Efectos de la estimulación transcraneal con corriente directa (tDCS) sobre el consumo de tabaco, la motivación y la autoeficacia para dejar de fumar / Effects of transcranial direct current stimulation (tDCS) on tobacco use, motivation and self-efficacy to quit smoking

Estudios recientes de estimulación transcraneal con corriente directa (tDCS), aplicada sobre la corteza prefrontal dorsolateral (CPFDL), han demostrado que pueden reducir el craving y el consumo de tabaco. Sin embargo, existen pocas investigaciones que hayan evaluado los efectos del tDCS sobre la motivación y la autoeficacia para dejar de fumar. El objetivo de este estudio fue evaluar los efectos de la tDCS sobre el patrón de consumo, la motivación y la autoeficacia percibida para dejar de fumar en 16 personas con Trastorno por Consumo de Tabaco (TCT). Se utilizó un diseño de series temporales con replicación intrasujeto ABAB. El tratamiento consistió en la aplicación de 10 sesiones repetidas de tDCS a 1.5 mA durante 20 minutos sobre la CPFDL (cátodo F3 y ánodo F4), una sesión diaria durante dos semanas (lunes a viernes). Tras una fase de descanso de un mes, se replicó el tratamiento intrasujeto en idénticas condiciones. La intervención completa duró nueve semanas y fue completada por 10 participantes. Los resultados mostraron una reducción significativa en la dependencia a la nicotina, el número de cigarrillos fumados y los niveles de monóxido de carbono (CO) en el aire espirado. Además, observamos una mejora significativa en la motivación y la autoeficacia percibida para dejar de fumar. Estos hallazgos sugieren que el tDCS, aplicado sobre la CPFDL, puede ser una técnica efectiva para usar como terapia coadyuvante a otras estrategias farmacológicas y/o psicológicas empleadas en las Unidades de Conductas Adictivas (UCAs), u otros centros de atención a las drogodependencias. Sin embargo, se necesitan más estudios que investiguen la interacción entre los efectos de la nicotina y el tDCS para encontrar la estrategia óptima de tratamiento. (AU)

Recent studies of transcranial direct current stimulation (tDCS), applied to the dorsolateral prefrontal cortex (CPFDL), have shown that they can reduce craving and smoking. However, there is little research that has evaluated the effects of tDCS on motivation and self-efficacy to quit smoking. The objective of this study was to evaluate the effects of tDCS on the pattern of consumption, motivation and perceived self-efficacy to quit smoking in 16 people with Tobacco Use Disorder (TUD). A time series design with intrasubject ABAB replication was used. The treatment consisted of applying 10 repeated sessions of tDCS at 1.5 mA for 20 minutes on the CPFDL (cathode F3 and anode F4), one daily session for two weeks (Monday to Friday). After a one-month rest phase, the intra-subject treatment was replicated under identical conditions. The entire intervention lasted nine weeks and was completed by 10 participants. The results showed a significant reduction in nicotine dependence, the number of cigarettes smoked and the levels of carbon monoxide (CO) in the exhaled air. Furthermore, we observed a significant improvement in motivation and perceived self-efficacy to quit smoking. These findings suggest that the tDCS, applied on the CPFDL, may be an effective technique to use as adjunctive therapy to other pharmacological and / or psychological strategies used in the Addictive Behavior Units, or other drug addiction care centers. However, more studies are needed to investigate the interaction between the effects of nicotine and tDCS to find the optimal treatment strategy. (AU)

Transcranial direct current stimulation (tDCS). An effective tool for improving episodic memory in young people? / Estimulación transcraneal por corriente eléctrica directa (tDCS). ¿Una herramienta efectiva para mejorar la memoria episódica en jóvenes?

