Sham High-definition Transcranial Direct Current Stimulation Research Articles

B - 36 Investigating High-Definition Transcranial Direct Current Stimulation for Remediating Word Finding Difficulty in Civilians with a History of Chronic Traumatic Brain Injury: a Pilot Study

Abstract Objective Verbal-retrieval deficits often occur after traumatic brain injury (TBI), but no effective treatment is available. In this study, High-Definition Transcranial Direct Current Stimulation (HD-tDCS) was applied to examine its potential effects on cognitive, especially verbal-retrieval, performance in individuals with chronic TBI. Method Four adults (mean age 48 years; 3 females) with self-reported word-finding difficulty confirmed by objective measures following mild to moderate non-military TBIs sustained over a year ago underwent a double-blind, cross-over, randomized, sham-controlled trial. Each participant received 10 sessions of active HD-tDCS and sham stimulation over the superior medial frontal cortex. A battery of neuropsychological tests was administered including verbal-retrieval measures (i. e. letter fluency, category fluency, Boston Naming Test/BNT) at baseline, immediately, and 8 weeks post-treatment. Post-treatment performance was compared to baseline using 2-tailed paired t-tests. Results Improvements on letter fluency were observed between baseline and immediate assessments post active HD-tDCS, approaching statistical significance (p = 0.076, Cohen’s d = 0.957, 7.5 ± 5.7 more items). No immediate effects with sham HD-tDCS (p > 0.10, 1.5 ± 3.5 more items) and no sustained effects (8 weeks after) were found with either active or sham HD-tDCS (ps > 0.10). Additionally, no significant changes were observed for category fluency or BNT (all ps > 0.10). Conclusion While our pilot study suggests a potential benefit for improved letter fluency immediately following active HD-tDCS compared to sham, the lack of sustained improvement after 8 weeks and the observed variability across different tests acknowledges the need for future larger-scale investigation across multiple cognitive domains.

High-definition transcranial direct current stimulation (HD-tDCS) in major depressive disorder with anxious distress—a study protocol for a double-blinded randomized sham-controlled trial

BackgroundComorbid anxiety disorders and anxious distress are highly prevalent among individuals with major depressive disorder (MDD). The presence of the DSM-5 anxious distress specifier (ADS) has been associated with worse treatment outcomes and chronic disease course. Few studies have evaluated the therapeutic effects of High-definition transcranial direct current stimulation (HD-tDCS) on depressive and anxiety symptoms among MDD patients with ADS. The current randomized controlled trial aims to assess the efficacy of HD-tDCS as an augmentation therapy with antidepressants compared to sham-control in subjects of MDD with ADS.MethodsMDD patients with ADS will be recruited and randomly assigned to the active HD-tDCS or sham HD-tDCS group. In both groups, patients will receive the active or sham intervention in addition to their pre-existing antidepressant therapy, for 2 weeks with 5 sessions per week, each lasting 30 min. The primary outcome measures will be the change of depressive symptoms, clinical response, and the remission rate as measured with the 17-item Hamilton Depression Rating Scale (HDRS-17) before and after the intervention and at the 2nd and 6th week after the completed intervention. Secondary outcome measures include anxiety symptoms, cognitive symptoms, disability assessment, and adverse effects.DiscussionThe HD-tDCS applied in this trial may have treatment effects on MDD with ADS and have minimal side effects.Trial registrationThe trial protocol is registered with www.chictr.org.cn under protocol registration number ChiCTR2300071726. Registered 23 May 2023.

