title: Externally induced frontoparietal synchronization modulates network dynamics and enhances working memory performance.
abstract: Cognitive functions such as working memory (WM) are emergent properties of large-scale network interactions. Synchronisation of oscillatory activity might contribute to WM by enabling the coordination of long-range processes. However, causal evidence for the way oscillatory activity shapes network dynamics and behavior in humans is limited. Here we applied transcranial alternating current stimulation (tACS) to exogenously modulate oscillatory activity in a right frontoparietal network that supports WM. Externally induced synchronization improved performance when cognitive demands were high. Simultaneously collected fMRI data reveals tACS effects dependent on the relative phase of the stimulation and the internal cognitive processing state. Specifically, synchronous tACS during the verbal WM task increased parietal activity, which correlated with behavioral performance. Furthermore, functional connectivity results indicate that the relative phase of frontoparietal stimulation influences information flow within the WM network. Overall, our findings demonstrate a link between behavioral performance in a demanding WM task and large-scale brain synchronization.
authors.affiliation: The Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom.|Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom.
authors.forename: Ines R
authors.identifier: 0000-0002-4787-2901
authors.initials: IR
authors.lastname: Violante
authors.affiliation: The Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom.
authors.forename: Lucia M
authors.initials: LM
authors.lastname: Li
authors.affiliation: Developmental Imaging and Biophysics Section, UCL Institute of Child Health, University College London, London, United Kingdom.
authors.forename: David W
authors.initials: DW
authors.lastname: Carmichael
authors.affiliation: The Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom.
authors.forename: Romy
authors.initials: R
authors.lastname: Lorenz
authors.affiliation: The Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom.
authors.forename: Robert
authors.identifier: 0000-0002-5801-6318
authors.initials: R
authors.lastname: Leech
authors.affiliation: The Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Hampshire
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, United Kingdom.
authors.forename: John C
authors.initials: JC
authors.lastname: Rothwell
authors.affiliation: The Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Sharp
mesh_terms: D000328:Adult; D003344:Cortical Synchronization; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term; D009415:Nerve Net / Q000502:physiology*; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Working memory; brain networks; brain stimulation; human; neuroscience; oscillations; synchronization; tACS