Conventional tDCS Research Articles

The effect of high-definition transcranial direct current stimulation on pain in somatic symptom disorder with predominant pain: A randomized single-blind sham-controlled crossover study

Somatic symptom disorder with predominant pain (SSD-P) is a commonly encountered disorder, yet treatment options often yield unsatisfactory outcomes. Transcranial direct current stimulation (tDCS) has proven useful in chronic pain conditions and may hold potential for treating somatoform pain. High-definition tDCS (HD-tDCS) offers more precise cortical stimulation than conventional tDCS. However, this modality has not been extensively studied in SSD-P. Consequently, this study aims to assess the effects of a novel HD-tDCS protocol on pain and other associated variables in patients with SSD-P. The Institute Ethics Committee approved the study, which was also registered in the Clinical Trials Registry of India. A single-blind, sham-controlled, crossover study design was employed. Thirty right-handed patients with DSM-5 diagnosis of SSD-P, aged 18 – 60 years and receiving stable treatment, were enrolled through consecutive sampling. After simple randomization, two repeated, short-interval sessions (2 mA, 20 min each) of either active or sham HD-tDCS were administered, followed by a washout period of 7 days and a subsequent crossover. Assessments were conducted at baseline, week 1, and week 2. Participants in active and sham arms were comparable on all baseline parameters. At the end of the 1st week, patients in the active group showed significant improvement in the study variables compared to the sham group. By week 2, all participants, irrespective of being in the active or sham arm, demonstrated a statistically significant difference (Cohen’s d > 0.8) in pain and associated parameters such as depression, anxiety, pain-related interference, burden, and disability (P < 0.01). Transient mild local side effects such as burning, pain, and itching were noted, with no cognitive side effects reported. In conclusion, this novel HD-tDCS protocol is effective in reducing pain in patients with SSD-P, with sustained effects up to 1 week.

Effectiveness and tolerability of adjunctive transcranial direct current stimulation (tDCS) in management of treatment-resistant depression: A retrospective chart review.

There is a limited number of studies from India investigating the role of transcranial direct current stimulation (tDCS) in treatment-resistant depression (TRD). This clinic-based study reports on the effectiveness of tDCS as an add-on treatment in individuals suffering from TRD. Twenty-six right-handed individuals suffering from major depressive disorder who failed to respond to adequate trials of at least two antidepressant drugs in the current episode received tDCS as an augmenting treatment. Twice daily sessions of conventional tDCS were given providing anodal stimulation at the left dorsolateral prefrontal cortex (DLPFC) and cathodal placement at the right DLPFC. A total of 20 sessions were given over 2 weeks. The outcome was assessed based on changes in scores of the Hamilton Rating Scale for Depression (HAMD) and Montgomery-Asberg Depression Rating Scale (MADRS). There was a significant reduction in outcome assessment after tDCS intervention as compared to baseline, with more than 50% of the participants showing response in both scales, which increased further to approximately 77% by the end of 1 month of the follow-up period. Twice daily tDCS sessions with anodal stimulation of left DLPFC and cathodal stimulation of right DLPFC is an effective add-on treatment strategy in individuals with TRD.

High-definition turns timing-dependent: Different behavioural consequences during and following cathodal high-definition transcranial direct current stimulation (HD tDCS) in a magnitude classification task.