HD-tDCS mitigates the executive vigilance decrement only under high cognitive demands

Maintaining vigilance is essential for many everyday tasks, but over time, our ability to sustain it inevitably decreases, potentially entailing severe consequences. High-definition transcranial direct current stimulation (HD-tDCS) has proven to be useful for studying and improving vigilance. This study explores if/how cognitive load affects the mitigatory effects of HD-tDCS on the vigilance decrement. Participants (N = 120) completed a modified ANTI-Vea task (single or dual load) while receiving either sham or anodal HD-tDCS over the right posterior parietal cortex (rPPC). This data was compared with data from prior studies (N = 120), where participants completed the standard ANTI-Vea task (triple load task), combined with the same HD-tDCS protocol. Against our hypotheses, both the single and dual load conditions showed a significant executive vigilance (EV) decrement, which was not affected by the application of rPPC HD-tDCS. On the contrary, the most cognitively demanding task (triple task) showed the greatest EV decrement; importantly, it was also with the triple task that a significant mitigatory effect of the HD-tDCS intervention was observed. The present study contributes to a more nuanced understanding of the specific effects of HD-tDCS on the vigilance decrement considering cognitive demands. This can ultimately contribute to reconciling heterogeneous effects observed in past research and fine-tuning its future clinical application.

Simultaneous high-definition transcranial direct current stimulation and robot-assisted gait training in stroke patients

This study investigates whether simultaneous high-definition transcranial direct current stimulation (HD-tDCS) enhances the effects of robot-assisted gait training in stroke patients. Twenty-four participants were randomly allocated to either the robot-assisted gait training with real HD-tDCS group (real HD-tDCS group) or robot-assisted gait training with sham HD-tDCS group (sham HD-tDCS group). Over four weeks, both groups completed 10 sessions. The 10 Meter Walk Test, Timed Up and Go, Functional Ambulation Category, Functional Reach Test, Berg Balance Scale, Dynamic Gait Index, Fugl-Meyer Assessment, and Korean version of the Modified Barthel Index were conducted before, immediately after, and one month after the intervention. The real HD-tDCS group showed significant improvements in the 10 Meter Walk Test, Timed Up and Go, Functional Reach Test, and Berg Balance Scale immediately and one month after the intervention, compared with before the intervention. Significant improvements in the Dynamic Gait Index and Fugl-Meyer Assessment were also observed immediately after the intervention. The sham HD-tDCS group showed no significant improvements in any of the tests. Application of HD-tDCS during robot-assisted gait training has a positive effect on gait and physical function in chronic stroke patients, ensuring long-term training effects. Our results suggest the effectiveness of HD-tDCS as a complementary tool to enhance robotic gait rehabilitation therapy in chronic stroke patients.

A - 17 Preliminary Neuropsychological Outcomes in a Randomized Controlled Trial of High-Definition Transcranial Direct Current Stimulation in Alzheimer's Clinical Syndrome.

The Alzheimer's Clinical Syndrome (ACS) is marked by global cognitive decline, and neural circuit dysfunction involving the dorsal anterior cingulate cortex (dACC) has been associated with some of the episodic memory and non-memory deficits in ACS. High-definition transcranial direct current stimulation (HD-tDCS) is a promising noninvasive treatment to lessen cognitive deficits in ACS, and this preliminary double-blinded trial examined whether HD-tDCS targeting the dACC could improve cognitive performance in ACS. Ten patients diagnosed with ACS (M age = 71.500; SD = 9.755) were randomized to receive sham (n = 2), 1mA (n = 5), or 2mA (n = 3) multi-electrode (4 cathodes x 1 anode) HD-tDCS for 10 daily sessions. Episodic memory, language, attention, and executive function measures were administered pre- and immediately post-treatment, and composite memory and non-memory scores were calculated. Paired samples t-tests examined significant differences (p < 0.05) between pre-treatment and post-treatment scores for each HD-tDCS group. For all three HD-tDCS groups, there were no significant improvements between pre-treatment and post-treatment scores for memory or non-memory abilities (p's > 0.05). This preliminary study showed that HD-tDCS applied over the dACC was unassociated with cognitive improvement in ACS. Future research with a larger sample will be needed to inform if this configuration of HD-tDCS could ameliorate cognitive deficits in ACS. Moreover, evaluation of HD-tDCS applied over other brain regions may yield additional insights, and a critical step will be to identify whether any clinical characteristics such as disease stage may influence the response to stimulation in ACS.

Alterations in learning-related cortical activation and functional connectivity by high-definition transcranial direct current stimulation after stroke: an fNIRS study.

