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Electrified emotions: Modulatory effects of transcranial direct stimulation on negative emotional reactions to social exclusion a

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Paolo Riva , Leonor J. Romero Lauro , Alessandra Vergallito , C. Nathan DeWall & Brad J. cd

Bushman a

Department of Psychology, University of Milano-Bicocca, Milan, Italy

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Department of Psychology, University of Kentucky, Lexington, KY, USA

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School of Communication and Department of Psychology, The Ohio State University, Columbus, OH, USA d

Department of Communication Science, VU University Amsterdam, Amsterdam, the Netherlands Published online: 20 Aug 2014.

To cite this article: Paolo Riva, Leonor J. Romero Lauro, Alessandra Vergallito, C. Nathan DeWall & Brad J. Bushman (2014): Electrified emotions: Modulatory effects of transcranial direct stimulation on negative emotional reactions to social exclusion, Social Neuroscience, DOI: 10.1080/17470919.2014.946621 To link to this article: http://dx.doi.org/10.1080/17470919.2014.946621

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SOCIAL NEUROSCIENCE, 2014 http://dx.doi.org/10.1080/17470919.2014.946621

Electrified emotions: Modulatory effects of transcranial direct stimulation on negative emotional reactions to social exclusion

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Paolo Riva1, Leonor J. Romero Lauro1, Alessandra Vergallito1, C. Nathan DeWall2, and Brad J. Bushman3,4 1

Department of Psychology, University of Milano-Bicocca, Milan, Italy Department of Psychology, University of Kentucky, Lexington, KY, USA 3 School of Communication and Department of Psychology, The Ohio State University, Columbus, OH, USA 4 Department of Communication Science, VU University Amsterdam, Amsterdam, the Netherlands 2

Social exclusion, ostracism, and rejection can be emotionally painful because they thwart the need to belong. Building on studies suggesting that the right ventrolateral prefrontal cortex (rVLPFC) is associated with regulation of negative emotions, the present experiment tests the hypothesis that decreasing the cortical excitability of the rVLPFC may increase negative emotional reactions to social exclusion. Specifically, we applied cathodal transcranial direct current stimulation (tDCS) over the rVLPFC and predicted an increment of negative emotional reactions to social exclusion. In Study 1, participants were either socially excluded or included, while cathodal tDCS or sham stimulation was applied over the rVLPFC. Cathodal stimulation of rVLPFC boosted the typical negative emotional reaction caused by social exclusion. No effects emerged from participants in the inclusion condition. To test the specificity of tDCS effects over rVLPFC, in Study 2, participants were socially excluded and received cathodal tDCS or sham stimulation over a control region (i.e., the right posterior parietal cortex). No effects of tDCS stimulation were found. Our results showed that the rVLPFC is specifically involved in emotion regulation and suggest that cathodal stimulation can increase negative emotional responses to social exclusion.

Keywords: Social exclusion; Social pain; Hurt feelings; Negative emotions; Transcranial direct current stimulation (tDCS); Cathodal stimulation.

Pain can be alleviated by morphine but the pain of social ostracism cannot be taken away Derek Jarman, English film director

Ostracism, exclusion, and rejection can induce both general negative emotions and specific hurt feelings (see Buckley, Winkel, & Leary, 2004; Leary & Leder, 2009; MacDonald & Leary, 2005). The reason is because humans are social animals and have a strong need to belong (Baumeister & Leary, 1995; Bowlby,

1958; James, 1890; Maslow, 1943; McClelland, 1951; Murray, 1938; Stevens & Fiske, 1995). Accordingly, research has found that humans fear the pain of social separation (Riva, Williams, & Gallucci, 2014) and that social connections are vital to our physical and psychological health (e.g., Cacioppo & Patrick, 2008; Williams, 2007, 2009). Several studies have found that social distress and physical pain can cause similar psychological consequences (Riva, Wirth, & Williams, 2011) and that

Correspondence should be addressed to: Paolo Riva, Department of Psychology, University of Milano-Bicocca, Piazza Ateneo Nuovo, 1-20126 Milano, Italy. E-mail: [email protected]

© 2014 Taylor & Francis

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social separation might activate some of the brain regions known to be associated with the experience of physical pain (Eisenberger, 2012; MacDonald & Leary, 2005). A brain structure involved in the experience and regulation of both social and physical pain is the right ventrolateral prefrontal cortex (rVLPFC).

