Bifrontal Transcranial Direct Current Stimulation Research Articles

Randomized Controlled Trial of Bifrontal Transcranial Direct Current Stimulation on Craving in Alcohol Use Disorder

Background: Transcranial direct current stimulation (tDCS) is a potential neuromodulation option for the management of cravings in patients with alcohol use disorder (AUD). This study aims to assess the efficacy and safety of tDCS in the management of craving for alcohol and to measure the change in subjective well-being in patients with AUD following tDCS intervention. Methods: Patients with AUD aged between 18 and 60 years were randomly assigned to active tDCS intervention and sham tDCS intervention groups, each consisting of 17 patients. Over the course of a week, five tDCS sessions were given, with the anode positioned on the scalp over the right dorsolateral prefrontal cortices (DLPFC) area, the cathode over the left DLPFC area, and a 2 mA current. After every session, a tDCS side effects checklist was used. Follow-up assessments were conducted at week 1, week 4, and week 8 of the recruitment using the alcohol urge questionnaire (AUQ) and the World Health Organization (WHO) (five) Well-Being Index (WHO-5). Results: A significantly greater reduction in AUQ scores was present in the active tDCS intervention group compared to the sham tDCS intervention at week 1 and week 4, but the difference was not significant at the end of 8 weeks. A significant improvement in WHO-5 scores was found in both groups; however, the difference between the groups was not significant at follow-ups. The side effects observed were mild to moderate in intensity, were short-lived, and did not require any active management. Conclusions: The tDCS may be useful in the acute reduction of craving in AUD. It is a safe and well-tolerated intervention modality.

Boosting affective control with bifrontal transcranial direct current stimulation (tDCS): a proof-of-concept study in healthy individuals

Affective control refers to the ability to regulate emotions and is considered a marker of mental health. Transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique, holds promise to enhance affective control. In this between-subjects study in healthy individuals, we investigated the effects of bifrontal tDCS on core processes and higher-level markers of affective control. As such, we assessed direct tDCS effects on emotional interference during an affective control task and indirect effects on an instructed reappraisal task afterward. Results showed that the affective control task combined with active tDCS, compared to sham, resulted in enhanced cognitive emotion regulation. Specifically, participants in the active tDCS condition showed an increased propensity to use reappraisal and were more successful in doing so. Moreover, there was reduced vagally mediated heart rate variability indicative of attenuated emotion and self-regulation, in the sham, but not in the active condition. Surprisingly, there were no effects of tDCS on emotional interference during the affective control task, with Bayesian analyses showing extreme evidence against these effects. Nevertheless, there was a positive association between the emotional interference during the affective control task and participants’ reappraisal success afterward for the active, but not the sham tDCS condition. The study offers valuable insights to guide future work on combined tDCS with affective control tasks or training on the ability to regulate emotions.

Combined Bifrontal Transcranial Direct Current Stimulation and Auditory Stroop Training in Chronic Tinnitus.

Patients with tinnitus experience difficulties in cognitive control and executive functions. Many of which are regarded as the cause of tinnitus rather than its complications. Methods for the improvement of inhibitory and cognitive control seem to be effective in the control of tinnitus. In this study, transcranial direct current stimulation and auditory Stroop exercise were have been to improve inhibitory control and the ability to ignore tinnitus in patients suffering from chronic tinnitus. 34 patients with chronic tinnitus (> 6months) were randomly divided into two groups. The first group consist of 17 patients who received 6 sessions of tDCS followed by 6 sessions of auditory Stroop training. The second group received 6 sessions of sham tDCS followed by 6 sessions of auditory Stroop training. The initial evaluations including pure tone audiometry, psychoacoustic measurements, tinnitus handicap inventory (THI) survey and visual analog scale (VAS) of annoyance and loudness were performed before, immediately after, and one month after the tDCS, sham, and Stroop training. The results of this study revealed a significant reduction in THI score, VAS of loudness, and annoyance of tinnitus. A significant correlation was detected between the reaction time of incongruent words in the Stroop task and improvement of THI score and VAS of annoyance. Combined tDCS and Stroop training efficiently improve chronic tinnitus.

