Abstract
Materials and methods Twelve healthy male subjects (median age 35 years) were studied at baseline, following i.v. lorazepam administration and after reversal of the benzodiazepine effects with i.v. flumazenil. Lorazepam was given at a low-dose in one subject (0.0225 mg/kg bolus + 2 μg/kg/h infusion) and at a high-dose (0.045 mg/kg bolus + 2.6 μg/kg/h infusion) in the rest. Threshold (Thr) was measured at 1% steps. SPs were investigated with two complementary methods. First, SPs were elicited using a wide range of stimulus intensities (SIs) (from 5 to 100% maximum SI at 5% increments). At each SI, 4 SPs were obtained and the average value of SP duration was used to construct a stimulus/ response (S/R) curve of SI vs. SP. The resulting S/R curves were then fitted to a Boltzman function, the best-fit values of which were statistically compared for each experimental condition (i.e., baseline vs. lorazepam vs. flumazenil). Second, a large number of SPs was elicited during the three experimental conditions using blocks of 4 stimuli with an intensity alternating between MT and 200% MT. This method was employed so as to reveal the dynamic, time-varying effects of lorazepam and flumazenil on SP duration at two stimulus intensity (SI) levels. Finally, active MEP recruitment curves were constructed and fitted to a Boltzman function the best-fit values of which were statistically compared for each experimental condition.
Highlights
TMS studies on the CNS effects of benzodiazepines have provided contradictory results
The resulting stimulus/ response (S/R) curves were fitted to a Boltzman function, the best-fit values of which were statistically compared for each experimental condition
The Max value of the silent period (SP) S/R curve decreased from 250.8 ± 30.3 ms at baseline to 206.8 ± 14.6 ms post-lorazepam (p < 0.01)
Summary
Vasilios Kimiskidis*1, Sotirios Papagiannopoulos, Dimitrios Kazis, Eleni Tsoukali, Georgios Theodoridis, Ioannis Niopas, Georgios Vassiliadis, Kyriaki Sotirakoglou and Aristidis Kazis. Address: 13rd Department of Neurology, Aristotle University, "George Papanikolaou" Thessaloniki, Greece, 24th Department of Neurology, Aristotle University of Thessaloniki, Greece, 3Toxicology Department, Aristotle University of Thessaloniki, Greece, 4Pharmacology Department, Aristotle University of Thessaloniki, Greece and 5Agricultural University of Athens, Greece. Published: 28 February 2006 Annals of General Psychiatry 2006, 5(Suppl 1):S226 doi:10.1186/1744-859X-5-S1-S226. cecocIonnteternat/tfiolensa/lpdSof/c1i7e4ty4-o8n59BXra-5in-Sa1n-dfuBlle.phdafv">iohuerr:e2In.onn Brain and Behaviour Meeting abstracts – A single PDF containing all abstracts in this Supplement is available
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