Stimulation Of Left DLPFC Research Articles

High definition transcranial direct current stimulation of the Cz improves social dysfunction in children with autism spectrum disorder: A randomized, sham, controlled study.

The purpose of this study was to determine the effect of the Cz of high-definition 5-channel tDCS (HD-tDCS) on social function in 4-12 years-old children with autism spectrum disorder (ASD). This study was a randomized, double-blind, pseudo-controlled trial in which 45 ASD children were recruited and divided into three groups with sex, age, and rehabilitation treatment as control variables. Each group of 15 children with ASD was randomly administered active HD-tDCS with the Cz as the central anode, active HD-tDCS with the left dorsolateral prefrontal cortex (F3) as the central anode, and sham HD-tDCS with the Cz as the central anode with 14 daily sessions in 3 weeks. The Social Responsiveness Scale Chinese Version (SRS-Chinese Version) was compared 1 week after stimulation with values recorded 1 week prior to stimulation. At the end of treatment, both the anodal Cz and anodal left DLFPC tDCS decreased the measures of SRS-Chinese Version. The total score of SRS-Chinese Version decreased by 13.08%, social cognition decreased by 18.33%, and social communication decreased by 10.79%, which were significantly improved over the Cz central anode active stimulation group, especially in children with young age, and middle and low function. There was no significant change in the total score and subscale score of SRS-Chinese Version over the Cz central anode sham stimulation group. In the F3 central anode active stimulation group, the total score of SRS-Chinese Version decreased by 13%, autistic behavior decreased by 19.39%, and social communication decreased by 14.39%, which were all significantly improved. However, there was no significant difference in effect between the Cz and left DLPFC stimulation conditions. HD-tDCS of the Cz central anode may be an effective treatment for social dysfunction in children with ASD.

Transcranial Direct-Current Stimulation Improves Verbal Fluency in Children with Attention Deficit Hyperactivity Disorder (ADHD).

Individuals with attention deficit hyperactivity disorder (ADHD) struggle with impaired verbal fluency as an executive function. The left and right dorsolateral prefrontal cortex (dlPFC) and the right inferior frontal gurus (IFG), which show reduced functionality in individuals with ADHD, are involved in verbal fluency. In this study, a total of thirty-seven children with ADHD participated in two separate experiments. Each experiment included three different stimulation conditions: anodal left dlPFC/cathodal right vmPFC stimulation, the reversed montage, and a sham stimulation in Experiment 1, and anodal right dlPFC, anodal right IFG with extracranial return electrode, and a sham stimulation in Experiment 2. During each session, participants performed semantic and phonemic verbal fluency tasks while receiving tDCS. The results revealed a significant main effect of stimulation condition on phonemic verbal fluency during anodal left dlPFC stimulation in Experiment 1, and on semantic verbal fluency during both real stimulation conditions in Experiment 2. In conclusion, this study suggests that anodal left dlPFC stimulation improves phonemic verbal fluency, while anodal right dlPFC and right IFG stimulation enhance semantic verbal fluency. This domain-specific improvement can be attributed to the distinct cognitive demands of phonemic and semantic verbal fluency tasks. Phonemic verbal fluency heavily relies on working memory processes, whereas semantic verbal fluency requires effective inhibitory control and cognitive flexibility.

Transcranial direct current stimulation alters the process of reward processing in children with ADHD: Evidence from cognitive modeling

BackgroundThe ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are the neural underpinnings of reward processing, which is impaired in individuals with attention deficit hyperactivity disorder (ADHD). In the present study, we aimed to explore the impact of the vmPFC and the dlPFC regulation on reward processing. MethodsTwenty-six children with ADHD performed the balloon analogue risk-taking task (BART) and chocolate delay discounting task (CDDT) during five different sessions of transcranial direct current stimulation (tDCS), separated by a one-week interval: anodal left dlPFC/cathodal right vmPFC, the reversed electrode positioning, anodal left dlPFC stimulation with extracranial return electrode, anodal right vmPFC stimulation with extracranial return electrodes, and sham stimulation. Four-parameter and constant-sensitivity models were used to model the data. ResultsIn the BART, anodal dlPFC/cathodal vmPFC stimulation facilitated conservative decision making, anodal tDCS over dlPFC with extracranial return electrode increased positive beliefs about the explosion of a balloon, and anodal vmPFC/cathodal dlPFC stimulation reduced ongoing learning in the process of decision making. In the CDDT, anodal vmPFC stimulation with extracranial return electrode decreased impatience in the process of the task. ConclusionThese results suggest a role of the left dlPFC and right vmPFC in the outcome of decision making and the process of risky decision making and delay discounting.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.

