Transcranial Direct Current Stimulation Protocol Research Articles

Targeting the left DLPFC and right VLPFC in unmarried romantic relationship breakup (love trauma syndrome) with intensified electrical stimulation: A randomized, single-blind, parallel-group, sham-controlled study

BackgroundEnding a romantic relationship is one of the most painful losses an adult experience. Neuroimaging studies suggest that there is a neuropsychological link between breakup experiences and bereaved individuals, and that specific prefrontal regions are involved. The aim of this study was to determine whether enhancement of left DLPFC and right VLPFC activity with a novel intensified anodal transcranial direct current stimulation protocol reduces core symptoms of love trauma syndrome (LTS) and improves treatment-related variables. MethodsIn this randomized, sham-controlled, single-blind parallel trial, we assessed the efficacy of an intensified anodal stimulation protocol (20 min, twice-daily sessions with 20 min intervals, 5 consecutive days) with two montages (left DLPFC vs right VLPFC) to reduce love trauma symptoms. 36 participants with love trauma syndrome were randomized in three tDCS condition (left DLPFC, right VLPFC, sham stimulation). LTS symptoms, treatment-related outcome variables (depressive state, anxiety, emotion regulation, positive and negative affect), and cognitive functions were assessed before, right after, and one month after intervention. ResultsBoth DLPFC and VLPFC protocols significantly reduced LTS symptoms, and improved depressive state and anxiety after the intervention, as compared to the sham group. The improving effect of the DLPFC protocol on love trauma syndrome was significantly larger than that of the VLPFC protocol. For emotion regulation and positive and negative affect, improved regulation of emotions and positive affect and reduced negative affect were revealed after intervention in the two real stimulation conditions compared to the sham. For cognitive functions, no significant difference was observed between the groups, but again a positive effect of intervention within groups in the real stimulation conditions (DLPFC and VLPFC) was found for most components of the cognitive tasks. ConclusionsEnhancement of left DLPFC and right VLPFC activity with intensified stimulation improves LTS symptoms and treatment-related variables. For LTS symptoms, DLPFC stimulation was more efficient than VLPFC stimulation., For the other variables, no significant difference was observed between these two stimulation groups. These promising results require replication in larger trials.

Frontal two-electrode transcranial direct current stimulation protocols may not affect performance on a combined flanker Go/No-Go task

Transcranial direct current stimulation (tDCS) has been tested to modulate cognitive control or response inhibition using various electrode montages. However, electrode montages and current polarities have not been systematically compared when examining tDCS effects on cognitive control and response inhibition. In this randomized, sham-controlled study, 38 healthy volunteers were randomly grouped into receiving one session of sham, anodal, and cathodal each in an electrode montage that targeted either the dorsolateral prefrontal cortex (DLPFC) or the fronto-medial (FM) region. Participants performed a combined flanker Go/No-Go task during stimulation. No effect of tDCS was found in the DLPFC and FM groups neither using anodal nor cathodal stimulation. No major adverse effects of tDCS were identified using either montage or stimulation type and the two groups did not differ in terms of the reported sensations. The present study suggests that single-session tDCS delivered in two two-electrode montages might not affect cognitive control or response inhibition, despite using widely popular stimulation parameters. This is in line with the heterogeneous findings in the field and calls for further systematic research to exclude less reliable methods from those with more pronounced effects, identify the determinants of responsiveness, and develop optimal ways to utilize this technique.

Alpha rhythm of electroencephalography was modulated differently by three transcranial direct current stimulation protocols in patients with ischemic stroke

The heterogeneity of transcranial direct current stimulation (tDCS) protocols and clinical profiles may explain variable results in modulating excitability in the motor cortex after stroke. However, the cortical electrical effects induced by different tDCS protocols remain unclear. Here, we aimed to compare rhythm changes in electroencephalography (EEG) induced by three tDCS position protocols and the association between tDCS effects and clinical factors in stroke. Nineteen patients with chronic ischemic stroke underwent four experimental sessions with three tDCS protocols [anodal (atDCS), cathodal (ctDCS), and bilateral (bi-tDCS)] and a sham protocol, according to a single-blind randomized crossover design. Resting-state EEG was acquired before and after each protocol. First, a paired-sample t-test was used to examine the difference in spectral power between pre- and post-stimulation. Then, linear and quadratic regression models were used separately to describe the association between the clinical factors of stroke and changes in spectral power which was significantly different between pre- and post-tDCS. Finally, repeated measures analysis of variance with lesion hemisphere, stimulation protocol, and the location was performed to investigate the effects of tDCS over time. The induced effect of tDCS was mainly reflected in the alpha rhythms. The alpha power was increased by atDCS, especially low-alpha (8–10 Hz), in localized areas of the central and distant areas of the frontal and parietal lobes. Bi-tDCS also affected alpha power but in a smaller area that mainly focused on high-alpha rhythms (10–13 Hz). However, ctDCS and sham had no significant effects on any EEG rhythm. The clinical factors of time since stroke and motor impairment level were related to the change in high-alpha induced by atDCS and bi-tDCS following quadratic regression models. The above-mentioned modulation effect lasted for 20 min without attenuation. In conclusion, our findings provide evidence that the alpha rhythm of EEG is modulated differently by different tDCS protocols and that high alpha is affected by clinical characteristics such as post-stroke time and motor deficits, which is of great significance for understanding the modulation effect of different tDCS protocols on stroke and the guidance of protocols to promote motor recovery following stroke.

