Effects Of tDCS Research Articles

Transcranial Direct Current Stimulation over the Posterior Parietal Cortex Increases Nontarget Retrieval during Visual Working Memory.

Visual working memory (VWM) requires precise feature binding. Previous studies have revealed a close relationship between the posterior parietal cortex (PPC) and feature binding during VWM; this study further examined their causal relationship through three transcranial direct current stimulation (tDCS) experiments. In Experiment 1 (N = 57), participants underwent three sessions of tDCS separately, including PPC stimulation, occipital cortex stimulation, and sham stimulation, and completed delayed estimation tasks for orientations before and after stimulation. Results showed that tDCS over PPC selectively prolonged recall response time (RT) and increased the probability of nontarget responses (a.k.a. failure of feature binding, pNT). In Experiment 2 (N = 29), combining metacognition estimation, we further investigated whether the effects of PPC stimulation were attributed to misbinding (i.e., participants self-reported "remembered" in nontarget responses) or informed guessing trials (participants self-reported "forgotten" in nontarget responses). We replicated the main findings in Experiment 1 and observed greater tDCS effects of PPC on RT in informed guessing trials while there are comparable effects on pNT in these two types of trials. In Experiment 3 (N = 28), we then examined whether the tDCS effects over PPC specifically influenced the memory retrieval process by using a change detection task. We found that PPC stimulation did not influence the recognition RT or accuracy. Together, this study provided direct causal evidence supporting the specific involvement of PPC in feature binding during VWM retrieval, from both aspects of speed and response preference, expanding our understanding of the neural basis of feature binding in VWM.

Cerebellar Transcranial Direct Current Stimulation in the Cerebellar Cognitive Affective Syndrome: A Randomized, Double-Blind, Sham-Controlled Trial.

The cerebellar cognitive affective syndrome (CCAS) encompasses cognitive and affective symptoms in patients with cerebellar disorders, for which no proven treatment is available. Our primary objective was to study the effect of cerebellar anodal transcranial direct current stimulation (tDCS) on cognitive performance in CCAS patients. Secondary effects on ataxia severity, mood, and quality of life were explored. We performed a randomized, double-blind, sham-controlled trial. Thirty-five patients with CCAS were included and received 10 sessions of 20 minutes sham (n = 17) or real (n = 18) tDCS, with a current of 2 mA. Cognitive performance was assessed using executive function subtests of the computerized Test of Attentional Performance (TAP), with the composite as primary endpoint. Secondary outcomes were ataxia severity, mood, and quality of life. Outcomes were evaluated 1, 3, 6, and 12 months post-intervention. Cerebellar tDCS was well tolerated and no serious adverse events related to the intervention occurred. No significant tDCS effect was found on cognitive performance. Improvement on the TAP was observed in the sham group 1 month post-treatment (estimate = -0.248, 95% CI, -0.49 to -0.01), but not clinically relevant. A positive tDCS effect was observed for ataxia severity 1 month post-treatment (estimate = -0.985, 95% CI, -1.94 to -0.03). Ten sessions of 20 minutes cerebellar anodal tDCS did not prove efficacious for CCAS-related cognitive impairment, but a significant positive effect of tDCS was found for ataxia severity, aligning with previous findings indicative of tDCS as a therapeutic neuromodulation tool in cerebellar disorders. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Transcranial Direct Current Stimulation Reduces Pressure Pain Sensitivity in Patients With Noncancer Chronic Pain.

Noncancer chronic pain is a clinical challenge because pharmacological treatment often fails to relieve pain. Transcranial direct current stimulation (tDCS) is a treatment that could have the potential for pain relief and improvement in quality of life. However, there is a lack of clinical trials evaluating the effects of tDCS on the pain system. The aim of the present study was to evaluate the effect of 5 days of anodal tDCS treatment on the pain system in patients with chronic noncancer pain using quantitative sensory testing and quality of life questionnaires: (1) Brief Pain Inventory-short form, (2) European Organization for Research and Treatment of Life Questionnaire-C30, and (3) Hospital Anxiety Depression Scale. Eleven patients with noncancer chronic pain (51 ± 13.6 y old, 5M) participated in the study. Anodal tDCS was applied for 5 consecutive days, followed by sham stimulation after a washout period of at least 2 weeks. Pressure pain thresholds and pain tolerance thresholds (PTT) were assessed in different body regions on days 1 and 5. Anodal tDCS appeared to maintain PTT at C5 (clavicle) on day 5, but sham stimulation decreased PTT ( P = 0.007). In addition, anodal tDCS increased PTT compared with sham at day 5 at Th10 ventral dermatomes ( P = 0.014). Both anodal and sham tDCS decreased the Brief Pain Inventory-short form total and interference scores, and the European Organization for Research and Treatment of Life Questionnaire-C30 fatigue score, but no interaction effect was observed. This study adds to the evidence in the literature that tDCS may be a potential therapeutic tool for the management of noncancer chronic pain.