Motor learning is a key component of stroke neurorehabilitation. High-definition transcranial direct current stimulation (HD-tDCS) was recently developed as a tDCS technique that increases the accuracy of current delivery to the brain using arrays of small electrodes. The purpose of this study was to investigate whether HD-tDCS alters learning-related cortical activation and functional connectivity in stroke patients using functional near-infrared spectroscopy (fNIRS). Using a sham-controlled crossover study design, 16 chronic stroke patients were randomly assigned to one of two intervention conditions. Both groups performed the sequential finger tapping task (SFTT) on five consecutive days, either with (a) real HD-tDCS or (b) with sham HD-tDCS. HD-tDCS (1 mA for 20 min, 4 × 1) was administered to C3 or C4 (according to lesion side). fNIRS signals were measured during the SFTT with the affected hand before (baseline) and after each intervention using fNIRS measurement system. Cortical activation and functional connectivity of NIRS signals were analyzed using a statistical parametric mapping open-source software package (NIRS-SPM), OptoNet II®. In the real HD-tDCS condition, oxyHb concentration increased significantly in the ipsilesional primary motor cortex (M1). Connectivity between the ipsilesional M1 and the premotor cortex (PM) was noticeably strengthened after real HD-tDCS compared with baseline. Motor performance also significantly improved, as shown in response time during the SFTT. In the sham HD-tDCS condition, functional connectivity between contralesional M1 and sensory cortex was enhanced compared with baseline. There was tendency toward improvement in SFTT response time, but without significance. The results of this study indicated that HD-tDCS could modulate learning-related cortical activity and functional connectivity within motor networks to enhance motor learning performance. HD-tDCS can be used as an additional tool for enhancing motor learning during hand rehabilitation for chronic stroke patients.

Effects of high-definition transcranial direct current stimulation on implicit emotion regulation of social pain in healthy individuals

BackgroundImplicit emotion regulation (ER), a form of ER, is essential for protecting mental health in the process of social interaction. Both the ventrolateral prefrontal cortex (VLPFC) and the dorsolateral prefrontal cortex (DLPFC) have been shown to be involved in ER processes, including explicit ER of social pain, but whether they play a role in implicit ER is unclear. MethodsWe investigated whether anodal high-definition transcranial direct current stimulation (HD-tDCS) of the right VLPFC (rVLPFC) or the right DLPFC (rDLPFC) influences implicit ER. In total, 63 healthy participants completed an emotion priming task, which measures the implicit ER of social pain, before and after receiving active or sham HD-tDCS (2 mA for 20 min, 10 consecutive days). Event-related potentials (ERPs) were recorded during task performance. ResultsCombined with the results of the behavioral and electrophysiological indices indicated that stimulation of both the rVLPFC and the rDLPFC by anodic HD-tDCS could significantly reduce the affective responses caused by social exclusion. The further results also suggested that rDLPFC activation may contribute to promoting the involvement of early cognitive resources in the implicit ER process of social pain, thus helping to reduce the subjective negative experience of individuals. LimitationsThere were no dynamic interactive emotional stimuli to induce social pain, and only static images of social exclusion were used. ConclusionOur study provides cognitive and neurological evidence that expands our knowledge of the role of the rDLPFC and the rVLPFC in social ER. It can also serve as a reference for targeted intervention of implicit ER in social pain.

High-Definition Transcranial Direct Current Stimulation Improves Decision-Making Ability: A Study Based on EEG

High-definition transcranial direct current stimulation (HD-tDCS) has been shown to modulate decision-making; however, the neurophysiological mechanisms underlying this effect remain unclear. To further explore the neurophysiological processes of decision-making modulated by HD-tDCS, health participants underwent ten anodal (n = 16)/sham (n = 17) HD-tDCS sessions targeting the left DLPFC. Iowa gambling task was performed simultaneously with electroencephalography (EEG) before and after HD-tDCS. Iowa gambling task performance, the P300 amplitude, and the power of theta oscillation as an index of decision-making were compared. Behavioral changes were found that showed anodal HD-tDCS could improve the decision-making function, in which participants could make more advantageous choices. The electrophysiological results showed that the P300 amplitude significantly increased in CZ, CPZ electrode placement site and theta oscillation power significantly activated in FCZ, CZ electrode placement site after anodal HD-tDCS. Significant positive correlations were observed between the changes in the percent use of negative feedback and the changes in theta oscillation power before and after anodal HD-tDCS. This study showed that HD-tDCS is a promising technology in improving decision-making and theta oscillation induced by may be a predictor of improved decision-making.

