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Lorazepam induces an atypical dissociation of visual and auditory event-related potentialsDepartamento de Psicobiologia, UNIFESP, Brazil
Setor de Neurofisiologia Clínica, Departamento de Neurologia, UNIFESP, São Paulo, Brazil
Departamento de Psicobiologia, UNIFESP, Brazil
Departamento Psicobiologia, UNIFESP R. Napoleão de Barros, 925 CEP 04024-002 São Paulo Brazil ofabueno{at}psicobio.epm.br Lorazepam has been reported to atypically disrupt visual processing compared to other benzodiazepines (BZs), but it is not known to what extent this effect extends to impairment in other modalities. Our objective was to compare the effects of lorazepam with those of flunitrazepam, a BZ with standard effects, on visual and auditory event-related potentials (ERPs) using the same paradigm. The study followed a placebocontrolled, double-blind, parallel group-design and involved single oral doses of lorazepam (2.0 mg), flunitrazepam (1.2 mg) and placebo. Thirty-six young, healthy subjects completed a test battery before and after treatment including classic behavioural tests, visual and auditory ERPs. Both drugs led to comparable alterations on behavioural tests and double-dissociations were found, indicating that the doses used were equipotent: lorazepam was more deleterious than flunitrazepam and placebo in fragmented shape identification, while simple reaction times were prolonged for flunitrazepam in comparison to lorazepam and placebo. Effects on P3 latencies were also distinct: alterations in both modalities for flunitrazepam were equivalent and greater than placebo's. In contrast, lorazepam at the frontal and central electrode sites led to greater changes in visual than in auditory latency, and also to longer visual latencies than flunitrazepam and placebo, but lorazepam's auditory latency effects were only different to placebo's at the parietal electrode site. Peripheral visual changes were not responsible for these effects. Differences in the impairment profile between equipotent doses of lorazepam and flunitrazepam suggests that lorazepam induces atypical central visual processing changes.
Key Words: benzodiazepines • event-related potentials • ERP • flunitrazepam • lorazepam • P3 • P100 • vision
Journal of Psychopharmacology, Vol. 17, No. 1,
31-40 (2003) This article has been cited by other articles:
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