Combined Effect of tDCS and Motor or Cognitive Activity in Patients with Alzheimer’s Disease: A Proof-of-Concept Pilot Study

(1) Background: Alzheimer’s disease (AD) accounts for 70% of dementia cases and with no effective pharmacological treatments, new rehabilitation methods are needed. Motor and cognitive activities and transcranial direct current stimulation (tDCS) have shown promise in stabilizing and enhancing cognitive functions. Objective: we want to investigate the effects of tDCS combined with motor or cognitive activity on cognitive functions in AD patients. (2) Methods: Patients with mild or moderate AD were randomized between anodic tDCS groups (MotA or CogA) and sham tDCS groups (MotS or CogS). They received two weeks of treatment (45 min, five days/week), with the first 15 min using tDCS stimulation on the dorsolateral prefrontal cortex. Cognitive assessments were conducted pre-treatment (T0), post-treatment (T1), and one week after (T2). (3) Results: Twenty-three patients were included. Statistical analysis showed significant differences between anodic tDCS groups (MotA + CogA) and sham tDCS groups (MotS + CogS) with advantages for the first in improving global cognitive status (p = 0.042), selective attention (p = 0.012), and sustained attention (p = 0.012). Further analysis indicated no differences between the two anodic tDCS groups between T0 and T1. (4) Conclusions: combined anodal tDCS with motor or cognitive activity could improve global cognitive state and attention, slowing cognitive decline in AD patients. The trial was registered on Clinical Trials: NCT06619795.

Slowing Cognitive Decline in Major Depressive Disorder and Mild Cognitive Impairment

Older adults with major depressive disorder (MDD) or mild cognitive impairment (MCI) are at high risk for cognitive decline. To assess the efficacy of cognitive remediation (CR) plus transcranial direct current stimulation (tDCS) targeting the prefrontal cortex in slowing cognitive decline, acutely improving cognition, and reducing progression to MCI or dementia in older adults with remitted MDD (rMDD), MCI, or both. This randomized clinical trial was conducted at 5 academic hospitals in Toronto, Ontario, Canada. Participants were older adults who had rMDD (with or without MCI, age ≥65 y) or MCI without rMDD (age ≥60 y). Assessments were made at baseline, month 2, and yearly from baseline for 3 to 7 years. CR plus tDCS (hereafter, active) or sham plus sham 5 days a week for 8 weeks followed by twice-a-year 5-day boosters and daily at-home CR or sham CR. The primary outcome was change in global composite cognitive score. Secondary outcomes included changes in 6 cognitive domains, moderating effect of the diagnosis, moderating effect of APOE ε4 status, change in composite score at month 2, and progression to MCI or dementia over time. Of 486 older adults who provided consent, 375 (with rMDD, MCI, or both) received at least 1 intervention session (mean [SD] age, 72.2 [6.4] years; 232 women [62%] and 143 men [38%]). Over a median follow-up of 48.3 months (range, 2.1-85.9), CR and tDCS slowed cognitive decline in older adults with rMDD or MCI (adjusted z score difference [active - sham] at month 60, 0.21; 95% CI, 0.07 to 0.35; likelihood ratio test [LRT] P = .006). In the preplanned primary analysis, CR and tDCS did not improve cognition acutely (adjusted z score difference [active - sham] at month 2, 0.06, 95% CI, -0.006 to 0.12). Similarly, the effect of CR and tDCS on delaying progression from normal cognition to MCI or MCI to dementia was weak and not significant (hazard ratio, 0.66; 95% CI, 0.40 to 1.08; P = .10). Preplanned analyses showed treatment effects for executive function (LRT P = .04) and verbal memory (LRT P = .02) and interactions with diagnosis (P = .01) and APOE ε4 (P < .001) demonstrating a larger effect among those with rMDD and in noncarriers of APOE ε4. The study showed that CR and tDCS, both targeting the prefrontal cortex, is efficacious in slowing cognitive decline in older adults at risk of cognitive decline, particularly those with rMDD (with or without MCI) and in those at low genetic risk for Alzheimer disease. ClinicalTrials.gov Identifier: NCT02386670.

