Search Results (59)

Transcranial direct current stimulation (tDCS) can modulate cortical excitability in a polarity-specific manner, yet identical protocols often produce inconsistent outcomes across sessions or individuals. This narrative review proposes that much of this variability arises from the brain’s intrinsic temporal landscape. Integrating evidence from chronobiology, sleep research, and non-invasive brain stimulation, we argue that tDCS produces reliable, polarity-specific after-effects only within a circadian–homeostatic “window of efficacy”. On the circadian (Process C) axis, intrinsic alertness, membrane depolarisation, and glutamatergic gain rise in the late biological morning and early evening, whereas pre-dawn phases are marked by reduced excitability and heightened inhibition. On the homeostatic (Process S) axis, consolidated sleep renormalises synaptic weights, widening the capacity for further potentiation, whereas prolonged wakefulness saturates plasticity and can even reverse the usual anodal/cathodal polarity rules. Human stimulation studies mirror this two-process fingerprint: sleep deprivation abolishes anodal long-term-potentiation-like effects and converts cathodal inhibition into facilitation, while stimulating at each participant’s chronotype-aligned (phase-aligned) peak time amplifies and prolongs after-effects even under equal sleep pressure. From these observations we derive practical recommendations: (i) schedule excitatory tDCS after restorative sleep and near the individual wake-maintenance zone; (ii) avoid sessions at high sleep pressure or circadian troughs; (iii) log melatonin phase, chronotype, recent sleep and, where feasible, core temperature; and (iv) consider mild pre-heating or time-restricted feeding as physiological primers. By viewing Borbély’s two-process model and allied metabolic clocks as adjustable knobs for plasticity engineering, this review provides a conceptual scaffold for personalised, time-sensitive tDCS protocols that could improve reproducibility in research and therapeutic gain in the clinic. Full article

Transcranial direct current stimulation (tDCS) modulates cortical excitability, thus inducing improvements in motor learning of simple tasks. In this study, we aimed to evaluate the effect of different tDCS conditions—anodal stimulation over the motor cortex (M1), anodal and cathodal stimulation over the prefrontal cortex (PFC), and sham—on the online and offline learning of a complex accuracy task (golf-putting) in novice golfers. Methods: A total of 40 young, healthy subjects (24 men, 16 women) without previous golf experience were randomly distributed in four groups receiving sham, anodal M1, anodal PFC or cathodal PFC tDCS. All subjects participated in two consecutive sessions. In the first session, they performed 15 blocks of 10 golf-putting along with tDCS stimulation. After 24 h, they performed the same task without tDCS. Results: Repeated measures ANOVA revealed a significant improvement in performance during the two consecutive golf-putting sessions regardless of the site and the stimulation conditions. Conclusion: Our findings suggest that tDCS over M1 or PFC does not confer additional benefits in the acquisition of complex, full-body motor skills such as golf-putting. Full article

Background: Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique for migraine prevention. This study evaluates the efficacy of tDCS compared to sham in preventing episodic migraine in adults. Methods: PubMed and Embase databases were searched until May 2025 to identify randomized controlled trials comparing tDCS with sham for the prevention of episodic migraine in adults. Risk of bias in the included trials was assessed using the Cochrane Risk of Bias Tool version 2. A random effect meta-analysis was conducted to evaluate the effects of cathodal and anodal tDCS on migraine frequency (days per month and attacks per month). Results: The meta-analysis included six trials with 172 participants (mean age 34 years, 82% females). Both cathodal (three studies, over the occipital area) and anodal (three studies, over the occipital or primary motor area) tDCS reduced the mean number of monthly migraine days and migraine attacks compared to sham. After pooling the outcomes and excluding two studies at high risk of bias, anodal tDCS over the occipital or primary motor area (standardized difference in means = −0.7, 95% CI: −1.7, 0.2, p = 0.124) and cathodal tDCS over the occipital area (standardized difference in means = −0.7, 95% CI: −1.1, −0.3, p = 0.000) reduced headache frequency compared to sham. However, the reduction with anodal tDCS was not statistically significant. Summary: tDCS may be effective in preventing episodic migraine. However, the evidence is limited by the small number of heterogeneous trials, with variation in electrode placement and stimulation intervals. Full article

