Effects Of tDCS Research Articles

Efficacy of Transcranial Direct Current Stimulation in Reducing Symptoms in Patients with Major Depressive Disorder: A Randomized Controlled Trial

Introduction: In the recent years, transcranial direct current stimulation (tDCS) has been considered by researchers as one of the possible effective approach in the treatment of major depressive disorder. However, the results of these investigations are often contradictory. According to this, the purpose of this study was to determine the effectiveness of tDCS in reducing symptoms of people with major depressive disorder.
 Methods: In the sham-controlled randomized trial, twenty people with major depressive disorder referred to a private psychiatric clinic in Tehran City, Iran. They were selected by convenience sampling and divided into the intervention and control groups by randomized block design. tDCS was administered 2 mA, 20 minutes per session, for 10 sessions, 3 days per week. Immediately after, and one month after the intervention, the scores of the two groups were assessed in the Hamilton Depression Rating Scale and Beck Depression Inventory. The data were analyzed using SPSS version 16 software and using statistical methods of repeated analysis of variance and independent and dependent t-test.
 Results: The results of repeated analysis of variance for Hamilton (F = 43.5 and P = 0.017) and Beck (F = 125.12 and P = 0.022) depression scores showed the significance of the interaction effect of time (four stages of measurement) and group membership (experiment and control) (P < 0.05). In depression scores in both Hamilton and Beck scales in the experimental group in the intervention stages (Hamilton scale, P = 0.019, Beck scale = P = 0.017) and follow-up (Hamilton scale, P = 0.01, Beck scale = P = 0.03) was significantly reduced compared to the control group.
 Conclusion: The results of this study confirmed the effectiveness of tDCS in reducing symptoms of major depressive disorder. More clinical trials are needed to prove the effectiveness of tDCS compared to a variety of treatments.

Effect of non-invasive brain stimulation on conscious disorder in patients after brain injury: a network meta-analysis.

To systematically evaluate the rehabilitation effect of non-invasive brain stimulation (NIBS) on disorder of consciousness (DOC) after brain injury and compare the effects of different NIBSs. Randomized controlled trials (RCTs) on the effect of NIBS on DOC after brain injury were retrieved from the PubMed, Cochrane Library, Web of Science, CNKI, VIP, Wanfang Data, and CBM databases from inception to October 2022. The risk of bias and quality of the trials were assessed following the Cochrane Handbook of Systematic Reviews and the physiotherapy evidence database Jadad Scale. Statistical analysis was conducted with RevMan 5.4 and R Studio. This study was registered on PROSPERO (No. CRD42022371334). A total of 28 articles were included involving 1118 patients. Meta-analysis showed that NIBS combined with routine rehabilitation had the highest effect than the routine rehabilitation and the sham NIBS combined with routine rehabilitation. The cumulative probability ranking results showed that the rTMS was best. The order of network meta-analysis with GCS (Glasgow Coma Scale) as the outcome index is rTMS combined with routine rehabilitation > tDCS combined with routine rehabilitation > routine rehabilitation > NIBS sham stimulation combined with routine rehabilitation. The order of network meta-analysis with CRS-R (Coma Recovery Scale-Revised) as the outcome index is rTMS combined with routine rehabilitation > tDCS combined with routine rehabilitation > NIBS sham stimulation combined with routine rehabilitation > routine rehabilitation. For patients with different conditions of DOC, the subgroup analysis results showed that rTMS improved the effect of patients with severe DOC better than those with unclear conditions of DOC, but the overall results of the two groups were not significantly different. On the contrary, the effect of tDCS on patients with DOC whose condition was not clear was better than that on patients with severe DOC, and the effect on patients with severe DOC was not significant (P > 0.05). In terms of safety, only 9 articles mentioned ADRs in the included literature, including 8 articles without ADRs, and 1 article with ADRs. Based on the research results of various indicators, NIBS can improve DOC after brain injury, and the rTMS is the best. Limited by the number and the quality of literature, the above conclusions need more high-quality research to verify.