Neuromodulation with transcranial direct current stimulation (tDCS) can transiently alter neural activity, but its spatial precision is low. High-definition (HD) tDCS was introduced to increase spatial precision by placing additional electrodes over the scalp. Initial evaluations of HD tDCS indicated polarity-specific neurophysiological effects-similar to conventional tDCS albeit with greater spatial precision. Here, we compared the effects of cathodal tDCS or HD tDCS in a 4 × 1 configuration over prefrontal cortex (PFC) regions on behavioural outcomes in a magnitude classification task. We report results on overall performance, on the numerical distance effect as a measure of numerical processing, and on the spatial-numerical associations of response codes (SNARC) effect, which was previously affected by prefrontal tDCS. Healthy volunteers (n = 68) received sham or cathodal HD tDCS at 1 mA over the left dorsolateral prefrontal cortex (DLPFC) or the left inferior frontal gyrus (IFG). Results were compared to an identical protocol with conventional cathodal tDCS to the left PFC versus sham (n = 64). Mixed effects models showed performance gains relative to sham tDCS in all conditions after tDCS (i.e. 'offline'), whereas montages over PFC and DLPFC already showed performance gains during tDCS (i.e. 'online'). In contrast to conventional tDCS, HD tDCS did not reduce the SNARC effect. Neither condition affected numerical processing, as expected. The results suggest that HD tDCS with cathodal polarity might require further adjustments (i.e. regarding tDCS intensity) for effective modulations of cognitive-behavioural performance, which could be achieved by individualised current density in electric field modelling.

Electric field simulation and appropriate electrode positioning for optimized transcranial direct current stimulation of stroke patients: an in Silico model

Transcranial Direct Current Stimulation (tDCS) has benefits for motor rehabilitation in stroke patients, but its clinical application is limited due to inter-individual heterogeneous effects. Recently, optimized tDCS that considers individual brain structure has been proposed, but the utility thereof has not been studied in detail. We explored whether optimized tDCS provides unique electrode positions for each patient and creates a higher target electric field than the conventional approach. A comparative within-subject simulation study was conducted using data collected for a randomized controlled study evaluating the effect of optimized tDCS on upper extremity function in stroke patients. Using Neurophet tES LAB 3.0 software, individual brain models were created based on magnetic resonance images and tDCS simulations were performed for each of the conventional and optimized configurations. A comparison of electrode positions between conventional tDCS and optimized tDCS was quantified by calculation of Euclidean distances. A total of 21 stroke patients were studied. Optimized tDCS produced a higher electric field in the hand motor region than conventional tDCS, with an average improvement of 20% and a maximum of 52%. The electrode montage for optimized tDCS was unique to each patient and exhibited various configurations that differed from electrode placement of conventional tDCS. Optimized tDCS afforded a higher electric field in the target of a stroke patient compared to conventional tDCS, which was made possible by appropriately positioning the electrodes. Our findings may encourage further trials on optimized tDCS for motor rehabilitation after stroke.

Differential effects of conventional and high-definition transcranial direct-current stimulation of the motor cortex on implicit motor sequence learning.

Conventional transcranial direct-current stimulation (tDCS) delivered to the primary motor cortex (M1) has been shown to enhance implicit motor sequence learning (IMSL). Conventional tDCS targets M1 but also the motor association cortices (MAC), making the precise contribution of these areas to IMSL presently unclear. We aimed to address this issue by comparing conventional tDCS of M1 and MAC to 4*1 high-definition (HD) tDCS, which more focally targets M1. In this mixed-factorial, sham-controlled, crossover study in 89 healthy young adults, we used mixed-effects models to analyse sequence-specific and general learning effects in the acquisition and short- and long-term consolidation phases of IMSL, as measured by the serial reaction time task. Conventional tDCS did not influence general learning, improved sequence-specific learning during acquisition (anodal: M= 42.64ms, sham: M= 32.87ms, p =.041), and seemingly deteriorated it at long-term consolidation (anodal: M= 75.37ms, sham: M= 86.63ms, p =.019). HD tDCS did not influence general learning, slowed performance specifically in sequential blocks across all learning phases (all p's < .050), and consequently deteriorated sequence-specific learning during acquisition (anodal: M= 24.13ms, sham: M= 35.67ms, p =.014) and long-term consolidation (anodal: M= 60.03ms, sham: M= 75.01ms, p =.002). Our findings indicate that the observed superior conventional tDCS effects on IMSL are possibly attributable to a generalized stimulation of M1 and/or adjacent MAC, rather than M1 alone. Alternatively, the differential effects can be attributed to cathodal inhibition of other cortical areas involved in IMSL by the 4*1 HD tDCS return electrodes, and/or more variable electric field strengths induced by HD tDCS, compared with conventional tDCS.

