Paper Info
Title
Transcranial alternating current stimulation modulates spontaneous low frequency fluctuations as measured with fMRI.
Abstract
Transcranial alternating current stimulation (tACS) is a promising tool for modulating brain oscillations. Combining tACS with functional magnetic resonance imaging (fMRI), we recently showed that tACS applied over the occipital cortex did not exert its strongest effect on regions below the electrodes, but mainly on more distant fronto-parietal regions. Theoretically, this effect could be explained by tACS-induced modulation of functional connectivity between directly stimulated areas and more distant but anatomically and functionally connected regions. In the present study, we aimed to characterize the effect of tACS on low frequency fMRI signal fluctuations. We employed simultaneous fMRI-tACS in 20 subjects during resting state (eyes open with central fixation for ~8min). Subjects received tACS at different frequencies (10, 16, 40Hz) and with different electrode montages (Cz-Oz, P5–P6) previously used in behavioral studies. Electric field simulations showed that tACS over Cz-Oz directly stimulates occipital cortex, while tACS over P5–P6 primarily targets parietal cortices. Group-level simulation-based functional connectivity maps for Cz-Oz and P5–P6 resembled the visual and fronto-parietal control resting-state networks, respectively. The effects of tACS were frequency and partly electrode montage dependent. In regions where frequency-dependent effects of tACS were observed, 10 and 40Hz tACS generally induced opposite effects. Most tACS effects on functional connectivity were observed between, as opposed to within, resting-state networks. The left fronto-parietal control network showed the most extensive frequency-dependent modulation in functional connectivity, mainly with occipito-parietal regions, where 10Hz tACS increased and 40Hz tACS decreased correlation values. Taken together, our results show that tACS modulates local spontaneous low frequency fluctuations and their correlations with more distant regions, which should be taken into account when interpreting tACS effects on brain function.
Year
DOI
Venue
2016
10.1016/j.neuroimage.2016.07.005
NeuroImage
Keywords
Field
DocType
tACS,Brain stimulation,fMRI,Oscillations,Entrainment,fALFF/ALFF,Intrinsic functional connectivity,Resting state,Cross-frequency coupling
Brain mapping,Neuroscience,Functional magnetic resonance imaging,Brain stimulation,Resting state fMRI,Transcranial alternating current stimulation,Psychology,Occipital lobe,Transcranial direct-current stimulation,Parietal lobe
Journal
Volume
ISSN
Citations 
141
1053-8119
2
PageRank 
References 
Authors
0.39
0
5
Name
Order
Citations
PageRank
Yuranny Cabral-Calderin130.78
Kathleen A. Williams220.39
Alexander Opitz3666.97
Peter Dechent4737.11
Melanie Wilke541.25