1. Investigating the interaction between white matter and brain state on tDCS-induced changes in brain network activity
- Author
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Inês R. Violante, Danielle Kurtin, Karl Zimmerman, Maneesh C. Patel, David J. Sharp, Robert Leech, David W. Carmichael, Adam Hampshire, Lucia M. Li, Imperial College Healthcare NHS Trust- BRC Funding, National Institute for Health Research, Wellcome Trust, UK DRI Ltd, and National Institute of Health and Medical Research
- Subjects
Traumatic brain injury ,Brain activity and meditation ,medicine.medical_treatment ,Biophysics ,Prefrontal Cortex ,Neurosciences. Biological psychiatry. Neuropsychiatry ,Transcranial Direct Current Stimulation ,Article ,White matter ,Magnetic resonance imaging ,Fractional anisotropy ,Salience network ,Humans ,Medicine ,11 Medical and Health Sciences ,Default mode network ,Neurology & Neurosurgery ,Transcranial direct-current stimulation ,business.industry ,General Neuroscience ,Brain ,Cognition ,medicine.disease ,White Matter ,medicine.anatomical_structure ,Brain stimulation ,White matter structure ,Stimulation ,Neurology (clinical) ,business ,Neuroscience ,RC321-571 - Abstract
Background Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation whose potential as a cognitive therapy is hindered by our limited understanding of how participant and experimental factors influence its effects. Using functional MRI to study brain networks, we have previously shown in healthy controls that the physiological effects of tDCS are strongly influenced by brain state. We have additionally shown, in both healthy and traumatic brain injury (TBI) populations, that the behavioral effects of tDCS are positively correlated with white matter (WM) structure. Objectives In this study we investigate how these two factors, WM structure and brain state, interact to shape the effect of tDCS on brain network activity. Methods We applied anodal, cathodal and sham tDCS to the right inferior frontal gyrus (rIFG) of healthy (n = 22) and TBI participants (n = 34). We used the Choice Reaction Task (CRT) performance to manipulate brain state during tDCS. We acquired simultaneous fMRI to assess activity of cognitive brain networks and used Fractional Anisotropy (FA) as a measure of WM structure. Results We find that the effects of tDCS on brain network activity in TBI participants are highly dependent on brain state, replicating findings from our previous healthy control study in a separate, patient cohort. We then show that WM structure further modulates the brain-state dependent effects of tDCS on brain network activity. These effects are not unidirectional - in the absence of task with anodal and cathodal tDCS, FA is positively correlated with brain activity in several regions of the default mode network. Conversely, with cathodal tDCS during CRT performance, FA is negatively correlated with brain activity in a salience network region. Conclusions Our results show that experimental and participant factors interact to have unexpected effects on brain network activity, and that these effects are not fully predictable by studying the factors in isolation., Highlights • We replicated the brain state and polarity dependent effects of tDCS. • White matter structure influences tDCS's state-dependent changes in neural activity • The parameters of tDCS may operate under a hierarchy of influence.
- Published
- 2021