Abstract
BackgroundTranscranial direct current stimulation (tDCS) is a noninvasive brain stimulation tool suited to alter cortical excitability and activity via the application of weak direct electrical currents. An increasing number of studies in the addiction literature suggests that tDCS modulates subjective self‐reported craving through stimulation of dorsolateral prefrontal cortex (DLPFC). The major goal of this study was to explore effects of bilateral DLPFC stimulation on resting state networks (RSNs) in association with drug craving modulation. We targeted three large‐scale RSNs; the default mode network (DMN), the executive control network (ECN), and the salience network (SN).MethodsFifteen males were recruited after signing written informed consent. We conducted a double‐blinded sham‐controlled crossover study. Twenty‐minute “real” and “sham” tDCS (2 mA) were applied over the DLPFC on two separate days in random order. Each subject received both stimulation conditions with a 1‐week washout period. The anode and cathode electrodes were located over the right and left DLPFC, respectively. Resting state fMRI was acquired before and after real and sham stimulation. Subjective craving was assessed before and after each fMRI scan. The RSNs were identified using seed‐based analysis and were compared using a generalized linear model.ResultsSubjective craving decreased significantly after real tDCS compared to sham stimulation (p = .03). Moreover, the analysis shows significant modulation of DMN, ECN, and SN after real tDCS compared to sham stimulation. Additionally, alteration of subjective craving score was correlated with modified activation of the three networks.DiscussionGiven the observed alteration of the targeted functional brain networks in methamphetamine users, new potentials are highlighted for tDCS as a network intervention strategy and rsfMRI as a suitable monitoring method for these interventions.
Highlights
IntroductionThe number of theoretical and empirical studies with a network perspective is rapidly increasing; correspondingly, evaluation of large-scale networks is made possible through the development of new neuroimaging methods
Beyond investigation of the contribution of specific brain areas to specific cognitive and behavioral processes, contemporary approaches are extended to address communication between these regions
In a more recent Event‐related potential (ERP) study, Nakamura-Palcious et al reported increased P3 activation over the ventral medial prefrontal cortex under drug-related cues in alcoholics and crack cocaine users during and after the treatment with bilateral Transcranial direct current stimulation (tDCS) over dorsolateral prefrontal cortex (DLPFC). They found increased diffusion tensor imaging (DTI) parameters relating to the connection between vmPFC and nucleus accumbens (NAcc); this increase was significantly correlated with craving decrease after repetitive tDCS (Nakamura- Palacios et al, 2016)
Summary
The number of theoretical and empirical studies with a network perspective is rapidly increasing; correspondingly, evaluation of large-scale networks is made possible through the development of new neuroimaging methods. This approach allows us to monitor functional segregation (i.e., regional information processing) as well as integration (i.e., combination of information from different brain regions), which is an important perspective for understanding human brain function as a complex interconnected system. The major goal of this study was to explore effects of bilateral DLPFC stimulation on resting state networks (RSNs) in association with drug craving modulation. Discussion: Given the observed alteration of the targeted functional brain networks in methamphetamine users, new potentials are highlighted for tDCS as a network intervention strategy and rsfMRI as a suitable monitoring method for these interventions
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