Modulation of facial muscle responses by another person's presence and affiliative touch during affective image viewing.

Stimulating CT-afferents by forearm caresses produces the subjective experience of pleasantness in the receiver and modulates subjective evaluations of viewed affective images. Receiving touch from another person includes the social element of another person's presence, which has been found to influence affective image evaluations without involving touch. The current study investigated whether these modulations translate to facial muscle responses associated with positive and negative affect across touch-involving and mere presence conditions. Female participants (N = 40, M(age) = 22.4, SD = 5.3) watched affective images (neutral, positive, negative) while facial electromyography was recorded (sites: zygomaticus, corrugator). Results from ANOVAs showed that providing touch to another person or oneself modulated zygomaticus site responses when viewing positive images. Providing CT-afferent stimulating touch (i.e., forearm caresses) to another person or oneself dampened the positive affective facial muscle response to positive affective images. Providing touch to another person generally increased corrugator facial muscle activity related to negative affect. Receiving touch did not modulate affective facial muscle responses during the viewing of affective images but may have effects on later cognitive processes. Together, previously reported social and touch modulations of subjective evaluations of affective images do not translate to facial muscle responses during affective image viewing, which were differentially modulated.

Anodal transcranial direct current stimulation over the posterior parietal cortex reduces the onset time to the rubber hand illusion and increases the body ownership.

The body ownership induced by the rubber hand illusion (RHI) has been related to a neural network involving a frontal-parietal circuit. Previous functional neuroimaging studies have demonstrated neural activation in the parietal area relative to the multisensory integration processing and to the recalibration of the felt position of body while a ventral premotor cortex activation has been linked to bodily self-attribution during the RHI. Our study aimed to investigate the effects of transcranial direct current stimulation (tDCS) on the posterior parietal cortex (PPC) or on the premotor cortex (PMv) during RHI to address the specific roles of these two brain areas in the illusion. 156 young adult participants (21.2 ± 3.13 years old; all right-handed) were enrolled for this between-subjects design experiment. Participants received anodal, cathodal and sham tDCS in three different sessions on the right PPC or right PMv and experienced visual-tactile stimulation from the brushes touching the rubber hand and their own left hand in synchronous or asynchronous manner. The RHI was quantified by the (1) onset time for the feeling of body ownership of the rubber hand, (2) proprioceptive drift, and (3) questionnaire about the intensity of the illusion as reported by the participant. All subjects felt the RHI during the synchronous condition. However, we found that the illusion onset time can be modulated by the anodal tDCS condition on the PPC: anodal tDCS decreased the illusion onset time and the subjective experience of body ownership. These findings suggest that the parietal area plays a crucial role in the speed of visual and tactile multisensory integration in the RHI and introduce tDCS as technique that can accelerate the time to integrate an artificial body part and increased the perception of body ownership.

Neuromodulating Attention and Mind-Wandering Processes with a Single Session Real Time EEG.

Our minds are continuously alternating between external attention (EA) and mind wandering (MW). An appropriate balance between EA and MW is important for promoting efficient perceptual processing, executive functioning, decision-making, auto-biographical memory, and creativity. There is evidence that EA processes are associated with increased activity in high-frequency EEG bands (e.g., SMR), contrasting with the dominance of low-frequency bands during MW (e.g., Theta). The aim of the present study was to test the effects of two distinct single session real-time EEG (rtEEG) protocols (SMR up-training/Theta down-training-SMR⇑Theta⇓; Theta up-training/SMR down-training-Theta⇑SMR⇓) on EA and MW processes. Thirty healthy volunteers were randomly assigned to one of two rtEEG training protocols (SMR⇑Theta⇓; Theta⇑SMR⇓). Before and after the rtEEG training, participants completed the attention network task (ANT) along with several MW measures. Both training protocols were effective in increasing SMR (SMR⇑Theta⇓) and theta (Theta⇑SMR⇓) amplitudes but not in decreasing the amplitude of down-trained bands. There were no significant effects of the rtEEG training in either EA or MW measures. However, there was a significant positive correlation between post-training SMR increases and the use of deliberate MW (rather than spontaneous) strategies. Additionally, for the Theta⇑SMR⇓ protocol, increase in post-training Theta amplitude was significantly associated with a decreased efficiency in the orientation network.

tDCS in Addiction and Impulse Control Disorders.