Non-invasive brain stimulation for fatigue in post-acute sequelae of SARS-CoV-2 (PASC)

Backgroundand purpose: Fatigue is among the most common persistent symptoms following post-acute sequelae of Sars-COV-2 infection (PASC). The current study investigated the potential therapeutic effects of High-Definition transcranial Direct Current Stimulation (HD-tDCS) associated with rehabilitation program for the management of PASC-related fatigue. MethodsSeventy patients with PASC-related fatigue were randomized to receive 3 mA or sham HD-tDCS targeting the left primary motor cortex (M1) for 30 min paired with a rehabilitation program. Each patient underwent 10 sessions (2 sessions/week) over five weeks. Fatigue was measured as the primary outcome before and after the intervention using the Modified Fatigue Impact Scale (MFIS). Pain level, anxiety severity and quality of life were secondary outcomes assessed, respectively, through the McGill Questionnaire, Hamilton Anxiety Rating Scale (HAM-A) and WHOQOL. ResultsActive HD-tDCS resulted in significantly greater reduction in fatigue compared to sham HD-tDCS (mean group MFIS reduction of 22.11 points vs 10.34 points). Distinct effects of HD-tDCS were observed in fatigue domains with greater effect on cognitive (mean group difference 8.29 points; effect size 1.1; 95% CI 3.56–13.01; P < .0001) and psychosocial domains (mean group difference 2.37 points; effect size 1.2; 95% CI 1.34–3.40; P < .0001), with no significant difference between the groups in the physical subscale (mean group difference 0.71 points; effect size 0.1; 95% CI 4.47–5.90; P = .09). Compared to sham, the active HD-tDCS group also had a significant reduction in anxiety (mean group difference 4.88; effect size 0.9; 95% CI 1.93–7.84; P < .0001) and improvement in quality of life (mean group difference 14.80; effect size 0.7; 95% CI 7.87–21.73; P < .0001). There was no significant difference in pain (mean group difference −0.74; no effect size; 95% CI 3.66–5.14; P = .09). ConclusionAn intervention with M1 targeted HD-tDCS paired with a rehabilitation program was effective in reducing fatigue and anxiety, while improving quality of life in people with PASC.

High-definition transcranial direct current stimulation (HD-tDCS) as augmentation therapy in late-life depression (LLD) with suboptimal response to treatment—a study protocol for a double-blinded randomized sham-controlled trial

BackgroundLate-life depression (LLD) has a poorer prognosis and higher relapse rate than younger adults, with up to one third of patients with LLD showing suboptimal response to antidepressant therapy. LLD has been associated with significant impairment in cognition and daily functioning. Few studies have evaluated the therapeutic effects of high-definition transcranial direct current stimulation (HD-tDCS) on depressive and cognitive symptoms of LLD. The current randomized controlled trial assesses the efficacy of HD-tDCS as an augmentation therapy with antidepressants compared to sham-control in subjects with LLD.MethodsFifty-eight patients with LLD will be recruited and randomly assigned to the active HD-tDCS or sham HD-tDCS group. In both groups, patients will receive the active or sham intervention in addition to their pre-existing antidepressant therapy, for 2 weeks with 5 sessions per week, each lasting 30 min. The primary outcome measures will be the change of depressive symptoms, clinical response and the remission rate as measured with the Hamilton Depression Rating scale (HAMD-17) before and after the intervention, and at the 4th and 12th week after the completed intervention. Secondary outcome measures include cognitive symptoms, anxiety symptoms, daily functioning and adverse effects. DiscussionOlder adults with depression are associated with poorer outcomes or unsatisfactory responses to antidepressant therapy, and significant cognitive decline. Therefore, a new effective treatment option is needed. This randomized control trial aims at assessing the efficacy of HD-tDCS on ameliorating the depressive, cognitive and anxiety symptoms, and improving the daily functioning of subjects with LLD.Trial registrationClinicalTrials.gov NCT05322863. Registered on 11 April 2022.