The main aim of the present study was to determine the effects of anodal vs sham tDCS administered on F3 (DLPFC) during the encoding phase of an episodic memory task, on the accuracy rate (AR) and reaction time (RT) measured in the immediate and delayed recall phases of the task, in a group of 23 healthy young participants.A randomized double-blind sham-controlled study of tDCS was carried out. The results evidenced significant main effects for factors Block, Session, and Delay on the AR and on RT, but not for the Group factor. Robust intra-session and inter-session learning effects but no Group (anodal vs sham tDCS) effect in episodic memory performance or in pre-post intervention neuropsychological tests were found. However, participants who received anodal tDCS showed shorter RT in the 24 hours delay interval and maintained it one week later, while those who received sham tDCS did not show the 24 hours RT shortening and even showed a RT increase one week later. These results could indicate a subtle modulatory effect of anodal tDCS on memory decay along delay intervals.The experimental protocol showed its potential utility to be used in samples of healthy elderly or mild cognitive impairment participants.(AU)

El objetivo principal del presente estudio fue determinar los efectos de la tDCS anódica vs placebo, administrada sobre F3 (CPFDL), durante la fase de codificación de una tarea de memoria episódica, sobre la tasa de aciertos (TA) y el tiempo de reacción (TR) medidos en las fases de recuerdo inmediato y demorado de la tarea, en un grupo de 23 participantes jóvenes sanos.Se realizó un estudio doble ciego aleatorizado. Los resultados evidenciaron efectos principales significativos para los factores Bloque, Sesión y Demora en la TA y en el TR, pero no para el factor del Grupo. Se encontraron efectos robustos de aprendizaje intrasesión e intersesiones, pero ningún efecto Grupo (tDCS anódica vs placebo) en el rendimiento de la memoria episódica o en los tests neuropsicológicos pre-post intervención. Sin embargo, los participantes que recibieron tDCS anódica mostraron un TR acortado en el intervalo de demora de 24 horas que mantuvieron una semana más tarde, mientras que los que recibieron tDCS placebo no mostraron acortamiento del TR a las 24 horas, pero si un aumento del TR una semana después. Estos resultados podrían indicar un sutil efecto modulador de la tDCS anódica en el decaimiento de la memoria en los intervalos de demora.El protocolo experimental mostró su utilidad potencial para ser utilizado en muestras de participantes mayores sanos o con deterioro cognitivo leve.(AU)

tDCS and exercise improve anxiety-like behavior and locomotion in chronic pain rats via modulation of neurotrophins and inflammatory mediators.

Anxiety disorders cause distress and are commonly found to be comorbid with chronic pain. Both are difficult-to-treat conditions for which alternative treatment options are being pursued. This study aimed to evaluate the effects of transcranial direct current stimulation (tDCS), treadmill exercise, or both, on anxiety-like behavior and associated growth factors and inflammatory markers in the hippocampus and sciatic nerve of rats with neuropathic pain. Male Wistar rats (n = 216) were subjected to sham-surgery or sciatic nerve constriction for pain induction. Fourteen days following neuropathic pain establishment, either bimodal tDCS, treadmill exercise, or a combination of both was used for 20 min a day for 8 consecutive days. The elevated plus-maze test was used to assess anxiety-like behavior and locomotor activity during the early (24 h) or late (7 days) phase after the end of treatment. BDNF, TNF-ɑ, and IL-10 levels in the hippocampus, and BDNF, NGF, and IL-10 levels in the sciatic nerve were assessed 48 h or 7 days after the end of treatment. Rats from the pain groups developed an anxiety-like state. Both tDCS and treadmill exercise provided ethological and neurochemical alterations induced by pain in the early and/or late phase, and a modest synergic effect between tDCS and exercise was observed. These results indicate that non-invasive neuromodulatory approaches can attenuate both anxiety-like status and locomotor activity and alter the biochemical profile in the hippocampus and sciatic nerve of rats with neuropathic pain and that combined interventions may be considered as a treatment option.

Simultaneous Application of Transcranial Direct Current Stimulation during Virtual Reality Exposure.

Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that changes the likelihood of neuronal firing through modulation of neural resting membranes. Compared to other techniques, tDCS is relatively safe, cost-effective, and can be administered while individuals are engaged in controlled, specific cognitive processes. This latter point is important as tDCS may predominantly affect intrinsically active neural regions. In an effort to test tDCS as a potential treatment for psychiatric illness, the protocol described here outlines a novel procedure that allows the simultaneous application of tDCS during exposure to trauma-related cues using virtual reality (tDCS+VR) for veterans with posttraumatic stress disorder (NCT03372460). In this double-blind protocol, participants are assigned to either receive 2 mA tDCS, or sham stimulation, for 25 minutes while passively watching three 8-minute standardized virtual reality drives through Iraq or Afghanistan, with virtual reality events increasing in intensity during each drive. Participants undergo six sessions of tDCS+VR over the course of 2-3 weeks, and psychophysiology (skin conductance reactivity) is measured throughout each session. This allows testing for within and between session changes in hyperarousal to virtual reality events and adjunctive effects of tDCS. Stimulation is delivered through a built-in rechargeable battery-driven tDCS device using a 1 (anode) x 1 (cathode) unilateral electrode set-up. Each electrode is placed in a 3 x 3 cm (current density 2.22 A/m2) reusable sponge pocket saturated with 0.9% normal saline. Sponges with electrodes are attached to the participant's skull using a rubber headband with the electrodes placed such that they target regions within the ventromedial prefrontal cortex. The virtual reality headset is placed over the tDCS montage in such a way as to avoid electrode interference.

Alzheimer's Disease, Neural Plasticity, and Functional Recovery.

Alzheimer's disease (AD) is the most common and devastating neurodegenerative condition worldwide, characterized by the aggregation of amyloid-ß and phosphorylated tau protein, and is accompanied by a progressive loss of learning and memory. A healthy nervous system is endowed with synaptic plasticity, among others neural plasticity mechanisms, allowing structural and physiological adaptations to changes in the environment. This neural plasticity modification sustains learning and memory, and behavioral changes and is severely affected by pathological and aging conditions, leading to cognitive deterioration. This article reviews critical aspects of AD neurodegeneration as well as therapeutic approaches that restore neural plasticity to provide functional recoveries, including environmental enrichment, physical exercise, transcranial stimulation, neurotrophin involvement, and direct electrical stimulation of the amygdala. In addition, we report recent behavioral results in Octodon degus, a promising natural model for the study of AD that naturally reproduces the neuropathological alterations observed in AD patients during normal aging, including neuronal toxicity, deterioration of neural plasticity, and the decline of learning and memory.

Addiction history moderates the effect of prefrontal 10-Hz transcranial alternating current stimulation on habitual action selection.

Individuals with substance use disorders (SUDs) transition more quickly from goal-directed to habitual action-selection, but the neural mechanisms underlying this phenomenon remain unclear. Data from animal models suggest that drugs of abuse can modify the neurocircuits that regulate action-selection, enhancing circuits that drive inflexible, habit-based stimulus-response (S-R) action-selection and weakening circuits that drive flexible, goal-directed actions. Here, we tested the effect of bilateral 10-Hz transcranial alternating current stimulation (10Ηz-tACs) of the dorsolateral prefrontal cortex on action-selection in men and women with a SUD history and an age- and sex-matched control group. We tested the hypothesis that true 10Ηz-tACS versus active sham stimulation would reduce perseverative errors after changed response contingencies for well-learned S-R associations, reflecting reduced habit-based action-selection, specifically in the SUD group. We found that 10 Hz-tACS increased perseverative errors in the control group, but in the SUD group, 10 Hz-tACS effects on perseverative errors depended on substance abuse duration: a longer addiction history was associated with a greater reduction of perseverative errors. These results suggest that 10Ηz-tACs altered circuit level dynamics regulating behavioral flexibility, and provide a foundation for future studies to test stimulation site, frequency, and timing specificity. Moreover, these data suggest that chronic substance abuse is associated with altered circuit dynamics that are ameliorated by 10Ηz-tACs. Determining the generalizability of these effects and their duration merits investigation as a direction for novel therapeutic interventions. These findings are timely based on growing interest in transcranial stimulation methods for treating SUDs.NEW & NOTEWORTHY Treating the executive dysfunction associated with addiction is hampered by redundancies in pharmacological regulation of different behavioral control circuits. Thus, nonpharmacological interventions hold promise for addiction treatment. Here, we show that, among people with an addiction history, 10-Hz transcranial alternating current stimulation (10Hz-tACS) of the dorsolateral prefrontal cortex can reduce habitual actions. The fact that 10Hz-tACS can regulate behavioral flexibility suggests its possible utility in reducing harmful habitual actions.