The study of addiction and impulsion control disorders has shown that behaviors of seeking and consumption of addictive substances are subserved by neurobiological alterations specifically related to brain networks for reward, stress, and executive control, representing the brain's adaptation to the continued use of an addictive substance. In parallel, studies using neuromodulation techniques such as transcranial direct current stimulation (tDCS) have demonstrated promising effects in modulating cognitive and motor functions. This review aims to describe the neurobiology of addiction and some of the most relevant cognitive models of addictive behavior and to clarify how tDCS application modulates the intake and craving for several addictive substances, such as food, alcohol, nicotine, cocaine, crack, methamphetamine, and cannabis. We also discuss the positive and null outcomes of the use of this neuromodulatory technique in the treatment of addiction disorders resulting from the use of these substances. The reviewed findings lead us to conclude that tDCS interventions hold several promising clinical avenues in addiction and impulsive control. However, methodological investigations are necessary for undercover optimal parameters before implementing its clinical application.

Contrasting effects of transcranial direct current stimulation on central and peripheral visual fields.

Recent research suggested that transcranial direct current stimulation (tDCS) can affect visual processing and that it can be useful in visual rehabilitation. Nevertheless, there are still few investigations on the subject. tDCS selectivity and the extent of its outcomes on visual perception are still to be assessed. Here, we investigate whether central and peripheral visual fields are equally affected by tDCS. We also tried to reproduce a previous work that has evaluated tDCS effects on the central visual field only (Kraft et al. 207:283-290, 2010). Fifteen healthy subjects participated in this randomized repeated-measure design study and received 1.5-mA anodal, cathodal and sham stimulation in different sessions, while performing 10-2 and 60-4 protocols in an automated perimeter. Anodal tDCS significantly decreased thresholds, but was limited to the most eccentric regions of the visual field measured (60°). This suggests that tDCS might be used for rehabilitation of peripheral visual field losses. We did not replicate the excitatory tDCS effect in the central visual field as previously reported by another group. Instead, we observed a trend toward an inhibitory (yet not statistically significant) effect of anodal tDCS on the central field. This might be explained by methodological differences. These results highlight that although tDCS is a technique with a low focality in the spatial domain, its effects might be highly focal in a functional domain. When taken together with previous findings, this also suggests that tDCS may have a differential effect on different retinotopic areas in the brain.

Transcranial direct current stimulation can selectively affect different processing channels in human visual cortex.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that can modulate cortical activity. Nonetheless, information regarding its functional specificity and the extent by which visual performance can be modulated is still lacking. Here, we used vision as model to address if it differentially affects different cell groups in the stimulated area. We applied tDCS to the occiput and performed a series of visual tests in a sham-controlled repeated-measures design. Achromatic contrast sensitivity was assessed psychophysically during tDCS, with tasks designed to target specific spatial frequency (SF) channels, inferred ON, OFF channels and inferred magnocellular and parvocellular pathways of the visual system. Sweep visual evoked potential (sVEP) for contrast sensitivity and Vernier acuity was recorded before and after tDCS. Anodal tDCS significantly increased thresholds for luminance decrements (OFF) only for the inferred magnocellular thresholds. Although tDCS had no significant effects on Vernier or contrast sVEP thresholds, it modulated suprathreshold amplitudes for both tasks. Cathodal tDCS increased sVEP amplitudes at a low SF, decreased it at a medium, and had no effect at a high SF. Cathodal tDCS increased sVEP phase lags for low and decreased it for high SF (maximum change corresponding to change in apparent latency >6 ms). Cathodal and anodal stimulation decreased amplitudes of sVEP Vernier responses. Exclusive tDCS effects on magnocellular thresholds agree with reports of pathway-specific tDCS effects. The dependence of tDCS effects on SF and contrast levels further suggests that tDCS differentially affects different cell groups in the visual cortex.

Reducing transcranial direct current stimulation-induced erythema with skin pretreatment: considerations for sham-controlled clinical trials.

