Increasing static motor corticospinal excitability and concomitant blockade of PAS-induced facilitation by combining NMDA-R and L-VGCC blockade

Introduction: Paired associative stimulation (PAS) induced motor cortex plasticity may be blocked by administration of the NMDA-R-antagonist Dextromethorphan (DXM, Stefan et al 2002) or the L-type-Ca-channel-blocker Nimodipine (NDP, Wolters et al 2003). Here we tested the effect of the combined application of DXM and NDP on static corticospinal excitability (SCSE) and PAS-induced plasticity. Methods: 11 healthy subjects (six women, aged 18 – 29 years, mean 21.8 ± 3.1 years) were tested in four pseudorandomized, single-blinded sessions each. In three sessions premedication (Exp. 1: placebo (PBO), Exp. 2: 120 mg D…