controlled crossover design. We found that carbamazepine decreased the P25 and P180 TEP components, and brivaracetam the N100 amplitude in the nonstimulated hemisphere, while tiagabine had no effect. Findings corroborate the view that the P25 represents axonal excitability of the corticospinal system, the N100 in the nonstimulated hemisphere propagated activity suppressed by inhibition of presynaptic neurotransmitter release, and the P180 late activity particularly sensitive to VGSC blockade. Pharmaco-physiological characterization of TEPs will facilitate utilization of TMS-EEG in neuropsychiatric disorders with altered excitability and/or network connectivity.

Keywords: TMS-evoked EEG response; brivaracetam; carbamazepine; electroencephalography; excitability; human cortex; tiagabine; transcranial magnetic stimulation.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anticonvulsants / pharmacology*
  • Carbamazepine / pharmacology
  • Cerebral Cortex / drug effects*
  • Cerebral Cortex / physiology
  • Cross-Over Studies
  • Double-Blind Method
  • Electroencephalography / drug effects
  • Electroencephalography / methods
  • Electromyography / drug effects
  • Electromyography / methods
  • Evoked Potentials / drug effects*
  • Evoked Potentials / physiology
  • Healthy Volunteers
  • Humans
  • Male
  • Pyrrolidinones / pharmacology
  • Tiagabine / pharmacology
  • Transcranial Magnetic Stimulation / drug effects*
  • Transcranial Magnetic Stimulation / methods
  • Young Adult


  • Anticonvulsants
  • Pyrrolidinones
  • Carbamazepine
  • brivaracetam
  • Tiagabine