Reduction of somatosensory functional connectivity by transcranial alternating current stimulation at endogenous mu-frequency
Christopher Gundlach,
Matthias M. Müller,
Maike Hoff,
Patrick Ragert,
Till Nierhaus,
Arno Villringer,
Bernhard Sehm
Affiliations
Christopher Gundlach
Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany; Department of Psychology, University of Leipzig, 04109 Neumarkt 9-19, Leipzig, Germany; Corresponding authors.
Matthias M. Müller
Department of Psychology, University of Leipzig, 04109 Neumarkt 9-19, Leipzig, Germany
Maike Hoff
Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany
Patrick Ragert
Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany; Institute for General Kinesiology and Exercise Sciences, Faculty of Sport Science, University of Leipzig, 04109 Leipzig, Germany
Till Nierhaus
Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany; Neurocomputation and Neuroimaging Unit (NNU), Department of Education and Psychology, Freie Universität Berlin, 14195 Berlin, Germany
Arno Villringer
Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany; MindBrainBody Institute at Berlin School of Mind and Brain, Charité Universitätsmedizin Berlin and Humboldt-University, 10099 Berlin, Germany; Universitätsklinik Halle (Saale), 06097 Halle (Saale), Germany
Bernhard Sehm
Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany; Universitätsklinik Halle (Saale), 06097 Halle (Saale), Germany; Department of Cognitive Neurology, University of Leipzig, 04103 Leipzig, Germany; Corresponding authors.
Alpha, the most prominent human brain rhythm, might reflect a mechanism of functional inhibition for gating neural processing. This concept has been derived predominantly from local measures of inhibition, while large-scale network mechanisms to guide information flow are largely unknown. Here, we investigated functional connectivity changes on a whole-brain level by concurrent transcranial alternating current stimulation (tACS) and resting-state functional MRI in humans. We specifically focused on somatosensory alpha-band oscillations by adjusting the tACS frequency to each individual´s somatosensory (mu-) alpha peak frequency (mu-tACS). Potential differences of Eigenvector Centrality of primary somatosensory cortex (S1) as well as on a whole brain level between mu-tACS and sham were analyzed. Our results demonstrate that mu-tACS induces a locally-specific decrease in whole-brain functional connectivity of left S1. An additional exploratory analysis revealed that this effect primarily depends on a decrease in functional connectivity between S1 and a network of regions that are crucially involved in somatosensory processing. Furthermore, the decrease in functional centrality was specific to mu-tACS and was not observed when tACS was applied in the gamma-range in an independent study. Our findings provide evidence that modulated somatosensory (mu-) alpha-activity may affect whole-brain network level activity by decoupling primary sensory areas from other hubs involved in sensory processing.