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THE REGULATORY FUNCTION OF rVLPFC The rVLPFC is a region involved in the regulation of negative emotions and physical pain (Berkman & Lieberman, 2009; Lieberman et al., 2004; Ochsner & Gross, 2005; Wager, Davidson, Hughes, Lindquist, & Ochsner, 2008). Accordingly, previous scholars have argued that the lateral prefrontal cortex (lPFC)—and especially rVLPFC—might be involved in various forms of emotion regulation (Berkman & Lieberman, 2009; Wager et al., 2008). Studies focused on the regulation of negative emotional stimuli have found a relationship between VLPFC activations and changes in reported emotion (Ochsner & Gross, 2005). Recent functional magnetic resonance imaging (fMRI) studies also suggest that rVLPFC might be directly involved in the regulation or inhibition of the distress resulting from social exclusion (Eisenberger, Lieberman, & Williams, 2003; Onoda et al., 2010). For instance, participants who showed higher rVLPFC activity while being excluded also reported lower levels of social distress, suggesting a regulatory function of the rVLPFC on feelings of social pain (Eisenberger et al., 2003). This pattern of correlational results provided evidence for the role of rVLPFC in the regulation of emotional reactions to social exclusion. A recent study has also demonstrated a causal relationship between rVLPFC activity and social pain regulation (Riva, Romero Lauro, DeWall, & Bushman, 2012). In that study, anodal transcranial direct current stimulation (tDCS) over rVLPFC reduced social pain following social exclusion, presumably by increasing activation in the rVLPFC. Furthermore, we also found that anodal tDCS over the rVLPFC reduced the relationship between social exclusion and aggression (Riva, Romero Lauro, DeWall, Chester, & Bushman, 2014).

cathode to the negatively charged anode. Although the physiologic mechanisms of action of tDCS are still largely unknown (Utz, Dimova, Oppenländer, & Kerkhoff, 2010), several studies have shown that tDCS can influence both brain functions and behavior in several domains, from general domains such as working memory (Fregni et al., 2005) and verbal fluency (Iyer et al., 2005) to more specific domains such as depression (Fregni et al., 2006), impulsive behavior (Jacobson, Javitt, & Lavidor, 2011), and physical pain perception (Boggio, Zaghi, Lopes, & Fregni, 2008). It is currently assumed that anodal stimulation causes a depolarization of cortical neurons (from their typical resting potential), which in turn will require less dendritic input to fire (depolarize) the neuron in the stimulated area. In contrast, cathodal stimulation causes a hyperpolarization of cortical neurons (thus requiring increasing dendritic input to fire them; Nitsche & Paulus, 2000). However, the cathodal inhibitory effect has been less frequently observed than the anodal excitatory effect (Jacobson et al., 2011) and thus is particularly worthy of further attention, especially in the context of high-level mental activity domains (Jacobson, Koslowsky, & Lavidor, 2012). In sum, this research has two aims. First, because cathodal stimulation over rVLPFC could interfere with the emotional self-regulatory function of the rVLPFC (Berkman & Lieberman, 2009; Lieberman et al., 2004; Ochsner & Gross, 2005; Wager et al., 2008), we tested whether cathodal stimulation could increase negative emotional responses to social exclusion in Study 1. Second, we examine the specificity of the effect, that is, whether cathodal tDCS stimulation over a brain region that does not directly influence activity in the rVLPFC would not affect people’s emotional reaction following social exclusion in Study 2.