Syncing the brain's networks: dynamic functional connectivity shifts from temporal interference.

Temporal interference (TI) stimulation, an innovative non-invasive brain stimulation approach, has the potential to activate neurons in deep brain regions. However, the dynamic mechanisms underlying its neuromodulatory effects are not fully understood. This study aims to investigate the effects of TI stimulation on dynamic functional connectivity (dFC) in the motor cortex. 40 healthy adults underwent both TI and tDCS in a double-blind, randomized crossover design, with sessions separated by at least 48 h. The total stimulation intensity of TI is 4 mA, with each channel's intensity set at 2 mA and a 20 Hz frequency difference (2 kHz and 2.02 kHz). The tDCS stimulation intensity is 2 mA. Resting-state functional magnetic resonance imaging (rs-fMRI) data were collected before, during, and after stimulation. dFC was calculated using the left primary motor cortex (M1) as the region of interest (ROI) and analyzed using a sliding time-window method. A two-way repeated measures ANOVA (group × time) was conducted to evaluate the effects of TI and tDCS on changes in dFC. For CV of dFC, significant main effects of stimulation type (P = 0.004) and time (P < 0.001) were observed. TI showed lower CV of dFC than tDCS in the left postcentral gyrus (P < 0.001). TI-T2 displayed lower CV of dFC than TI-T1 in the left precentral gyrus (P < 0.001). For mean dFC, a significant main effect of time was found (P < 0.001). TI-T2 showed higher mean dFC than tDCS-T2 in the left postcentral gyrus (P = 0.018). Within-group comparisons revealed significant differences between time points in both TI and tDCS groups, primarily in the left precentral and postcentral gyri (all P < 0.001). Results were consistent across different window sizes. 20 Hz TI stimulation altered dFC in the primary motor cortex, leading to a significant decreasing variability and increasing mean connectivity strength in dFC. This outcome indicates that the 20 Hz TI frequency interacted with the motor cortex's natural resonance.

Understanding novel neuromodulation pathways in tDCS: brain stem recordings in rats during trigeminal nerve direct current stimulation

tDCS is widely assumed to cause neuromodulation via the electric field in the cortex acting directly on cortical neurons. However, recent evidence suggests that tDCS may indirectly influence brain activity through cranial nerve pathways, notably the trigeminal nerve, but these neuromodulatory pathways remain unexplored. To investigate the first stages in this potential pathway we developed an animal model to study the effect of trigeminal nerve direct current stimulation (TN-DCS) on neuronal activity in the principal sensory nucleus (NVsnpr) and the mesencephalic nucleus of the trigeminal nerve (MeV). We conducted experiments on twenty-four male Sprague Dawley rats (n = 10 NVsnpr, n = 10 MeV during anodic stimulation, and n = 4 MeV during cathodic stimulation). DC stimulation, ranging from 0.5 to 3 mA, targeted the trigeminal nerve’s marginal branch. Concurrently, single-unit electrophysiological recordings were obtained using a 32-channel silicon probe, encompassing three 1-min intervals: pre, during, and post-stimulation. Xylocaine trigeminal nerve blockage served as a control. TN-DCS increased neuronal spiking activity in both NVsnpr and MeV, returning to baseline during the post-stimulation phase. The 3 mA DC stimulation of the blocked trigeminal nerve failed to induce increased spiking activity in the trigeminal nuclei. These findings provide empirical support for trigeminal nuclei modulation via TN-DCS, suggesting the cranial nerve pathways could play a role in mediating the tDCS effects in humans.