Efficacy and safety of HD-tDCS and respiratory rehabilitation for critically ill patients with COVID-19 The HD-RECOVERY randomized clinical trial

Background and purposeAcute Respiratory Distress Syndrome (ADRS) due to coronavirus disease 2019 (COVID-19) has been associated with muscle fatigue, corticospinal pathways dysfunction, and mortality. High-Definition transcranial Direct Current Stimulation (HD-tDCS) may be used to attenuate clinical impairment in these patients. The HD-RECOVERY randomized clinical trial was conducted to evaluate the efficacy and safety of HD-tDCS with respiratory rehabilitation in patients with moderate to severe ARDS due to COVID-19. MethodsFifty-six critically ill patients were randomized 1:1 to active (n = 28) or sham (n = 28) HD-tDCS (twice a day, 30-min, 3-mA) plus respiratory rehabilitation for up to 10 days or until intensive care unit discharge. The primary outcome was ventilator-free days during the first 28 days, defined as the number of days free from mechanical ventilation. Furthermore, secondary outcomes such as delirium, organ failure, hospital length of stay and adverse effects were investigated. ResultsActive HD-tDCS induced more ventilator-free days compared to sham HD-tDCS. Patients in the active group vs in the sham group experienced lower organ dysfunction, delirium, and length of stay rates over time. In addition, positive clinical response was higher in the active vs sham group. There was no significant difference in the prespecified secondary outcomes at 5 days. Adverse events were similar between groups. ConclusionsAmong patients with COVID-19 and moderate to severe ARDS, use of active HD-tDCS compared with sham HD-tDCS plus respiratory rehabilitation resulted in a statistically significant increase in the number of ventilator-free days over 28 days. HD-tDCS combined with concurrent rehabilitation therapy is a safe, feasible, potentially add-on intervention, and further trials should examine HD-tDCS efficacy in a larger sample of patients with COVID-19 and severe hypoxemia.

Adjunctive High-Definition Transcranial Direct Current Stimulation in Brain Glutamate-Glutamine and γ-Aminobutyric Acid, Withdrawal and Craving During Early Abstinence Among Patients With Opioid Use Disorder on Buprenorphine-Naloxone: A Proton Magnetic Resonance Spectroscopy-Based Pilot Study.

Our study aimed to (1) examine the effect of adjunctive high-definition transcranial direct current stimulation (HD-tDCS) in craving and withdrawal among patients with opioid use disorder on buprenorphine-naloxone, and (2) examine effect of HD-tDCS changes in glutamate-glutamine and γ-aminobutyric acid (GABA) at the left dorsolateral prefrontal cortex (DLPFC) among patients with opioid use disorder on buprenorphine-naloxone. This was a pilot randomized double-blind, sham-controlled parallel-group study. A total of 28 patients on buprenorphine-naloxone (6/1.5 mg/d) were randomly allocated into 2 groups for active and sham HD-tDCS stimulation. High-definition transcranial direct current stimulation was administered twice daily for consecutive 5 days, from days 2 to 6. The Clinical Opiate Withdrawal Scale (COWS), the Desire for Drug Questionnaire (DDQ), the Obsessive-Compulsive Drug Use Scale (OCDUS), and glutamate-glutamine and GABA at DLPFC via proton magnetic resonance spectroscopy were measured at baseline and on day 7. Both active and sham groups had comparable changes in DDQ, OCDUS (except 2 subcomponents), COWS, and glutamate-glutamine and GABA at DLPFC. In the active HD-tDCS group, statistically significant reductions were observed in DDQ, OCDUS, and COWS but not in glutamate-glutamine and GABA. The adjunctive active HD-tDCS group showed comparable changes in craving and withdrawal, and glutamate-glutamine and GABA at DLPFC compared with sham HD-tDCS. Craving and withdrawal but not glutamate-glutamine and GABA at DLPFC decreased significantly with adjunctive HD-tDCS. Future studies with larger sample size and online assessment of glutamate-glutamine and GABA would enhance our knowledge.