In this study, we aimed to assess the effects of transcranial direct current stimulation (tDCS) stimulation on brain metabolism in a patient with typical hemorrhagic stroke in a subacute phase. The patient was evaluated with ¹⁸F-FDG PET (18F-fluoro-2-deoxy-D-glucose positron emission tomography) during tDCS brain stimulation at 6, 8, and 10 weeks from the event. The patient underwent the following protocol: baseline cerebral ¹⁸F-FDG-PET (T0); cerebral ¹⁸F-FDG-PET during anodal-tDCS on the affected hemisphere (T1); and cerebral ¹⁸F-FDG-PET during cathodal-tDCS on the unaffected hemisphere (T2). Baseline PET examination revealed marked hypometabolism of the right nucleo-capsular hemorrhagic lesion; at T1, an increase in brain metabolism was shown in the stimulated hemisphere and unexpectedly in the non-stimulated hemisphere; at T2, a reduction in metabolism was documented in the hemisphere ipsilateral to the inhibiting current applied by tDCS. The use of PET may provide new insights into the effects of tDCS on brain metabolism, providing in vivo information about the plasticity mechanisms of the injured brain. Further studies, using a combination of PET and tDCS, are necessary to further clarify the mechanisms of action of this stimulation technique to the clinical and functional outcomes. Full article

This study examined transient effects of transcranial direct current stimulation (tDCS) on bilateral force control in lower extremities. We recruited 14 healthy young adults and administered bilateral ankle-dorsiflexion force control tasks at 10% of maximal voluntary contraction. Participants were able to use real-time visual information on a targeted force level and forces produced by both feet. While performing bilateral force control, we provided active- and sham-tDCS in a random order. Bilateral tDCS protocol used for this study included anodal and cathodal stimulation targeting left and right leg areas of the primary motor cortex between hemispheres. Bilateral force control capabilities were estimated by calculating force accuracy, variability and regularity. In addition, we determined whether force control patterns differed between feet across active- and sham-tDCS conditions. The findings revealed that force accuracy and variability were significantly improved after applying active-tDCS protocol as compared with those for sham-tDCS condition. However, no differences in force control between feet were observed. These findings suggest that bilateral tDCS protocols may be a viable option for improving motor functions of lower limbs. Full article

Objectives: This research investigated the impact of transcranial Direct Current Stimulation (tDCS) on sense of agency (SoA) when focusing on cortical regions like the cerebellum, the dorsolateral prefrontal cortex (DLPFC), and the angular gyrus (AG). To this aim, three experiments were carried out, and agency was assessed through the Wundt Clock Paradigm, which provides a measure of intentional binding. Methods: The first experiment provided offline cathodal stimulation applied to the right cerebellum, with the return electrode placed on the left DLPFC, and participants were randomly assigned to either the placebo group or the active group. The second experiment adopted the same montage as the previous one, but the online stimulation was provided in a within-subjects design. Results: Since none of these studies targeting the cerebellum produced significant results on the agency measures, we carried out a third experiment aimed to replicate a previous study that provided inhibitory stimulation of the left AG. However, this also showed no modulations of SoA. Conclusions: Several explanations could be given for these negative results. For example, the inter-individual variability, task complexity, and limitations of tDCS technology may contribute to the inconsistencies of the results. Also, the failure to replicate a previous study raises the issue of the replicability crisis in psychology. Nevertheless, this study may represent an important reference for research aimed at modulating SoA through the neuromodulation of brain areas included in the agency network. Future studies could benefit from assessing individual cognitive abilities supporting agency, optimizing stimulation protocols, and exploring alternative brain stimulation techniques to obtain significant results. Full article

Background: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation for treatment-resistant obsessive compulsive disorder (OCD). We aim to compare the treatment outcomes of a newly developed dual-site cathodal tDCS method over the orbitofrontal cortex (OFC) and pre-supplementary motor area (pre-SMA) and two previously reported montages (cerebellum-OFC and pre-SMA) in patients with treatment-resistant OCD. Methods: Eighteen OCD patients were randomly assigned to receive twice-daily 2 mA/20 min sessions for 10 consecutive weekdays, with the active cathode placed on the cerebellum-OFC, bilateral pre-SMA, or OFC-pre-SMA tDCS. The primary outcome was the change in the Yale–Brown Obsessive Compulsive Scale (Y-BOCS). The resting electroencephalogram (EEG) was recorded to obtain the default mode network (DMN) via low-resolution electromagnetic tomography. Each patient received one-week and one-month follow-ups after two weeks of stimulation. Results: At the end of the stimulation, the Y-BOCS scores in the cerebellum-OFC, pre-SMA, and OFC-pre-SMA tDCS groups (n = 6 in each group) were decreased by 14.15 ± 13.31, 7.4 ± 9.59, and 20.75 ± 8.70%, respectively, but no significant differences were found among the groups. In the OFC-pre-SMA tDCS group, OC symptoms significantly decreased by a mean of −20.75% immediately after the 20th tDCS session, and the improvement remained at 1 week and 1 month after tDCS. EEG source functional connectivity analyses revealed increased functional connectivity within the frontal network after OFC-pre-SMA tDCS, whereas decreased functional connectivity within the DMN was observed after cerebellum-OFC tDCS. Conclusions: Dual-site cathodal tDCS over the OFC and pre-SMA might be considered a potential montage to treat patients with treatment-resistant OCD. Future studies using randomized sham-controlled designs are needed. Full article