Impact of Combined Bifrontal Transcranial Direct- Current Stimulation and Conflict Processing Training on Tinnitus: a Protocol for Single-Blind Randomized Controlled Trial

Background and Aim: The deficit in cognitive functions and central executive function is one of the popular hypotheses on the underlying cause of tinnitus. These factors are not only the complications of tinnitus but are also involved in the generation of it. In this study, bifrontal transcranial Direct Current Stimulation (tDCS) and conflict processing will be used in the form of auditory Stroop training to improve cognitive performance and inhibition control for tinnitus management.
 Methods: This study will be carried out on 34 chronic tinnitus patients. The initial evaluations include the tinnitus psychoacoustic evaluations, determination of the tinnitus handicap through tinnitus handicap inventory, and examining the annoyance and loudness of tinnitus through the visual analog scale after which the participants will be investigated in two groups. The first group will receive sessions of tDCS followed by six sessions of conflict processing training. The second group will first receive tDCS in the form of sham, to be followed by six sessions of auditory Stroop. The evaluations will be repeated after each intervention.
 Discussion: Studies have shown that successive sessions of conflict processing training can enhance cognitive plasticity and inhibition function. As conflict processing training has not been addressed as rehabilitation training in the people suffering from tinnitus, these processes will be designed in four tasks as rehabilitation exercises in Farsi language and applied along with tDCS to the people with chronic tinnitus to decrease and control tinnitus by improving cognitive and inhibition control.
 Trial registration: Iranian Registry of Clinical Trials (IRCT20120215009014N366) on Sep 17th, 2020.
 Keywords: Tinnitus; conflict processing; Stroop training; inhibition

Preliminary effects of prefrontal tDCS on dopamine-mediated behavior and psychophysiology

The ability to manipulate dopamine in vivo through non-invasive, reversible mechanisms has the potential to impact clinical, translational, and basic research. Recent PET studies have demonstrated increased dopamine release in the striatum after bifrontal transcranial direct current stimulation (tDCS). We sought to extend this work by examining whether bifrontal tDCS could demonstrate an effect on behavioral and physiological correlates of subcortical dopamine activity. We conducted a preliminary between-subjects study (n = 30) with active and sham tDCS and used spontaneous eye blink rate (EBR), facial attractiveness ratings, and greyscales orienting bias as indirect proxies for dopamine functioning. The initial design and analyses were pre-registered (https://osf.io/gmnpc). Stimulation did not significantly affect any of the three measures, though effect sizes were often moderately large and were all in the predicted directions. Additional exploratory analyses suggested that stimulation’s effect on EBR might depend on pre-stimulation dopamine levels. Our results suggest that larger samples than those that are standard in tDCS literature should be used to assess the effect of tDCS on dopamine using indirect measures. Further, exploratory results add to a growing body of work demonstrating the importance of accounting for individual differences in tDCS response.

Impact of bifrontal transcranial Direct Current Stimulation on decision-making and stress reactivity. A pilot study

Stress is an adaptive response with repercussions on the human health. The dorsolateral prefrontal cortex (DLPFC) is thought to be involved in stress regulation by contributing to limit its biological and behavioral pejorative consequences. Here, to investigate the contribution of the DLPFC in stress response, we applied transcranial Direct Current Stimulation (tDCS) over the DLPFC during acute stress exposure in healthy participants. We hypothesized that active tDCS compared to sham would impact top-down control of the DLPFC on goal-directed behavior and hypothalamo–pituitary–adrenal (HPA) axis activity.In a double-blind sham-controlled study, 30 healthy subjects were randomly allocated to receive either active (2 mA, n = 15) or sham tDCS (n = 15) with the anode over the left DLPFC and the cathode over the right DLFPC. During the 30-min stimulation period, participants faced an experimental acute stress paradigm. Changes in goal-directed behavior were measured with a decision-making task. HPA axis reactivity was assessed by repeated measures of salivary cortisol.Acute stress decreased appetite for immediate reward in the sham group (mean - 4.40%; p = 0.017) whereas no significant effect of stress was observed in the active group. During stress exposure, we observed a significant larger elevation of salivary cortisol (p = 0.045; Cohen's d = 0.431) in the sham tDCS group (+179.8%; Standard error of the mean (SEM) = 20.6) than in the active group (+138.5%; SEM = 14.2).Stimulating the DLPFC using bifrontal tDCS may prevent stress-induced acute effects on both biological and behavioral outcomes.

