***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Transcranial direct current stimulation ( tDCS ) of the human motor cortex results in polarity-specific shifts of cortical excitability during and after stimulation . Anodal tDCS enhances and cathodal stimulation reduces excitability . Animal experiments have demonstrated that the effect of anodal tDCS is caused by neuronal depolarisation , while cathodal tDCS hyperpolarises cortical neurones . However , not much is known about the ion channels and receptors involved in these effects . Thus , the impact of the sodium channel blocker carbamazepine , the calcium channel blocker flunarizine and the NMDA receptor antagonist dextromethorphane on tDCS-elicited motor cortical excitability changes of healthy human subjects were tested . tDCS- protocol s inducing excitability alterations ( 1 ) only during tDCS and ( 2 ) eliciting long-lasting after-effects were applied after drug administration . Carbamazepine selectively eliminated the excitability enhancement induced by anodal stimulation during and after tDCS . Flunarizine result ed in similar changes . Antagonising NMDA receptors did not alter current-generated excitability changes during a short stimulation , which elicits no after-effects , but prevented the induction of long-lasting after-effects independent of their direction . These results suggest that , like in other animals , cortical excitability shifts induced during tDCS in humans also depend on membrane polarisation , thus modulating the conductance of sodium and calcium channels . Moreover , they suggest that the after-effects may be NMDA receptor dependent . Since NMDA receptors are involved in neuroplastic changes , the results suggest a possible application of tDCS in the modulation or induction of these processes in a clinical setting . The selective elimination of tDCS-driven excitability enhancements by carbamazepine proposes a role for this drug in focussing the effects of cathodal tDCS , which may have important future clinical applications OBJECTIVE Because neuroimaging studies have shown that cue-provoked smoking craving is associated with changes in the activity of the bilateral dorsolateral prefrontal cortex ( DLPFC ) , we aim ed to investigate whether a powerful technique of noninvasive brain stimulation , transcranial direct current stimulation ( tDCS ) , reduces cue-provoked smoking craving as indexed by a visual analog scale . METHOD We performed a r and omized , sham-controlled crossover study in which 24 subjects received sham and active tDCS ( anodal tDCS of the left and right DLPFC ) in a r and omized order . Craving was induced by cigarette manipulation and exposure to a smoking video . The study ran from January 2006 to October 2006 . RESULTS Smoking craving was significantly increased after exposure to smoking-craving cues ( p < .0001 ) . Stimulation of both left and right DLPFC with active , but not sham , tDCS reduced craving significantly when comparing craving at baseline and after stimulation , without ( p = .007 ) and with ( p = .005 ) smoking-craving cues . There were no significant mood changes in any of the conditions of stimulation . Adverse events were mild and distributed equally across all treatment conditions . CONCLUSIONS Our findings extend the results of a previous study on the use of brain stimulation to reduce craving , showing that cortical stimulation with tDCS is beneficial for reducing cue-provoked craving , and thus support the further exploration of this technique for smoking cessation Prefrontal dysfunction is a hallmark in drug addiction , yet interventions exploring modulation of prefrontal cortex function in drug addiction have not been fully investigated with regard to physiological alterations . We tested the hypothesis that non-invasive prefrontal stimulation would change neural activity in crack-cocaine addiction , investigating the effects of transcranial Direct Current Stimulation ( tDCS ) of Dorsolateral Prefrontal Cortex ( DLPFC ) induced cortical excitability modulation on the visual P3 Event Related Potentials ( ERP ) component under neutral and drug cue exposition in crack-cocaine addicts . Thirteen crack-cocaine users were r and omly distributed to receive five applications ( once a day , every other day ) of bilateral ( left cathodal/right anodal ) tDCS ( 20 min , 2 mA , 35 cm2 ) or sham tDCS over the DLPFC . Brain activity was measured under crack-related or neutral visual-cued ERPs . There were significant differences in P3-related parameters when comparing group of stimulation ( active vs. sham tDCS ) and number of sessions ( single vs. repetitive tDCS ) . After a