Effects of HF-rTMS over the left and right DLPFC on proactive and reactive cognitive control

Disentangling the effects of near-infrared light stimulation and exercise on cognitive function in fNIRS studies

Functional near-infrared spectroscopy (fNIRS) studies often aim to measure changes in the brain's hemodynamic response in relation to a specific intervention. We recently showed how a fNIRS device could induce photobiomodulatory effects on cognition by using its near-infrared (NIR) light. However, so far, fNIRS research has overlooked the stimulatory potential intrinsic to this technique. The work by Kuwamizu et al. (2023) on pupil dynamics during exercise is no exception. Here, we suggest a fix to their experimental design, which could be taken into account in other fNIRS studies, to guarantee an adequate level of control for possible unconsidered photobiomodulatory effects.

Evaluation of Orexin-A Salivary Levels and its Correlation with Attention After Non-invasive Brain Stimulation in Female Volleyball Players

BACKGROUND

The capacity to change attention from one area to another depending on the many environmental circumstances present is a crucial aspect of selective attention and is strictly correlated to reaction time. The cholinergic system of the basal forebrain is crucial for attentive abilities. Several inputs, particularly orexin neurons, whose cell bodies are found in the postero-lateral hypothalamus, can activate the cholinergic system. The aim of this study was to investigate if high frequencies rTMS at dorsolateral prefrontal cortex (DLPFC) in highly trained volleyball players can change Orexin-A levels, attention and reaction time. This study was a double-blinded (participant and evaluator) matched-pair experimental design. Twenty right-handed female volleyball players were recruited for the study (age 24.6 ± 2.7 years; height 177.0 ± 5.5 cm; body mass 67.5 ± 6.5 kg; BMI 21.5 ± 1.2).

RESULTS

The main finding of this study was that 10 Hz rTMS to the DLPFC seems to increase Orexin-A salivary levels and the percentage of correct answers, while decreasing RT. After rTMS, the athletes show an increase in the percentage of correct answers immediately after the end of stimulation, and also after 15 and 30 min. Moreover, the athletes show decreases in reaction time after the end of stimulation and after 15 and 30 min to the end of stimulation, while no differences were found at the end of stimulation. Finally, the athletes show significant increases in Orexin-A salivary levels after stimulation with a peak after 30' of the end.

CONCLUSION

The results of our study seem to indicate that there is a relationship between salivary Orexin-A levels and RT. These results could provide useful tools for modulating sports training; in fact, if confirmed, they could lead coaches to offer their athletes rTMS sessions appropriately integrated with training. In fact, alternating attention is a mental flexibility that enables people to change their point of focus and switch between tasks requiring various levels of cognition.

Motivational context and neurocomputation of stop expectation moderate early attention responses supporting proactive inhibitory control

Alterations in attention to cues signaling the need for inhibitory control play a significant role in a wide range of psychopathology. However, the degree to which motivational and attentional factors shape the neurocomputations of proactive inhibitory control remains poorly understood. The present study investigated how variation in monetary incentive valence and stake modulate the neurocomputational signatures of proactive inhibitory control. Adults (N = 46) completed a Stop-Signal Task (SST) with concurrent EEG recording under four conditions associated with stop performance feedback: low and high punishment (following unsuccessful stops) and low and high reward (following successful stops). A Bayesian learning model was used to infer individual's probabilistic expectations of the need to stop on each trial: P(stop). Linear mixed effects models were used to examine whether interactions between motivational valence, stake, and P(stop) parameters predicted P1 and N1 attention-related event-related potentials (ERPs) time-locked to the go-onset stimulus. We found that P1 amplitudes increased at higher levels of P(stop) in punished but not rewarded conditions, although P1 amplitude differences between punished and rewarded blocks were maximal on trials when the need to inhibit was least expected. N1 amplitudes were positively related to P(stop) in the high punishment condition (low N1 amplitude), but negatively related to P(stop) in the high reward condition (high N1 amplitude). Critically, high P(stop)-related N1 amplitude to the go-stimulus predicted behavioral stop success during the high reward block, providing evidence for the role of motivationally relevant context and inhibitory control expectations in modulating the proactive allocation of attentional resources that affect inhibitory control. These findings provide novel insights into the neurocomputational mechanisms underlying proactive inhibitory control under valence-dependent motivational contexts, setting the stage for developing motivation-based interventions that boost inhibitory control.

Comparative efficacy of repetitive transcranial magnetic stimulation protocols for obsessive-compulsive disorder: A network meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has been found to be helpful for the treatment of obsessive-compulsive disorder (OCD). However, the relative efficacy of different rTMS protocols is unclear.

OBJECTIVE

To conduct a systematic review and network meta-analysis (NMA) of published literature to compare the relative efficacy of different rTMS protocols for decreasing Yale-Brown Obsessive Compulsive Severity (Y-BOCS) scores in patients with OCD.