Cortical current density magnitudes during transcranial direct current stimulation correlate with skull thickness in children, adolescent and young adults.

Transcranial direct current stimulation protocols are often applied with a fixed parameter set to all subjects participating in an interventional study. This might lead to considerable effect variation in inhomogeneous subject groups or when transferring stimulation protocols to different age groups. The aim of this study was to evaluate magnitude differences of the electric current density distribution on the gray matter surface in children, adolescent and adults in correlation with the individual volume conductor geometry. We generated individual six compartment finite element models from structural magnetic resonance images of four children (age: 10.95 a±1.32 a), eight adolescents (age: 15.10 a±1.16 a) and eight young adults (age: 21.62 a±2.45 a). We determined the skull thickness in the models as Euclidean distance between the surface of the cerebrospinal fluid compartment and outer skull boundary. For tDCS simulations, we modeled 5×7cm patch electrodes impressing 1mA current intensity as anode and cathode over the left M1 and the right fronto-polar orbit, respectively. The resulting current density was analyzed on the gray matter surface. Our results demonstrate higher cortical current density magnitudes in children compared to adults for a given tDCS current strength. Above the evaluated cortex, the skull thickness increased with age. In conclusion, we underline the importance of age-dependent and individual models in tDCS simulations.

Effects of different transcranial direct current stimulation protocols on visuo-spatial contextual learning formation: evidence of homeostatic regulatory mechanisms

In the present study we tested the effects of different transcranial direct current stimulation (tDCS) protocols in the formation of visuo-spatial contextual learning (VSCL). The study comprised three experiments designed to evaluate tDCS-induced changes in VSCL measures collected during the execution of a visual search task widely used to examine statistical learning in the visuo-spatial domain. In Experiment 1, we probed for the effects of left-posterior parietal cortex (PPC) anodal-tDCS (AtDCS) at different timings (i.e. offline and online) and intensities (i.e. 3 mA and 1.5 mA). The protocol producing the more robust effect in Experiment 1 was used in Experiment 2 over the right-PPC, while in Experiment 3, cathodal-tDCS (CtDCS) was applied over the left-PPC only at a high intensity (i.e. 3 mA) but varying timing of application (offline and online). Results revealed that high intensity offline AtDCS reduced VSCL regardless of the stimulation side (Experiment 1 and 2), while no significant behavioral changes were produced by both online AtDCS protocols (Experiment 1) and offline/online CtDCS (Experiment 3). The reduced VSCL could result from homeostatic regulatory mechanisms hindering normal task-related neuroplastic phenomena.

No evidence for any effect of multiple sessions of frontal transcranial direct stimulation on mood in healthy older adults

The dorsolateral prefrontal cortex (DLPFC) is part of a network important for emotional regulation and the possibility of modulating activity in this region with transcranial direct current stimulation (TDCS) to change mood has gained great interest, particularly for application in clinical populations. Whilst results in major depressive disorder have been promising, less is known about the effects of TDCS on mood in non-clinical populations. We hypothesized that multiple sessions of anodal TDCS applied over the left DLPFC would enhance mood, primarily as measured by the Profile of Mood States questionnaire, in healthy older adults. In addition, in an exploratory analysis, we examined the potentially moderating role of working memory training. Working memory, just like emotional regulation, taxes the DLPFC, which suggests that engaging in a working memory task whilst receiving TDCS may have a different effect on activity in this region and consequently mood. A total of 123 participants between 65 and 75 years of age were randomly assigned to receive either 20 sessions of TDCS, with or without working memory training, or 20 sessions sham stimulation, with or without working memory training. We found no support for enhancement of mood due to TDCS in healthy older adults, with or without cognitive training and conclude that the TDCS protocol used is unlikely to improve mood in non-depressed older individuals.

