Wilke, Melanie

[["dc.bibliographiccitation.firstpage","94"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Human Brain Mapping"],["dc.bibliographiccitation.lastpage","121"],["dc.bibliographiccitation.volume","37"],["dc.contributor.author","Cabral-Calderin, Yuranny"],["dc.contributor.author","Weinrich, Christiane Anne"],["dc.contributor.author","Schmidt-Samoa, Carsten"],["dc.contributor.author","Poland, Eva"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Bähr, Mathias"],["dc.contributor.author","Wilke, Melanie"],["dc.date.accessioned","2017-09-07T11:54:45Z"],["dc.date.available","2017-09-07T11:54:45Z"],["dc.date.issued","2016"],["dc.description.abstract","Transcranial alternating current stimulation (tACS) has emerged as a promising tool for manipulating ongoing brain oscillations. While previous studies demonstrated frequency-specific effects of tACS on diverse cognitive functions, its effect on neural activity remains poorly understood. Here we asked how tACS modulates regional fMRI blood oxygenation level dependent (BOLD) signal as a function of frequency, current strength, and task condition. TACS was applied over the posterior cortex of healthy human subjects while the BOLD signal was measured during rest or task conditions (visual perception, passive video viewing and motor task). TACS was applied in a blockwise manner at different frequencies (10, 16, 60 and 80 Hz). The strongest tACS effects on BOLD activity were observed with stimulation at alpha (10 Hz) and beta (16 Hz) frequency bands, while effects of tACS at the gamma range were rather modest. Specifically, we found that tACS at 16 Hz induced BOLD activity increase in fronto-parietal areas. Overall, tACS effects varied as a function of frequency and task, and were predominantly seen in regions that were not activated by the task. Also, the modulated regions were poorly predicted by current density modeling studies. Taken together, our results suggest that tACS does not necessarily exert its strongest effects in regions below the electrodes and that region specificity might be achieved with tACS due to varying susceptibility of brain regions to entrain to a given frequency. (C) 2015 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc."],["dc.identifier.doi","10.1002/hbm.23016"],["dc.identifier.fs","618728"],["dc.identifier.gro","3141752"],["dc.identifier.isi","000369150500007"],["dc.identifier.pmid","26503692"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/14044"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/680"],["dc.language.iso","en"],["dc.notes.intern","WoS Import 2017-03-10 / Funder: Hermann and Lilly Schilling Foundation"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.notes.submitter","PUB_WoS_Import"],["dc.relation.eissn","1097-0193"],["dc.relation.issn","1065-9471"],["dc.rights","CC BY-NC-ND 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc-nd/4.0"],["dc.title","Transcranial Alternating Current Stimulation Affects the BOLD Signal in a Frequency and Task-dependent Manner"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","178"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Neuroforum"],["dc.bibliographiccitation.lastpage","189"],["dc.bibliographiccitation.volume","18"],["dc.contributor.author","Wilke, Melanie"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Schmidt-Samoa, Carsten"],["dc.date.accessioned","2017-09-07T11:43:41Z"],["dc.date.available","2017-09-07T11:43:41Z"],["dc.date.issued","2012"],["dc.description.abstract","Räumlicher Neglect stellt eine schwerwiegende Konsequenz von Hirnläsionen dar und ist durch die perzeptuelle und motorische Vernachlässigung einer Raumhälfte gekennzeichnet. Die zu Neglect führenden Läsionen treten innerhalb verteilter Netzwerke auf, die sich sowohl aus kortikalen Arealen (z.B. fronto-parietalen) als auch aus subkortikalen Strukturen (z.B. dem thalamischen Pulvinar) zusammensetzen. Die Entwicklung effektiver therapeutischer Strategien setzt ein detailliertes Verständnis der wichtigen Knotenpunkte und ihrer Interaktionen voraus. Allerdings sind präzise Informationen dazu aus Patientenstudien, aufgrund der Größe und Variabilität der mit Neglect assoziierten Läsionen, oft nur schwer zu erhalten. Experimentelle Modelle, bei denen definierte Gehirnregionen systematisch inaktiviert werden können, stellen daher eine wichtige Ergänzung zu den klassischen Läsionsstudien dar. Neglect-Modelle wurden beispielsweise bei nicht-humanen Primaten mithilfe lokaler, reversibler pharmakologischer Inaktivierung entwickelt, sowie bei gesunden Probanden mithilfe nicht-invasiver Stimulations-/Inaktivierungsmethoden wie der transkraniellen Magnetstimulation. In diesem Artikel diskutieren wir Theorien zum räumlichen Neglect, insbesondere die des hemisphärischen Ungleichgewichtes, und ihre empirische Evidenz. Ein Fokus liegt dabei auf Ergebnissen aus funktionellen Bildgebungsstudien, welche die Auswirkungen lokaler Läsionen auf dynamische Netzwerkaktivität untersuchen."],["dc.identifier.doi","10.1515/nf-2012-0103"],["dc.identifier.gro","3151609"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8423"],["dc.language.iso","de"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","1868-856X"],["dc.title","Experimentelle Modelle für räumlichen Neglect (Studien in humanen und nicht-humanen Primaten)"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","135"],["dc.bibliographiccitation.journal","Cortex"],["dc.bibliographiccitation.lastpage","149"],["dc.bibliographiccitation.volume","99"],["dc.contributor.author","Wilke, Melanie"],["dc.contributor.author","Schneider, Lukas"],["dc.contributor.author","Dominguez-Vargas, Adan-Ulises"],["dc.contributor.author","Schmidt-Samoa, Carsten"],["dc.contributor.author","Miloserdov, Kristina"],["dc.contributor.author","Nazzal, Ahmad"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Cabral-Calderin, Yuranny"],["dc.contributor.author","Scherberger, Hansjörg"],["dc.contributor.author","Kagan, Igor"],["dc.contributor.author","Bähr, Mathias"],["dc.date.accessioned","2018-02-08T10:49:56Z"],["dc.date.available","2018-02-08T10:49:56Z"],["dc.date.issued","2018-02"],["dc.description.abstract","Expansion