Efficacy and safety of intermittent theta burst stimulation (iTBS) in treatment resistant depression

IntroductionRepetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulatory treatment option, which is used in a variety of neurological and psychiatric diseases. It is approved for depression treatment and recommended in international guidelines. A significant reduction in treatment duration was achieved by using theta burst stimulation (TBS) protocols, which are practicable and non-inferior to conventional TMS.ObjectivesTo analyse the efficacy and safety of intermittent theta burst stimulation (iTBS) of left DLPFC in inpatients with treatment-resistant depression.MethodsWe evaluated n=44 inpatients with treatment resistant major depressive disorder (n=37) and bipolar depression (n=7), who were treated with the 5 Hz intermittent TBS once daily for 3-6 weeks according to clinical decision. A total of 600 pulses and 200 bursts were applied in each treatment session. Clinical and response data were obtained by chart review.ResultsMean age at time of first stimulation was 54 years. 61,3 % of patients were female. On average, the current episode started 21 months before the first stimulation. In total, 924 treatment sessions were performed. On average, patients received 21 sessions. The mean MADRS Score pre-treatment was 27.2. Post-treatment, there was a clear reduction in depression severity (MADRS 18.3). No severe adverse events and no seizures occurred in this clinical observational analysis.ConclusionsIntermittent TBS is efficacious and safe in patients with chronic and refractory depression.DisclosureNo significant relationships.

Hostility bias or sadness bias in excluded individuals: does anodal transcranial direct current stimulation of right VLPFC vs. left DLPFC have a mitigating effect?

Exclusion has multiple adverse effects on individual's well-being. It induces anger and hostile cognitions leading to aggressive behavior. The purpose of this study was to test whether exclusion would affect recognition of anger on ambivalent faces of the excluders. We hypothesized that exclusion would elicit more anger encoding (hostility bias) than inclusion, but this effect would be mitigated by anodal tDCS of right VLPFC or left DLPFC-regions engaged in negative affect regulation. Participants (N = 96) were recognizing emotions (anger, sadness, happiness) on ambiguous faces of individuals who-as they were told-liked them or not. Results showed that exclusion induced more sadness bias. tDCS to VLPFC decreased anger and increased sadness recognition on excluders' faces compared with includers' faces, expressing a mixture of these two emotions. Additionally, stimulation to VLPFC and DLPFC decreased latencies for faces expressing sadness (sad-angry and happy-sad) but increased for happy-angry faces. Stimulation to VLPFC also increased reaction time to excluders faces while stimulation of DLPFC decreased reaction latency to includers faces. Results were discussed with the reference to the form of exclusion, motivational mechanism affected by disliking but also to lateralization (valence vs. arousal theory) and cortical regions engaged in encoding sadness after a threat to belonging.

The Effects of a Single Transcranial Direct Current Stimulation Session on Impulsivity and Risk Among a Sample of Adult Recreational Cannabis Users.

Individuals with substance use disorders exhibit risk-taking behaviors, potentially leading to negative consequences and difficulty maintaining recovery. Non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) have yielded mixed effects on risk-taking among healthy controls. Given the importance of risk-taking behaviors among substance-using samples, this study aimed to examine the effects of tDCS on risk-taking among a sample of adults using cannabis. Using a double-blind design, 27 cannabis users [M(SD) age = 32.48 (1.99), 41% female] were randomized, receiving one session of active or sham tDCS over the bilateral dorsolateral prefrontal cortex (dlPFC). Stimulation parameters closely followed prior studies with anodal right dlPFC and cathodal left dlPFC stimulation. Risk-taking—assessed via a modified Cambridge Gambling Task—was measured before and during tDCS. Delay and probability discounting tasks were assessed before and after stimulation. No significant effects of stimulation on risk-taking behavior were found. However, participants chose the less risky option ∼86% of the trials before stimulation which potentially contributed to ceiling effects. These results contradict one prior study showing increased risk-taking among cannabis users following tDCS. There was a significant increase in delay discounting of a $1000 delayed reward during stimulation for the sham group only, but no significant effects for probability discounting. The current study adds to conflicting and inconclusive literature on tDCS and cognition among substance-using samples. In conclusion, results suggest the ineffectiveness of single session dlPFC tDCS using an established stimulation protocol on risk-taking, although ceiling effects at baseline may have also prevented behavior change following tDCS.