No tDCS augmented working memory training benefit in undergraduates rewarded with course credit.

BACKGROUND: The goal of working memory (WM) training is to expand capacity of this executive function. Transcranial direct current stimulation (tDCS) paired with WM training is more consistent than either alone. We have reported that tDCS targeting frontal and/or parietal regions enhanced theta phase locking, reduced alpha power, and strengthened theta-gamma phase amplitude coupling. OBJECTIVE: To determine whether tDCS to frontal or parietal sites optimized WM training gains we pre-registered a tDCS-WM training study. METHODS: 80 undergraduates were randomly assigned to one of four anodal tDCS montages: frontal (F4), parietal (P4), alternating (P4-F4), and sham (P4 or F4). Participants completed 5-training sessions over one week and returned for follow-up testing after 30 days of no-contact. RESULTS: No group showed significant improvement in trained or transfer task performance at the end of training nor at follow-up. CONCLUSIONS: This null finding marks a failure to replicate in undergraduates training benefits observed in graduate students. We argue that motivation is essential to elicit improved performance in training protocols.

A role for the right dorsolateral prefrontal cortex in enhancing regulation of both craving and negative emotions in internet gaming disorder: A randomized trial.

Reward-seeking and relief from negative emotions are two central motivational drives underlying addictions. Impaired executive control over craving and negative emotions contributes to compulsive addictive behaviors. Neuroimaging evidence has implicated the prefrontal cortex (PFC) in regulating craving or emotions. This study aims at examining whether anodal transcranial direct current stimulation (tDCS) over a specific region of the PFC would enhance both regulation processes. Thirty-three men with internet gaming disorder received active (1.5 mA for 20 minutes) and sham tDCS over the right dorsolateral PFC (dlPFC) one week apart in a randomized order. During each stimulation session, participants regulated craving for gaming during a regulation of craving (ROC) task and negative emotions during an emotion regulation (ER) task using cognitive reappraisal. Subjective ratings of craving and negative emotions and skin conductance responses (SCRs) were recorded. For both craving and negative emotions, tDCS of the right dlPFC facilitated downregulation and upregulation: active relative to sham tDCS decreased ratings (ROC: 95% CI of difference -1.38 to -0.56, p < 0.001; ER: -1.65 to -0.70, p < 0.001) and/or SCRs (ROC: -1.99 to -0.41 µs, p = 0.004) for downregulation, and increased ratings (ROC: 0.24 to 0.82, p = 0.001; ER: 0.26 to 0.72, p < 0.001) for upregulation. These findings provide the first experimental evidence confirming that tDCS of the right dlPFC enhances both craving- and negative-emotion-regulation. This suggests a promising approach for concurrently enhancing executive control over two central motivational drives underlying addictions.

Multisession transcranial direct current stimulation facilitates verbal learning and memory consolidation in young and older adults.

This study investigated effects of multisession transcranial direct-current stimulation on learning and maintenance of novel memory content and scrutinised effects of baseline cognitive status and the role of multi-session tDCS on overnight memory consolidation. In a prospective, randomized, double-blind, parallel-group, sham-tDCS controlled design, 101 healthy young and older adults completed a five-day verbal associative learning paradigm while receiving multisession tDCS to the task-relevant left prefrontal cortex. In older adults, active multisession tDCS enhanced recall performance after each daily training session. Effects were maintained the next morning and during follow-up assessments (one week; three months). In young adults, multisession tDCS significantly increased long-term recall. Unlike previous findings in the motor domain, beneficial effects of multisession tDCS on cognitive learning and memory were notexclusively due to enhanced memory consolidation. Positive stimulation effects were primarily found in participants with lower baseline learning ability, suggesting that multisession tDCS may counteract memory impairment in health and disease.

