title: Carbamazepine reduces short-interval interhemispheric inhibition in healthy humans.
abstract: OBJECTIVE
  We sought to elucidate the influence of centrally active drugs on interhemispheric inhibition (IHI) between primary motor cortices in healthy humans.
  
  
  METHODS
  We therefore studied IHI before and 2h after intake of a single oral dose of carbamazepine, dextrometorphane, lorazepam, or placebo and compared it with the well known results for short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). Drugs were tested in separate sessions and in random order.
  
  
  RESULTS
  While SICI and ICF were not altered by carbamazepine, IHI was reduced at the interstimulus interval of 8 ms. Dextrometorphane tended to enhance SICI and to reduce ICF and had no effect on IHI. Lorazepam reduced ICF as expected and enhanced IHI at the long intervals of 50 and 80ms. A moderate trend for interhemispheric facilitation was inconsistently observed at the interval 2 ms and blocked by carbamazepine. In addition, carbamazepine increased the motor threshold.
  
  
  CONCLUSIONS
  We conclude that circuits mediating short interstimulus intervals of IHI are susceptible to sodium channel blockade.
  
  
  CONCLUSIONS
  The results increase our knowledge of interhemispheric transmission.
authors.affiliation: Department of Clinical Neurophysiology, University of Göttingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Sommer
authors.forename: Elena
authors.initials: E
authors.lastname: Gileles
authors.forename: Kathrin
authors.initials: K
authors.lastname: Knappmeyer
authors.forename: Holger
authors.initials: H
authors.lastname: Rothkegel
authors.forename: Rafael
authors.initials: R
authors.lastname: Polania
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
mesh_terms: D000328:Adult; D002220:Carbamazepine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000187:drug effects* / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
chemical_list: D002220:Carbamazepine