STUDY 1 Study 1 tested the hypothesis that cathodal stimulation over rVLPFC increases negative emotional responses to social exclusion.

METHOD NEUROMODULATION VIA tDCS Participants tDCS is a neuromodulatory technique that involves attaching two electrodes to the scalp and conducting a weak electrical current from the positively charged

Participants were 82 healthy university students (50 females; Mage = 21.9, SD = 3.51) with a negative

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history for medical disorders, substance abuse or dependence, use of central nervous system-effective medication, and, particularly, psychiatric and neurological disorders, including brain surgery, tumor, or intracranial metal implantation (Poreisz, Boros, Antal, & Paulus, 2007). Participants received 10 € ($13) for their voluntary participation.

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Procedure Participants were tested individually. They were told the researchers were studying the effects of mental visualization. After informed consent was obtained, participants received cathodal tDCS or sham stimulation over the rVLPFC. Stimulation was applied using a constant current regulator (DC-Stimulator, NeuroConn GmbH, Germany). The experimenter was blind to experimental condition. A saline-soaked pair of surface sponge electrodes placed over the participant’s head transferred direct current. To stimulate the rVLPFC, the cathodal stimulation electrode was placed over F6 (Montreal Neurological Institute coordinates: 58, 30, 8; Onoda et al., 2010), consistent with the international 10–20 system for electroencephalogram (EEG) electrode placement. As a further control, using a frameless stereotactic neuronavigation system (Nexstim Ltd., Helsinki, Finland) on some participant’s MRIs, we verified that the electrode position over F6 actually targeted the rVLPFC. The reference (anodal) electrode was placed over the contralateral supraorbital area. The stimulation electrode was 25 cm2, whereas the reference electrode was 35 cm2, in order to increase the focality of the stimulation (Nitsche et al., 2008). A constant current of 1.5 mA intensity was applied for 20 min, leading to a current density of 0.06 mA/cm2 for the stimulation electrode and 0.04 mA/cm2 for the reference electrode. For sham stimulation, the electrodes were placed in the same position, but the stimulator turned off automatically after 15 s and turned on for 15 s at the end of 20 min. Thus, all participants believed they received stimulation for 20 min. Five minutes before the end of the tDCS or sham stimulation, participants played a virtual online balltossing game—Cyberball (Eisenberger et al., 2003) —which manipulated social exclusion versus inclusion. Participants were told they were playing with two other players and that the three of them would take turns throwing a ball to each other. In actuality, a preset computer program controlled everything. By random assignment, participants were either included, receiving the ball a third of the time (10

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tosses), or excluded, receiving the ball twice from each computer-controlled player and then never again. As a manipulation check, participants estimated the percentage of throws (0–100%) they received. After playing Cyberball, participants rated the social pain felt during the game (i.e., “The Cyberball game was a painful experience”). Participants also completed four items assessing the core emotional marker of social exclusion—hurt feelings (i.e., “I felt hurt, ” “I felt pained,” “I felt injured, ” and “I felt wounded”; Cronbach’s α = .87; adapted from Buckley et al., 2004) —and three items assessing other general negative emotions (i.e., “I felt angry, ” “I felt sad, ” and “I felt anxious”; Cronbach’s α = .80). All items were rated on 10-point scales (1 = not at all to 10 = extremely). Order of presentation of the items was randomized within subjects. A debriefing followed.

RESULTS Preliminary analyses Participant gender Because there were no main or interactive effects involving participant gender, the data from men and women were combined. Thus, we did not include gender as a factor in the subsequent analyses. Social exclusion manipulation check A 2 (inclusionary status: social inclusion vs. exclusion) × 2 (stimulation type: cathodal vs. sham stimulation) between-subjects analysis of variance (ANOVA) found that excluded participants reported receiving fewer tosses (13.78%) than did included participants (27.17%), F(1,78) = 46.68, p < .001, d = 1.55. Crucially, percentage of throws was not affected by the stimulation type [interaction: F (1,75) = 0.002, p > .96, η2p = .00], suggesting that participants in the tDCS and sham stimulation groups were equally cognitively aware of their inclusionary status during the game.