Background/Objectives: Multiple Sclerosis (MS) is a chronic neurological condition that impairs motor and sensory functions, particularly gait. Non-invasive neuromodulation techniques aim to enhance functional recovery and motor–cognitive outcomes, though their effectiveness remains debated. This study compared the effects of transcranial direct current stimulation (tDCS) and trans-spinal direct current stimulation (tsDCS), combined with robotic-assisted gait training (RAGT), on motor function and fatigue in people with MS (pwMS). Methods: This double-blind, randomized, sham-controlled clinical trial included 35 pwMS, who participated in 12 sessions of 20 min anodal tDCS (n = 11), cathodal tsDCS (n = 12), or sham treatment (n = 12), in addition to RAGT. Primary outcomes were assessed using the Timed 25-foot Walk (T25-FW), Timed Up and Go (TUG), walking speed, and Multiple Sclerosis Walking Scale-12 (MSWS-12). Fatigue was assessed with the Fatigue Severity Scale (FSS) and the Fatigue Impact Scale (FIS). ClinicalTrials number: NCT06121635. Results: Significant improvements in gait speed, T25-FW, MSWS-12, TUG scores, and fatigue (FSS) favored tDCS and tsDCS over sham stimulation. While no differences were found between tDCS and tsDCS, the tsDCS group showed a significant improvement in the FIS physical subscale compared to sham, unlike the tDCS group. Conclusions: tDCS and tsDCS, combined with RAGT, improve walking and reduce fatigue in pwMS, highlighting their potential in motor rehabilitation. Full article

Stroke remains a leading cause of global disability and mortality despite advancements in acute interventions. Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique, has primarily been studied for its effects on cortical excitability, with limited exploration of its neuroprotective and hemodynamic benefits. This review examines the role of tDCS in stroke, with a focus on neuroprotection in acute settings and cerebral blood flow (CBF) modulation in both acute and chronic phases. tDCS offers rapid, localized delivery to salvageable ischemic tissue, exerting pleiotropic effects that address a broader spectrum of pathological processes compared to pharmacological agents. Cathodal tDCS shows promise in acute ischemic stroke for neuroprotection in small-scale clinical studies, enhancing CBF and promoting vessel recanalization, while anodal tDCS demonstrates stronger effects on CBF, particularly in chronic stroke and hypoperfusion cases. Bihemispheric stimulation may offer additional benefits, with evidence suggesting a dose-dependent relationship between stimulation parameters and therapeutic outcomes. Further research is warranted to optimize stimulation protocols, evaluate safety and feasibility, and explore the potential of tDCS to promote neuroplasticity and functional recovery across different stroke populations and stages. By addressing these gaps, tDCS could emerge as a valuable adjunctive therapy in stroke management, complementing current interventions and expanding therapeutic windows. Full article

Speech-language therapy (SLT) is the most effective technique to improve language performance in persons with aphasia. However, residual language impairments remain even after intensive SLT. Recent studies suggest that combining transcranial direct current stimulation (tDCS) with SLT may improve language performance in persons with aphasia. However, our understanding of how tDCS and SLT impact brain and behavioral relation in aphasia is poorly understood. We investigated the impact of tDCS and SLT on a behavioral measure of scripted conversation and on functional connectivity assessed with multiple methods, both resting-state functional magnetic resonance imaging (rs–fMRI) and resting-state electroencephalography (rs–EEG). An individual with aphasia received 15 sessions of 20-min cathodal tDCS to the right angular gyrus concurrent with 40 min of SLT. Performance during scripted conversation was measured three times at baseline, twice immediately post-treatment, and at 4- and 8-weeks post-treatment. rs–fMRI was measured pre-and post-3-weeks of treatment. rs–EEG was measured on treatment days 1, 5, 10, and 15. Results show that both communication performance and left hemisphere functional connectivity may improve after concurrent tDCS and SLT. Results are in line with aphasia models of language recovery that posit a beneficial role of left hemisphere perilesional areas in language recovery. Full article

