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Influence of the N-methyl-D-aspartate antagonist memantine on human motor cortex excitability
P Schwenkreis1, K Witscher, F Janssen
1Department of Neurology, Ruhr-University Bochum, BG-Kliniken Bergmannsheil, Germany. peter.u.schwenkreis@ruhr-uni-bochum.de
Abstract:
The aim of our study was to investigate the effect of the N-methyl-D-aspartate (NMDA) antagonist memantine on motor excitability in humans. Seven healthy volunteers received memantine or placebo, respectively, over a period of 8 days. At day 8, transcranial magnetic stimulation (TMS) was performed using a paired pulses paradigm in order to assess intracortical inhibition and facilitation. Additionally, motor threshold and silent period duration after TMS were measured as well as M waves, F waves and peripheral silent period after electrical peripheral nerve stimulation. Intracortical inhibition was enhanced, and intracortical facilitation reduced after memantine ingestion in comparison to placebo, whereas no significant difference could be observed regarding the other neurophysiological parameters. We conclude that the NMDA receptor is involved in the regulation of excitability of intracortical interneuronal circuits.
Insights
Memantine, an N-methyl-D-aspartate (NMDA) receptor antagonist, enhanced intracortical inhibition and reduced facilitation in healthy volunteers. This suggests NMDA receptors regulate intracortical interneuronal excitability.
Area of Science:
- Neuroscience
- Human Motor Control
- Pharmacology
Background:
- The N-methyl-D-aspartate (NMDA) receptor plays a crucial role in synaptic plasticity and neuronal excitability.
- Understanding the role of NMDA receptors in modulating motor cortex excitability is essential for developing targeted therapies.
Purpose of the Study:
- To investigate the effects of the NMDA antagonist memantine on human motor cortex excitability.
- To assess changes in intracortical inhibition and facilitation following memantine administration.
Main Methods:
- Seven healthy volunteers participated in a double-blind, placebo-controlled study.
- Transcranial magnetic stimulation (TMS) with a paired pulses paradigm was used to measure intracortical inhibition and facilitation.
- Motor threshold, silent period duration, M waves, F waves, and peripheral silent period were also assessed.
Main Results:
- Memantine significantly enhanced intracortical inhibition compared to placebo.
- Memantine significantly reduced intracortical facilitation.
- No significant differences were observed in other neurophysiological parameters between memantine and placebo groups.
Conclusions:
- The NMDA receptor is implicated in the regulation of intracortical interneuronal circuit excitability.
- Memantine's effects on motor excitability highlight the role of glutamatergic neurotransmission in motor control.