Entrainment of brain oscillations by transcranial alternating current stimulation.
Novel methods for neuronal entrainment [1-4] provide the unique opportunity to modulate perceptually relevant brain oscillations [5, 6] in a frequency-specific manner and to study their functional impact on distinct cognitive functions. Recently, evidence has emerged that tACS (transcranial alternating current stimulation) can modulate cortical oscillations [7-9]. However, the study of electrophysiological effects has been hampered so far by the absence of concurrent electroencephalogram (EEG) recordings. Here, we applied 10 Hz tACS to the parieto-occipital cortex and utilized simultaneous EEG recordings to study neuronal entrainment during stimulation. We pioneer a novel approach for simultaneous tACS-EEG recordings and successfully separate stimulation artifacts from ongoing and event-related cortical activity. Our results reveal that 10 Hz tACS increases parieto-occipital alpha activity and synchronizes cortical oscillators with similar intrinsic frequencies to the entrainment frequency. Additionally, we demonstrate that tACS modulates target detection performance in a phase-dependent fashion highlighting the causal role of alpha oscillations for visual perception.
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany. Electronic address: r.helfrich@uke.de.
Randolph F
RF
Helfrich
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
Till R
TR
Schneider
Experimental Psychology Lab, Center for Excellence "Hearing4all," European Medical School, University of Oldenburg, 26111 Oldenburg, Germany; Research Center Neurosensory Science, University of Oldenburg, 26111 Oldenburg, Germany.
Stefan
S
Rach
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
Sina A
SA
Trautmann-Lengsfeld
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
Andreas K
AK
Engel
Experimental Psychology Lab, Center for Excellence "Hearing4all," European Medical School, University of Oldenburg, 26111 Oldenburg, Germany; Research Center Neurosensory Science, University of Oldenburg, 26111 Oldenburg, Germany.
Christoph S
CS
Herrmann
D016477:Artifacts; D001921:Brain / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D014796:Visual Perception / Q000502:physiology*