Stimulating human prefrontal cortex increases reward learning

Work in computational psychiatry suggests that mood disorders may stem from aberrant reinforcement learning processes. Specifically, it has been proposed that depressed individuals believe that negative events are more informative than positive events, resulting in higher learning rates from negative outcomes (Pulcu and Browning, 2019). In this proof-of-concept study, we investigated whether transcranial direct current stimulation (tDCS) applied to dorsolateral prefrontal cortex, as commonly used in depression treatment trials, might change learning rates for affective outcomes. Healthy adults completed an established reinforcement learning task (Pulcu and Browning, 2017) in which the information content of reward and loss outcomes was manipulated by varying the volatility of stimulus-outcome associations. Learning rates on the tasks were quantified using computational models. Stimulation over dorsolateral prefrontal cortex (DLPFC) but not motor cortex (M1) increased learning rates specifically for reward outcomes. The effects of prefrontal tDCS were cognitive state-dependent: tDCS applied during task performance increased learning rates for wins; tDCS applied before task performance decreased both win and loss learning rates. A replication study confirmed the key finding that tDCS to DLPFC during task performance increased learning rates specifically for rewards. Taken together, these findings demonstrate the potential of tDCS for modulating computational parameters of reinforcement learning that are relevant to mood disorders.

Transcranial direct current stimulation effects in the pain threshold and in oxidative stress parameters of neuropathic pain rats

Transcranial direct current stimulation (tDCS) can modulate cortical excitability and relieve neuropathic pain (NP), but the role of several biomarkers in this process is not well understood. This study aimed to analyze the effects of tDCS on biochemical parameters in rats with neuropathic pain (NP) induced by chronic constriction injury (CCI) of the right sciatic nerve. Eighty-eight male 60-day-old Wistar rats were divided into nine groups: control (C), control-electrode off (CEoff), control-tDCS (C-tDCS), sham-lesion (SL), sham-lesion electrode off (SLEoff), sham-lesion (SL-tDCS), lesion (L), lesion electrode off (LEoff), and lesion-tDCS (L-tDCS). After NP establishment, 20-minute bimodal tDCS for 8 consecutive days was applied to the rats. Fourteen days after the induction of NP, rats developed mechanical hyperalgesia with a decreased threshold, and at the end of treatment, an increase in the pain threshold was observed in NP rats. In addition, NP rats had increased levels of reactive species (RS) in the prefrontal cortex, while superoxide dismutase (SOD) activity was decreased in NP rats. In the spinal cord, nitrite levels and glutathione-S-transferase (GST) activity decreased in the L-tDCS group, and it was observed that increased levels in total sulfhydryl content for neuropathic pain rats were reversed by tDCS. In serum analyses, the neuropathic pain model increased the levels of RS and thiobarbituric acid-reactive substances (TBARS) and decreased the activity of butyrylcholinesterase (BuChE). In conclusion, bimodal tDCS increased total sulfhydryl content in the spinal cord of rats with neuropathic pain, positively modulating this parameter.

P-67 Effect of anodal tDCS over the right dorsolateral prefrontal cortex on emotion regulation – Behavioral results

P-67 Effect of anodal tDCS over the right dorsolateral prefrontal cortex on emotion regulation – Behavioral results

The Comparable Effect of tDCS and Core Exercises on Balance and Mobility in Patients With Multiple Sclerosis

Objectives: As a major feature of the disease, motor-related complications, including loss of balance and reduced ability to walk were seen in multiple sclerosis (MS). The purpose of this study was to investigate the effect of core stability exercises and transcranial direct-current stimulation (tDCS) as a non-invasive brain stimulation on balance, walking capacity, and quality of life in patients with MS. Methods: In this randomized clinical trial study with a pretest-posttest design, 29 female patients with an Expanded Disability Status Scale (EDSS) of less than 4.5 (3.75±1.31) and a mean age of 38.36±7.99 years were purposefully selected from patients referring to MS society of Tehran during 2021 and then randomly assigned to the following three groups: core stability exercises, anodal tDCS, and sham. Variables, such as balance, walking capacity, and quality of life were measured before and after the interventions. Subjects in the core stability training group participated in core stability exercises for three weeks, and subjects in both sham and anodal tDCS groups received direct brain electrical stimulation for five sessions. Results: A significant improvement in balance and walking capacity were seen both in the anodal tDCS and the core stability training groups (P<0.05). Moreover, mobility was significantly changed in the tDCS group (P<0.05). However, no significant difference in the quality of life was seen between the groups. Discussion: Our findings indicate comparable effects of tDCS, and core stability training on balance and walking capacity in patients with MS. Therefore, in addition to exercises, tDCS can be considered a promising tool for the neurorehabilitation of patients with MS.