Dissociating the role of dACC and dlPFC for emotion appraisal and mood regulation using cathodal tDCS.

Several neuroimaging studies have shown that a distributed network of brain regions is involved in our ability to appraise the emotions we experience in daily life. In particular, scholars suggested that the dorsal anterior cingulate cortex (dACC) may play a role in the appraisal of emotional stimuli together with subcortical regions, especially when stimuli are negatively valenced, and the dorsolateral prefrontal cortex (dlPFC) may play a role in regulating emotions. However, proofs of the causal role of these regions are lacking. In the present study, we aim at testing this model by stimulating both the dACC and the left dlPFC via cathodal tDCS. Twenty-four participants were asked to attend and rate the arousal and valence of negative and neutral emotional stimuli (pictures and words) in three different experimental sessions: cathodal stimulation of dACC, left dlPFC, or sham. In addition to the experimental task, the baseline affective state was measured before and after the stimulation to further assess the effect of stimulation over the baseline affective state after the experimental session. Results showed that cathodal stimulation of dACC, but not the left dlPFC, was associated with reduced arousal ratings of emotional stimuli, both compared with the sham condition. Moreover, cathodal stimulation of left dlPFC decreased participant's positive affective state after the session. These findings suggest for the first time, a dissociation between the dACC and dlPFC, with the former more involved in emotion appraisal, and the latter more involved in mood modulation.

Proof of concept study to develop a novel connectivity-based electric-field modelling approach for individualized targeting of transcranial magnetic stimulation treatment

Resting state functional connectivity (rsFC) offers promise for individualizing stimulation targets for transcranial magnetic stimulation (TMS) treatments. However, current targeting approaches do not account for non-focal TMS effects or large-scale connectivity patterns. To overcome these limitations, we propose a novel targeting optimization approach that combines whole-brain rsFC and electric-field (e-field) modelling to identify single-subject, symptom-specific TMS targets. In this proof of concept study, we recruited 91 anxious misery (AM) patients and 25 controls. We measured depression symptoms (MADRS/HAMD) and recorded rsFC. We used a PCA regression to predict symptoms from rsFC and estimate the parameter vector, for input into our e-field augmented model. We modeled 17 left dlPFC and 7 M1 sites using 24 equally spaced coil orientations. We computed single-subject predicted ΔMADRS/HAMD scores for each site/orientation using the e-field augmented model, which comprises a linear combination of the following elementwise products (1) the estimated connectivity/symptom coefficients, (2) a vectorized e-field model for site/orientation, (3) rsFC matrix, scaled by a proportionality constant. In AM patients, our connectivity-based model predicted a significant decrease depression for sites near BA9, but not M1 for coil orientations perpendicular to the cortical gyrus. In control subjects, no site/orientation combination showed a significant predicted change. These results corroborate previous work suggesting the efficacy of left dlPFC stimulation for depression treatment, and predict better outcomes with individualized targeting. They also suggest that our novel connectivity-based e-field modelling approach may effectively identify potential TMS treatment responders and individualize TMS targeting to maximize the therapeutic impact.

Evaluation of cognitive performance in clinically depressed patients using THINC-it after rTMS treatment

Background: This study evaluates the cognitive performance of 265 patients (nmales =31, Mage = 43.8 years, SD = 17.66) primarily diagnosed with MDD, using THINC-it subtests: (Choice Reaction Time Identification Task (CRT), One-Back Test (NBack), Digit Symbol Substitution Test (DSST), Trail Making Test-Part B (TMT) and Perceived Deficits Questionnaire for Depression-5-Item (PDQ-5-D)) before and after an acute course of rTMS in a natural, clinical setting. Methods: Patients treated for five days a week for 7-8 weeks over the right dorsolateral prefrontal cortex (dlPFC) at 1 Hz for 360 pulses followed by left dlPFC stimulation at 20 Hz for 1200 pulses. PHQ-9 & GAD-7 were completed weekly while CHRT, QIDS, & Zung were given pre/post treatment course. Results: 57.36% of patients achieved remission (≥ 70% improvement on PHQ-9) and significant moderate effect was found after rTMS in overall performance on the CRT (d = -.38, p < .001), TMT (d = -.39, p < .001), & PDQ-5-D (d = -.82, p < .001). Significant smaller effect was found in the NBack correct responses (d = -.24, p = .0005), NBack longer streak (d = -.27, p = .0000), DSST best reaction time (d = .15, p = .05), DSST nodes completed (d = -.21, p = .0004), DSST longest streak (d = -.16, p = .04), TMT errors (d = .23, p = .004), and TMT longest streak (d = -.20, p = .01). Conclusions: Detrimental cognitive effects were not observed or reported. Cognitive performance after TMS suggests patients’ executive function, working memory, processing speed, and attention may have improved. Funding: Patients who were already seeking TMS treatment were financially responsible for their acute courses of TMS treatment. Therapy may have been covered by insurance and/or privately paid for by the patient. Tablets used to conduct the assessments and for TMS therapy documentation are privately owned by our company, a private clinical practice. THINC-it Cognitive Screener is a free application used as part of our standard of care for all patients.