Effects of High-Definition Transcranial Direct Current Stimulation Over the Left Fusiform Face Area on Face View Discrimination Depend on the Individual Baseline Performance.

A basic human visual function is to identify objects from different viewpoints. Typically, the ability to discriminate face views based on in-depth orientation is necessary in daily life. Early neuroimaging studies have identified the involvement of the left fusiform face area (FFA) and the left superior temporal sulcus (STS) in face view discrimination. However, many studies have documented the important role of the right FFA in face processing. Thus, there remains controversy over whether one specific region or all of them are involved in discriminating face views. Thus, this research examined the influence of high-definition transcranial direct current stimulation (HD-tDCS) over the left FFA, left STS or right FFA on face view discrimination in three experiments. In experiment 1, eighteen subjects performed a face view discrimination task before and immediately, 10 min and 20 min after anodal, cathodal and sham HD-tDCS (20 min, 1.5 mA) over the left FFA in three sessions. Compared with sham stimulation, anodal and cathodal stimulation had no effects that were detected at the group level. However, the analyses at the individual level showed that the baseline performance negatively correlated with the degree of change after anodal tDCS, suggesting a dependence of the change amount on the initial performance. Specifically, tDCS decreased performance in the subjects with better baseline performance but increased performance in those with poorer baseline performance. In experiments 2 and 3, the same experimental protocol was used except that the stimulation site was the left STS or right FFA, respectively. Neither anodal nor cathodal tDCS over the left STS or right FFA influenced face view discrimination in group- or individual-level analyses. These results not only indicated the importance of the left FFA in face view discrimination but also demonstrated that individual initial performance should be taken into consideration in future research and practical applications.

Polarity-specific high-definition transcranial direct current stimulation of the anterior and posterior default mode network improves remote memory retrieval

BackgroundPrevious studies show that activity in the posterior default mode network (pDMN), including the posterior cingulate cortex and the precuneus, is correlated with the success of long-term episodic memory retrieval. However, the role of the anterior DMN (aDMN) including the medial prefrontal cortex is still unclear. Some studies show that activating the medial prefrontal cortex improves memory retrieval while other studies show deactivation of the medial prefrontal cortex in successful retrieval of episodic memories, suggesting a possible functional dissociation between the aDMN and pDMN. ObjectiveIn the current study, we aim to causally explore this probable dissociation using high-definition transcranial direct current stimulation (HD-tDCS). MethodsWe perform a randomised double-blinded two-visit placebo-controlled study with 84 healthy young adults. During Visit 1 they learn 75 Swahili-English word-associations. Seven days later, they randomly receive either anodal, cathodal or sham HD-tDCS targeting the pDMN or aDMN while they recall what they have previously learned. ResultsWe demonstrate that anodal stimulation of the pDMN and cathodal stimulation of the aDMN, equally improve the percentage of Swahili-English word-associations recalled 7 days after learning. ConclusionsModulating the activity in the aDMN and pDMN causally affect memory retrieval performance. HD-tDCS of the aDMN and pDMN shows that anodal stimulation of the pDMN and cathodal stimulation of the aDMN increases memory retrieval performance one week after the learning phase. Given consistent evidence, it is highly likely that we are increasing the activity in the pDMN with anodal pDMN stimulation. However, it is not clear if cathodal HD-tDCS targetting aDMN works via decoupling from the pDMN or via indirectly disinhibit pDMN.