Effect of transcranial direct current stimulation on tinnitus modulation: A randomized, double-blind, and placebo-controlled clinical trial: Effect of tDCS on tinnitus modulation: A clinical trial

ObjectivesTo evaluate the short and long-term effects of anodal tDCS (a-tDCS) targeting the left temporoparietal area (LTA) on tinnitus severity, annoyance, and loudness. MethodsThis is a double-blind, randomized, sham-controlled, and parallel-group clinical trial. A total of 42 individuals with tinnitus were randomized to a-tDCS (n = 24) or sham tDCS (n = 18). The a-tDCS group received tDCS over the LTA during five consecutive day sessions (2 mA, 20 min). The sham group received a placebo current with the same characteristics as the a-tDCS group. Participants were assessed at baseline, after the fifth session, and at the 30-day follow-up, using hearing assessments and symptom questionnaires. ResultsThere was no effect of comparison between groups or interaction effect (time x group) in all hearing assessments and symptom questionnaires. There was only a main effect of time for Tinnitus Handicap Inventory - THI [F(1.642, 45.988) = 5.128; p = 0.014; η2 = 0.155]. Bonferroni post hoc showed that there was a significant difference in THI in the sham group between pre and post-treatment [CI (0.107, 14.643; p = 0.046)]. However, there was no difference between pre-treatment and follow-up THI, or between post-treatment and follow-up THI. There was no treatment effect on tinnitus severity (assessed by Tinnitus Functional Inventory - TFI), tinnitus annoyance or loudness (assessed by Visual Analogue Scale - VAS), or tinnitus pitch, loudness or minimum masking level (assessed by tinnitometry). ConclusionFive consecutive sessions of a-tDCS targeting LTA do not improve tinnitus severity, annoyance, and loudness. Future studies should investigate if other tDCS protocols are effective or a combination of tDCS with other forms of treatment.

The subjective experience of transcranial electrical stimulation: a within-subject comparison of tolerability and side effects between tDCS, tACS, and otDCS.

Low-intensity transcranial electrical stimulation (tES), including techniques like transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and oscillatory transcranial direct current stimulation (otDCS), has been widely explored for its neuromodulatory effects on motor, cognitive, and behavioral processes. Despite well-established safety, these techniques can induce varying degrees of discomfort and side effects, potentially impacting their application. This study presents a within-subject sham-controlled experiment directly comparing the subjective experience and side effects of tDCS, tACS, and otDCS. Participants reported their discomfort levels at multiple time points during 20-min stimulation sessions and completed a side-effects questionnaire before and after each session. Results indicated that the overall discomfort levels were low across all conditions, with ≥95% reporting the absence of discomfort or mild procedure-induced discomfort. Nevertheless, tDCS and otDCS were slightly less comfortable compared to sham, especially at the beginning of stimulation, with tACS-induced discomfort levels being overall comparable to sham. The most common side / adverse effects were mild skin sensations, including itching and tingling, particularly with tDCS and otDCS, while tACS occasionally caused phosphenes and blurred vision. These findings provide a systematic comparison of tES-induced discomfort and side effects between different tES techniques, highlighting the high safety of tES, but also the importance of considering within- and between-person variability and time-course effects in tES applications.

Transcranial direct current stimulation (tDCS) and cycling performance on the 3-minute aerobic test (3mAT): placebo and nocebo effects

Transcranial direct current stimulation (tDCS) has been used extensively but research on its efficacy within the sport and exercise science realm has been inconsistent. There may be placebo and nocebo effects present with its use. Our objective was to determine if subjects can be influenced to believe that tDCS will improve cycling performance. Subjects were separated into a belief group (B; 5 women, 6 men) and a disbelief group (DB; 9 women, 3 men). The B group was told that the stimulation would improve performance on a subsequent cycling test. In the DB group, subjects were told that it was not effective and would hinder performance. The cycling test was a 3-minute aerobic test (3mAT) where subjects maintained the highest power output possible for three minutes, after completing a full 20 min warmup. During the warmup, they were given either no stimulation (control) or 2 mA bilateral stimulation over the M1 region. There was a very slight increase in maximal minute power for the B group (0.22%) and a small decrease for the DB group (-1.00%); however, these differences were not significant. No significant differences were found for any of the cycling variables. In conclustion, tDCS was unable to improve performance on the 3mAT. These findings, in conjunction with others, suggest that the acute effect of tDCS is still questionable when aiming to enhance endurance performance.