Efficacy and neurophysiological predictors of treatment response of adjunct bifrontal transcranial direct current stimulation (tDCS) in treating unipolar and bipolar depression

BackgroundAlthough add-on transcranial direct current stimulation (tDCS) is a promising intervention for treating unipolar (UD) and bipolar depression (BD), its moderate antidepressant efficacy urges research into biomarkers for predicting therapeutic response and achieving highly targeted applications. MethodsThis open-label trial enrolled UD (N=58) and BD (N=22) patients who had failed 1 or more trials of adequate pharmacologic interventions (ClinicalTrials.gov ID: NCT03287037). Bifrontal tDCS (anode/cathode: F3/F4) was applied using a 2 mA current for 20 min, twice daily, for 5 consecutive weekdays. Depression was measured with Hamilton Depression Rating Scale-17 (HAMD) at baseline, after 10-session stimulation, 1- and 4-week follow-ups. Heart rate (HR) and heart rate variability (HRV) was measured at baseline, during the initial 5 min of the 1st session, after 10-session stimulation, 1- and 4-week follow-ups. Cognitive performance and other outcomes were also assessed. ResultsBifrontal tDCS rapidly and equally improved depression in both groups. The effects persisted until the end of the trial. Both groups had similar improvements in cognitive performance, anxiety, and psychosocial functioning. Compared with baseline, increased vagally-mediated HRV was observed one month after tDCS for both groups. A positive correlation was found between HR deceleration within the 1st session and treatment response after 10-session tDCS only among UD patients, explaining 20% of the variance. ConclusiontDCS as an adjunct therapy is effective for both UD and BD. Data suggest that the greater the increase in parasympathetic signaling during the 1st session, the better the clinical response after 10-session tDCS for UD patients.

Effects of bifrontal transcranial direct current stimulation on brain glutamate levels and resting state connectivity: multimodal MRI data for the cathodal stimulation site

Transcranial direct current stimulation (tDCS) over prefrontal cortex (PFC) regions is currently proposed as therapeutic intervention for major depression and other psychiatric disorders. The in-depth mechanistic understanding of this bipolar and non-focal stimulation technique is still incomplete. In a pilot study, we investigated the effects of bifrontal stimulation on brain metabolite levels and resting state connectivity under the cathode using multiparametric MRI techniques and computational tDCS modeling. Within a double-blind cross-over design, 20 subjects (12 women, 23.7 ± 2 years) were randomized to active tDCS with standard bifrontal montage with the anode over the left dorsolateral prefrontal cortex (DLPFC) and the cathode over the right DLPFC. Magnetic resonance spectroscopy (MRS) was acquired before, during, and after prefrontal tDCS to quantify glutamate (Glu), Glu + glutamine (Glx) and gamma aminobutyric acid (GABA) concentration in these areas. Resting-state functional connectivity MRI (rsfcMRI) was acquired before and after the stimulation. The individual distribution of tDCS induced electric fields (efields) within the MRS voxel was computationally modelled using SimNIBS 2.0. There were no significant changes of Glu, Glx and GABA levels across conditions but marked differences in the course of Glu levels between female and male participants were observed. Further investigation yielded a significantly stronger Glu reduction after active compared to sham stimulation in female participants, but not in male participants. For rsfcMRI neither significant changes nor correlations with MRS data were observed. Exploratory analyses of the effect of efield intensity distribution on Glu changes showed distinct effects in different efield groups. Our findings are limited by the small sample size, but correspond to previously published results of cathodal tDCS. Future studies should address gender and efield intensity as moderators of tDCS induced effects.