Medial Prefrontal High-Definition Transcranial Direct Current Stimulation to Improve Pain Modulation in Chronic Low Back Pain: A Pilot Randomized Double-blinded Placebo-Controlled Crossover Trial

Chronic low back pain (CLBP) is highly disabling, but often without identifiable source. Focus has been on impaired anti-nociceptive mechanisms contributing to pain maintenance, though methods of targeting this impairment remain limited. This randomised-controlled cross-over pilot trial used active versus sham medial prefrontal cortex (mPFC) high-definition transcranial direct current stimulation (HD-tDCS) for 3-consecutive days to improve descending pain inhibitory function. Twelve CLBP patients were included with an average visual analogue scale (VAS) pain intensity of 3.0 ± 1.5 and pain duration of 5.3 ± 2.6 years. Pressure pain thresholds (PPTs), conditioned pain modulation (CPM), and temporal summation of pain (TSP) assessed by cuff algometry, as well as pain symptomatology (intensity, unpleasantness, quality, disability) and related psychological features (pain catastrophizing, anxiety, affect), were assessed on Day1 before 3 consecutive days of HD-tDCS sessions (each 20 minutes), at 24-hours (Day 4) and 2-weeks (Day 21) following final HD-tDCS. Blinding was successful. No significant differences in psychophysical (PPT, CPM, TSP), symptomatology or psychological outcomes were observed between active and sham HD-tDCS on Day4 and Day21. CPM-effects at Day 1 negatively correlated with change in CPM-effect at Day4 following active HD-tDCS (P = .002). Lack of efficacy was attributed to several factors, not least that patients did not display impaired CPM at baseline. Trial registration: ClinicalTrials.gov (NCT03864822). PerspectiveMedial prefrontal HD-tDCS did not alter pain, psychological nor psychophysical outcomes, though correlational analysis suggested response may depend on baseline pain inhibitory efficacy, with best potential effects in patients with severe impairments in descending pain inhibitory mechanisms. Future work should focus on appropriate patient selection and optimising stimulation targeting.

Modulation of control: Can HD-tDCS targeting the dACC reduce impulsivity?

BackgroundThe dorsal anterior cingulate cortex (dACC) and its neurocircuits are central in impulsivity, and maladaptive dACC activity has been implicated in psychological disorders characterized by high trait impulsivity. High-Definition transcranial Direct Current Stimulation (HD-tDCS) is a non-invasive neuromodulation tool that, with certain electrode configurations, can be optimized for targeting deeper subcorticalbrainstructures, such as the dACC. ObjectivesUsing behavioural and electrophysiological measures we investigated whether HD-tDCS targeting the dACC could modulate two key components of impulsivity, inhibitory control and error processing. MethodsTwenty-three healthy adults with high trait impulsivity participated in two experimental sessions. Participants received active or sham HD-tDCS in counterbalanced order with a wash-out period of at least 3 days, as part of a single-blind, cross-over design. EEG was recorded during the Go-NoGo task before, directly after, and 30 min after HD-tDCS. ResultsHD-tDCS targeting the dACC did not affect inhibitory control performance on the Go-NoGo task, but there was evidence for a delayed change in underlying neurophysiological components of motor inhibition (NoGo P3) and error processing (error related negativity; ERN) after one session of HD-tDCS. ConclusionHD-tDCS has potential to modulate underlying neurophysiological components of impulsivity. Future studies should further explore to what degree the dACC was affected and whether multi-session HD-tDCS has the capacity to also induce behavioural changes, particularly in clinical samples characterized by high trait impulsivity.

Modulation of Repeated Anodal HD-tDCS on Attention in Healthy Young Adults.

High-definition transcranial direct current stimulation (HD-tDCS) is a valid brain stimulation technology to optimize cognitive function. Recent evidence indicates that single anodal tDCS session enhances attention; however, the variation in attention produced by repeated anodal HD-tDCS over a longer period of time has not been explored. We examined the modulation of attention function in healthy young participants (39 young adults) who received repeated HD-tDCS sustained for 4 weeks. The results showed a robust benefit of anodal HD-tDCS on executive control and psychomotor efficiency, but not on orienting, alerting, or selective attention (inhibition); the benefit increased successively over 4 weeks; and the enhancement on executive control of each week was significant compared to baseline in the anodal group. In addition, the subjects’ performances on the test of executive control and psychomotor efficiency gradually restored to the initial level in the sham group, which appeared obviously from week 3 (after 9 interventions), but the improvement of attention in the anodal group was persistent. We conclude that repeated anodal HD-tDCS provides a positive benefit on executive control and psychomotor efficiency and has obvious accumulative effect after 9 or more times intervention compared to sham HD-tDCS. Additionally, our findings might provide pivotal guidance for the formulation of a strategy for the use of repeated anodal HD-tDCS to modulate on attention function.