Primary analyses Feelings of social pain A 2 × 2 ANOVA found that excluded participants experienced more social pain during the Cyberball game (M = 2.45, SD = 2.12) than did included participants

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Figure 1. Feelings of social pain experienced during Cyberball game in excluded and included participants given cathodal or sham stimulation. Capped vertical bars denote 1 SE. Cathodal and sham stimulation groups differed in the excluded condition, but not in the included condition.

(M = 1.29, SD = 0.86), F(1,78) = 11.08, p = .001, d = 0.75. Moreover, participants given cathodal stimulation experienced more social pain (M = 2.28, SD = 2.13) than did those given sham stimulation (M = 1.45, SD = 1.01), F(1,78) = 5.02, p = .028, d = 0.51. However, these main effects were qualified by their predicted interaction, F(1,78) = 5.58, p = .021, η2p = .07. As can be seen in Figure 1, socially excluded participants given cathodal stimulation experienced more social pain than those given sham stimulation, F(1,78) = 10.38, p = .002, d = 0.80. Among socially included participants, no differences emerged between the tDCS and sham stimulation, F(1,78) = 0.008, p = .931, d = 0.020. Hurt feelings A 2 × 2 ANOVA found that excluded participants experienced more hurt feelings (M = 2.98, SD = 1.66) than did included participants (M = 1.48, SD = .91), F(1,78) = 26.48, p < .001, d = 1.12. There was no main effect for stimulation type, but it was in the predicted direction and the effect-size estimate was not trivial, F(1,78) = 2.44, p = .12, d = 0.35. Most important, the predicted interaction effect was significant, F(1,78) = 4.50, p = .037, η2p = .05. As can be seen in Figure 2A, socially excluded participants given cathodal stimulation experienced more hurt feelings than those given sham stimulation, F(1,78) = 6.64, p = .012, d = 0.67. Among socially included participants, no differences emerged between the tDCS and sham stimulation, F(1,78) = 0.16, p = .692, d = 0.090.

Figure 2. Hurt feelings (A) and negative emotions (B) in excluded and included participants given cathodal or sham stimulation. Capped vertical bars denote 1 SE. Cathodal and sham stimulation groups differed in the excluded condition, but not in the included condition.

Negative emotions Finally, a 2 × 2 ANOVA revealed that excluded participants felt more negative emotions (M = 3.43, SD = 1.71) than did included participants (M = 1.59, SD = 1.17), F(1,78) = 33.45, p < .001, d = 1.25. There was no main effect for stimulation type, but it was in the predicted direction and the effect-size estimate was not trivial, F(1,78) = 2.37, p = .13, d = 0.35. As expected, there was a significant interaction effect, F(1,78) = 4.61, p = .035, η2p = .06. Socially excluded participants given cathodal stimulation experienced higher levels of negative emotions than those given sham stimulation (see Figure 2B), F(1,78) = 6.66,

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p = .012, d = 0.72. Among socially included participants, no differences emerged between the tDCS and sham stimulation, F(1,78) = 0.19, p = .667, d = 0.098.

