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A single dose of lorazepam reduces paired‐pulse suppression of median nerve evoked somatosensory evoked potentials
Author(s) -
Stude Philipp,
Lenz Melanie,
Höffken Oliver,
Tegenthoff Martin,
Dinse Hubert
Publication year - 2016
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13224
Subject(s) - somatosensory system , lorazepam , somatosensory evoked potential , neuroscience , inhibitory postsynaptic potential , transcranial magnetic stimulation , stimulation , stimulus (psychology) , pulse (music) , psychology , electrophysiology , median nerve , chemistry , anesthesia , medicine , physics , detector , optics , psychotherapist , psychiatry
Paired‐pulse behaviour in the somatosensory cortex is an approach to obtain insights into cortical processing modes and to obtain markers of changes of cortical excitability attributable to learning or pathological states. Numerous studies have demonstrated suppression of the response to the stimulus that follows a first one after a short interval, but the underlying mechanisms remain elusive, although there is agreement that GABA ergic mechanisms seem to play a crucial role. We therefore aimed to explore the influence of the GABA A agonist lorazepam on paired‐pulse somatosensory evoked potentials ( SEP s). We recorded and analysed SEP s after paired median nerve stimulation in healthy individuals before and after they had received a single dose of 2.5 mg of lorazepam as compared with a control group receiving placebo. Paired‐pulse suppression was expressed as a ratio of the amplitudes of the second and the first peaks. We found that, after lorazepam application, paired‐pulse suppression of the cortical N20 component remained unchanged, but suppression of the N20–P25 complex was significantly reduced, indicative of GABA ergic involvement in intracortical processing. Our data suggest that lorazepam most likely enhances inhibition within the cortical network of interneurons responsible for creating paired‐pulse suppression, leading to reduced inhibitory drive with a subsequently reduced amount of suppression. The results provide further evidence that GABA A ‐mediated mechanisms are involved in the generation of median nerve evoked paired‐pulse suppression.