Modulation of the executive control network by anodal tDCS over the left dorsolateral prefrontal cortex improves task shielding in dual tasking

Task shielding is an important executive control demand in dual-task performance enabling the segregation of stimulus–response translation processes in each task to minimize between-task interference. Although neuroimaging studies have shown activity in left dorsolateral prefrontal cortex (dlPFC) during various multitasking performances, the specific role of dlPFC in task shielding, and whether non-invasive brain stimulation (NIBS) may facilitate task shielding remains unclear. We therefore applied a single-blind, crossover sham-controlled design in which 34 participants performed a dual-task experiment with either anodal transcranial direct current stimulation (atDCS, 1 mA, 20 min) or sham tDCS (1 mA, 30 s) over left dlPFC. Task shielding was assessed by the backward-crosstalk effect, indicating the extent of between-task interference in dual tasks. Between-task interference was largest at high temporal overlap between tasks, i.e., at short stimulus onset asynchrony (SOA). Most importantly, in these conditions of highest multitasking demands, atDCS compared to sham stimulation significantly reduced between-task interference in error rates. These findings extend previous neuroimaging evidence and support modulation of successful task shielding through a conventional tDCS setup with anodal electrode over the left dlPFC. Moreover, our results demonstrate that NIBS can improve shielding of the prioritized task processing, especially in conditions of highest vulnerability to between-task interference.

Individual response to transcranial direct current stimulation as a function of working memory capacity and electrode montage.

Attempts to improve cognitive abilities via transcranial direct current stimulation (tDCS) have led to ambiguous results, likely due to the method's susceptibility to methodological and inter-individual factors. Conventional tDCS, i.e., using an active electrode over brain areas associated with the targeted cognitive function and a supposedly passive reference, neglects stimulation effects on entire neural networks. We investigated the advantage of frontoparietal network stimulation (right prefrontal anode, left posterior parietal cathode) against conventional and sham tDCS in modulating working memory (WM) capacity dependent transfer effects of a single-session distractor inhibition (DIIN) training. Since previous results did not clarify whether electrode montage drives this individual transfer, we here compared conventional to frontoparietal and sham tDCS and reanalyzed data of 124 young, healthy participants in a more robust way using linear mixed effect modeling. The interaction of electrode montage and WM capacity resulted in systematic differences in transfer effects. While higher performance gains were observed with increasing WM capacity in the frontoparietal stimulation group, low WM capacity individuals benefited more in the sham condition. The conventional stimulation group showed subtle performance gains independent of WM capacity. Our results confirm our previous findings of WM capacity dependent transfer effects on WM by a single-session DIIN training combined with tDCS and additionally highlight the pivotal role of the specific electrode montage. WM capacity dependent differences in frontoparietal network recruitment, especially regarding the parietal involvement, are assumed to underlie this observation.

Transcranial direct current stimulation (tDCS) in depression induces structural plasticity

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique involving administration of well-tolerated electrical current to the brain through scalp electrodes. TDCS may improve symptoms in neuropsychiatric disorders, but mixed results from recent clinical trials underscore the need to demonstrate that tDCS can modulate clinically relevant brain systems over time in patients. Here, we analyzed longitudinal structural MRI data from a randomized, double-blind, parallel-design clinical trial in depression (NCT03556124, N = 59) to investigate whether serial tDCS individually targeted to the left dorso-lateral prefrontal cortex (DLPFC) can induce neurostructural changes. Significant (FWEc p < 0.05) treatment-related gray matter changes were observed with active high-definition (HD) tDCS relative to sham tDCS within the left DLPFC stimulation target. No changes were observed with active conventional tDCS. A follow-up analysis within individual treatment groups revealed significant gray matter increases with active HD-tDCS in brain regions functionally connected with the stimulation target, including the bilateral DLPFC, bilateral posterior cingulate cortex, subgenual anterior cingulate cortex, and the right hippocampus, thalamus and left caudate brain regions. Integrity of blinding was verified, no significant differences in stimulation-related discomfort were observed between treatment groups, and tDCS treatments were not augmented by any other adjunct treatments. Overall, these results demonstrate that serial HD-tDCS leads to neurostructural changes at a predetermined brain target in depression and suggest that such plasticity effects may propagate over brain networks.