Feasibility of Computerized Cognitive-Behavioral Therapy Combined With Bifrontal Transcranial Direct Current Stimulation for Treatment of Major Depression

Cognitive behavioral therapy (CBT) is effective in the treatment of major depressive disorder (MDD). Transcranial Direct Current Stimulation (tDCS) has demonstrated preliminary antidepressant effects and beneficial effects on cognitive function. We investigated the feasibility and acceptability of using tDCS to enhance the effects of computer-based CBT for treatment of MDD. In a randomized, double-blind, sham-controlled study, 14 patients with MDD on stable or no pharmacotherapy received active or sham bifrontal tDCS for four weeks with concurrent CBT. Ten participants completed the protocol. Three withdrew from the study because of lack of efficacy or dislike of the eCBT program. One was discontinued from the protocol by the investigators. Treatment was well tolerated, and most side-effects were mild and consistent with prior tDCS research. Pooled data from both groups showed significant baseline to endpoint improvement in depression (p = 0.008). Overall percent change on the HAMD-21 was 28.98%. The study was underpowered to detect differences in tDCS treatment groups. Combining tDCS with computer-based CBT is feasible for MDD. Further work is needed to evaluate potential synergistic effects of combined tDCS and CBT.

Delayed effect of bifrontal transcranial direct current stimulation in patients with treatment-resistant depression: a pilot study

BackgroundTranscranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique, which has yielded promising results in treating major depressive disorder. However, its effect on treatment-resistant depression remains to be determined. Meanwhile, as an emerging treatment option, patients’ acceptability of tDCS is worthy of attention.MethodsThis pilot study enrolled 18 patients (women = 13) with treatment-resistant unipolar (n = 13) or bipolar (n = 5) depression. Twelve sessions of tDCS were administered with anode over F3 and cathode over F4. Each session delivered a current of 2 mA for 30 min per ten working days, and at the 4th and 6th week. Severity of depression was determined by Montgomery–Åsberg Depression Rating Scale (MADRS); cognitive performance was assessed by a computerized battery.ResultsScores of MADRS at baseline (29.6, SD = 9.7) decreased significantly to 22.9 (11.7) (p = 0.03) at 6 weeks and 21.5 (10.3) (p = 0.01) at 8 weeks. Six (33.3%) participants were therapeutically responsive to tDCS. MADRS scores of responders were significantly lower than those of non-responders at the 6th and 8th week. Regarding change of cognitive performance, improved accuracy of paired association (p = 0.017) and social cognition (p = 0.047) was observed at the 8th week. Overall, tDCS was perceived as safe and tolerable. For the majority of patients, it is preferred than pharmacotherapy and psychotherapy.ConclusionsTDCS can be a desirable option for treatment-resistant depression, however, its efficacy may be delayed; identifying predictors of therapeutic response may achieve a more targeted application. Larger controlled studies with optimized montages and sufficient periods of observation are warranted.Trial registrationThis trial has been registered at the Chinese Clinical Trial Registry (ChiCTR-INR-16008179).

Modulating Activity in the Prefrontal Cortex Changes Intertemporal Choice for Loss: A Transcranial Direct Current Stimulation Study.

