title: Piracetam affects facilitatory I-wave interaction in the human motor cortex.
abstract: OBJECTIVE
  To investigate by means of transcranial magnetic stimulation (TMS) the effect of a single oral dose of the GABA derivate piracetam on intracortical facilitatory I-wave interaction.
  
  
  METHODS
  The study was performed in 8 healthy volunteers. Before, 1, 3, 6, and 24 h after intake of 4000 mg piracetam, MEPs in the relaxed abductor digiti minimi muscle were elicited by a recently introduced double pulse TMS technique with a suprathreshold first and a subthreshold second stimulus. From interstimulus intervals of 0.5-5.1 ms 3 periods were observed in which MEP facilitation showed maxima - so-called peaks of I-wave interaction - and which were separated by two troughs with no facilitation. We studied the changes in timing and size of the peaks over time.
  
  
  RESULTS
  With piracetam, I-wave peaks showed a reduction in size as well as a shortening of the latencies at which the peaks occurred. Both changes were significant at 6 h after drug intake compared to baseline. The effects were partially reversible after 24 h.
  
  
  CONCLUSIONS
  The mode of action of piracetam within the nervous system is almost unknown. The peak size reduction was similar to effects that were seen under GABAergic drugs, although GABAergic properties of piracetam have not been observed so far. Shortening of the I-wave peak latencies is a new phenomenon. The results are discussed on the basis of the known therapeutic effects of piracetam in cortical myoclonus and as nootropic agent.
authors.affiliation: Department of Clinical Neurophysiology, University of Goettingen, Robert-Koch-Strasse 40, D-37075, Goettingen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Wischer
authors.forename: W
authors.initials: W
authors.lastname: Paulus
authors.forename: M
authors.initials: M
authors.lastname: Sommer
authors.forename: F
authors.initials: F
authors.lastname: Tergau
mesh_terms: D000328:Adult; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000187:drug effects; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D009044:Motor Cortex / Q000187:drug effects* / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010812:Physical Stimulation; D010889:Piracetam / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives
chemical_list: D005680:gamma-Aminobutyric Acid; D010889:Piracetam