Electric field simulations of transcranial direct current stimulation in children with perinatal stroke.

Perinatal stroke (PS) is a focal vascular brain injury and the leading cause of hemiparetic cerebral palsy. Motor impairments last a lifetime but treatments are limited. Transcranial direct-current stimulation (tDCS) may enhance motor learning in adults but tDCS effects on motor learning are less studied in children. Imaging-based simulations of tDCS-induced electric fields (EF) suggest differences in the developing brain compared to adults but have not been applied to common pediatric disease states. We created estimates of tDCS-induced EF strength using five tDCS montages targeting the motor system in children with PS [arterial ischemic stroke (AIS) or periventricular infarction (PVI)] and typically developing controls (TDC) aged 6-19 years to explore associates between simulation values and underlying anatomy. Simulations were performed using SimNIBS https://simnibs.github.io/simnibs/build/html/index.html using T1, T2, and diffusion-weighted images. After tissue segmentation and tetrahedral mesh generation, tDCS-induced EF was estimated based on the finite element model (FEM). Five 1mA tDCS montages targeting motor function in the paretic (non-dominant) hand were simulated. Estimates of peak EF strength, EF angle, field focality, and mean EF in motor cortex (M1) were extracted for each montage and compared between groups. Simulations for eighty-three children were successfully completed (21 AIS, 30 PVI, 32 TDC). Conventional tDCS montages utilizing anodes over lesioned cortex had higher peak EF strength values for the AIS group compared to TDC. These montages showed lower mean EF strength within target M1 regions suggesting that peaks were not necessarily localized to motor network-related targets. EF angle was lower for TDC compared to PS groups for a subset of montages. Montages using anodes over lesioned cortex were more sensitive to variations in underlying anatomy (lesion and tissue volumes) than those using cathodes over non-lesioned cortex. Individualized patient-centered tDCS EF simulations are prudent for clinical trial planning and may provide insight into the efficacy of tDCS interventions in children with PS.

Effects of Anodal Transcranial Direct Current Stimulation on the Primary Motor Cortex in Women With Fibromyalgia: A Randomized, Triple-Blind Clinical Trial

ObjectivesThe aim of this study was to analyze the effects of ten sessions of active transcranial direct current stimulation transcranial direct current stimulation (tDCS) (2 mA) with 13:20:13 stimulation at M1 in women with fibromyalgia (FM). To the best of our knowledge, this is the first article that uses this protocol in patients with FM. The main hypothesis is that the protocol would be effective in decreasing pain and that the results would last for up to 90 days. Materials and MethodsThis study was a randomized clinical trial with 35 women with FM divided into two groups, active tDCS group and sham tDCS group. A conventional tDCS device was used to deliver 2 mA for 13 minutes, with a 20-minute break followed by a further 13 minutes of stimulation for ten sessions. The anodal stimulus was in the left primary motor cortex M1 region. The primary outcome was a change in the visual analog scale and the Survey of Pain Attitudes pain score at the end of treatment, after 30 days, and 90 days after the end of treatment. Secondary outcomes included changes in the Fibromyalgia Impact Questionnaire, Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale, World Health Organization's Quality of Life Questionnaire, and Fatigue Assessment Scale. The Research Ethics Committee of the Centro Universitário da Grande Dourados under registration number Certificado de Apresentação de Apreciação Ética approved this research: 36444920.5.0000.5159. The study was registered in The Brazilian Registry of Clinical Trials with the identifier RBR-8wc8rjq. ResultsThe active tDCS group showed improvement in pain after ten sessions (p < 0.001), after 30 days (p < 0.01), and after 90 days (p < 0.001) compared with sham tDCS. In addition, improvement in quality of life (QoL) and fatigue was observed in the active tDCS group. ConclusionThe results of this study suggest that active tDCS with an intensity of 2 mA for ten sessions was effective in decreasing pain and fatigue and improving QoL in patients with FM.