Comparing the effects of anodal and cathodal transcranial direct current stimulation of primary motor cortex at varying intensities on motor learning in healthy young adults.

Inconsistent results are observed in the effects of transcranial direct current stimulation (tDCS) with different montages on motor learning. This study aimed to compare the effects of anodal and cathodal tDCS (c-tDCS) over primary motor cortex (M1) at different intensities on motor learning in healthy young adults. The participants were randomly divided into: (1) 1mA M1 c-tDCS, (2) 1mA M1 anodal tDCS (a-tDCS), (3) 2mA M1 c-tDCS, (4) 2mA M1 a-tDCS and (5) M1 sham tDCS groups. The groups received 20-min stimulation with serial reaction time task (SRTT) incidentally, while the tDCS was turned off after 30 s in the sham tDCS group. Response time (RT) and error rate (ER) during SRTT were assessed prior, during and 72 h after the intervention. The results of the paired t-test indicated that online learning occurred in all groups (p< 0.05), except in M1 c-tDCS (1mA) (p> 0.05). One-way ANOVA analysis also indicated that there were differences in offline learning (RT (F(DF) =5.19(4); p< 0.001; and ER (F(DF) =9(4), p< 0.0001) among groups, with more offline learning in 1mA M1 a-tDCS, 2mA M1 c-tDCS and 2mA M1 a-tDCS groups (p< 0.05). On the other hand, the 1mA M1 c-tDCS group did not indicate any consolidation effect or even a trend toward negative offline learning. M1 a-tDCS with different intensities and also 2mA M1 c-tDCS may be helpful for the enhancement of motor learning in young healthy adults. This study enhances our understanding of tDCS intensity and polarity effects on motor learning, with potential for optimizing therapeutic protocols.

Effect of non-invasive brain stimulation on post-stroke cognitive impairment: a meta-analysis.

Previous studies have suggested that repetitive transcranial magnetic stimulation (rTMS) may be an effective and safe alternative treatment for post-stroke cognitive impairment (PSCI). Similarly, the application of transcranial direct current stimulation (tDCS) during stroke rehabilitation has been shown to improve cognitive function in PSCI patients. However, there have been conflicting results from some studies. Therefore, this study aims to conduct a meta-analysis to evaluate the effects of tDCS and rTMS on PSCI. The meta-analysis search for articles published from the initial availability date to 5 February 2024 in databases. The extracted study data were entered into STATA 12.0 software for statistical analysis. This meta-analysis provides evidence that both rTMS and tDCS have a positive impact on general cognitive function in PSCI patients [immediate effect of rTMS: standard mean difference (SMD) = 2.58, 95% confidence interval (CI) = 1.44 to 3.71; long-term effect of rTMS: SMD = 2.33, 95% CI = 0.87-3.78; immediate effect of tDCS: SMD = 2.22, 95% CI = 1.31-3.12]. Specifically, rTMS was found to significantly improve attention, language, memory, and visuospatial functions, while it did not show a significant therapeutic effect on executive function (attention: SMD = 3.77, 95% CI = 2.30-5.24; executive function: SMD = -0.52, 95% CI = -3.17-2.12; language: SMD = 3.43, 95% CI = 1.50-5.36; memory: SMD = 3.52, 95% CI = 1.74-5.30; visuospatial function: SMD = 4.71, 95% CI = 2.61-6.80). On the other hand, tDCS was found to significantly improve executive and visuospatial functions but did not show a significant improvement in attention function and memory (attention: SMD = 0.63, 95% CI = -0.30-1.55; executive function: SMD = 2.15, 95% CI = 0.87-3.43; memory: SMD = 0.99, 95% CI = -0.81-2.80; visuospatial function: SMD = 2.64, 95% CI = 1.04-4.23). In conclusion, this meta-analysis demonstrates that both rTMS and tDCS are effective therapeutic techniques for improving cognitive function in PSCI. However, more large-scale studies are needed to further investigate the effects of these techniques on different cognitive domains in PSCI.

