title: Effects of diazepam, baclofen and thiopental on the silent period evoked by transcranial magnetic stimulation in humans.
abstract: The cortical silent period evoked by magnetic transcranial stimulation and the peripheral silent period were studied in healthy subjects after intravenous injection of diazepam, baclofen or thiopental. None of the drugs tested changed the peripheral silent period. But, unexpectedly, diazepam significantly shortened the cortical silent period, the inhibitory effect lasting about 30 min. In experiments using paired transcranial stimuli, the conditioning shock inhibited the test response to a similar extent with and without diazepam. Although baclofen did not change the cortical silent period, it reduced the size of the H reflex in the forearm muscles. Thiopental also left the duration of the cortical silent period unchanged. These findings show that the cortical silent period can be modified pharmacologically. Diazepam possibly shortens the silent period by modulating GABA A receptors at a subcortical site.
authors.affiliation: Dipartimento di Scienze Neurologiche, Università di Roma, La Sapienza, Rome, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Inghilleri
authors.forename: A
authors.initials: A
authors.lastname: Berardelli
authors.forename: P
authors.initials: P
authors.lastname: Marchetti
authors.forename: M
authors.initials: M
authors.lastname: Manfredi
mesh_terms: D000328:Adult; D001418:Baclofen / Q000494:pharmacology*; D003975:Diazepam / Q000494:pharmacology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects*; D005442:Flumazenil / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology*; D018757:GABA Modulators / Q000494:pharmacology*; D006801:Humans; D008875:Middle Aged; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects; D013874:Thiopental / Q000494:pharmacology*; D050781:Transcranial Magnetic Stimulation
chemical_list: D018755:GABA Agonists; D018757:GABA Modulators; D005442:Flumazenil; D001418:Baclofen; D013874:Thiopental; D003975:Diazepam