Pain is a multifaceted, multisystem disorder that adversely affects neuro-psychological processes. This study compares the effectiveness of central stimulation (transcranial direct current stimulation—tDCS over F3/F4) and peripheral stimulation (transcutaneous electrical nerve stimulation—TENS over the median nerve) in pain inhibition during a cognitive task in healthy volunteers and to observe potential neuro-cognitive improvements. Eighty healthy participants underwent a comprehensive experimental protocol, including cognitive assessments, the Cold Pressor Test (CPT) for pain induction, and tDCS/TENS administration. EEG recordings were conducted pre- and post-intervention across all conditions. The protocol for this study was categorized into four groups: G1 (control), G2 (TENS), G3 (anodal-tDCS), and G4 (cathodal-tDCS). Paired t-tests (p < 0.05) were conducted to compare Pre-Stage, Post-Stage, and neuromodulation conditions, with t-values providing insights into effect magnitudes. The result showed a reduction in pain intensity with TENS (p = 0.002, t-value = −5.34) and cathodal-tDCS (p = 0.023, t-value = −5.08) and increased pain tolerance with TENS (p = 0.009, t-value = 4.98) and cathodal-tDCS (p = 0.001, t-value = 5.78). Anodal-tDCS (p = 0.041, t-value = 4.86) improved cognitive performance. The EEG analysis revealed distinct neural oscillatory patterns across the groups. Specifically, G2 and G4 showed delta-power reductions, while G3 observed an increase. Moreover, G2 exhibited increased theta-power in the occipital region during CPT and Post-Stages. In the alpha-band, G2, G3, and G4 had reductions Post-Stage, while G1 and G3 increased. Additionally, beta-power increased in the frontal region for G2 and G3, contrasting with a reduction in G4. Furthermore, gamma-power globally increased during CPT1, with G1, G2, and G3 showing reductions Post-Stage, while G4 displayed a global decrease. The findings confirm the efficacy of TENS and tDCS as possible non-drug therapeutic alternatives for cognition with alleviation from pain. Full article

The psychological refractory period (PRP) effect occurs when two stimuli that require separate responses are presented sequentially, particularly with a short and variable time interval between them. Fatigue is a suboptimal psycho-physiological state that leads to changes in strategies. In recent years, numerous studies have investigated the effects of transcranial direct current stimulation (tDCS) on motor control. The present study aimed to investigate the effects of two tDCS methods, anodal and cathodal, on PRP in ten different conditions of stimulus-onset asynchronies (SOAs) under non-fatigue and mental fatigue conditions. The participants involved 39 male university students aged 19 to 25 years. In the pre-test, they were assessed using the PRP measurement tool under both non-fatigue and mental fatigue conditions. The mental fatigue was induced by a 30-min Stroop task. The test consisted of two stimuli with different SOAs (50, 75, 100, 150, 300, 400, 600, 900, 1200, and 1500 ms). The first was a visual stimulus with three choices (letters A, B, and C). After a random SOA, the second stimulus, a visual stimulus with three choices (colors red, yellow, and blue), was presented. Subsequently, participants were randomly assigned to the anodal, cathodal, and sham stimulation groups and underwent four consecutive sessions of tDCS stimulation. In the anodal and cathodal stimulation groups, 20 min of tDCS stimulation were applied to the PLPFC area in each session, while in the sham group, the stimulation was artificially applied. All participants were assessed using the same measurement tools as in the pre-test phase, in a post-test phase one day after the last stimulation session, and in a follow-up phase four days after that. Inferential statistics include mixed ANOVA, one-way ANOVA, independent, and dependent t-tests. The findings indicated that the response time to the second stimulus was longer at lower SOAs. However, there was no significant difference between the groups in this regard. Additionally, there was no significant difference in response time to the second stimulus between the fatigue and non-fatigue conditions, or between the groups. Therefore, tDCS had no significant effect. There was a significant difference between mental fatigue and non-fatigue conditions in the psychological refractory period. Moreover, at lower SOAs, the PRP was longer than at higher SOAs. In conditions of fatigue, the active stimulation groups (anodal and cathodal) performed better than the sham stimulation group at higher SOAs. Considering the difference in response to both stimuli at different SOAs, some central aspects of the response can be simultaneously parallel. Fatigue also affects parallel processing. This study supports the response integration phenomenon in PRP, which predicts that there will be an increase in response time to the first stimulus as the interval between the presentation of the two stimuli increases. This finding contradicts the bottleneck model. In this study, the effectiveness of cathodal and anodal tDCS on response time to the second stimulus and PRP was found to be very small. Full article

