Transcranial random noise stimulation-induced plasticity is NMDA-receptor independent but sodium-channel blocker and benzodiazepines sensitive.
BACKGROUND
Application of transcranial random noise stimulation (tRNS) between 0.1 and 640 Hz of the primary motor cortex (M1) for 10 min induces a persistent excitability increase lasting for at least 60 min. However, the mechanism of tRNS-induced cortical excitability alterations is not yet fully understood.


OBJECTIVE
The main aim of this study was to get first efficacy data with regard to the possible neuronal effect of tRNS.


METHODS
Single-pulse transcranial magnetic stimulation (TMS) was used to measure levels of cortical excitability before and after combined application of tRNS at an intensity of 1 mA for 10 min stimulation duration and a pharmacological agent (or sham) on eight healthy male participants.


RESULTS
The sodium channel blocker carbamazepine showed a tendency toward inhibiting MEPs 5-60 min poststimulation. The GABA A agonist lorazepam suppressed tRNS-induced cortical excitability increases at 0-20 and 60 min time points. The partial NMDA receptor agonist D-cycloserine, the NMDA receptor antagonist dextromethorphan and the D2/D3 receptor agonist ropinirole had no significant effects on the excitability increases seen with tRNS.


CONCLUSIONS
In contrast to transcranial direct current stimulation (tDCS), aftereffects of tRNS are seem to be not NMDA receptor dependent and can be suppressed by benzodiazepines suggesting that tDCS and tRNS depend upon different mechanisms.
Department of Clinical Neurophysiology, Georg-August University Göttingen, Germany ; Department of Epileptology, University of Bonn Bonn, Germany.
Leila
L
Chaieb
Department of Clinical Neurophysiology, Georg-August University Göttingen, Germany.
Andrea
A
Antal
Department of Clinical Neurophysiology, Georg-August University Göttingen, Germany.
Walter
W
Paulus
D-cycloserine (D-CYC: partial NMDA receptor agonist); carbamazepine (CBZ: sodium channel blocker); dextromethorphan (DMO: NMDA receptor antagonist); lorazepam (LOR: GABAA receptor agonist); ropinirole (ROP: D2/D3 receptor agonist); transcranial direct current stimulation (tDCS); transcranial magnetic stimulation (TMS); transcranial random noise stimulation (tRNS)