single session of tDCS , P3 current intensity in the left DLPFC increased during neutral cues and decreased during crack-related cues . This effect was opposite to what was observed in the sham-tDCS group . In contrast , repetitive tDCS increased current density not only in the DLPFC , but also in a wider array of prefrontal areas , including presumably the frontopolar cortex ( FPC ) orbitofrontal cortex ( OFC ) and anterior cingulate cortex ( ACC ) , when subjects were visualizing crack-related cues . Thus , single and repetitive application of tDCS can impact cognitive processing of neutral and especially crack-related visual cues in prefrontal areas , which may be of importance for treatment of crack-cocaine addiction This study examined the effects of bihemispheric and unihemispheric transcranial Direct Current Stimulation ( tDCS ) over the inferior frontal gyrus ( IFG ) on proactive control . Sixteen participants were r and omized to receive ( i ) bihemispheric tDCS , with a 35cm2 anodal electrode of the right IFG and a 35cm2 cathode electrode of left IFG or ( ii ) unihemispheric tDCS , with a 35cm2 anodal electrode of the right IFG and a 100cm2 electrode of the left IFG or ( iii ) sham tDCS , while performing a prepotent inhibition task . There were significant speed-accuracy tradeoff effects in terms of switch costs : unihemispheric tDCS significantly decreased the accuracy when compared to bihemispheric , and sham tDCS , while increased response time when comparing to bihemispheric and sham tDCS . The computational model showed a symmetrical field intensity for the bihemispheric tDCS montage , and an asymmetrical for the unihemispheric tDCS montage . This study confirms that unihemispheric tDCS over the rIFG has a significant impact on response inhibition . The lack of results of bihemispheric tDCS brings two important findings for this study : ( i ) left IFG seems to be also critically associated with inhibitory response control , and ( ii ) these results highlight the importance of considering the dual effects of tDCS when choosing the electrode montage Background : Transcranial direct current stimulation over the dorsolateral prefrontal cortex has been shown to be clinical ly useful in the treatment of drug addiction . Methods : We conducted a double-blind r and omized clinical trial aim ing to assess the effects of bilateral dorsolateral prefrontal cortex transcranial direct current stimulation ( left cathodal/right anodal ) on crack-cocaine addiction . We defined craving as the primary outcome , and other clinical measurements , including depressive and anxiety symtoms , and quality of life , as secondary outcomes . Seventeen male crack-cocaine users ( mean age 30.4±9.8 SD ) were r and omized to receive 5 sessions of active transcranial direct current stimulation ( 2 mA , 35cm2 , for 20 minutes ) , every other day , and 19 males ( mean age 30.3±8.4 SD ) to receive sham-transcranial direct current stimulation ( placebo ) as control group . Results : Craving scores were significantly reduced in the transcranial direct current stimulation group after treatment when compared with sham-transcranial direct current stimulation ( P=.028 ) and baseline values ( P=.003 ) , and decreased linearly over 4 weeks ( before , during , and after treatment ) in the transcranial direct current stimulation group only ( P=.047 ) . Changes of anxiety scores towards increase in the sham-transcranial direct current stimulation and decrease in the transcranial direct current stimulation group ( P=.03 ) , and of the overall perception of quality of life ( P=.031 ) and of health ( P=.048 ) towards decrease in the sham-transcranial direct current stimulation group and increase in the transcranial direct current stimulation group differed significantly between groups . Conclusions : Repetitive bilateral transcranial direct current stimulation over the dorsolateral prefrontal cortex reduced craving for crack-cocaine use , decreased anxiety , and improved quality of life . We hypothesize that transcranial direct current stimulation effects may be associated with increased prefrontal processing and regulation of craving behavior BACKGROUND Functional neuroimaging studies have shown that specific brain areas are associated with alcohol craving including the dorsolateral prefrontal cortex ( DLPFC ) . We tested whether modulation of DLPFC using transcranial direct current stimulation ( tDCS ) could alter alcohol craving in patients with alcohol dependence while being exposed to alcohol cues . METHODS We performed a r and omized sham-controlled study in which 13 subjects received sham and active bilateral tDCS delivered