Brain stimulation therapeutics

This chapter covers how repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) presently affects smoking cessation. 14 human studies have examined the efficacy of rTMS on cue craving, cigarette consumption, or smoking cessation using a variety of different coils, locations, and treatment parameters. These studies included 7 randomized-controlled trials (RCT) and 7 experimental studies. Most studies (12/14) reported that rTMS reduced cue-induced craving, 5 showed that it decreased cigarette consumption, and 3/4 reported that multiple sessions of rTMS increased the quit rate. In contrast to rTMS, tDCS has 6 RCT studies, of which only 2 studies reported that tDCS reduced craving, and only 1 reported that it reduced cigarette consumption. Three studies failed to find an effect of tDCS on cravings. No tDCS studies reported changing quitting rates in people who smoke. Despite the early positive results of tDCS on nicotine dependence symptoms, 2 larger RCTs recently failed to find a therapeutic effect of tDCS for smoking cessation. In conclusion, rTMS studies demonstrate that multiple sessions help quit smoking, and it has gained FDA approval for that purpose. However, more studies are needed to examine the effect of tDCS with different treatment parameters.

Prefrontal transcranial direct current stimulation over the right prefrontal cortex reduces proactive and reactive control performance towards emotional material in healthy individuals

The prefrontal cortex plays a crucial role in cognitive processes, both during anticipatory and reactive modes of cognitive control. Transcranial Direct Current Stimulation (tDCS) can modulate these cognitive resources. However, there is a lack of research exploring the impact of tDCS on emotional material processing in the prefrontal cortex, particularly in regard to proactive and reactive modes of cognitive control. In this study, 35 healthy volunteers underwent both real and sham tDCS applied to the right prefrontal cortex in a counterbalanced order, and then completed the Cued Emotion Control Task (CECT). Pupil dilation, a measure of cognitive resource allocation, and behavioral outcomes, such as reaction time and accuracy, were collected. The results indicate that, as compared to sham stimulation, active right-sided tDCS reduced performance and resource allocation in both proactive and reactive modes of cognitive control. These findings highlight the importance of further research on the effects of tDCS applied to the right prefrontal cortex on cognitive engagement, particularly for clinical trials utilizing the present electrode montage in combination with cognitive interventions.

Transcranial Direct Current Stimulation Modulates Working Memory Maintenance Processes in Healthy Individuals.

The effects of transcranial direct current stimulation (tDCS) at the pFC are often investigated using cognitive paradigms, particularly working memory tasks. However, the neural basis for the neuromodulatory cognitive effects of tDCS, including which subprocesses are affected by stimulation, is not completely understood. We investigated the effects of tDCS on working memory task-related spectral activity during and after tDCS to gain better insights into the neurophysiological changes associated with stimulation. We reanalyzed data from 100 healthy participants grouped by allocation to receive either sham (0 mA, 0.016 mA, and 0.034 mA) or active (1 mA or 2 mA) stimulation during a 3-back task. EEG data were used to analyze event-related spectral power in frequency bands associated with working memory performance. Frontal theta event-related synchronization (ERS) was significantly reduced post-tDCS in the active group. Participants receiving active tDCS had slower RTs following tDCS compared with sham, suggesting interference with practice effects associated with task repetition. Theta ERS was not significantly correlated with RTs or accuracy. tDCS reduced frontal theta ERS poststimulation, suggesting a selective disruption to working memory cognitive control and maintenance processes. These findings suggest that tDCS selectively affects specific subprocesses during working memory, which may explain heterogenous behavioral effects.