Combined Transcranial Direct Current Stimulation and Pain Neuroscience Education for Chronic Low Back Pain: A Randomized Controlled Trial.

Priming the neural circuity likely targeted by pain neuroscience education (PNE), using transcranial direct current stimulation (tDCS) may enhance the efficacy of PNE. The aim of this study was to compare the effects of active tDCS + PNE to sham tDCS + PNE on measures of pain, pain behaviors, and cognitive function in participants with chronic low back pain (CLBP) and high pain catastrophizing. 20 participants were recruited and randomly allocated into the active tDCS + PNE (n = 10) or sham tDCS + PNE (n = 10) groups. All participants received five sessions of their assigned interventions over a 2-week period. The active tDCS + PNE group received 20 minutes of 2 mA, anodal current applied to the left dorsolateral prefrontal cortex. Within groups, both interventions demonstrated significant improvement in NPRS, PCS, and TSK. The active tDCS + PNE group also demonstrated significant improvement on the SCWT, CTMT2-Inhibitory, and CTMT2-Set Shifting. Between groups, the active tDCS + PNE group showed significantly greater improvement on the PCS, SCWT, and CTMT2-Inhibitory. The results of this pilot study suggest that active tDCS + PNE appeared to provide greater improvement than sham tDCS + PNE on levels of pain catastrophizing and attentional interference in participants with CLBP and high pain catastrophizing, consistent with both interventions targeting brain regions involved in those processes. Considering the differences between groups, tDCS appears to provide a priming effect on PNE.

Effects of o-tDCS and tDCS on Maximal Grip Strength

Effects of o-tDCS and tDCS on Maximal Grip Strength

Unraveling the brain dynamics of Depersonalization-Derealization Disorder: a dynamic functional network connectivity analysis

BackgroundDepersonalization-Derealization Disorder (DPD), a prevalent psychiatric disorder, fundamentally disrupts self-consciousness and could significantly impact the quality of life of those affected. While existing research has provided foundational insights for this disorder, the limited exploration of brain dynamics in DPD hinders a deeper understanding of its mechanisms. It restricts the advancement of diagnosis and treatment strategies. To address this, our study aimed to explore the brain dynamics of DPD.MethodsIn our study, we recruited 84 right-handed DPD patients and 67 healthy controls (HCs), assessing them using the Cambridge Depersonalization Scale and a subliminal self-face recognition task. We also conducted a Transcranial Direct Current Stimulation (tDCS) intervention to understand its effect on brain dynamics, evidenced by Functional Magnetic Resonance Imaging (fMRI) scans. Our data preprocessing and analysis employed techniques such as Independent Component Analysis (ICA) and Dynamic Functional Network Connectivity (dFNC) to establish a comprehensive disease atlas for DPD. We compared the brain's dynamic states between DPDs and HCs using ANACOVA tests, assessed correlations with patient experiences and symptomatology through Spearman correlation analysis, and examined the tDCS effect via paired t-tests.ResultsWe identified distinct brain networks corresponding to the Frontoparietal Network (FPN), the Sensorimotor Network (SMN), and the Default Mode Network (DMN) in DPD using group Independent Component Analysis (ICA). Additionally, we discovered four distinct dFNC states, with State-1 displaying significant differences between DPD and HC groups (F = 4.10, P = 0.045). Correlation analysis revealed negative associations between the dwell time of State-2 and various clinical assessment factors. Post-tDCS analysis showed a significant change in the mean dwell time for State-2 in responders (t-statistic = 4.506, P = 0.046), consistent with previous clinical assessments.ConclusionsOur study suggests the brain dynamics of DPD could be a potential biomarker for diagnosis and symptom analysis, which potentially leads to more personalized and effective treatment strategies for DPD patients.Trial registrationsThe trial was registered at the Chinese Clinical Trial Registry on 03/01/2021 (Registration number: ChiCTR2100041741, https://www.chictr.org.cn/showproj.html?proj=66731) before the trial.

TDCS Cranial Nerve Co-Stimulation: Unveiling Brainstem Pathways Involved in Trigeminal Nerve Direct Current Stimulation in Rats.