Transcranial direct current stimulation (tDCS) is a non-invasive and painless technique of brain neuromodulation that applies a low-intensity galvanic current to the scalp with the aim of stimulating specific areas of the brain. Preliminary investigations have indicated the potential therapeutic efficacy of multisession tDCS applied to the auditory cortex (AC) in the treatment of chronic tinnitus. The aim of this study was to explore the therapeutic effects of repeated sessions of bilateral tDCS targeting the AC on chronic tinnitus. A double-blinded randomized placebo-controlled trial was conducted on patients (n = 48) with chronic intractable tinnitus (>2 years duration). Participants were randomly allocated to two groups: one receiving tDCS (n = 26), with the anode/cathode placed over the left/right AC, and the other receiving a placebo treatment (n = 22). A 20 min daily session of 2 mA current was administered for five consecutive days per week over two consecutive weeks, employing 35 cm² electrodes. Tinnitus handicap inventory (THI) scores, tinnitus loudness, and tinnitus distress were measured using a visual analogue scale (VAS), and were assessed before intervention, immediately after, and at one-month follow-up. Anodal tDCS significantly reduced THI from 72.93 ± 10.11 score to 46.40 ± 15.36 after the last session and 49.68 ± 14.49 at one-month follow-up in 18 out of 25 participants (p < 0.001). The risk ratio (RR) of presenting an improvement of ≥20 points in the THI after the last session was 10.8 in patients treated with tDCS. Statistically significant reductions were observed in distress VAS and loudness VAS (p < 0.001). No statistically significant differences in the control group were observed. Variables such as age, gender, duration of tinnitus, laterality of tinnitus, baseline THI scores, and baseline distress and loudness VAS scores did not demonstrate significant correlations with treatment response. Repeated sessions of bilateral AC tDCS may potentially serve as a therapeutic modality for chronic tinnitus. Full article

Objectives: Existing applications of non-invasive brain stimulation in the modulation of balance ability are focused on the primary motor cortex (M1). It is conceivable that other brain and spinal cord areas may be comparable or more promising targets in this regard. This study compares transcranial direct current stimulation (tDCS) over (i) the M1, (ii) the cerebellum, and (iii) trans-spinal direct current stimulation (tsDCS) in the modulation of balance ability. Methods: Forty-two sports students were randomized in this placebo-controlled study. Twenty minutes of anodal 1.5 mA t/tsDCS over (i) the M1, (ii) the cerebellum, and (iii) the spinal cord, as well as (iv) sham tDCS were applied to each subject. The Y Balance Test, Single Leg Landing Test, and Single Leg Squat Test were performed prior to and after each intervention. Results: The Y Balance Test showed significant improvement after real stimulation of each region compared to sham stimulation. While tsDCS supported the balance ability of both legs, M1 and cerebellar tDCS supported right leg stand only. No significant differences were found in the Single Leg Landing Test and the Single Leg Squat Test. Conclusions: Our data encourage the application of DCS over the cerebellum and spinal cord (in addition to the M1 region) in supporting balance control. Future research should investigate and compare the effects of different stimulation protocols (anodal or cathodal direct current stimulation (DCS), alternating current stimulation (ACS), high-definition DCS/ACS, closed-loop ACS) over these regions in healthy people and examine the potential of these approaches in the neurorehabilitation. Full article

Apraxia of speech is a persistent speech motor disorder that affects speech intelligibility. Studies on speech motor disorders with transcranial Direct Current Stimulation (tDCS) have been mostly directed toward examining post-stroke aphasia. Only a few tDCS studies have focused on apraxia of speech or childhood apraxia of speech (CAS), and no study has investigated individuals with CAS and Trisomy 21 (T21, Down syndrome). This N-of-1 randomized trial examined the effects of tDCS combined with a motor learning task in developmental apraxia of speech co-existing with T21 (ReBEC RBR-5435x9). The accuracy of speech sound production of nonsense words (NSWs) during Rapid Syllable Transition Training (ReST) over 10 sessions of anodal tDCS (1.5 mA, 25 cm) over Broca’s area with the cathode over the contralateral region was compared to 10 sessions of sham-tDCS and four control sessions in a 20-year-old male individual with T21 presenting moderate–severe childhood apraxia of speech (CAS). The accuracy for NSW production progressively improved (gain of 40%) under tDCS (sham-tDCS and control sessions showed < 20% gain). A decrease in speech severity from moderate–severe to mild–moderate indicated transfer effects in speech production. Speech accuracy under tDCS was correlated with Wernicke’s area activation (P3 current source density), which in turn was correlated with the activation of the left supramarginal gyrus and the Sylvian parietal–temporal junction. Repetitive bihemispheric tDCS paired with ReST may have facilitated speech sound acquisition in a young adult with T21 and CAS, possibly through activating brain regions required for phonological working memory. Full article