Brain perfusion alterations induced by standalone and combined non-invasive brain stimulation over the dorsolateral prefrontal cortex

Abstract Non-invasive brain stimulation (NIBS) interventions are promising for the treatment of psychiatry disorders. Notwithstanding, the mechanisms of action of NIBS over the dorsolateral prefrontal cortex (DLPFC), a hub that modulates affective and cognitive processes, have not been completely mapped. We aimed to investigate regional cerebral blood flow (rCBF) changes over the DLPFC and the interconnected subgenual anterior cingulate cortex (sgACC) of different NIBS protocols using a Single Photon Emission Computed Tomography (SPECT). Twenty-three healthy subjects were allocated to randomly undergo four sessions of NIBS applied once a week: transcranial direct current stimulation (tDCS), intermittent theta-burst stimulation (iTBS), combined tDCS+iTBS and placebo. The radiotracer 99m-Technetium-ethylene-cysteine-dimer (99m-ECD) was injected intravenously during the NIBS session, and SPECT images were acquired after the session. Results revealed none of the active interventions changing rCBF on the targeted DLPFC, but the combination tDCS+iTBS increased rCBF on the right sgACC. TDCS respectively increased and decreased rCBF on DLPFC sub-regions under the cathode and anode, while iTBS did not show any significant changes compared to placebo. Our findings encourage future clinical trials combining tDCS+iTBS for psychiatric population and mechanistic studies to investigate the effects of tDCS and iTBS over the DLPFC. Research Category and Technology and Methods Basic Research: 9. Transcranial Direct Current Stimulation (tDCS)

Efectiveness of transcranial Direct Current Stimulation (tDCS) on Parkinson´s Disease (PD)-related pain: effects on pain processing features in PD patients

Abstract Background: PD-related pain is a prevalent and under-reported non-motor symptom that severely impacts patients' quality of life. Nevertheless, there is a lack of non-pharmacologic protocols to manage this symptom. Regarding their pain processing features, PD patients have reduced pain thresholds (PT), an augmented Temporal Summation (TS) after repetitive nociceptive stimulus, and the impairment of their Conditioned Pain Modulation (CPM) is correlated with greater severity and premature onset of the disease. Both pain and PD cause a reduction in corticomotor excitability, governed by the primary motor cortex (M1). TDCS applied to M1 increases corticospinal excitability, not only in the stimulated area but also in sensory and emotional pain processing structures. TDCS would be effective in treating central sensitivity-related pain, however, it has not been tested yet in PD-related pain. Objective: To estimate the effectiveness of tDCS on pain processing features in PD patients. Methods: This is a randomized, triple-blind, parallel design clinical trial with 18 subjects (61.3±11.52 years old). They were randomly assigned to one of two intervention groups: active-tDCS (9) vs. sham-tDCS (9). The active group received 10 consecutive sessions of 20 min of tDCS with active anode on M1 at 2 mA intensity. The sham group followed the same protocol, but the tDCS stimulator was turned off at 30 seconds. All subjects were evaluated pre, post, and 15 days post-intervention with the variables Pain Expansion (the sum of PTs), TS, and CPM. Results: There are statistically significant improvements between groups post-intervention for CPM (p=0.010), and 15 days post-intervention for CPM (p=0.032) and Pain Expansion (p=0.022) in favor of active-tDCS when compared with sham-tDCS. There are no statistically significant differences in the group-time interaction for the TS (p= 0.780). Research Category and Technology and Methods Clinical Research: 9. Transcranial Direct Current Stimulation (tDCS) Keywords: tDCS, Parkinson´s Disease, Pain Expansion, Conditioned Pain Modulation

Investigation of The Learning and Memory Enhancing Effects of 0.25 mA and 0.5 mA Anodal and Cathodal Transcranial Direct Current Stimulations in Healthy Rats