OBJECTIVES: Transcranial direct current stimulation (tDCS)-induced erythema (skin reddening) has been described as an adverse effect that can harm blinding integrity in sham-controlled designs. To tackle this issue, we investigated whether the use of topical pretreatments could decrease erythema and other adverse effects associated with tDCS. MATERIALS AND METHODS: Thirty healthy volunteers were recruited, and four interventions were applied 30 min prior to tDCS in a Latin square design: placebo, ketoprofen 2%, hydroxyzine 1%, and lidocaine 5%. TDCS was applied for 30 min (2 mA, anode and cathode over F3 and F4, respectively) in two active sessions with a minimum 1-week interval. The Draize erythema scoring system scale was used to assess erythema intensity; a tDCS questionnaire was used to assess other adverse effects (e.g., tingling, itching, burning sensation, and pain). RESULTS: We found that ketoprofen (but not hydroxyzine or lidocaine) significantly attenuated tDCS-induced erythema regarding intensity and duration, with a medium effect compared with placebo. Erythema was overall mild, short-lived (lasting 18-24 min after tDCS ending), and more intense under the anode. Subjects with darker skin color also tended to present less intense tDCS-induced erythema. The prevalence of other adverse effects was low and did not differ between dermatological groups. CONCLUSIONS: Ketoprofen 2% topical pretreatment might be an interesting strategy to reduce tDCS-induced erythema and might be useful for blinding improvement in further sham-controlled tDCS trials.

Enhancement of affective processing induced by bifrontal transcranial direct current stimulation in patients with major depression.

OBJECTIVE: Our aim was to evaluate whether one single section of transcranial direct current stimulation (tDCS), a neuromodulatory technique that noninvasively modifies cortical excitability, could induce acute changes in the negative attentional bias in patients with major depression. SUBJECTS AND METHODS: Randomized, double-blind, sham-controlled, parallel design enrolling 24 age-, gender-matched, drug-free, depressed subjects. Anode and cathode were placed over the left and right dorsolateral prefrontal cortex. We performed a word Emotional Stroop Task collecting the response times (RTs) for positive-, negative-, and neutral-related words. The emotional Stroop effect for negative vs. neutral and vs. positive words was used as the measure of attentional bias. RESULTS: At baseline, RTs were significantly slower for negative vs. positive words. We found that active but not sham tDCS significantly modified the negative attentional bias, abolishing slower RT for negative words. CONCLUSION: Active but not sham tDCS significantly modified the negative attentional bias. These findings add evidence that a single tDCS session transiently induces potent changes in affective processing, which might be one of the mechanisms of tDCS underlying mood changes.

Addressing climate change with behavioral science: A global intervention tournament in 63 countries.

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.

Heart rate variability is a trait marker of major depressive disorder: evidence from the sertraline vs. electric current therapy to treat depression clinical study.

Decreased heart rate variability (HRV) is a cardiovascular predictor of mortality. Recent debate has focused on whether reductions in HRV in major depressive disorder (MDD) are a consequence of the disorder or a consequence of pharmacotherapy. Here we report on the impact of transcranial direct current stimulation (tDCS), a non-pharmacological intervention, vs. sertraline to further investigate this issue. The employed design was a double-blind, randomized, factorial, placebo-controlled trial. One hundred and eighteen moderate-to-severe, medication-free, low-cardiovascular risk depressed patients were recruited for this study and allocated to either active/sham tDCS (10 consecutive sessions plus two extra sessions every other week) or placebo/sertraline (50 mg/d) for 6 wk. Patients were age and gender-matched to healthy controls from a concurrent cohort study [the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)]. The impact of disorder, treatment and clinical response on HRV (root mean square of successive differences and high frequency) was examined. Our findings confirmed that patients displayed decreased HRV relative to controls. Furthermore, HRV scores did not change following treatment with either a non-pharmacological (tDCS) or pharmacological (sertraline) intervention, nor did HRV increase with clinical response to treatment. Based on these findings, we discuss whether reduced HRV is a trait-marker for MDD, which may predispose patients to a host of conditions and disease even after response to treatment. Our findings have important implications for our understanding of depression pathophysiology and the relationship between MDD, cardiovascular disorders and mortality.

Effects of co-players' identity and reputation in the public goods game.

Players' identity and their reputation are known to influence cooperation in economic games, but little is known about how they interact. Our study aimed to understand how presenting pre-programmed co-players' identities (face photos; names) along with their previous cooperation history (reputation) could influence participants' cooperative decisions in a public goods game. Participants (N = 759) were allocated to one of six experimental groups: (i) control (no information); (ii) only reputation (neutral, free-rider, or cooperative); (iii) only face; (iv) face with reputation; (v) only name; (vi) name with reputation. In the reputation group, cooperation significantly decreased when free-riders were playing and significantly increased when they were cooperators. Person's identity affected cooperativeness only when combined with reputation: face photo mitigated the negative effect of the free-rider reputation, while name identity mitigated any significant effect expected for reputation. Our study suggests a hierarchy: reputation changes cooperation, but a person's identity can modulate reputation.

