Modulation of frontal effective connectivity during speech

Holland, Rachel, Leff, Alex P, Penny, William D, Rothwell, John C and Crinion, Jenny (2016) Modulation of frontal effective connectivity during speech. NeuroImage, 140. pp. 126-133. ISSN 1053-8119

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    Abstract

    Noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting, polarity-dependent changes in neocortical excitability. In a previous concurrent tDCS-fMRI study of overt picture naming, we reported significant behavioural and regionally specific neural facilitation effects in left inferior frontal cortex (IFC) with anodal tDCS applied to left frontal cortex (Holland et al., 2011). Although distributed connectivity effects of anodal tDCS have been modelled at rest, the mechanism by which 'on-line' tDCS may modulate neuronal connectivity during a task-state remains unclear. Here, we used Dynamic Causal Modelling (DCM) to determine: (i) how neural connectivity within the frontal speech network is modulated during anodal tDCS; and, (ii) how individual variability in behavioural response to anodal tDCS relates to changes in effective connectivity strength. Results showed that compared to sham, anodal tDCS elicited stronger feedback from inferior frontal sulcus (IFS) to ventral premotor (VPM) accompanied by weaker self-connections within VPM, consistent with processes of neuronal adaptation. During anodal tDCS individual variability in the feedforward connection strength from IFS to VPM positively correlated with the degree of facilitation in naming behaviour. These results provide an essential step towards understanding the mechanism of 'online' tDCS paired with a cognitive task. They also identify left IFS as a 'top-down' hub and driver for speech change.

    Item Type: Article
    Additional Information: Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
    Depositing User: Pure Connector
    Date Deposited: 19 Aug 2017 06:06
    Last Modified: 31 Aug 2018 15:32
    URI: https://ueaeprints.uea.ac.uk/id/eprint/64577
    DOI: 10.1016/j.neuroimage.2016.01.037

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