Objective: Our aim in this study was to investigate the effects of tDCS, which is known to be effective on AM-PA and NMDA, with different anodal and cathodal stimulation types and 0.25 mA and 0.5 mA current intensi-ties on learning and memory by behavioral and molecular mechanisms. Methods: 50 male Wistar rats weighing 290-310 g were divided into 5 groups as control, C1-tDCS, C2-tDCS, A1-tDCS and A2-tDCS. In the C1-tDCS group, 0.25 mA cathodal tDCS stimulation for 30 min per day for 5 days, in the C2-tDCS group for 30 min per day for 0.5 mA cathodal tDCS stimulation for 5 days, in the A1-tDCS group for 5 days with 0.25 mA anodal tDCS stimulation for 30 min per day and A2-tDCS group The tDCS group received 0.5 mA anodal tDCS stimulation for 30 minutes per day for 5 days. On the 6th and 7th days of the experiment, the locomotor activity, learning and memory behaviors of the rats were evaluated by open field test, y maze test and object localization test. In addition, glutamate levels were measured in hippocampus tis-sues by ELISA method. Results: It was observed that there were non-significant decreases in the results of the C1-tDCS and C2-tDCS groups in which cathodal stimulation was applied compared to the control group in locomotor activity, learning and memory data. On the other hand, an increase was observed in the data of the A1-tDCS and A2-tDCS groups in which anodal stimulation was applied, and the increase in the data of the A2-tDCS group from these groups was found to be statistically significant compared to the control (p<0.05). Similar results were also seen in glu-tamate levels. A non-significant decrease in glutamate levels was observed in the C1-tDCS and C2-tDCS groups compared to the control, while an insignificant increase in glutamate levels in the A1-tDCS group was observed. On the other hand, there was a significant increase in glutamate level in the A1-tDCS group compared to the control group (p<0.05). Conclusion: In conclusion, our data showed that 0.5 mA anodal tDCS stimulation for 30 min for 5 days can enhance learning and memory on the glutamatergic pathway.

Effects of bihemispheric transcranial direct current stimulation on motor recovery in subacute stroke patients: a double-blind, randomized sham-controlled trial

BackgroundBihemispheric transcranial direct current stimulation (tDCS) of the primary motor cortex (M1) can simultaneously modulate bilateral corticospinal excitability and interhemispheric interaction. However, how tDCS affects subacute stroke recovery remains unclear. We investigated the effects of bihemispheric tDCS on motor recovery in subacute stroke patients.MethodsWe enrolled subacute inpatients who had first-ever ischemic stroke at subcortical regions and moderate-to-severe baseline Fugl-Meyer Assessment of Upper Extremity (FMA-UE) score 2–56. Participants between 14 and 28 days after stroke were double-blind, randomly assigned (1:1) to receive real (n = 13) or sham (n = 14) bihemispheric tDCS (with ipsilesional M1 anode and contralesional M1 cathode, 20 min, 2 mA) during task practice twice daily for 20 sessions in two weeks. Residual integrity of the ipsilesional corticospinal tract was stratified between groups. The primary efficacy outcome was the change in FMA-UE score from baseline (responder as an increase ≥ 10). The secondary measures included changes in the Action Research Arm Test (ARAT), FMA-Lower Extremity (FMA-LE) and explorative resting-state MRI functional connectivity (FC) of target regions after intervention and three months post-stroke.ResultsTwenty-seven participants completed the study without significant adverse effects. Nineteen patients (70%) had no recordable baseline motor-evoked potentials (MEP-negative) from the paretic forearm. Compared with the sham group, the real tDCS group showed enhanced improvement of FMA-UE after intervention (p < 0.01, effect size η2 = 0.211; responder rate: 77% vs. 36%, p = 0.031), which sustained three months post-stroke (p < 0.01), but not ARAT. Interestingly, in the MEP-negative subgroup analysis, the FMA-UE improvement remained but delayed. Additionally, the FMA-LE improvement after real tDCS was not significantly greater until three months post-stroke (p < 0.01). We found that the individual FMA-UE improvements after real tDCS were associated with bilateral intrahemispheric, rather than interhemispheric, FC strengths in the targeted cortices, while the improvements after sham tDCS were associated with predominantly ipsilesional FC changes after adjustment for age and sex (p < 0.01).ConclusionsBihemispheric tDCS during task-oriented training may facilitate motor recovery in subacute stroke patients, even with compromised corticospinal tract integrity. Further studies are warranted for tDCS efficacy and network-specific neuromodulation.Trial registration: This study is registered with ClinicalTrials.gov: (ID: NCT02731508).