The effects of transcranial direct current stimulation (tDCS) are typically attributed to the polarization of cortical neurons by the weak electric fields it generates in the cortex. However, emerging evidence indicates that certain tDCS effects may be mediated through the co-stimulation of peripheral or cranial nerves, particularly the trigeminal nerve (TN), which projects to critical brainstem nuclei that regulate the release of various neurotransmitters throughout the central nervous system. Despite this, the specific pathways involved remain inadequately characterized. In this study, we examined the effects of acute transcutaneous TN direct current stimulation (TN-DCS) on tonic (i.e. mean spike rate and spike rate over time) and phasic (number of bursts, spike rate per burst, burst duration, and inter-burst interval) activities while simultaneously recording single-neuron activity across three brainstem nuclei in rats: the locus coeruleus (LC), dorsal raphe nucleus (DRN), and median raphe nucleus (MnRN). We found that TN-DCS significantly modulated tonic activity in the LC, with notable interactions between stimulation amplitude, polarity, and time epoch affecting mean spike rates. Similar effects were observed in the DRN regarding tonic activity. Further, phasic activity in the LC was influenced by TN-DCS, with changes in burst number, duration, and inter-burst intervals linked to stimulation parameters. Conversely, MnRN tonic activity following TN-DCS remained unchanged. Importantly, xylocaine administration to block TN abolished the effects on tonic activities in both the LC and DRN. These results suggest that tDCS effects may partially arise from indirect modulation of the TN, leading to altered neuronal activity in DRN and LC. Besides, the differential changes in tonic and phasic LC activities underscore their complementary roles in mediating TN-DCS effects on higher cortical regions. This research bears significant translational implications, providing mechanistic insights that could enhance the efficacy of tDCS applications and deepen our understanding of its neurophysiological effects.

The Impact of Bilateral Cerebellar Transcranial Direct Current Stimulation on Balance Control in Healthy Young Adults.

Cerebellar transcranial direct current stimulation (tDCS) has been shown to influence movement functions, but little is known about the specific effects of stimulation polarity on balance control. This study investigated the impact of bilateral cerebellar tDCS on balance functions as a function of stimulation polarity. In this randomized, controlled trial, thirty-nine healthy young adults were assigned to one of three groups: right anodal/left cathodal cerebellar stimulation (AC group), right cathodal/left anodal cerebellar stimulation (CA group), and a control sham group. Each participant underwent a daily 30-minute session of tDCS at 2mA for one week. Balance function was assessed pre- and post-intervention and the data were analyzed using generalized estimating equations. The CA group exhibited a significant reduction in sway area when standing on the left leg and on both stable and unstable surfaces with eyes open, compared to both the AC and sham groups. However, there were no significant differences among the groups in terms of sway length, anteroposterior velocity, or mediolateral velocity. Our results indicate the polarity-dependent effects of bilateral cerebellar tDCS on balance functions, with enhanced stability observed only following cathodal tDCS over the right cerebellum paired with anodal tDCS over the left cerebellum. This polarity-specific modulation may have implications for developing cerebellar neuromodulation interventions for movement disorders.

Effect of tDCS combined with virtual reality for post-stroke cognitive impairment: a randomized controlled trial study protocol

BackgroundPost-stroke cognitive impairment (PSCI) not only increases patient mortality and disability, but also adversely affects motor function and the ability to perform routine daily activities. Current therapeutic approaches for, PSCI lack specificity, primarily relying on and medication and traditional cognitive therapy supplemented by a limited array of tools. Both transcranial direct current stimulation (tDCS) and virtual reality (VR) training have demonstrated efficacy in improving cognitive performance among PSCI patients. Previous findings across various conditions suggest that implementing a therapeutic protocol combining tDCS and VR (tDCS - VR) may yield superior in isolation. Despite this, to our knowledge, no clinical investigation combining tDCS and VR for PSCI rehabilitation has been conducted. Thus, the purpose of this study is to explore the effects of tDCS - VR on PSCI rehabilitation.MethodsThis 4-week, single-center randomized clinical trial protocol will recruit 200 patients who were randomly assigned to one of four groups: Group A (tDCS + VR), Group B (tDCS + sham VR), Group C (sham tDCS + VR), Group D (sham tDCS + sham VR). All four groups will receive conventional cognitive rehabilitation training. The primary outcome measurement utilizes the Mini-Mental State Examination (MMSE). Secondary outcome measures include the Montreal Cognitive Assessment, Frontal Assessment Battery, Clock Drawing Test, Digital Span Test, Logic Memory Test, and Modified Barthel Index. Additionally, S-YYZ-01 apparatus for diagnosis and treating language disorders assesses subjects’ speech function. Pre- and post-four-week intervention assessments are conducted for all outcome measures. Functional near-infrared spectroscopy (fNIRS) is employed to observe changes in oxygenated hemoglobin (HbO), deoxy-hemoglobin (HbR), and total hemoglobin (HbT) in the cerebral cortex.DiscussionOur hypothesis posits that the tDCS - VR therapy, in opposed to individual tDCS or VR interventions, could enhance cognitive function, speech ability and daily living skills in PSCI patients while concurrently augmenting frontal cortical activity. This randomized study aims to provide a robust theoretical foundation supported by scientific evidence for the practical implementation of the tDCS - VR combination as a secure and efficient PSCI rehabilitation approach.Trial registrationChictr.org.cn Identifier: ChiCTR2300070580. Registered on 17th April 2023.

