Consolidation of human motor cortical neuroplasticity by D-cycloserine.
D-Cycloserine (CYC), a partial N-methyl-D-aspartate (NMDA) agonist, has been shown to improve cognitive functions in humans. However, the neurophysiological basis of this effect is unclear so far. We studied the impact of this drug on long-lasting after-effects of transcranial direct current (tDCS)-generated motor cortical excitability shifts, as revealed by transcranial magnetic stimulation-elicited motor-evoked potentials. While anodal tDCS enhances motor cortical excitability, cathodal tDCS diminishes it. Both effects seem to be NMDA receptor dependent. D-CYC selectively potentiated the duration of motor cortical excitability enhancements induced by anodal tDCS. D-CYC alone did not modulate excitability. The potency of this drug to consolidate neuronal excitability enhancements, most probably by stabilizing the strengthening of NMDA receptors, which is a probable neurophysiological derivate of learning processes, makes it an interesting substance to improve cognitive functions.
Nitsche
Michael A
MA
Department Clinical Neurophysiology, Georg-August-University, Goettingen, Germany. mnitsch1@gwdg.de
Jaussi
Wiebke
W
Liebetanz
David
D
Lang
Nicolas
N
Tergau
Frithjof
F
Paulus
Walter
W
D000328:Adult; D000963:Antimetabolites / Q000494:pharmacology*; D003523:Cycloserine / Q000494:pharmacology*; D004525:Efferent Pathways / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000187:drug effects; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000187:drug effects*; D009473:Neuronal Plasticity / Q000187:drug effects*; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D013569:Synapses / Q000187:drug effects
D000963:Antimetabolites; D016194:Receptors, N-Methyl-D-Aspartate; D003523:Cycloserine