Modulation Effects of Repeated Transcranial Direct Current Stimulation at the Dorsolateral Prefrontal Cortex: A Pulsed Continuous Arterial Spin Labeling Study.

Transcranial direct current stimulation (tDCS) is a promising non-invasive method to modulate brain excitability. The aim of this study was to better understand the cerebral blood flow (CBF) changes during and after repeated tDCS at the right dorsolateral prefrontal cortex (DLPFC) in healthy participants using pulsed continuous arterial spin labeling (pCASL). Elucidating CBF changes associated with repeated tDCS may shed light on the understanding of the mechanisms underlying the therapeutic effects of tDCS. tDCS was applied for three consecutive days for 20 min at 2 mA, and MRI scans were performed on day 1 and 3. During anodal tDCS, increased CBF was detected in the bilateral thalamus on day 1 and 3 (12% on day 1 and of 14% on day 3) and in the insula on day 1 (12%). After anodal tDCS on day 1, increased CBF was detected in the cerebellum and occipital lobe (11.8%), while both cathodal and sham tDCS were associated with increased CBF in the insula (11% and 10%, respectively). Moreover, anodal tDCS led to increased CBF in the lateral prefrontal cortex and midcingulate cortex in comparison to the sham. These findings suggest that tDCS can modulate the CBF and different tDCS modes may lead to different effects.

Bilateral transcranial direct current stimulation may be a feasible treatment of Parkinsonian tremor.

Parkinsonian tremor is a common pathological tremor that affects over 6 million people worldwide. It lowers patients' quality of life and threatens their career development, especially when patients' occupation requires dexterous manipulation. In spite of current available treatments in clinics, there is a lack of low-cost, low side-effect, effective solutions for Parkinsonian tremor. Transcranial direct current stimulation (tDCS) may be an alternative treatment. In this research, we explored the immediate effect of tDCS with a novel bilateral electrode setup over Parkinsonian tremor. In such a bilateral setup, the cathode was placed over the primary cortex contralateral to the more affected side of Parkinsonian tremor while the anode symmetrically over the other hemisphere. It was designed as a modification to the traditional cathodal setup. The performance of this bilateral setup was compared with three other setups including anodal setup, cathodal setup, and sham (control). A randomized, sham-controlled, double-blind, crossover experiment was carried out over 13 qualified patients diagnosed with idiopathic Parkinson's disease (PD). Before and after the stimulus of each tDCS setup, subjects were tested before and after tDCS with four measures, including the Unified Parkinson's Disease Rating Scale (UPDRS), Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS), Purdue Pegboard Test (PPT) and a self-design Continuous Tremor Signal Assessment (CTSA). Tremor intensity calculated from CTSA data were regarded as the primary outcome of the experiment. Statistical results of CTSA, FTMTRS and PPT showed both bilateral tDCS and cathodal tDCS effectively suppressed Parkinsonian tremor. A quantitative comparison of the effect in tremor suppression indicated the optimal suppressive effect was obtained with bilateral tDCS. Based on the results of UPDRS, anodal tDCS was found to benefit subjects' overall performance the most, however, it had little effect in improving Parkinsonian tremor, as revealed by the results of other evaluations. Our study suggests a beneficial immediate effect of bilateral tDCS in Parkinsonian tremor suppression. In addition, we assume there may be an underlying interhemispheric unbalance of cortical excitability which contributes to Parkinsonian tremor genesis. Identifier: ChiCTR2100054804.