Intertemporal choice refers to decisions involving tradeoffs between costs and benefits occurring at different times. Studies have found that weighting the time and benefits during decision-making involves a complex neural network that includes the dorsolateral prefrontal cortex (DLPFC). However, in contrast to literature regarding intertemporal choice for gains, studies have not provided causal evidence that the DLPFC is involved in intertemporal choice for losses. We examined whether bifrontal transcranial direct current stimulation (tDCS) applied over the right and left prefrontal cortex can alter the balance of intertemporal preference in the loss condition. A total of 60 participants performed delay discounting tasks for losses while receiving either right anodal/left cathodal, left anodal/right cathodal, or sham stimulation. The results showed that participants tended to choose larger delayed losses after receiving left anodal/right cathodal tDCS. Left anodal/right cathodal tDCS significantly decreased the discounting rate compared with the sham stimulation. These findings confirm that DLPFC activity is critical during intertemporal decision-making for losses.

Adjunctive Role of Bifrontal Transcranial Direct Current Stimulation in Distressed Patients with Severe Tinnitus.

BackgroundThis study assessed the therapeutic effect of adjunctive bifrontal transcranial direct current stimulation (tDCS) in patients with tinnitus.MethodsForty-four patients who visited our university hospital with a complaint of non-pulsatile subjective tinnitus in January through December 2016 were enrolled. All patients received directive counseling and sound therapy, such as a sound generator or hearing aids, and/or oral clonazepam. Patients who agreed to undergo additional bifrontal tDCS were classified as the study group (n = 26). For tDCS, 1.5 mA of direct current was applied to the prefrontal cortex with a 10–20 EEG system for 20 minutes per session.ResultsThe Tinnitus Handicap Inventory (THI), Beck Depression Inventory, and Visual Analog Scale (VAS) scores decreased significantly after treatment (P < 0.001). Patients who had a moderate or catastrophic handicap were significantly more likely to respond favorably to bifrontal tDCS (P = 0.026). There was no correlation of number of tDCS sessions with change in the THI or VAS score (P > 0.05). Logistic regression analysis revealed that the initial THI score was independently associated with improvement in the THI. However, tDCS was not a significant determinant of recovery.ConclusiontDCS can be used as an adjunctive treatment in patients with severe tinnitus. Although tDCS did not decrease the loudness of tinnitus, it could alleviate the distress associated with the condition in some patients with a moderate or catastrophic handicap.

Hypomania Induced by Bifrontal Transcranial Direct Current Stimulation in a Patient with Bipolar Depression.

Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique, has been increasingly used to treat bipolar depression. Researchers recently noticed the risk of tDCS-emergent mania/hypomania in depressed patients and started to evaluate this risk by launching a meta-analysis. Here we present a female with bipolar II depression who rapidly developed hypomanic switching during bifrontal tDCS.

The Effects of Acute Multisession Bifrontal Transcranial Direct Current Stimulation on Intractable Tinnitus and comorbid depression and anxiety: A Study Protocol for Randomized Controlled Trial

Background and Objective: Transcranial Direct Current Stimulation (tDCS) may exert therapeutic effects on tinnitus. This Randomized Control Trial (RCT) with double blind and placebo design investigates the potential therapeutic effects of Transcranial Direct Current Stimulation on chronic and intractable tinnitus using a new protocol. Acute repeated sessions of bifrontal Transcranial Direct Current Stimulation with two months follow up will be used for treatment of tinnitus symptoms and comorbid anxiety and depression. To best of our knowledge, this is the first randomized control trial investigating the effects of acute Transcranial Direct Current Stimulation exposure in intractable tinnitus. Methods: This randomized control trial is conducted as double blinded placebo controlled with parallel group in patients with chronic intractable tinnitus. The patients will be randomly divided into two real or intervention and sham or placebo Transcranial Direct Current Stimulation. The real Transcranial Direct Current Stimulation group will receive two sessions per day with intersession interval of 6 hours for 5 consecutive days per week for one week (total 10 sessions). The Transcranial Direct Current Stimulation parameters include bifrontal (anode/cathode over right/left dorsolateral prefrontal cortex (DLPFC) 2 mA current (current density 57.1 μA/cm2), each session 20 min through 35 cm2 electrodes. The sham group will receive the same Transcranial Direct Current Stimulation parameters and electrode montage and after 30 seconds, the device will be turned off without informing the patient. The primary outcome is the score of Tinnitus Handicap Inventory (THI) measured at baseline (pre-intervention) and post-intervention at immediately, one, and two months after last session. The secondary outcomes are tinnitus loudness, tinnitus distress, depression, and anxiety scores. The tinnitus loudness and distress are measured with a 0-10 Numerical Rating Scale (NRS) preintervention and post-intervention at immediately, one hour, one week, one, and two months after the last Transcranial Direct Current Stimulation session. Beck Depression (BDI-II) and Anxiety Inventories (BAI) is respectively used for measuring depression and anxiety score pre- and post-intervention. Finally, the adverse effects of and tolerability to Transcranial Direct Current Stimulation will be assessed in both real and sham groups using customized questionnaire. Discussion: To the best of our knowledge this is the first RCT investigating the effects of daily two sessions of Transcranial Direct Current Stimulation in repeated regime on chronic intractable tinnitus symptoms, depression, anxiety, and adverse effects in a long term study of two months follow-up.