Understanding racial bias through electroencephalography.

Research on racial bias in social and cognitive psychology has focused on automatic cognitive processes such as categorisation or stereotyping. Neuroimaging has revealed differences in the neural circuit when processing social information about one's own or another's ethnicity. This review investigates the influence of racial bias on human behaviour by reviewing studies that examined changes in neural circuitry (i.e. ERP responses) during automatic and controlled processes elicited by specific tasks. This systematic analysis of specific ERP components across different studies provides a greater understanding of how social contexts are perceived and become associated with specific stereotypes and behavioural predictions. Therefore, investigating these related cognitive and neurobiological functions can further our understanding of how racial bias affects our cognition more generally and guide more effective programs and policies aimed at its mitigation.

Responding to unfair offers made by a friend: neuroelectrical activity changes in the anterior medial prefrontal cortex.

When receiving unfair monetary offers from another person, the most common response is punishment. Existing literature on the Ultimatum Game indicates that individuals frequently refuse unfair offers even when this results in a loss for themselves. Here, we present behavioral and neurophysiological evidence demonstrating that friendship substantially modifies this response. When the proposer was a friend rather than an unknown person, unfair offers were less frequently rejected and the medial frontal negativity (MFN) typically associated with unfair offers was reversed to positive polarity. The underlying generators were located in inferior-mesial and right inferior- and medial-lateral frontal regions (BA10 and BA11). These findings highlight the fundamental role of the anterior prefrontal cortex in interpersonal economic interaction and, particularly, present new evidence on the effects of social distance on the MFN.

When humor is a matter of heart: Effects on emotional state and interbeat interval.

Previous studies demonstrated that exposure to humor has beneficial effects on psychological well-being. In the present work, we investigated the behavioral and psychophysiological effects of different types of humor on psychological well-being and on the performance during the execution of a stressful cognitive task. To this aim, we examined the behavioral and psychophysiological effects of ToM humorous and Slapstick humorous comic strips before and after executing a stressful cognitive task. We hypothesized that only slapstick humor could reduce the level of anxiety, increase positive affect and improve performance on the cognitive task. Our findings revealed that, at a specific point in time, exposure to ToM Humor and No Humor strips were associated with lower IBI (higher HR, increase in cardiac recruitment) than slapstick humor. This result suggests that humor involving ToM abilities and No Humor strips elicited a greater cognitive engagement level than slapstick humor. Moreover, in an exploratory analysis we found a positive correlation between cardiac deactivation during the exposure to slapstick Humor and individual empathy scores, suggesting that the empathy skills might influence cardiac recruitment and the level of cognitive engagement during the exposure to humorous material.

Mood and cognitive effects of transcranial direct current stimulation in post-stroke depression.

Depression following stroke (PSD) affects up to 33% of patients and is associated with increased mortality. Antidepressant drugs have several side effects; therefore novel treatments are needed. Transcranial direct current stimulation (tDCS) has induced mood and cognitive gain in several neuropsychiatric conditions but has not been tested for PSD to date. Here, we report a patient with significant mood and cognitive impairment who showed marked amelioration of these symptoms following anodal stimulation (2 mA per 30 minutes per 10 days) over the left dorsolateral prefrontal cortex. We discuss the possible mechanisms of tDCS in improving PSD. This initial preliminary data is useful to encourage further controlled trials on the field.

Evaluations of affective stimuli modulated by another person's presence and affiliative touch.

Affiliative touch carries affective meaning and affects the receiver. Although research demonstrates that receiving touch modulates the neural processing of emotions, its effects on evaluations of affective stimuli remain unexplored. The current research examined the effects of affiliative touch on the evaluation of affective images across 3 studies and aimed to disentangle the effect of another person's mere presence from the addition of affiliative touch. Participants thus underwent experimental conditions of social manipulation (presence, alone) and touch manipulations (receiving, self-providing, providing to experimenter) while viewing affective images (negative, neutral, and positive valence) and evaluated their valence. Study 1 included hand-squeezing (N = 39), and Study 2 included forearm-stroking (N = 40) in a within-subjects design. Study 3 included hand-squeezing (N = 109) in a between-subjects design. Across both studies, the results suggested that the receiving condition decreased the negativity of negative images, and the providing condition reduced the positivity of positive images. Furthermore, the other presence condition increased the positivity of positive images compared with the alone condition in Study 1 and to the receiving condition in Study 2. Hand-squeezing and forearm-stroking had differential effects on affective image evaluations depending on the image valence and who provided the touch. Overall, receiving touch seems to attenuate negative evaluations in negative contexts and the presence of others amplifies positive evaluations in positive situations. Discussion highlights the importance of affiliative touch within social interactions. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Clinical predictors associated with duration of repetitive transcranial magnetic stimulation treatment for remission in bipolar depression: a naturalistic study.