Modulation of income redistribution decisions by anodal tDCS over the medial prefrontal cortex.

One cause of the persistence of income inequality may be rooted in people's resistance to change the existing income distribution. Prior studies have shown that the medial prefrontal cortex (mPFC) may be associated with the decision making that influences income distribution. However, it is unclear whether the mPFC is involved in income redistribution tasks when third-party decision makers are unaffected by the outcome of the decision. In this study, we elucidate the neural mechanism underlying the tolerance of income inequality and the decision making that is related to income redistribution. By applying the transcranial direct current stimulation (tDCS) over the mPFC, we investigate whether the change in the activation of the mPFC can influence a subject's inclination to expropriate a rich person's endowment and transfer it to a poor person. The main finding is that the anodal stimulation significantly reduced the subject's inclination to redistribute wealth from the rich to the poor, and lowered the rate of accepting options for redistribution. However, the willingness of income redistribution did not change following the cathodal stimulation compared with the sham condition. The effect of the anodal stimulation was constant across three types of initial inequality. The stimulation effect is likely caused by the subject's enhanced loss aversion or desire to reinforce social hierarchies.

Efficacy and acceptability of transcranial direct current stimulation (tDCS) for major depressive disorder: An individual patient data meta-analysis.

We evaluated the efficacy and acceptability of transcranial direct current stimulation (tDCS) for treating acute depressive episodes using individual patient data that provide more precise estimates than aggregate data meta-analysis. A systematic review of placebo-controlled trials on tDCS as only intervention was conducted until December-2018. Data from each study was collated to estimate odds ratio (OR) and number needed to treat (NNT) of response and remission, and depression improvement. Endpoints were pre-determined. Nine eligible studies (572 participants), presenting moderate/high certainty of evidence, were included. Active tDCS was significantly superior to sham for response (30.9% vs. 18.9% respectively; OR = 1.96, 95%CI [1.30-2.95], NNT = 9), remission (19.9% vs. 11.7%, OR = 1.94 [1.19-3.16], NNT = 13) and depression improvement (effect size of ß = 0.31, [0.15-0.47]). Moreover, continuous clinical improvement was observed even after the end of acute tDCS treatment. There were no differences in all-cause discontinuation rates and no predictors of response were identified. To conclude, active tDCS was statistically superior to sham in all outcomes, although its clinical effects were moderate.

Transcranial direct current stimulation (tDCS) over vmPFC modulates interactions between reward and emotion in delay discounting.

Delay discounting requires computing trade-offs between immediate-small rewards and later-larger rewards. Negative and positive emotions shift decisions towards more or less impulsive responses, respectively. Models have conceptualized this trade-off by describing an interplay between "emotional" and "rational" processes, with the former involved during immediate choices and relying on the ventromedial prefrontal cortex (vmPFC), and the latter involved in long-term choices and relying on the dorsolateral prefrontal cortex (dlPFC). Whether stimulation of the vmPFC modulates emotion-induced delay discounting remains unclear. We applied tDCS over the vmPFC in 20 healthy individuals during a delay discounting task following an emotional (positive, negative) or neutral induction. Our results showed that cathodal tDCS increased impulsivity after positive emotions in high impulsivity trials. For low impulsivity trials, anodal tDCS decreased impulsivity following neutral induction compared with emotional induction. Our findings demonstrate that the vmPFC integrates reward and emotion most prominently in situations of increased impulsivity, whereas when higher cognitive control is required the vmPFC appears to be less engaged, possibly due to recruitment of the dlPFC. Understanding how stimulation and emotion influence decision-making at the behavioural and neural levels holds promise to develop interventions to reduce impulsivity.