Balanced bifrontal transcranial direct current stimulation enhances working memory in adults with high-functioning autism: a sham-controlled crossover study

BackgroundWorking memory (WM) often is impaired in autism spectrum disorder (ASD). Such impairment may underlie core deficits in cognition and social functioning. Transcranial direct current stimulation (tDCS) has been shown to enhance WM in both healthy adults and clinical populations, but its efficacy in ASD is unknown. We predicted that bifrontal tDCS would improve WM performances of adults with high-functioning autism during active stimulation compared to sham stimulation and that such enhancement would generalize to an untrained task.MethodsTwelve adults with high-functioning ASD engaged in a battery of WM tasks that included backward spatial span, backward digit span, spatial n-back and letter n-back. While engaged, 40 min of 1.5 mA bifrontal stimulation was applied over the left and the right dorsolateral prefrontal cortices (DLPFC). Using a single-blind crossover design, each participant received left anodal/right cathodal stimulation, right anodal/left cathodal stimulation, or sham stimulation, in randomized counterbalanced order on three separate days. Following tDCS, participants again engaged in letter and spatial n-back tasks before taking the Brief Test of Attention (BTA). We used repeated-measures ANOVA to compare overall performance on the WM battery as measured by a composite of z-scores for all five measures. Post hoc ANOVAs, t tests, Friedman’s tests, and Wilcoxon signed-rank tests were used to measure the online and offline effects of tDCS and to assess performances on individual measures.ResultsCompared to sham stimulation, both left DLPFC anodal stimulation (t11 = 5.4, p = 0.0002) and right DLPFC anodal stimulation (t11 = 3.57, p = 0.004) improved overall WM performance. Left anodal stimulation (t11 = 3.9, p = 0.003) and right anodal stimulation (t11 = 2.7, p = 0.019) enhanced performances during stimulation. Enhancement transferred to an untrained task 50 min after right anodal stimulation (z11 = 2.263, p = 0.024). The tasks that showed the largest effects of active stimulation were spatial span backward (z11 = 2.39, p = 0.017) and BTA (z11 = 2.263, p = 0.024).ConclusionsIn adults with high-functioning ASD, active bifrontal tDCS given during WM tasks appears to improve performance. TDCS benefits also transferred to an untrained task completed shortly after stimulation. These results suggest that tDCS can improve WM task performance and could reduce some core deficits of autism.Trial registrationNCT01602263

Combined Bifrontal Transcranial Direct Current Stimulation and Tailor-Made Notched Music Training in Chronic Tinnitus.