Choosing the right measure: comparing two common electric field modeling outcome measures in TMS, conventional tDCS and HD-tDCS simulations.

Choosing the right measure: comparing two common electric field modeling outcome measures in TMS, conventional tDCS and HD-tDCS simulations.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.

MRI-Based Personalized Transcranial Direct Current Stimulation to Enhance the Upper Limb Function in Patients with Stroke: Study Protocol for a Double-Blind Randomized Controlled Trial.

Transcranial direct current stimulation (tDCS) has been shown to have the potential to improve the motor recovery of the affected upper limbs in patients with stroke, and recently, several optimized tDCS methods have been proposed to magnify its effectiveness. This study aims to determine the effectiveness of personalized tDCS using brain MRI-based electrical field simulation and optimization, to enhance motor recovery of the upper limbs in the patients. This trial is a double-blind, randomized controlled trial in the subacute to chronic rehabilitation phase. Forty-two adult stroke patients with unilateral upper limb involvement will be randomly allocated to three groups: (1) personalized tDCS with MRI-based electrical field simulation and optimized stimulation, (2) conventional tDCS with bihemispheric stimulation of the primary motor cortex, and (3) sham tDCS. All three groups will undergo 10 intervention sessions with 30 min of 2-mA intensity stimulation, during a regular upper limb rehabilitation program over two weeks. The primary outcome measure for the motor recovery of the upper limb impairment is the Fugl-Meyer assessment for the upper extremity score at the end of the intervention, and the secondary measures include changes in the motor evoked potentials, the frequency power and coherence of the electroencephalography, performance in activities of daily living, and adverse events with a 1-month follow-up assessment. The primary outcome will be analyzed on the intention-to-treat principle. There is a paucity of studies regarding the effectiveness of personalized and optimized tDCS that considers individual brain lesions and electrical field characteristics in the real world. No feasibility or pivotal studies have been performed in stroke patients using brain MRI, to determine a lesion-specific tDCS simulation and optimization that considers obstacles in the segmentation and analysis of the affected brain tissue, such as ischemic and hemorrhagic lesions. This trial will contribute to addressing the effectiveness and safety of personalized tDCS, using brain MRI-based electrical field simulation and optimization, to enhance the motor recovery of the upper limbs in patients with stroke.

Stimulation Montage Achieves Balanced Focality and Intensity

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique to treat brain disorders by using a constant, low current to stimulate targeted cortex regions. Compared to the conventional tDCS that uses two large pad electrodes, multiple electrode tDCS has recently received more attention. It is able to achieve better stimulation performance in terms of stimulation intensity and focality. In this paper, we first establish a computational model of tDCS, and then propose a novel optimization algorithm using a regularization matrix λ to explore the balance between stimulation intensity and focality. The simulation study is designed such that the performance of state-of-the-art algorithms and the proposed algorithm can be compared via quantitative evaluation. The results show that the proposed algorithm not only achieves desired intensity, but also smaller target error and better focality. Robustness analysis indicates that the results are stable within the ranges of scalp and cerebrospinal fluid (CSF) conductivities, while the skull conductivity is most sensitive and should be carefully considered in real clinical applications.

Transcranial Direct Current Stimulation Targeting the Entire Motor Network Does Not Increase Corticospinal Excitability.