of the dorsal pulvinar in humans and its anatomical connectivity suggests its involvement in higher-order cognitive and visuomotor functions. We investigated visuomotor performance in a 31 year old patient (M.B.) with a lesion centered on the medial portion of the dorsal pulvinar (left > right) due to an atypical Sarcoidosis manifestation. Unlike lesions with a vascular etiology, the lesion of M.B. did not include primary sensory or motor thalamic nuclei. Thus, this patient gave us the exceedingly rare opportunity to study the contribution of the dorsal pulvinar to visuomotor behavior in a human without confounding losses in primary sensory or motor domains. We investigated reaching, saccade and visual decision making performance. Patient data in each task was compared to at least seven age matched healthy controls. While saccades were hypometric towards both hemifields, the patient did not show any spatial choice bias or perceptual deficits. At the same time, he exhibited reach and grasp difficulties, which shared features with both, parietal and cerebellar damage. In particular, he had problems to form a precision grip and exhibited reach deficits expressed in decreased accuracy, delayed initiation and prolonged movement durations. Reach deficits were similar in foveal and extrafoveal viewing conditions and in both visual hemifields but were stronger with the right hand. These results suggest that dorsal pulvinar function in humans goes beyond its subscribed role in visual cognition and is critical for the programming of voluntary actions with the hands."],["dc.identifier.doi","10.1016/j.cortex.2017.10.011"],["dc.identifier.pmid","29216478"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/12057"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.doi","10.1016/j.cortex.2017.10.011"],["dc.relation.eissn","1973-8102"],["dc.relation.issn","1973-8102"],["dc.title","Reach and grasp deficits following damage to the dorsal pulvinar"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","898"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Movement Disorders Clinical Practice"],["dc.bibliographiccitation.lastpage","900"],["dc.bibliographiccitation.volume","4"],["dc.contributor.author","Wilke, Melanie"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Bähr, Mathias"],["dc.date.accessioned","2018-04-23T11:48:57Z"],["dc.date.available","2018-04-23T11:48:57Z"],["dc.date.issued","2017"],["dc.identifier.doi","10.1002/mdc3.12544"],["dc.identifier.gro","3142066"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/13610"],["dc.language.iso","en"],["dc.notes.intern","lifescience updates Crossref Import"],["dc.notes.status","final"],["dc.relation.issn","2330-1619"],["dc.title","Sarcoidosis Manifestion Centered on the Thalamic Pulvinar Leading to Persistent Astasia"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["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.firstpage","121"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of Neuroscience Methods"],["dc.bibliographiccitation.lastpage","131"],["dc.bibliographiccitation.volume","215"],["dc.contributor.author","Helms, Gunther"],["dc.contributor.author","Garea-Rodriguez, Enrique"],["dc.contributor.author","Schlumbohm, Christina"],["dc.contributor.author","König, Jessica"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Fuchs, Eberhard"],["dc.contributor.author","Wilke, Melanie"],["dc.date.accessioned","2017-09-07T11:43:43Z"],["dc.date.available","2017-09-07T11:43:43Z"],["dc.date.issued","2013"],["dc.description.abstract","Purpose was to adapt structural and quantitative magnetic resonance imaging (MRI) from humans to common marmoset monkeys on a clinical 3T scanner and to demonstrate the value for translational research.Three-dimensional T1- and T2-weighted MRI and gradient echo-based multi-parameter mapping was performed on nine adult animals using a wrist coil. Structural MRI was applied in a model of targeted experimental autoimmune encephalomyelitis (EAE). Magnetization transfer (MT) and T1 parameter maps were used to depict axon-rich cortical areas. After intraveneous triple dose of gadobutrol, the excretion half-time was determined from consecutive measurements of R1 = 1/T1. Diffusion tensor imaging (DTI) was performed at 1 mm resolution.At 0.4 mm resolution, total measurement time (30 min) was compatible with injection anesthesia, permitting rapid screening and frequent follow-up. Structural MRI depicted the EAE lesion in white matter. Quantitative values of T1, MT, and R2 in marmoset brain were comparable to humans, except for smaller R2 indicating lower iron content in basal ganglia. The middle temporal V5 area and the cortical layer IV could be identified, but were considerably better delineated when averaging two images at 0.33 mm resolution (70 min). A similar distribution volume (23%), but a shorter excretion half time than in humans (30 min) was observed. DTI was feasible only in larger structures, such as major axonal tracts.High-resolution MRI of common marmosets proved feasible using clinical MRI hardware. A rapid 3D examination protocol was established for screening under injection anesthesia, thus avoiding the adverse effects of inhalation anesthesia."],["dc.identifier.doi","10.1016/j.jneumeth.2013.02.011"],["dc.identifier.gro","3151620"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/8433"],["dc.language.iso","en"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","0165-0270"],["dc.title","Structural and quantitative neuroimaging of the common marmoset monkey using a clinical MRI system"],["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"]]