High-definition transcranial direct current stimulation in anorexia nervosa: A pilot study.

Anorexia nervosa (AN) is a serious psychiatric condition often associated with poor outcomes. Biologically informed treatments for AN, such as brain stimulation, are lacking, in part due to the unclear nature of the neurobiological contributions to the illness. However, recent research has suggested a specific neurobiological target for the treatment of AN, namely stimulation of the inferior parietal lobe (IPL). The aim of this study was to stimulate-noninvasively-the left IPL in individuals with AN using high-definition transcranial direct current stimulation (HD-tDCS). Twenty participants will be randomized to receive 10 daily sessions of HD-tDCS or sham HD-tDCS (placebo). Assessments will be carried out at baseline and end point, as well as 4- and 12-week follow-ups. This pilot investigation will primarily determine the feasibility and acceptability of this intervention.

Stimulating the left dorsolateral prefrontal cortex improves the memory representation of threats among individuals with high avoidant attachment

Prior research has suggested that individuals with high avoidant attachment may demonstrate a vigilant attentional bias and selective attentional avoidance towards attachment-related negative information (threat information). Similarly, some evidence suggests that impairment of hot working memory (WM) or emotional-related WM occurs in highly avoidant individuals. Moreover, functional MRI studies have demonstrated that the less-activated left dorsolateral prefrontal cortex (L-DLPFC) is related to the impairment of cognitive control for threat stimuli in individuals with high avoidant attachment. Therefore, in the present study, the causal role of the L-DLPFC on hot WM presentation was investigated by the high-definition transcranial direct current stimulation (HD-tDCS) technique, and cognitive control for internal mental representations in WM was measured by the Internal Shift Task (IST).The results showed that the highly avoidant participants performed faster on the emotional IST than low avoidant participants in the sham condition. In the emotional IST, highly avoidant participants were slower after receiving anodal HD-tDCS than in the sham condition. Moreover, the switching cost of the emotional IST was significantly smaller in the highly avoidant group than low avoidant group under the sham HD-tDCS condition. Interestingly, in the emotional IST, the switching cost of highly avoidant individuals was significantly greater in the anodal stimulation group than the sham stimulation group. Conversely, the switching cost of low avoidant individuals was significantly smaller with anodal stimulation than for sham stimulation. The findings indicate that anodal HD-tDCS over the L-DLPFC can effectively enhance the ability of memory representation towards threat information in highly avoidant individuals. This study extends causal research by showing that the L-DLPFC is an important brain region for hot WM representations.

Effects of High-Definition Transcranial Direct Current Stimulation (HD-tDCS) of the Intraparietal Sulcus and Dorsolateral Prefrontal Cortex on Working Memory and Divided Attention.

Objective: There is a need to elucidate the underlying neural mechanisms subserving working memory and divided attention functioning. Recent neuroimaging studies provide evidence for anatomical co-localization of both functions. In the present study we used a functional intervention, whereby we applied a novel type of focalised, non-invasive brain stimulation, High-Definition transcranial Direct Current Stimulation (HD-tDCS), to the regions subserving these processes, the left intraparietal sulcus (IPS) and left dorsolateral prefrontal cortex (LDLPFC). Our aim was therefore to modulate activity in these regions using HD-tDCS and thereby assess their relevance for working memory, divided attention and their shared sub-processes.Method: 78 participants were evenly randomized to one of three conditions in a single blind, parallel group study design. Anodal or sham HD-tDCS was applied to either the left IPS or LDLPFC while participants completed a verbal working memory task, a divided attention task, and two tasks measuring subcomponents of working memory (updating and maintenance).Results: Focalised stimulation of the IPS and LDLPFC did not significantly modulate performance compared to sham stimulation. However, moderate effect sizes were obtained for at least one HD-tDCS condition relative to sham for all tasks, warranting further research into the functional importance of the IPS in subserving these abilities.Conclusions: The current results may be useful for informing future tDCS studies for modulating working memory and divided attention functioning.