Williams, Kathleen Anne

[["dc.bibliographiccitation.firstpage","88"],["dc.bibliographiccitation.journal","NeuroImage"],["dc.bibliographiccitation.lastpage","107"],["dc.bibliographiccitation.volume","141"],["dc.contributor.author","Cabral-Calderin, Yuranny"],["dc.contributor.author","Williams, Kathleen A."],["dc.contributor.author","Opitz, Alexander"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Wilke, Melanie"],["dc.date.accessioned","2017-09-07T11:43:41Z"],["dc.date.available","2017-09-07T11:43:41Z"],["dc.date.issued","2016"],["dc.description.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 ~ 8 min). Subjects received tACS at different frequencies (10, 16, 40 Hz) 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 40 Hz 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 10 Hz tACS increased and 40 Hz 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."],["dc.identifier.doi","10.1016/j.neuroimage.2016.07.005"],["dc.identifier.gro","3151615"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8428"],["dc.language.iso","en"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","1053-8119"],["dc.title","Transcranial alternating current stimulation modulates spontaneous low frequency fluctuations as measured with fMRI"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","124"],["dc.bibliographiccitation.journal","Journal of Visualized Experiments"],["dc.contributor.author","Williams, Kathleen A."],["dc.contributor.author","Cabral-Calderin, Yuranny"],["dc.contributor.author","Schmidt-Samoa, Carsten"],["dc.contributor.author","Weinrich, Christiane Anne"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Wilke, Melanie"],["dc.date.accessioned","2018-10-10T09:02:41Z"],["dc.date.available","2018-10-10T09:02:41Z"],["dc.date.issued","2017"],["dc.description.abstract","Transcranial alternating current stimulation (tACS) is a promising tool for noninvasive investigation of brain oscillations. TACS employs frequency-specific stimulation of the human brain through current applied to the scalp with surface electrodes. Most current knowledge of the technique is based on behavioral studies; thus, combining the method with brain imaging holds potential to better understand the mechanisms of tACS. Because of electrical and susceptibility artifacts, combining tACS with brain imaging can be challenging, however, one brain imaging technique that is well suited to be applied simultaneously with tACS is functional magnetic resonance imaging (fMRI). In our lab, we have successfully combined tACS with simultaneous fMRI measurements to show that tACS effects are state, current, and frequency dependent, and that modulation of brain activity is not limited to the area directly below the electrodes. This article describes a safe and reliable setup for applying tACS simultaneously with visual task fMRI studies, which can lend to understanding oscillatory brain function as well as the effects of tACS on the brain."],["dc.fs.pkfprnr","60165"],["dc.identifier.doi","10.3791/55866"],["dc.identifier.fs","633451"],["dc.identifier.pmid","28605386"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15927"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.eissn","1940-087X"],["dc.title","Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]