Transferability of cathodal tDCS effects from the primary motor to the prefrontal cortex: A multimodal TMS-EEG study

Neurophysiological effects of transcranial direct current stimulation (tDCS) have been extensively studied over the primary motor cortex (M1). Much less is however known about its effects over non-motor areas, such as the prefrontal cortex (PFC), which is the neuronal foundation for many high-level cognitive functions and involved in neuropsychiatric disorders. In this study, we, therefore, explored the transferability of cathodal tDCS effects over M1 to the PFC. Eighteen healthy human participants (11 males and 8 females) were involved in eight randomized sessions per participant, in which four cathodal tDCS dosages, low, medium, and high, as well as sham stimulation, were applied over the left M1 and left PFC. After-effects of tDCS were evaluated via transcranial magnetic stimulation (TMS)-electroencephalography (EEG), and TMS-elicited motor evoked potentials (MEP), for the outcome parameters TMS-evoked potentials (TEP), TMS-evoked oscillations, and MEP amplitude alterations. TEPs were studied both at the regional and global scalp levels. The results indicate a regional dosage-dependent nonlinear neurophysiological effect of M1 tDCS, which is not one-to-one transferable to PFC tDCS. Low and high dosages of M1 tDCS reduced early positive TEP peaks (P30, P60), and MEP amplitudes, while an enhancement was observed for medium dosage M1 tDCS (P30). In contrast, prefrontal low, medium and high dosage tDCS uniformly reduced the early positive TEP peak amplitudes. Furthermore, for both cortical areas, regional tDCS-induced modulatory effects were not observed for late TEP peaks, nor TMS-evoked oscillations. However, at the global scalp level, widespread effects of tDCS were observed for both, TMS-evoked potentials and oscillations. This study provides the first direct physiological comparison of tDCS effects applied over different brain areas and therefore delivers crucial information for future tDCS applications.

Effect of transcranial direct current stimulation on postpartum depression: A study protocol for a randomized controlled trial.

Postpartum depression (PPD) is a complex combination of physiological, emotional, and behavioral alterations associated with postpartum chemical, social, and psychological variations. It does harm to the relationship between family members that could potentially last for years. However, standard depression treatments are not ideal for PPD, and the outcomes of these treatments are debatable. Transcranial direct current stimulation (tDCS) is an emerging technology that could provide patients with PPD with a safe and non-pharmacological treatment. tDCS can relieve depression by directly stimulating the prefrontal cortex through the excitatory effect of the anode. It may also ease depression indirectly by promoting the production and release of the neurotransmitter GABA. The mechanism of tDCS makes it an ideal therapeutic approach to treat PPD, although it has not been widely used, and its effect has not been evaluated systematically and effectively. A double-blind, randomized controlled trial will be conducted involving 240 tDCS-naive patients with PPD, who will be randomly divided into two groups. One group will receive routine clinical treatment and care with active tDCS, and the other group will receive routine clinical treatment and care with sham tDCS. Each group of patients will receive a 3-week intervention during which they will receive 20 min of active or sham tDCS 6 days per week. The Montgomery-Åsberg Depression Rating Scale will be administered before the intervention as a baseline and on each weekend throughout the intervention phase. Before and after the intervention, the Perceived Stress Scale and the Positive and Negative Affect Schedule will be evaluated. Side effects and abnormal reactions will be recorded during each treatment. As antidepressants are banned in the study, the results will not be affected by drugs and will therefore be more accurate. Nonetheless, this experiment will be conducted in a single center as a small sample experiment. Therefore, future studies are required to confirm the effectiveness of tDCS in treating PPD.

Transcranial direct current stimulation over the right dorsolateral prefrontal cortex increases oxyhemoglobin concentration and cognitive performance dependent on cognitive load