Transcranial direct current stimulation (tDCS) over the contralateral primary motor cortex of the target muscle (conventional tDCS) has been described to enhance corticospinal excitability, as measured with transcranial magnetic stimulation. Recently, tDCS targeting the brain regions functionally connected to the contralateral primary motor cortex (motor network tDCS) was reported to enhance corticospinal excitability more than conventional tDCS. We compared the effects of motor network tDCS, 2 mA conventional tDCS, and sham tDCS on corticospinal excitability in 21 healthy participants in a randomized, single-blind within-subject study design. We applied tDCS for 12 min and measured corticospinal excitability with TMS before tDCS and at 0, 15, 30, 45, and 60 min after tDCS. Statistical analysis showed that neither motor network tDCS nor conventional tDCS significantly increased corticospinal excitability relative to sham stimulation. Furthermore, the results did not provide evidence for superiority of motor network tDCS over conventional tDCS. Motor network tDCS seems equally susceptible to the sources of intersubject and intrasubject variability previously observed in response to conventional tDCS.

The Infraslow Frequency Oscillatory Transcranial Direct Current Stimulation Over the Left Dorsolateral Prefrontal Cortex Enhances Sustained Attention.

BackgroundThe vigilance fluctuation and decrement of sustained attention have large detrimental consequences to most tasks in daily life, especially among the elderly. Non-invasive brain stimulations (e.g., transcranial direct current stimulation, tDCS) have been widely applied to improve sustained attention, however, with mixed results.ObjectiveAn infraslow frequency oscillatory tDCS approach was designed to improve sustained attention.MethodsThe infraslow frequency oscillatory tDCS (O-tDCS) over the left dorsolateral prefrontal cortex at 0.05 Hz was designed and compared with conventional tDCS (C-tDCS) to test whether this new protocol improves sustained attention more effectively. The sustained attention was evaluated by reaction time and accuracy.ResultsCompared with the C-tDCS and sham, the O-tDCS significantly enhanced sustained attention by increasing response accuracy, reducing response time, and its variability. These effects were predicted by the evoked oscillation of response time at the stimulation frequency.ConclusionSimilar to previous studies, the modulation effect of C-tDCS on sustained attention is weak and unstable. In contrast, the O-tDCS effectively and systematically enhances sustained attention by optimizing vigilance fluctuation. The modulation effect of O-tDCS is probably driven by neural oscillations at the infraslow frequency range.

Effects of transcranial direct current stimulation on patients with post-stroke fatigue: a study protocol for a double-blind randomized controlled trial

IntroductionPost-stroke fatigue (PSF) is an abnormal, persistent, and unexplained physical and psychological tiredness in patients after stroke. It is a common symptom of stroke patients with poor quality of life and bleak prognosis, and the incidence rate is up to 39% to 72%. It has been widely reported that medicine treatments achieved a lot of progress, there still needs to develop more powerful new strategies to more powerful effect. The transcranial direct-current stimulation (tDCS) shows great potential for the treatment of PSF. This study proposes to apply a double-blind randomized controlled clinical trial to explore the effect and safety of tDCS combined with routine rehabilitation for PSF.Methods and analysisOne hundred patients with PSF will be randomly divided into two groups. One of the groups will receive conventional rehabilitation therapy and active tDCS, whereas another group will receive conventional rehabilitation treatment and sham tDCS. Both groups will receive the intervention for 4 weeks, during which time they will undergo either active or sham tDCS 20 min a day, 6 days a week. Primary outcome: Fatigue Severity Scale (FSS) will be measured at baseline every weekend during the intervention period. Secondary results: Fatigue Impact Scale (FIS), Functional Assessment Chronic Illness Therapy (Fatigue) (FACIT-F), and Specialized Quality of Life Scale in Stroke (SS-QOL) will be measured at baseline and at the end of the intervention time of 4 weeks. Throughout the study, adverse events and adverse reactions will be measured during every treatment. The research study “Effects of transcranial direct current stimulation on patients with post-stroke fatigue” has been approved by the Ethics Committee of the First Affiliated Hospital of Nanchang University: Clinical Medicine Ethics Review [2015]043 in Nov 2015.DiscussionThis study will provide insight into the efficacy of transcranial direct-current stimulation for post-stroke fatigue. This is a double-blind randomized controlled trial whose aim is to assess the effects of tDCS on PSF. This study can provide more information about the treatment of PSF. This study has a period of follow-up, which allows for greater accuracy. It is a single-center trial, and this may be a limitation. The other limitation of this study is the relatively small number of participants; thus, the influence of chance on experimental results cannot be completely ruled out.Trial registrationChinese Clinical Trial Registry ChiCTR2000031120. Registered on March 22, 2020. This protocol version number is V1.1.