Comparison of the Effectiveness of Different transcranial direct current stimulation Protocols (tDCS) with Cognitive Exercises in Improving Response Inhibition in Normal Individuals

Comparison of the Effectiveness of Different transcranial direct current stimulation Protocols (tDCS) with Cognitive Exercises in Improving Response Inhibition in Normal Individuals

Hiccups amelioration following a transcranial direct current stimulation protocol targeting central structures

Hiccups amelioration following a transcranial direct current stimulation protocol targeting central structures

Bilateral Prefrontal Cortex Anodal tDCS Effects on Self-reported Aggressiveness in Imprisoned Violent Offenders

Reduced activity of the frontal lobes, and particularly of the prefrontal cortex, has been related with violent behavior, aggression and crime. The causal importance of prefrontal cortex activity for aggressive behaviors and the self-perception of aggressiveness needs however to be clarified. The aim of this study was to explore the effect of an anodal transcranial direct current stimulation protocol (tDCS, 1.5 mA, 15 min), which, according to previous studies, enhances cortical excitability, applied bilaterally over the prefrontal cortex on self-reported aggressiveness. Two imprisoned violent offender cohorts, discerned by the degree of aggressiveness (murderers vs. non-murderers), were included in this single-blind sham-controlled study. Self-reported aggressiveness was recorded before and after 3 tDCS sessions (one session per day). Four dimensions of aggression were evaluated by means of the standardized Buss–Perry Aggression Questionnaire (BAQ). In both inmate groups the results revealed an aggression-reducing effect of tDCS on the Physical aggression, Anger, and Verbal aggression dimensions of the BAQ. In the Hostility dimension, tDCS significantly reduced aggression only in the group of murderers. These results suggest that modulation of prefrontal cortex excitability by 3 consecutive sessions of tDCS reduces self-reported aggressiveness similarly in murderer and non-murderer samples.

Metaplasticity: A Promising Tool to Disentangle Chronic Disorders of Consciousness Differential Diagnosis.

The extent of cortical reorganization after brain injury in patients with Vegetative State/Unresponsive Wakefulness Syndrome (UWS) and Minimally Conscious State (MCS) depends on the residual capability of modulating synaptic plasticity. Neuroplasticity is largely abnormal in patients with UWS, although the fragments of cortical activity may exist, while patients MCS show a better cortical organization. The aim of this study was to evaluate cortical excitability in patients with disorders of consciousness (DoC) using a transcranial direct current stimulation (TDCS) metaplasticity protocol. To this end, we tested motor-evoked potential (MEP) amplitude, short intracortical inhibition (SICI), and intracortical facilitation (ICF). These measures were correlated with the level of consciousness (by the Coma Recovery Scale-Revised, CRS-R). MEP amplitude, SICI, and ICF strength were significantly modulated following different metaplasticity TDCS protocols only in the patients with MCS. SICI modulations showed a significant correlation with the CRS-R score. Our findings demonstrate, for the first time, a partial preservation of metaplasticity properties in some patients with DoC, which correlates with the level of awareness. Thus, metaplasticity assessment may help the clinician in differentiating the patients with DoC, besides the clinical evaluation. Moreover, the responsiveness to metaplasticity protocols may identify the subjects who could benefit from neuromodulation protocols.

Developing clinically practical transcranial direct current stimulation protocols to improve saccadic eye movement control.

Recent research indicates that anodal transcranial direct current stimulation (tDCS) applied over the frontal eye field (FEF) can improve saccadic eye movement control in healthy young adults. The current research set out to determine whether similar results can be produced using a clinically practical protocol, whether tDCS applied over the dorsolateral prefrontal cortex (DLPFC) might also afford benefits, and whether benefits extend to older adults. Twenty young and 10 older adults completed two active (FEF and DLPFC) and one sham stimulation session. To aid clinical translation, the method of positioning the electrodes entailed simple measurements only. Saccadic performance following anodal tDCS applied over the FEF or DLPFC did not differ from the sham condition in either age group. Additionally, saccadic performance contralateral to the active electrodes showed no evidence of benefits over ipsilateral performance. These results call into question whether the protocol utilized can be applied effectively using only simple measurements to localize the relevant frontal subregion. Future efforts to develop a clinically practical tDCS protocol to improve saccadic eye movement control should include a sham control condition and consider adjusting the tDCS electrode montage and current strength to optimize the chances of conferring benefits in the population under study.