Repetitive transcranial magnetic stimulation (rTMS) has been widely tested and shown to be effective for unipolar depression. Although it has also been investigated for bipolar depression (BD), there are only few rTMS studies with BD. Here, we investigated 56 patients with BD who received rTMS treatment until remission (defined as Hamilton Depression Rating Scores < or =7). We used simple and multiple logistic regressions to identify clinical and demographic predictors associated with duration of treatment (defined as <15 vs. >15 rTMS sessions). Age, refractoriness, number of prior depressive episodes, and severe depression at baseline were associated with a longer rTMS treatment. In the multivariate analysis, refractoriness (likelihood ratio (LR) = 4.33; p < 0.01) and baseline severity (LR = 0.18, p < 0.01) remained significant predictors. Our preliminary study showed that, in remitted patients, refractoriness and severity of index episode are associated with the need of a longer rTMS treatment; providing preliminary evidence of important factors associated with rTMS parameters adjustment.

Neuromodulation of decision-making in the addictive brain.

Noninvasive brain stimulation of the dorsolateral prefrontal cortex with repetitive transcranial magnetic stimulation and transcranial direct current stimulation can modify decision-making behaviors in healthy subjects. The same type of noninvasive brain stimulation can suppress drug craving in substance user patients, who often display impaired decision-making behaviors. We discuss the implications of these studies for the cognitive neurosciences and their translational applications to the treatment of addictions. We propose a neurocognitive model that can account for our findings and suggests a promising therapeutic role of brain stimulation in the treatment of substance abuse and addictive behavior disorders.

Using social and behavioural science to support COVID-19 pandemic response.

The COVID-19 pandemic represents a massive global health crisis. Because the crisis requires large-scale behaviour change and places significant psychological burdens on individuals, insights from the social and behavioural sciences can be used to help align human behaviour with the recommendations of epidemiologists and public health experts. Here we discuss evidence from a selection of research topics relevant to pandemics, including work on navigating threats, social and cultural influences on behaviour, science communication, moral decision-making, leadership, and stress and coping. In each section, we note the nature and quality of prior research, including uncertainty and unsettled issues. We identify several insights for effective response to the COVID-19 pandemic and highlight important gaps researchers should move quickly to fill in the coming weeks and months.

Modulation of emotions associated with images of human pain using anodal transcranial direct current stimulation (tDCS).

Viewing images of other humans in pain elicits a variety of responses including distress, anxiety, and a sensation that is similar to pain. We aimed to evaluate whether transcranial direct current stimulation (tDCS) could be effective in modulating the emotional aspects of pain as to further explore mechanisms of tDCS in pain relief. Twenty-three healthy subjects rated images with respect to unpleasantness and discomfort/pain (baseline), and then received stimulation with tDCS under four different conditions of stimulation: anodal tDCS of the left primary motor cortex (M1), dorsolateral prefrontal cortex (DLPFC), occipital cortex (V1); and sham tDCS. The order of conditions was randomized and counterbalanced across subjects. During each stimulation session (after 3 min of stimulation), subjects were shown a new set of aversive images and were again asked to rate the images with respect to unpleasantness and discomfort/pain. The results showed that ratings of unpleasantness and discomfort/pain were significantly decreased during DLPFC tDCS only, as compared to baseline and sham tDCS. The other conditions of stimulation (M1 and V1 tDCS) did not result in any significant changes. These results support the notion that DLPFC is a critical area for the emotional processing of pain and also suggests that DLPFC may be a potential target of stimulation for alleviation of pain with a significant emotional-affective component. Our results also suggest that the mechanism of tDCS in modulating emotional pain involve pathways that are independent of those modulating the somatosensory perception of pain.