Background and ObjectivesWe evaluated the short-term treatment outcomes of combined bifrontal transcranial direct current stimulation (tDCS) and tailor-made notched music training (TMNMT) in tinnitus patients. The associations of patient characteristics with treatment responsiveness were investigated.Subjects and MethodsFour sessions of bifrontal tDCS (F4: anode, F3: cathode) and TMNMT were conducted over a 2-week period in tinnitus patients. For tDCS, the stimulation intensity was 1.5 mA and the duration was approximately 20 min. During tDCS, patients listened to music lacking the frequency band within 1 octave of the tinnitus frequency. Patients were also instructed to listen to this music at home for at least 2 hours per day. One month after the final tDCS session, loudness (LD), awareness (AW), annoyance (AN), and effect on life (EL) of tinnitus were assessed subjectively using a visual analog scale.ResultsA total of 14 patients were enrolled in this study. After treatment, a 50% or greater improvement in AN, AW, EL, and LD was observed in 57.1, 42.9, 35.7, and 28.6% of patients, respectively. Furthermore, 78.6% of patients showed a 50% or greater improvement in their tinnitus handicap inventory scores. For AN, the absence of sleep disturbance was significantly associated with treatment responsiveness (p=0.041, OR=24.0).ConclusionsCombined bifrontal tDCS and TMNMT is a promising treatment for chronic tinnitus. To maximize the treatment outcomes of this therapy, sleep disturbances should also be addressed in candidate patients.

P173 Bi-frontal transcranial direct current stimulation does modulate sleep, but does not affect sleep-related memory consolidation

The crucial role of a hippocampal-cortical replay that gradually strengthens hippocampus-independent cortico-cortical connections has been recently emphasized for the prefrontal cortex (PFC). In a prior analysis, we demonstrated that bi-frontal anodal tDCS significantly decreased total sleep time in healthy participants. To further elucidate the relevance of prefrontal activity levels for sleep-related memory consolidation, we explore the effects of bi-frontal tDCS on pre-post sleep memory consolidation. 18 healthy participants (13 females, age 53.1 ± 6.6 years) underwent three experimental nights with one of three counterbalanced tDCS protocols (anodal, cathodal, sham) immediately prior to polysomnography (11 pm to 7 am, interval of 3–7 d). tDCS was transferred via two pairs of electrodes (5 × 7 cm over FP1/FP2 and 10 cm x 10 cm over P3/P4) covered with electrode cream (1 mA over each target electrode, ramp up/down of 30 s, interstimulus interval 20 min). At 8 pm, 46 semantically related word-pairs were presented in a randomized order (Presentation® software) followed by repeatedly tapping a five-element sequence of numbers as fast and accurately as possible. At 8 am on the following morning, memory retrieval was assessed in a cued recall test for word-pairs (percentage of correctly retrieved referred to encoded words) and in a finger tapping test session (percentage of average speed and accuracy improvement). Bi-frontal tDCS did not result in significant changes in pre-post sleep memory consolidation in either of the examined memory systems. Specifically, repeated measures analyses of variance detected no significant condition effect for the percentage of correct word pairs ( F = 0.2, p = 0.820, pETA 2 = 0.012), finger tapping speed ( F = 1.9, p = 0.167, pETA 2 = 0.113) or accuracy ( F = 0.1, p = 0.827, pETA 2 = 0.010). In contrast to our finding of a decreased total sleep time in healthy participants following bi-frontal anodal tDCS, the stimulation protocol did not influence sleep-related memory consolidation. As mainly remote memory has been proposed to be dependent on the PFC, the test interval could have been too short to detect long-term memory effects. Besides, the results support that sleep modulating tDCS can be considered a safe and promising tool without severe adverse cognitive effects.

A Randomized Controlled Pilot Trial Suggesting That Cathodal Bi-Frontal Transcranial Direct Current Stimulation (tDCS) May Shorten Sleep Onset Latency, and Increase Sleep Efficiency When Applied Before An Afternoon Nap

A Randomized Controlled Pilot Trial Suggesting That Cathodal Bi-Frontal Transcranial Direct Current Stimulation (tDCS) May Shorten Sleep Onset Latency, and Increase Sleep Efficiency When Applied Before An Afternoon Nap

The added value of auditory cortex transcranial random noise stimulation (tRNS) after bifrontal transcranial direct current stimulation (tDCS) for tinnitus.

Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Research has suggested that functional abnormalities in tinnitus patients involve auditory as well as non-auditory brain areas. Transcranial electrical stimulation (tES), such as transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex and transcranial random noise stimulation (tRNS) to the auditory cortex, has demonstrated modulation of brain activity to transiently suppress tinnitus symptoms. Targeting two core regions of the tinnitus network by tES might establish a promising strategy to enhance treatment effects. This proof-of-concept study aims to investigate the effect of a multisite tES treatment protocol on tinnitus intensity and distress. A total of 40 tinnitus patients were enrolled in this study and received either bifrontal tDCS or the multisite treatment of bifrontal tDCS before bilateral auditory cortex tRNS. Both groups were treated on eight sessions (two times a week for 4weeks). Our results show that a multisite treatment protocol resulted in more pronounced effects when compared with the bifrontal tDCS protocol or the waiting list group, suggesting an added value of auditory cortex tRNS to the bifrontal tDCS protocol for tinnitus patients. These findings support the involvement of the auditory as well as non-auditory brain areas in the pathophysiology of tinnitus and demonstrate the idea of the efficacy of network stimulation in the treatment of neurological disorders. This multisite tES treatment protocol proved to be save and feasible for clinical routine in tinnitus patients.

EPV 10. Bi-frontal transcranial direct current stimulation does not modulate sleep continuity in patients with insomnia

Objective and background The most influential neurobiological model of insomnia disorder is the ‘hyperaorusal model’, which states increased level of arousal during day and nighttime as a fundamental characteristic of the disorder ( Riemann et al., 2010 ). Prior work emphasizes the crucial role of cortical activity levels and cortico-thalamic feedback in this disorder ( Nofzinger et al., 2004 ). In a prior study, our research group demonstrated that bi-frontal anodal tDCS significantly decreased total sleep time (TST) and increased cortical arousal during wakefulness as indexed by resting state EEG gamma power in healthy participants ( Frase et al., 0000 ). To further elucidate the relevance of prefrontal activity levels in insomnia disorder, we tested the hypothesis that bi-frontal cathodal tDCS results in an increase of TST by reducing cortical hyperarpousal in patients with insomnia with anodal tDCS inducing reverse effects. Methods Nineteen patients with nonorganic insomnia (13 females, 6 males, age 43.8 ± 15.1 years, 20–60 years) were included in the analysis. After adaptation to the sleep laboratory conditions, each participant underwent a baseline and three experimental nights in intervals of 3–7 days with a tDCS protocol immediately prior to polysomnography (11 pm to 7 am) according to standard procedures. The polysomnographic parameter total sleep time (TST) was defined as the main outcome parameter for of sleep continuity. Three different conditions (activation, deactivation, sham) were applied in a counterbalanced order. tDCS was delivered by a battery-driven, micro-processor-controlled constant current stimulator (Neuro-conn, Illmenau, Germany) and transferred by two pairs of electrodes (5 cm × 7 cm and 10 cm × 10 cm) covered with electrode cream positioned over FP1/FP2, respectively over P3/P4. A current of 1 mA was applied over each target electrode with a ramp up/ramp down of 30 s at the start and end of each stimulation and an interstimulusinterval (ISI) of 20 min. Results In contrast to our hypothesis, bi-frontal tDCS did not result in significant changes in sleep continuity or architecture. Analyses of subjective sleep ratings detected no differences between conditions (Repeated measures ANOVAs conducted for all three conditions separately, all p > 0.6). Discussion In contrast to our findings in healthy participants, the current results in patients with insomnia do not show differences in sleep continuity after tDCS. Instead, the sleep pattern in insomnia patients appears to be robust to cortical stimulation, which could be caused by persistant hyperarousal overriding possible tDCS-effects.