Optimizing Transcranial Direct Current Stimulation Protocols to Promote Long-Term Learning

Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has the potential to induce polarity-specific changes in neural activity within targeted brain regions. There is growing interest in the use of this technology for the enhancement of higher cognitive functions, and application of tDCS directly before or concomitant with task performance has shown promise in modulating a range of behavioral outcomes, including motor skill acquisition, working memory performance, and implicit and explicit learning. The proposed mechanism for the observed enhancements is a temporary and targeted shift in the excitability of the cortical regions that subserve the relevant tasks, lasting from minutes up to about an hour after cessation of stimulation. Although empirical work does support at least a partial role for this mechanism, an arguably more potent but relatively underexplored phenomenon is thought to occur in the hours or days after stimulation—that is, a facilitation of consolidative processes. Here, we review the literature describing the nature of tDCS-enhanced consolidation and argue that some of the mixed results among the single-session studies that currently dominate the extant literature may be explained by a failure to take advantage of these potentially powerful offline effects. Accordingly, we further contend that the full potential of tDCS cannot be truly realized without a longitudinal design which allows for tDCS to act directly upon learning by promoting consolidation between sessions. Finally, we review preliminary evidence that these consolidation effects can be even further enhanced via strategically spaced out stimulation sessions, which take advantage of a long-held tenet in the literature that distributed learning produces better outcomes than massed learning. We conclude by proposing potential study designs to encourage the use of tDCS as more than merely a method to promote temporary enhancement, but also a technique to enhance long-term learning.

EEG Recordings During Sham Control Transcranial Direct Current Stimulation Protocol

EEG Recordings During Sham Control Transcranial Direct Current Stimulation Protocol

Are the effects of tDCS in language rehabilitation in primary progressive aphasia specific to the task trained?

Are the effects of tDCS in language rehabilitation in primary progressive aphasia specific to the task trained?

Effect of Transcranial Direct Current Stimulation Protocol for Treating Depression Among Hemodialysis Patients: A Proof-of-Concept Trial.

Effect of Transcranial Direct Current Stimulation Protocol for Treating Depression Among Hemodialysis Patients: A Proof-of-Concept Trial.

Modeling studies for designing transcranial direct current stimulation protocol in Alzheimer's disease.

Transcranial direct current stimulation (tDCS) has been proposed as a technique for brain activity modulation. In this technique, a weak current (usually 1–2 mA) is delivered to scalp through two sponge electrodes. There are two types of tDCS stimulation: cathodal and anodal, which inhibit and facilitate neuronal activity, respectively (Hansen, 2012). tDCS has been shown to be effective in Alzheimer's disease (AD). Several studies have revealed that tDCS application can improve memory performance in Alzheimer's patients (APs) (Ferrucci et al., 2008; Boggio et al., 2009, 2012). For example, results of a single session tDCS study (Ferrucci et al., 2008) revealed that anodal/cathodal tDCS significantly enhanced/worsened word recognition in AD patients. In another study, application of anodal stimulation over DLPFC of APs has led to recognition memory improvement in a visual memory task (Boggio et al., 2009). These effects seem to be persistent, as in a multi-session tDCS study (Boggio et al., 2012), improvement in patients' visual recognition lasted for 4 weeks. Current pathway through brain plays a key role in the observed effects. Currently, modeling studies provide the only way for determining the pattern of current flow during tDCS. In recent years, finite element modeling has been suggested as a reliable and helpful tool in clinical therapeutic applications (Bikson et al., 2012). A critical issue which is required to be considered in modeling studies is the inter-individual anatomical variations. A modeling study has shown the profound role of individual cortical morphology in determination of current flow distribution for healthy people (Datta et al., 2012). Also the impact of pathologic anatomy (skull defects and lesions) on modulation of current flow has been examined in some previous studies (Datta et al., 2010, 2011). Specifically, in AD loss of neuronal structures and synaptic damages result in cortex shrinkage and ventricular enlargement (Frisoni et al., 2010). This changes the volume of CSF- referred as “super highway” for current flow- and therefore can significantly alters current pathway in these patients' head compared to healthy subjects (Bikson et al., 2012). These studies suggest that it is not precise to determine the dosage of applied current only based on healthy human modeling or clinical trial outcomes. We hypothesize that change in cortical thickness due to brain atrophy has significant effects on current flow pattern. These anatomical alterations may shift the stimulated areas and peak current density location in head. They may even alter the expected results from tDCS application. We suggest that cortical thickness is required to be considered in modeling studies to obtain more precise pattern of current flow in head and the stimulated brain regions. Specifically, AD affects differently on each patient's brain structure. We suggest developing individualized models based on each patient's MRI data. These models can be used by clinicians to find the optimal electrode montage and current amplitude for each patient. Using Individual-based models for designing clinical protocols could provide us with better interpretation of the results.