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DISCUSSION In Study 1, participants who were socially excluded or included received cathodal tDCS or sham stimulation over the rVLPFC. Excluded participants were cognitively aware of their inclusionary status, yet cathodal tDCS (but not sham stimulation) increased the feelings of social pain, hurt feelings, and negative emotions caused by social exclusion. No effects of tDCS stimulation emerged for included participants. These findings provide causal evidence supporting the regulatory role of the rVLPFC on emotional responses following social exclusion. However, in order to strengthen these results, any unspecific effect of tDCS needs to be ruled out. By including the sham condition, we controlled for any unspecific effect of tDCS (e.g., placebo effect and discomfort). However, we did not test whether cathodal tDCS per se (regardless of the stimulation site) can affect people’s emotional reactions. This issue is even more crucial because the spatial resolution of tDCS is low, and several recent neuroimaging, EEG, transcranial magnetic stimulation (TMS), and computational modeling studies converge in suggesting that the effects of the stimulation are widespread rather than confined to the area underneath the electrodes (Keeser et al., 2011; Miranda, Mekonnen, Salvador, & Ruffini, 2013; Romero Lauro et al., 2014).

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part in Study 1, but were from the same population and met the same inclusion criteria. Participants received 10 € ($13) for their participation.

Procedure The procedure was the same as for Study 1, with two exceptions. First, all participants were socially excluded. Second, the cathodal electrode was placed over the right posterior parietal cortex (rPPC) in a site corresponding to P2 electrode, whereas the reference (anodal) electrode was placed over the contralateral supraorbital area. We chose this stimulation site for two reasons. First, rPPC does not seem to be involved (at least directly) in emotion regulation (see Berkman & Lieberman, 2009; Lieberman et al., 2004; Ochsner & Gross, 2005; Wager et al., 2008). Second, one of our previous studies (based on a combination of TMS with simultaneous EEG recording) showed that tDCS stimulation over the right parietal cortex affected activity in the left homologue parietal cortex and in the contralateral frontal region (likely due to the supraorbital position of the reference electrode), but it did not affect activity in the right frontal area (including the rVLPFC; Romero Lauro et al., 2014).

RESULTS Preliminary analyses Participant gender

STUDY 2 Study 2 tested the specific role of rVLPFC in modulating emotional reactions following social exclusion. Thus, in Study 2, we applied cathodal stimulation over a control region and then measured people’s emotional reactions following social exclusion. We predicted that cathodal tDCS stimulation over a brain region that does not directly influence activity in the rVLPFC and does not seem to be involved in emotion regulation would not affect people’s emotional reaction following social exclusion.

METHOD Participants Participants were 40 healthy university students (25 females; Mage = 23.2, SD = 3.36) who did not take

Because there were no main or interactive effects involving participant sex, the data from men and women were combined. Social exclusion manipulation check As expected, the number of throws participants reported receiving in the tDCS condition (M = 9.05, SD = 5.27) did not differ from the number reported in the sham condition (M = 11.65, SD = 7.26), t(38) = 1.29, p > .20. Furthermore, no difference emerged among the percentage of throws reported by the two groups of participants of Study 2 (i.e., those receiving cathodal or sham stimulation over the rPPC) and that reported by excluded participants receiving sham tDCS stimulation over rVLPFC in Study 1, F(2,56) = 2.07, p = .135. Therefore, similar to Study 1, the percentage of throws was not affected by the tDCS manipulation.

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Primary analyses Feelings of social pain

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As expected, feelings of social pain did not differ between the sham (M = 2.30, SD = 2.18) and the tDCS (M = 2.55, SD = 1.87) conditions, t(38) = 0.39, p > .70. We found no difference among feelings of social pain reported by these two groups receiving cathodal or sham stimulation over the rPPC and those reported by excluded participants receiving sham tDCS stimulation in Study 1, F(2,56) = 1.36, p > .26. Hurt feelings The four items assessing hurt feelings were internally consistent (Cronbach’s α = .91). As expected, hurt feelings did not differ between the sham (M = 2.86, SD = 2.04) and the cathodal tDCS stimulation over the rPPC (M = 3.39, SD = 1.78), t(38) = 0.87, p > .39. We found no difference among hurt feelings reported by these two groups receiving cathodal or sham stimulation over the rPPC and those reported by excluded participants receiving sham tDCS stimulation in Study 1, F(2,56) = 1.56, p > .22. Negative emotions The three items assessing other general negative emotions were internally consistent (Cronbach’s α = .69). As expected, negative emotions did not differ between the sham (M = 3.08, SD = 1.79) and the tDCS condition (M = 3.53, SD = 1.82), t(38) = 0.78, p > .43. Again, no differences were found among negative emotions reported by these two groups receiving cathodal or sham stimulation over the rPPC and those reported by excluded participants receiving sham tDCS stimulation in Study 1, F(2,56) = 1.13, p > .63.