OC14 : Personalized multichannel transcranial direct current electrical stimulation guided by SEEG in drug-resistant epilepsy: clinical and neurophysiological effects

In refractory epilepsy, transcranial direct electrical stimulation (tDCS) is applied to decrease cortical activity with two (conventional tDCS) or several electrodes (multifocal tDCS). We investigated effects of personalized multisession, SEEG-targeted multifocal tDCS on seizure frequency (SF) and scalp functional connectivity (Fc) as measured by EEG in patients with drug-resistant epilepsy (DRE). Ten patients suffering from DRE were recruited to study therapeutic and neurophysiological effects of long-term multifocal tDCS treatment (Starstim, Neuroelectrics). Therapy consisted of three cycles where each stimulation cycle corresponded to five consecutive days where each patient received 2x20 min tDCS at 2 mA separated by 20 min off. The montages were personalized to target epileptogenic area of each patient as defined by SEEG recordings. SF after the treatment was compared with baseline. Fc changes were analysed using EEG recordings performed before and after each stimulation cycle. After the last tDCS session, 50% of patients (responders) had a SF decrease of 50% or more compared with baseline. We estimated Fc changes between cycles and across responder (R) and non-responder (NR) patients. R presented a decrease in Fc (p<0.05) at the third session in alpha and beta frequency bands compared to the first one. We validated the clinical usefulness of personalized multifocal tDCS targeting epileptic areas identified by SEEG. Moreover, we demonstrated that a decrease in SF is associated to a significant decrease of Fc after three stimulation cycles. Such results suggest that tDCS-induced functional plasticity changes may underlie the clinical outcome differences between R and NR.

Comparing the effects of focal and conventional tDCS on motor skill learning: A proof of principle study

Transcranial direct current stimulation (tDCS) has emerged as a promising intervention in clinical and behavioral neuroscience; however, the response variability to this technique has limited its impact, partly due to the widespread of current flow with conventional methods. Here, we investigate whether a more targeted, focal approach over the primary motor cortex (M1) is advantageous for motor learning and targeting specific neuronal populations. Our preliminary results show that focal stimulation leads to enhanced skill learning and differentially recruits distinct pathways to M1. This finding suggests that focal tDCS approaches may improve the outcomes of future studies aiming to enhance behavior.

Conventional and HD-tDCS May (or May Not) Modulate Overt Attentional Orienting: An Integrated Spatio-Temporal Approach and Methodological Reflections.

Transcranial Direct Current Stimulation (tDCS) has been employed to modulate visuo-spatial attentional asymmetries, however, further investigation is needed to characterize tDCS-associated variability in more ecological settings. In the present research, we tested the effects of offline, anodal conventional tDCS (Experiment 1) and HD-tDCS (Experiment 2) delivered over the posterior parietal cortex (PPC) and Frontal Eye Field (FEF) of the right hemisphere in healthy participants. Attentional asymmetries were measured by means of an eye tracking-based, ecological paradigm, that is, a Free Visual Exploration task of naturalistic pictures. Data were analyzed from a spatiotemporal perspective. In Experiment 1, a pre-post linear mixed model (LMM) indicated a leftward attentional shift after PPC tDCS; this effect was not confirmed when the individual baseline performance was considered. In Experiment 2, FEF HD-tDCS was shown to induce a significant leftward shift of gaze position, which emerged after 6 s of picture exploration and lasted for 200 ms. The present results do not allow us to conclude on a clear efficacy of offline conventional tDCS and HD-tDCS in modulating overt visuospatial attention in an ecological setting. Nonetheless, our findings highlight a complex relationship among stimulated area, focality of stimulation, spatiotemporal aspects of deployment of attention, and the role of individual baseline performance in shaping the effects of tDCS.