Comparison of transcranial electrical stimulation regimens for effects on inhibitory circuit activity in primary somatosensory cortex and tactile spatial discrimination performance.

Transcranial electrical stimulation (tES) can be used to modulate inhibitory circuits in primary somatosensory cortex, resulting in improved somatosensory function. However, efficacy may depend on the specific stimulus modality and patterns. For instance, transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS), and transcranial pulsed current stimulation (tPCS) were found to stably and effectively modulate neuronal excitability, while anodal transcranial direct current stimulation (tDCS) appeared less effective overall but with substantial response heterogeneity among subjects. Therefore, we compared the effects of tES applied to primary somatosensory cortex on somatosensory evoked potential paired-pulse depression (SEP-PPD) and tactile discrimination performance in 17 neurologically healthy subjects. In Experiment 1, somatosensory evoked potential N20/P25_SEP-PPD, N20_SEP-PPD, and P25_SEP-PPD responses were assessed before and immediately after anodal tDCS, tACS (stimulation frequency, 140 Hz), tRNS (stimulation frequency, 0.1-640 Hz), anodal tPCS (pulse width, 50 ms; inter-pulse interval, 5 ms), and sham stimulation applied to primary somatosensory cortex. In Experiment 2, a grating orientation task (GOT) was performed before and immediately after the same anodal tDCS, tRNS, anodal tPCS, and sham stimulation regimens. Anodal tDCS and anodal tPCS decreased N20_SEP-PPD, and tRNS increased the first N20 SEP amplitude. Furthermore, tRNS and anodal tPCS decreased GOT discrimination threshold (improved performance). These results suggest that tRNS and anodal tPCS can improve sensory perception by modulating neuronal activity in primary somatosensory cortex.

A Positive Mood Induction for Reducing the Formation of Nocebo Effects from Side Effect Information.

BACKGROUND: Providing treatment side effect information can increase the occurrence of side effects through nocebo effects. Nocebo effects from side effect information raise a dilemma for health care, as there is an ethical obligation to disclose potential unpleasant treatment information to patients. PURPOSE: To test the hypothesis that a positive mood induction can block the development of nocebo effects that result from treatment side effect information. METHODS: In a laboratory setting, healthy participants were assigned to one of four conditions in a between-subjects randomized factorial trial. First, participants took part in a mood induction procedure, with half receiving a positive mood induction and the other half a neutral mood induction. Next, participants were told they would experience transcranial direct current stimulation (tDCS). Prior to a sham tDCS task, half of the participants were informed that headache pain is a side effect of tDCS, whereas the other half were not given this information. RESULTS: In the neutral mood condition, the provision of headache side effect information lead to a greater occurrence of headaches, more frequent headaches, and a higher maximum level of headache pain as compared to those given no side effect information. In the positive mood condition, a similar increase in headache pain did not manifest from the provision of side effect information. CONCLUSIONS: This is the first experiment to find that a positive mood induction can block the formation of nocebo effects that arise from side effect information. Inducing positive moods may be an effective strategy for reducing nocebo effects in a variety of clinical settings.

Differential effects of transcranial direct current stimulation on antiphase and inphase motor tasks: A pilot study.

Ageing is associated with a decline in motor function that critically interferes with activities of daily living involving manual dexterity. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that has been shown to enhance manual dexterity in healthy aging adults. The supplementary motor area (SMA) is involved in motor preparation and bimanual control; therefore, bihemispheric tDCS incorporating the SMA may preferentially enhance bimanual motor movements in healthy older adults. The aim of the current study was to determine if tDCS incorporating SMA could improve manual dexterity in older adults. Twenty-four adults, aged 67-84 participated in this double-blind, randomized, cross over design, pilot study. One group of participants (n = 17) were randomized to receive stimulation or sham on their first visit and received the contrary on their second visit, seven days later. A second group of participants (n = 10) received three consecutive days of tDCS while performing a motor task. Participants performed unimanual and bimanual hand movements while receiving 2 mA of tDCS. The total time for participants to complete three trials of each task was recorded. No significant differences in performance times were observed between single or tri session tDCS and sham conditions. However, tDCS had opposing effects on the motor consolidation of anti-phase and in-phase bimanual tasks. During the tri session paradigm, older adults improved performance learning of antiphase bimanual movements more quickly than inphase bimanual movements, suggesting a different mechanism of action of these two movements.