DISCUSSION In Study 2, participants received cathodal tDCS or sham stimulation over the rPPC and then were socially excluded. No effects of tDCS stimulation emerged for any of the emotional measures, suggesting that stimulating a brain region that does not affect activity in the rVLPFC does not modulate people’s feelings of social pain, hurt feelings, and negative emotions due to social exclusion.

GENERAL DISCUSSION In the present research, we found that non-invasive brain polarization through cathodal tDCS over rVLPFC increased feelings of social pain, hurt feelings, and negative emotions resulting from social exclusion. Among socially included participants, no differences emerged between cathodal and sham stimulation. We showed that participants in the exclusion and inclusion conditions correctly perceived the game type they were playing, suggesting that the tDCS stimulation did not alter their cognitive ability to accurately detect their inclusionary status. Our hypothesis was based on prior neuroimaging studies, suggesting that the rVLPFC inhibits pain resulting from social exclusion (Eisenberger et al., 2003; Onoda et al., 2010; Riva et al., 2012). It was also based on the assumption that cathodal stimulation can decrease global neural activity of the target area, thus inhibiting its functionality (Nitsche & Paulus, 2000). However, there is no reason to think that a large portion of the brain such as rVLPFC is selectively involved in the regulation of negative emotions caused by social exclusion. More specifically, several brain imaging studies suggest that the rVLPFC might be directly involved in the regulation or suppression of negative emotions elicited by a wide array of stimuli (Berkman & Lieberman, 2009; Cohen, Berkman, & Lieberman, 2013; Lieberman et al., 2004; Ochsner & Gross, 2005; Wager et al., 2008). For instance, one study found that activity in the rVLPFC was correlated with reduced negative emotional experience during reappraisal of aversive images (Wager et al., 2008). Furthermore, previous research has shown that changes in VLPFC activity are associated with several emotional disorders, including schizophrenia, bipolar, and major depressive disorders (Phillips, Drevets, Rauch, & Lane, 2003). A diminished neural response in the ventralprefrontal cortical area to emotional expressions of fear was found in participants with major depressive disorder (Lawrence et al., 2004). In a study on cognitive reappraisal, anxious individuals required increased engagement of lateral and medial PFC in order to successfully reduce negative emotions (Campbell-Sills et al., 2011). The current research extended this literature by providing a causal test of the role of rVLPFC in emotion regulation. In the emotion regulation literature, lateralprefrontal regions have been implicated in situation-focused (vs. self-focused) emotion regulation that involves externally focused processing (Ochsner et al., 2004). We argue that the same situation-focused emotion regulation might be associated with reactions to social exclusion. Therefore, future research should test