TDCS Anodic Stimulation of Left Hemisphere DLPFC Regulates Hot Executive Performance

tDCS Anodic Stimulation of Left Hemisphere DLPFC Regulates Hot Executive Performance

Randomized, crossover, sham-controlled, double-blind study of transcranial direct current stimulation of left DLPFC on executive functions .

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique commonly used to modulate cognitive functions; so-called "anodal" stimulation is considered to increase cortical excitability while "cathodal" stimulation is presumed to have the opposite result. Yet, a growing number of recent studies question the robustness of this polarity-dependent effect, namely because of the important inter-individual variability with regards to tDCS modulatory effects. A plausible reason for this heterogenous response may lay in task impurity issues in the evaluation of cognitive functions. To address the question of task impurity the NIH-Examiner, a neuropsychological test battery that uses latent variables, which assess the common variance across multiple measures of a given concept, was administered to 24 healthy individuals following tDCS. This battery contains 11 tasks and provides latent variables for general executive functioning, fluency, cognitive control and working memory. Anodal, cathodal, and sham stimulation (20 minutes, 1.5 mA) was administered over left dorsolateral prefrontal cortex and right supra-orbital area in a randomized, crossover, sham-controlled, double blind protocol. Factorial scores and task performance indices of executive function were not modulated by tDCS. Offline tDCS has limited impact on executive functions at both the task and factorial levels. This suggests that reducing task impurity does not increase the effectiveness of tDCS in modulating cognitive functions.

P.3.017 - Differential effects of left and right prefrontal magnetic stimulation on resting state connectivity in healthy individuals

Introduction High frequency repetitive transcranial magnetic stimulation (HF-rTMS) has gained great interest in multiple clinical and research fields. With HF-rTMS a coil – wherein an alternating current is running – is placed on top of the skull, creating a magnetic field that influences the perpendicular neural tissue, thereby stimulating the neuronal activity of the targeted cortical area [1]. Although it is believed that HF-rTMS accomplishes its effect by influencing entire neuronal networks [2]. One cortical area frequently chosen as stimulation target is the dorsolateral prefrontal cortex (dlPFC), as it is part of the control network. However, despite its popularity and frequent use, very little is known about the differential effect of HF-rTMS over the left and right dlPFC on intrinsic functional connectivity networks in healthy individuals. Therefore the current study will address this issue. Methods The current study assessed the differential effects of left or right dlPFC HF-rTMS (corrected for sham) on intrinsic functional connectivity networks in a sample of 45 healthy individuals. The study was a randomized, single-blind trial with two sessions. During the first session demographic data were obtained and a baseline resting state functional magnetic resonance imaging (rsfMRI) scan was performed. During the second session subjects were randomized to either sham dlPFC HF-rTMS (n=15), left active dlPFC HF-rTMS (n=15) or right active dlPFC HF-rTMS (n=15) directly followed by a second rsfMRI scan. A HF-rTMS session consisted of sixty trains of 5 seconds at a frequency of 10Hz. During the sham condition the coil was tilted 90 degrees relative to the skull. This condition was used in order to correct for time and placebo effects. Independent Component Analysis (ICA) were performed to assess baseline differences and stimulation effects on within and between network functional connectivity. The five components of interest were the left frontal parietal network, right frontal parietal network, default mode network, salience network and reward network. Results The three stimulation groups did not differ on within as well as between functional connectivity of the five components of interest at baseline. Regarding the stimulation effects on within network connectivity, stimulation of the left dlPFC resulted in decreased functional connectivity in the salience network whereas right dlPFC stimulation resulted in increased functional connectivity within this network. Regarding the stimulation effects on between network connectivity, no differences between left or right dlPFC stimulation were found. Discussion Stimulation of either the left or the right dlPFC (compared to sham stimulation) thus seems to lead to opposite effects within the salience network. Since the role of this network in directing attention between internal and external processes [3], and decreased functional connectivity is associated with worsened cognitive functioning in aging [4], the results of this study might have implications for the clinical effects of HF-rTMS over the dlPFC. Therefore future (clinical) studies should implement questionnaires and/ or neurocognitive tasks in order to be able to relate changes in functional connectivity to changes in cognitive functioning.