Improving working memory and pain inhibition in older persons using transcranial direct current stimulation.

The aim of the present study was to examine whether transcranial Direct Current Stimulation (tDCS) could enhance working memory and pain inhibition in older persons. Fifteen volunteers (7 women, 8 men; mean ± SD: 64 ± 4.4 y.o.) participated in two tDCS sessions during which an n-back task was performed with two levels of working memory load, while painful stimulation was delivered at the ankle. The experiment included five within-subject counterbalanced conditions (pain alone and 0-back or 2-back with or without pain) performed twice during each session. Compared with the pre-tDCS baseline, anodal tDCS decreased response times and improved pain inhibition by working memory in the 2-back condition (p < 0.01), but not in the 0-back or pain alone conditions, while sham tDCS produced no effect (all p > 0.3). These results indicate that working memory and pain inhibition can be improved by tDCS in older persons.

The effect of expectation on transcranial direct current stimulation (tDCS) to suppress food craving and eating in individuals with overweight and obesity.

Transcranial direct current stimulation (tDCS) is a neuromodulation technique with potential to treat eating disorders and obesity. As for any potential treatment, it is important to assess the degree to which expectation effects contribute to its reported efficacy. This study assessed the effect of tDCS on amount of food craving and eating while tightly controlling treatment expectation. N = 74 adults with overweight or obesity were informed of the known effects of tDCS to suppress craving and eating. Once electrodes were on the head, half of the participants were told they were receiving real, and the other half sham tDCS. Within these groups, approximately half actually received real and the other half sham tDCS. Stimulation parameters used were those previously found to reduce craving and eating, including in our lab: 2 mA, anode right/cathode left targeting the dorsolateral prefrontal cortex for 20 min (real), or only for the first and last minute (sham). Analyses controlled for demographics, hunger, trait impulsiveness, eating motives, dieting, binge eating, suggestibility, and baseline craving and eating. Participants told they were receiving real tDCS craved and ate less than participants told they were receiving sham tDCS (both p < 0.01), regardless of tDCS condition administered. There was no main effect of real vs. sham tDCS on craving or eating or an interaction between tDCS condition and expectation. The scientific validation of tDCS as a treatment for eating-related conditions hinges on controlling for the powerful effects of expectation. This can include the type of information provided on consent forms and participants' ability to guess real from sham conditions.

Prefrontal TDCS attenuates medial prefrontal connectivity upon being criticized in individuals scoring high on perceived criticism.

The mechanisms by which transcranial direct current stimulation (tDCS) influences emotional processing - and whether this is related to individual vulnerability for psychopathology - are still poorly understood. The present study aimed to investigate if one prefrontal tDCS session modulates mood and neural functional connectivity after being exposed to negative information differently in individuals low or high in perceived criticism (PC), which has been related to vulnerability for psychiatric illness. In a randomized cross-over design, one session of MRI-compatible prefrontal tDCS (neuronavigated placement of the anodal electrode at the left dorsolateral prefrontal cortex and the cathodal electrode at the right supraorbital region; vs. sham) was administered to healthy females, prior to listening to self-referential criticism. PC-dependent (low vs. high PC) changes in mood and resting-state functional connectivity patterns following tDCS and after hearing criticism were explored. After being criticized all females (low and high PC) felt angrier and more depressed, both in the active tDCS or sham tDCS condition. However, in contrast to low PC females, in high PC females prefrontal tDCS reduced connectivity between the left dorsal anterior cingulate cortex and the right dorsomedial prefrontal cortex following criticism. Despite having no differential effects on self-reported mood, prefrontal tDCS reduces medial prefrontal neural connectivity after being criticized in high PC females compared to low PC females. Depending on individual vulnerability for psychopathology, a single tDCS session differentially affects neural processing of negative emotional information, especially in brain regions involved in monitoring, experiencing and appraising/evaluating emotional material.