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whether stimulation over rVLPFC modulates emotional reactions caused by aversive stimuli other than social exclusion (e.g., hot temperatures, foul odors, and loud noises). In recent studies, we found that anodal stimulation could decrease feelings of social pain (Riva et al., 2012) and behavioral aggression following social exclusion (Riva et al., 2014). The present research offers evidence that cathodal stimulation yields an opposite effect (increment of negative emotions caused by social exclusion) compared to anodal one over the same area (rVLPFC). Whereas the coupling of anodalexcitatory and cathodal-inhibitory effects are well established in the sensory and motor domains, at both the physiological and the behavioral level, they are not well established in higher-level mental activity domains (e.g., emotion regulation; Jacobson et al., 2012). As a case in point, the anodal facilitation effect has been found in several empirical studies (Boggio et al., 2008; Fregni et al., 2005, 2006; Iyer et al., 2005; Riva et al., 2012), whereas cathodal inhibition is more controversial. The chance to inhibit rather than facilitate the individual’s regulatory ability over an emotional or a behavioral response, as showed by the results of the present study, is promising, especially for the treatment of neuropsychiatric and neuropsychological disease where both an excessive (e.g., borderline personality disorder; Staebler, Helbing, Rosenbach, & Renneberg, 2011) or a reduced (e.g., right brain damage patients; Borod, Bloom, Brickman, Nakhutina, & Curko, 2002) emotional sensitivity to social exclusion might be problematic. The present research considered some critical issues linked to non-specific effect of tDCS stimulation. First, in order to rule out the possibility that our results were due to non-specific aspects of the stimulation (e.g., placebo effect and discomfort), we included a sham stimulation condition. Second, we examined the issue of the spatial specificity by testing whether the same effects would have been obtained by stimulating another brain region. This issue was crucial because the spatial resolution of tDCS is known to be somewhat poor. Therefore, it was particularly critical for establishing the specificity of the observed effects that we tested the effect of tDCS on another brain region not involved in emotion processing (i.e., rPPC).

Limitations and future research The main limitation of tDCS is its low spatial resolution. Scholars have suggested that tDCS effects largely come from the cortical area beneath the electrode

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(see Zaghi, Acar, Hultgren, Boggio, & Fregni, 2010). However, recent computer-based modeling (Miranda et al., 2013), neuroimaging (Keeser et al., 2011) and TMS–EEG (Pellicciari, Brignani, & Miniussi, 2013; Romero Lauro et al., 2014) studies provided evidence for the presence of widespread effects of the stimulation affecting other brain regions that are structurally or functionally connected to the stimulated one. Therefore, future research should further explore the cortical network involved in the top-down regulation of negative emotions by rVLPFC. For instance, previous research found that dorsal anterior cingulate cortex (dACC) activity mediated the relationship between rVLPFC activity and self-reported social distress (Eisenberger et al., 2003), suggesting that rVLPFC might directly down-regulate dACC activity. Future research should thus investigate the effective connectivity between these two areas applying dynamic causal modeling with fMRI or even better a more “data-driven” approach such as a TMS–EEG integrated system.

CONCLUSION The current study used cathodal tDSC to test the hypothesis that obstructing emotion regulation processes may increase negative emotional reactions to social exclusion. It also examined the specificity of this effect by testing whether stimulating a brain region uninvolved in emotion regulation processes (e.g., the rPPC) altered emotional reactions to social exclusion. Overall, our research provides experimental evidence on the role of the rVLPFC in modulating negative emotional reactions associated with threats to social belongingness. Beyond their theoretical impact, our findings suggest that tDCS stimulation of rVLPFC might prove particularly helpful in clinical conditions linked to emotional dysregulation. More specifically, cathodal stimulation applied over the rVLPFC may prove useful in treatments with patients that are iposensitive to social exclusion (such as right brain damage patients; Borod et al., 2002). By contrast, anodal stimulation of the same region might help those who are hypersensitive to rejections cues, such as those with borderline personality disorder (Sadikaj, Russel, Moskowitz, & Paris, 2010). Derek Jarman was correct in noting that “Pain can be alleviated by morphine but the pain of social ostracism cannot be taken away.” There is no quick fix for the social pain either. Cathodal stimulation over the

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rVLPFC can make the pain worse, like throwing salt into an open wound. Original manuscript received 30 January 2014 Revised manuscript accepted 14 July 2014 First published online 20 August 2014

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tDCS, SOCIAL EXCLUSION, & EMOTIONS

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Electrified emotions: Modulatory effects of transcranial direct stimulation on negative emotional reactions to social exclusion.

Social exclusion, ostracism, and rejection can be emotionally painful because they thwart the need to belong. Building on studies suggesting that the ...
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