Differential Effects of Left and Right Prefrontal High-Frequency Repetitive Transcranial Magnetic Stimulation on Resting-State Functional Magnetic Resonance Imaging in Healthy Individuals.

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has gained great interest in multiple clinical and research fields and is believed to accomplish its effect by influencing neuronal networks. The dorsolateral prefrontal cortex (dlPFC) is frequently chosen as the cortical target for HF-rTMS. However, very little is known about the differential effect of HF-rTMS over the left and right dlPFC on intrinsic functional connectivity networks in patients or in healthy individuals. The current study assessed the differential effects of left or right HF-rTMS (corrected for sham) on intrinsic independent component analysis (ICA)-defined functional connectivity networks in a sample of 45 healthy individuals. All subjects had a first scanning session in which baseline functional connectivity was assessed. During the second session, individuals received one session of left, right, or sham dlPFC HF-rTMS (60 5-sec trains of 10 Hz at 110% motor threshold). The sham condition was used to correct for time and placebo effects. ICAs were performed to assess baseline differences and stimulation effects on within- and between-network functional connectivity. Stimulation of the left dlPFC resulted in decreased functional connectivity in the salience network, whereas right dlPFC stimulation resulted in increased functional connectivity within this network. No differences between left or right dlPFC stimulation were found in between-network connectivity. These results suggest that left and right HF-rTMS may have differential effects, and more research is needed on the clinical consequences.

Unilateral repetitive transcranial magnetic stimulation differentially affects younger and older adults completing a verbal working memory task

Functional neuroimaging studies have found that lateralization of activity in the dorsolateral prefrontal cortex (dlPFC) is reduced with aging. In the present study, repetitive transcranial magnetic stimulation (rTMS) was used to disrupt dlPFC activity in order to test the relationship of dlPFC laterality and age in verbal working memory (WM). Young (n=36) and older (n=35) subjects received 1Hz-rTMS (sham or active) to left or right dlPFC and WM performance was assessed pre- and post-stimulation via the n-back task. Significant increases in WM accuracy were observed following rTMS in the right dlPFC and sham conditions, but not with the left dlPFC stimulation. This was accompanied by a decrease in left P1 latency was also observed following left dlPFC stimulation. In contrast, older adults did not show a disruption in WM performance following rTMS in any of the stimulation conditions and exhibited increased left P3 amplitude following left stimulation. Our results show that changes in prefrontal laterality are evident with increasing age (left stimulation affects younger adults while older adults are not affected by stimulation) and this change is associated with specific neurophysiologic measures.

The efficacy of repetitive transcranial magnetic stimulation of left DLPFC with personalized targeting in major depression: preliminary results of pseudo-randomised study

The efficacy of repetitive transcranial magnetic stimulation of left DLPFC with personalized targeting in major depression: preliminary results of pseudo-randomised study