Transcranial direct current stimulation (tDCS) has been explored as a potential method for cognitive enhancement. tDCS may induce a cascade of neurophysiological changes including alterations in cerebral oxygenation. However, the effects of tDCS on the cognitive-cerebral oxygenation interaction remains unclear. Further, oxygenation variability across individuals remains minimally controlled for. The purpose of this sham-controlled study was to test the effects of anodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) on the interaction between working memory and cerebral oxygenation while controlling for individual oxygenation variability. Thirty-three adults received resting-state functional near-infrared spectroscopy (fNIRS) recordings over bilateral prefrontal cortices. Following this, working memory was tested using a Toulouse n-back task concurrently paired with fNIRS, with measurements taken before and after 20 min of anodal or sham tDCS at 1.5 mA. With individual oxygenation controlled for, anodal tDCS was found to increase the oxyhemoglobin concentration over the right DLPFC during the 2-back (q = .015) and 3-back (q = .008) conditions. Additionally, anodal tDCS was found to improve accuracy during the 3-back task by 13.4 % (p = .028) and decrease latency by 250 ms (p = .013). The increase in oxyhemoglobin was strongly correlated with increases in accuracy (p = .041) and decreases in latency during the 3-back span (p = .017). Taken together, anodal tDCS over the right DLPFC was found to regionally increase oxyhemoglobin concentrations and improve working memory performance in higher cognitive load conditions.

Suppression of top-down influence decreases both behavioral and V1 neuronal response sensitivity to stimulus orientations in cats.

How top-down influence affects behavioral detection of visual signals and neuronal response sensitivity in the primary visual cortex (V1) remains poorly understood. This study examined both behavioral performance in stimulus orientation identification and neuronal response sensitivity to stimulus orientations in the V1 of cat before and after top-down influence of area 7 (A7) was modulated by non-invasive transcranial direct current stimulation (tDCS). Our results showed that cathode (c) but not sham (s) tDCS in A7 significantly increased the behavioral threshold in identifying stimulus orientation difference, which effect recovered after the tDCS effect vanished. Consistently, c-tDCS but not s-tDCS in A7 significantly decreased the response selectivity bias of V1 neurons for stimulus orientations, which effect could recover after withdrawal of the tDCS effect. Further analysis showed that c-tDCS induced reduction of V1 neurons in response selectivity was not resulted from alterations of neuronal preferred orientation, nor of spontaneous activity. Instead, c-tDCS in A7 significantly lowered the visually-evoked response, especially the maximum response of V1 neurons, which caused a decrease in response selectivity and signal-to-noise ratio. By contrast, s-tDCS exerted no significant effect on the responses of V1 neurons. These results indicate that top-down influence of A7 may enhance behavioral identification of stimulus orientations by increasing neuronal visually-evoked response and response selectivity in the V1.

Transcranial direct current stimulation for focal status epilepticus or lateralized periodic discharges in four patients in a critical care setting.

Transcranial direct current stimulation (tDCS) has been advocated for various neurological conditions, including epilepsy. A 1-4-mA cathodal current applied to the scalp over a seizure focus can reduce spikes and seizures. This series of four patients with focal status epilepticus is among the first case series to demonstrate benefit of tDCS in the critical care setting. Patients in the intensive care unit were referred for tDCS treatment when focal status epilepticus or clinically relevant lateralized periodic discharges did not resolve with conventional antiseizure medications and anesthetics. Battery-powered direct cathodal current at 2mA was delivered by an ActivaDose (Caputron) tDCS device via a saline-soaked sponge on the scalp over the seizure focus. Anode was on the contralateral forehead or shoulder. Treatment was for 30 min, repeated twice in a day, then again 1-4 times more over the next few days. Three females and one male, aged 34-68 years, were treated. Etiologies of status epilepticus were posterior reversible encephalopathy syndrome in association with immunosuppressants for a liver transplant, perinatal hypoxic-ischemic injury, a prior cardioembolic parietal stroke, and central nervous system lupus. tDCS led to significant reduction of interictal spikes (.78 to .38/s, p< .0001) in three cases and electrographic seizures (3.83/h to 0/h, p< .001) in two cases. Medication reductions were enabled in all cases subsequent to tDCS. The only side effect of tDCS was transient erythema under the sponge in one case. Two patients died of causes unrelated to tDCS, one was discharged to a nursing home, and one became fully responsive as seizures were controlled with tDCS. Spikes and electrographic seizure frequency significantly improved within 1 day of tDCS. Results are potentially confounded by multiple ongoing changes in medications and treatments. These results might encourage further investigation of tDCS in the critical care setting, but verification by controlled studies will be required.