Safety of 5 kHz tACS.
BACKGROUND
Sinusoidal transcranial alternating current stimulation (tACS) at 5 kHz applied for 10 min at 1 mA intensity over the hand area of the primary motor cortex (M1) results in sustained changes in cortical excitability as previously demonstrated.


OBJECTIVE
Here we have assessed safety aspects of this stimulation method by measuring neuron-specific enolase (NSE) levels, examining electroencephalogram (EEG) traces and analyzing anatomical data by using magnetic resonance imaging (MRI).


METHODS
Altogether 18 healthy volunteers participated in the study. tACS was applied at 5 kHz for a duration of 10 min over the left M1 at an intensity of 1 mA.


RESULTS
After stimulation no significant changes were detected in NSE levels, no structural alterations were observed in the anatomical scans and no pathological changes were found in the EEG recordings.


CONCLUSIONS
Our data imply that the application of tACS is safe at least within these parameters and with these applied protocols.
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany; Department of Epileptology, University of Bonn, Bonn, Germany.
Leila
L
Chaieb
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany. Electronic address: AAntal@gwdg.de.
Andrea
A
Antal
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany; Department of Psychology, University of Milan Bicocca, Milan, Italy.
Alberto
A
Pisoni
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany.
Catarina
C
Saiote
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany.
Alexander
A
Opitz
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany; Institute of Medical Psychology and Medical Sociology, University Medical Center, Georg-August University of Göttingen, Göttingen, Germany.
Géza Gergely
GG
Ambrus
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany.
Niels
N
Focke
Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch-Str. 40, Göttingen 37075, Germany.
Walter
W
Paulus
D000328:Adult; D004558:Electric Stimulation / Q000009:adverse effects* / Q000379:methods*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D010751:Phosphopyruvate Hydratase / Q000097:blood*; D010865:Pilot Projects; D055815:Young Adult
D010751:Phosphopyruvate Hydratase
Alternating current stimulation; Human; M1; Side effects