Primary Motor Cortex Transcranial Direct Current Stimulation Modulates Temporal Summation of the Nociceptive Withdrawal Reflex in Healthy Subjects.

OBJECTIVE: Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) has shown efficacy in a number of chronic pain conditions. Despite attempts to dissect the analgesic mechanisms, it is unknown whether M1 tDCS modulates the central integration of spinal nociception. To test this, we investigated the top-down modulation of spinal excitability using temporal summation (TS) of the nociceptive withdrawal reflex (NWR). METHODS: In this randomized, blinded, cross-over study, eight healthy subjects received electrically evoked TS of the NWR, which was delivered at 5 Hz at a threshold and a suprathreshold (1.1× threshold) to elicit TS resulting in different levels of pain. Subjects were asked to rate their pain after each stimulation. Changes in the TS of the NWR and pain ratings were investigated following 20 minutes of 2-mA anodal tDCS or sham stimulation applied over M1. RESULTS: Baseline recordings showed that TS of the NWR was induced with both threshold and suprathreshold stimulation. Suprathreshold stimulation was also associated with a higher pain intensity rating. After brain stimulation, there was no effect over the lower-intensity TS of the NWR or pain ratings in both the tDCS and sham conditions. However, tDCS reduced TS of the NWR and associated pain ratings following higher-intensity suprathreshold stimulation. CONCLUSIONS: These results indicate that M1 tDCS can indirectly modulate the central integration of suprathreshold nociceptive processing in the spinal cord. It is possible that the analgesic efficacy of tDCS is dependent on plasticity induced within pain pathways following repeated, high-intensity stimulation, which may explain the beneficial effects seen in chronic pain patients.

Sleep Quality, Depression, and Quality of Life After Bilateral Anodal Transcranial Direct Current Stimulation in Patients with Parkinson's Disease.

BACKGROUND Sleep dysfunctions impose a large burden on quality of life for patients with Parkinson's disease (PD). Several studies on PD reported potential therapeutic effects of transcranial direct current stimulation (tDCS) on motor and non-motor functions, but not related to sleep quality. Therefore, the present study examined sleep quality, depression perception, and quality of life changes after bilateral anodal tDCS in patients with PD. MATERIAL AND METHODS Twenty-one patients (n=21) with PD underwent 10 sessions (20 min each, 5 per week) of bilateral anodal tDCS stimulation applied simultaneously over the left and right prefrontal and motor areas. The Pittsburgh Sleep Quality Index (PSQI) total score and sub-scores, Geriatric Depression Scale (GDS), and Health-related quality of life questionnaire (SF-36) were measured pre/post bilateral tDCS anodal stimulation. RESULTS PSQI total score (P=0.045), sleep latency sub-score (P=0.02), and GDS total score (P=0.016) significantly decreased, and physical and mental components scores of SF-36 (P=0.018 and P=0.001, respectively) significantly increased after bilateral anodal tDCS stimulation. The GDS score decrease was directly correlated with decrease in PSQI total score (P=0.01), sleep latency sub-score (P=0.002), and sleep disturbance sub-score (P=0.003). In addition, the GDS score decrease was inversely correlated with increasing mental component score of SF-36 (P=0.001), which was directly correlated with an increase in sleep efficiency sub-score (P=0.03) and the physical component score of SF-36 (P=0.0001). CONCLUSIONS Bilateral anodal tDCS stimulation showed potential therapeutic effects in patients with PD in terms of sleep quality and depression level improvement, which together improved mental and physical quality of life in patients with PD.