P106 Multimodal assessment of TMS-induced acute effects

Question Transcranial magnetic stimulation (TMS) has become a promising therapeutic treatment and neuroscientific research tool, yet how it works is not fully understood. We developed a dedicated MR coil array positioned beneath the TMS coil that allows for concurrent stimulation and imaging and flexible positioning while ensuring TMS efficiency, high MR sensitivity and the use of parallel/multiband imaging sequences. Here we aimed to explain acute effects of TMS over left DLPFC using a new online TMS/fMRI setup in combination with advanced imaging and neuronavigation methods. Resting State functional connectivity and DTI Tractography shall further explain resulting activation patterns at a network level. Methods The study was performed on a 3T Tim Trio scanner (Siemens, Erlangen, Germany). The TMS system used included a MagProX100 stimulator and MRi-B91 MR-compatible TMS coil (Magventure, Farum, Denmark). Five right-handed female subjects (age: 28.6 ± 4.3 years) were examined. Functional images were acquired using EPI (echo-planar imaging) sequence with TR/TE = 1000/33 ms, 28 slices, 1.5 × 1.5 × 3mm3. The experimental procedure is depicted in Fig. 1. FMRI data analyses were performed using SPM12. The design matrix comprised four regressors representing different stimulation amplitudes. DTI tractography was performed using DSI Studio. Figure options Download full-size image Download high-quality image (729 K) Download as PowerPoint slide Results TMS led to intensity-dependent activation increase in the left DLPFC and the contralateral DLPFC ( Figure options Download full-size image Download high-quality image (874 K) Download as PowerPoint slide Fig. 2): Higher stimulation intensities evoked higher bilateral activation. ACC showed a more complex response pattern. Resting-state functional connectivity maps using the stimulation target as seed-voxel showed a network very similar to the TMS-derived activation pattern (Fig. 2). DTI tractography provided additional information about the axonal connection between the left DLPFC stimulation site and the right DLPFC activation cluster. Conclusion This is the first study to assess the acute influence of TMS over DLPFC at an individual level, made possible by a dedicated concurrent TMS/fMRI coil array. Here we show a dose-dependent increase in activity not only underneath the stimulation site but also on the contralateral homologous area and apparent mediating responses in the ACC. This network is confirmed by additional resting-state and tractography data.

Anodal transcranial direct current stimulation over right dorsolateral prefrontal cortex alters decision making during approach-avoidance conflict.

Approach-avoidance conflict (AAC) refers to situations associated with both rewarding and threatening outcomes. The AAC task was developed to measure AAC decision-making. Approach behavior during this task has been linked to self-reported anxiety sensitivity and has elicited anterior cingulate, insula, caudate and right dorsolateral prefrontal cortex (dlPFC) activity, with right lateral PFC tracking the extent of approach behavior. Guided by these results, we used excitatory transcranial direct current stimulation (tDCS) to demonstrate the causal involvement of right dlPFC in AAC decision-making. Participants received anodal tDCS at 1.5mA over either left or right dlPFC or sham stimulation, while performing the AAC task and a control short-term memory task. Analyses of variance (ANOVA) revealed that for individuals with high anxiety sensitivity excitatory right (but not left or sham) dlPFC stimulation elicited measurable decreases in approach behavior during conflict. Excitatory left (but not right or sham) dlPFC simulation improved performance on the control task. These results support a possible asymmetry between the contributions of right and left dlPFC to AAC resolution during emotional decision-making. Increased activity in right dlPFC may contribute to anxiety-related symptoms and, as such, serve as a neurobehavioral target of anxiolytic treatments aiming to decrease avoidance behavior.

High-definition tDCS alters impulsivity in a baseline-dependent manner

In intertemporal choice (ITC), people discount future rewards in proportion to the time delay until reward receipt. Despite recent non-invasive brain stimulation studies suggesting a general causal link between dorsolateral prefrontal cortex (dlPFC) activity and ITC impulsivity, results regarding the functional specificity of dlPFC are mixed. We used high-definition transcranial direct current stimulation (HD-tDCS) to map changes in causal impulsivity through bi-directional modulation of left and right dlPFC during ITC. Model-free and model-based analyses demonstrated that anodal and cathodal stimulation of left dlPFC, but not right dlPFC, decreased and increased impulsivity, respectively. Critically, an individual differences analysis revealed that modulation of impulsivity was contingent on participants' baseline impulsivity. Overall, our results might reconcile the discrepancies in the existing literature and suggest a baseline-dependent role for left dlPFC during ITC.

Insight facilitation with add-on tDCS in schizophrenia

Impaired insight in schizophrenia patients has been linked with prefrontal deficits. In this open-label study, we examined for potential insight facilitation effects of add-on tDCS (with anodal stimulation of left DLPFC and cathodal stimulation over left temporo-parietal junction) in schizophrenia patients (N=21) with persistent auditory hallucinations despite adequate antipsychotic treatment. Following tDCS, there was a significant improvement in insight with concurrent significant reduction in auditory hallucination severity. Improvement in insight correlated significantly with improvement in severity of auditory hallucinations. These findings suggest improvement of insight with add-on tDCS in schizophrenia with persistent auditory hallucinations.