Effects of anodal transcranial direct current stimulation on intracranial compliance in the subacute phase of stroke

ObjectivesTranscranial direct current stimulation (tDCS) increases cerebral blood flow. This study evaluated the effects of anodal tDCS (A-tDCS) on intracranial compliance (ICC) in patients with subacute stroke using a non-invasive method. MethodsThis was a randomized, proof-of-concept, double-blind, pilot study. Patients with ischemic stroke of the middle cerebral artery (MCA) were divided into the following two groups: 1) A-tDCS in the motor cortex on the affected side for 30min at 2mA, and 2) sham tDCS in the motor cortex on the affected side. The primary outcomes were intracranial compliance (P2/P1 ratio and time-to-peak [TTP]) and ICC normalization after the intervention (P2/P1 ratio <1). Secondary outcomes were systolic and diastolic blood pressures, heart rate, and peripheral oxygen saturation. ResultsNo significant differences were observed in the P2/P1 ratio (P = 0.509) and TTP (P = 0.480) between the groups. However, the A-tDCS group was significantly associated with a normal P2/P1 ratio after intervention (B = 2.583; standard error [SE]: 1.277; P = 0.043; corrected for age and stroke severity). No significant associations were observed between the groups and systolic blood pressure (F = 0.16; P = 0.902), diastolic blood pressure (F = 0.18; P = 0.892), heart rate (F = 0.11; P = 0.950), or peripheral oxygen saturation (F = 0.21; P = 0.750). ConclusionICC morphology normalization was observed in the A-tDCS group. However, no differences were observed in the P2/P1 ratio, TTP, or hemodynamic variables between the groups. A sample size of 66 patients with ischemic stroke of the MCA can be estimated using the observed effect size and standard α = 5% and β = 20% for future trials. Furthermore, this will aid in conducting the necessary randomized trials targeting these populations.

Effects of anodal transcranial direct current stimulation on postural stability in subacute stroke: A randomized control trial.

Anodal transcranial direct current stimulation (tDCS) promotes neuromodulation and neuroplasticity in the brain. The aim of this study was to determine the long-term effects of the anodal tDCS on postural and trunk stability, physical performance, anticipatory postural adjustment and quality of life in sub-acute stroke patients. Thirty-six participants with sub-acute stroke were divided into experimental and control groups using sealed envelope randomization. Outcome measures comprised the Postural Assessment Scale for Stroke, Trunk Impairment Scale, Time Up and Go Test, Functional Reach Test, and Stroke-Specific Quality of Life Scale. Assessments were conducted at 0, 3, 6, 9, and 12 weeks. Within-group analysis revealed significant improvement in both the experimental (p-value < 0.05) and control groups (p-value < 0.005). Notably, significant effects were observed in postural stability after intervention, and during one of the detraining assessments, the experimental group showed superior results compared to the control group in subacute stroke. Anodal tDCS yield significant short- and long-term effects on postural stability, while short term effects on trunk stability. Additionally, long term effects were observed on the physical performance and anticipatory postural adjustments while no effects at quality of life either short or long term basis among the subacute stroke patients.