to DLPFC ( anodal left/cathodal right and anodal right/cathodal left ) . For sham stimulation , the electrodes were placed at the same positions as in active stimulation ; however , the stimulator was turned off after 30s of stimulation . Subjects were presented videos depicting alcohol consumption to increase alcohol craving . RESULTS Our results showed that both anodal left/cathodal right and anodal right/cathodal left significantly decreased alcohol craving compared to sham stimulation ( p<0.0001 ) . In addition , we found that following treatment , craving could not be further increased by alcohol cues . CONCLUSIONS Our findings showed that tDCS treatment to DLPFC can reduce alcohol craving . These findings extend the results of previous studies using noninvasive brain stimulation to reduce craving in humans . Given the relatively rapid suppressive effect of tDCS and the highly fluctuating nature of alcohol craving , this technique may prove to be a valuable treatment strategy within the clinical setting BACKGROUND The ability to exert self-control over temptation is a fundamental component of smoking behavior change . Transcranial direct current stimulation ( tDCS ) of the dorsolateral prefrontal cortex ( DLPFC ) has been shown to modulate cognitive control circuits . Although prior studies show that stimulation reduces cigarette craving and self-reported smoking , effects on ability to resist smoking have not been investigated directly . OBJECTIVES We assessed effects of a single 20-minute session of 1.0 mA anodal stimulation over the left DLPFC with cathodal stimulation over the right supra-orbital area ( vs. sham stimulation ) on ability to resist smoking in a vali date d smoking lapse paradigm . METHODS Twenty-five participants completed two  tDCS sessions ( active and sham stimulation ) in a within-subject , double-blind , r and omized and counterbalanced order with a 2-week washout period . Following overnight abstinence , participants received tDCS in the presence of smoking related cues ; they had the option to smoke at any time or receive $ 1 for every 5 minutes they abstained . After 50 minutes , they participated in a 1 hour ad libitum smoking session . Primary and secondary outcomes were time to first cigarette and cigarette consumption , respectively . RESULTS In multiple regression models , active tDCS ( compared to sham ) significantly increased latency to smoke ( p = 0.02 ) and decreased the total number of cigarettes smoked ( p = 0.014 ) during the session . CONCLUSION These findings suggest that acute anodal stimulation over the left DLPFC ( with cathodal stimulation over the right supra-orbital area ) can improve ability to resist smoking , supporting the therapeutic potential of tDCS for smoking cessation treatment We aim ed to assess whether modulation of the dorsolateral prefrontal cortex ( DLFPC ) with noninvasive brain stimulation , namely transcranial direct current stimulation ( tDCS ) , modifies  food craving in healthy subjects . We performed a r and omized sham-controlled cross-over study in which 23 subjects received sham and active tDCS  ( anode left/cathode right and anode right/cathode left ) of the DLPFC . Subjects were exposed to food and also watched a movie of food associated with strong craving . Desire for food consumption was evaluated by visual analogue scales ( VAS ) and food consumption before and after treatment . In addition we measured visual attention to food using an eye tracking system . Craving for viewed foods as indexed by VAS was reduced by anode right/cathode left tDCS . After sham stimulation , exposure to real food or food-related movie increased craving ; whereas after anode left/cathode right tDCS , the food-related stimuli did not increase craving levels , as revealed by the VAS scale . Moreover , compared with sham stimulation , subjects fixated food-related pictures less frequently after anode right/cathode left tDCS and consumed less food after both active stimulation conditions . These changes were not related to mood changes after any type of tDCS treatment . The effects of tDCS on food craving might be related to a modulation of neural circuits associated with reward and decision-making BACKGROUND Transcranial direct current stimulation ( tDCS ) is increasingly discussed as a new option to support the cognitive rehabilitation in neuropsychiatric disorders . However , the therapeutic impact of tDCS is limited by high inter-individual variability . Genetic factors most likely contribute to this variability by modulating the effects of tDCS . OBJECT 
    Output:
    
The overall effects of tDCS on impulsivity are promising .