METHOD

Relevant articles published between 1985 to September 2023 were searched from the Cochrane Central Register of Controlled Trials, PubMed and PsycInfo. Double or single-blinded randomized controlled studies conducted on patients with OCD comparing an active rTMS protocol with either another active or sham rTMS protocol were included. Network meta-analysis (NMA) was conducted using a frequentist approach. Standardized mean difference (SMD) of change in Y-BOCS scores was calculated employing Hedge's g. Pairwise meta-analysis using random effects model was conducted which was extended to the NMA using restricted maximum likelihood estimation procedure. Surface under the cumulative ranking (SUCRA) probabilities were used to rank the interventions.

RESULTS

Excitatory rTMS of the bilateral dorsolateral prefrontal cortex (DLPFC), inhibitory rTMS of right DLPFC, inhibitory as well as excitatory rTMS of bilateral medial prefrontal cortex/anterior cingulate cortex (mPFC/ACC) and inhibitory rTMS of bilateral supplementary motor area (SMA) were superior to sham stimulation. The DLPFC and mPFC/ACC protocols had a higher probability of being among the top-ranked interventions. The majority of studies had a modest sample size and at least some concerns in the risk of bias assessment.

CONCLUSION

rTMS targeting either the medial or lateral prefrontal cortices is a promising intervention for resistant OCD. There is a need to confirm these findings in large systematic studies.

Repetitive transcranial magnetic stimulation (rTMS) as a tool for cognitive enhancement in healthy adults: a review study

As human beings, we have always sought to expand on our abilities, including our cognitive and motor skills. One of the still-underrated tools employed to this end is repetitive transcranial magnetic stimulation (rTMS). Until recently, rTMS was almost exclusively used in studies with rehabilitation purposes. Only a small strand of literature has focused on the application of rTMS on healthy people with the aim of enhancing cognitive abilities such as decision-making, working memory, attention, source memory, cognitive control, learning, computational speed, risk-taking, and impulsive behaviors. It, therefore, seems that the findings in this particular field are the indirect results of rehabilitation research. In this review paper, we have set to investigate such studies and evaluate the rTMS effectuality in terms of how it improves the cognitive skills in healthy subjects. Furthermore, since the most common brain site used for rTMS protocols is the dorsolateral prefrontal cortex (DLPFC), we have added theta burst stimulation (TBS) wave patterns that are similar to brain patterns to increase the effectiveness of this method. The results of this study can help people who have high-risk jobs including firefighters, surgeons, and military officers with their job performance.

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) on global cognitive function of elderly in mild to moderate Alzheimer's disease: a systematic review and meta-analysis

OBJECTIVE

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) is a non-invasive brain stimulation technique used to improve cognitive deficits in patients with Alzheimer's disease (AD). This systematic review and meta-analysis aimed to evaluate the efficacy of HF-rTMS in improving global cognitive function rehabilitation in elderly patients with mild to moderate AD.

METHODS

A detailed literature search of publications using ten databases (Chinese: Wanfang, VIP Periodical, SinoMed, the Chinese National Knowledge Infrastructure; English: PubMed, Embase, OVID, Web of Science, Cochrane Library, and EBSCOhost) was performed to identify English and Chinese language articles published up to December 2022. We only included randomized controlled trials (RCTs) that evaluate the effect of HF-rTMS on elderly patients with mild to moderate AD. The retrieved studies were carefully reviewed, extracted data, and assessed quality.

RESULTS

Seventeen studies, including 1161 elderly patients with mild to moderate AD, were included in this meta-analysis. Compared to the control group, HF-rTMS could increase MMSE (mean difference [MD] = 3.64; 95%CI 1.86-5.42; P < 0.0001), MoCA (MD = 3.69; 95%CI 1.84-5.54; P < 0.0001), P300 amplitude (MD = 1.09; 95%CI 0.45-1.72; P = 0.0008), and total effective rate scores (MD = 3.64; 95% CI 2.14-6.18; P < 0.00001) while decreasing ADAS-Cog (MD =  - 3.53; 95%CI - 4.91- - 2.15; P < 0.00001) and P300 latency scores (MD =  - 38.32; 95%CI - 72.40- - 4.24; P = 0.03). Our study showed that HF-rTMS could improve the global cognitive function of elderly patients with mild to moderate AD.

CONCLUSION

HF-rTMS can improve global cognitive function in elderly patients with mild to moderate AD, which is an effective and safe rehabilitation treatment tool for AD patients.

Social Regulation of the Neural Threat Response Predicts Subsequent Markers of Physical Health

OBJECTIVE

Social support has been linked to a vast range of beneficial health outcomes. However, the physiological mechanisms of social support are not well characterized. Drawing on functional magnetic resonance imaging and health-related outcome data, this study aimed to understand how neural measures of "yielding"-the reduction of brain activity during social support-moderate the link between social support and health.

METHODS

We used a data set where 78 participants around the age of 24 years were exposed to the threat of shock when holding the hand of a partner. At ages 28 to 30 years, participants returned for a health visit where inflammatory activity and heart rate variability were recorded.

RESULTS

Findings showed a significant interaction between dorsal anterior cingulate cortex-related yielding and perceived social support on C-reactive protein levels ( β = -0.95, SE = 0.42, z = -2.24, p = .025, 95% confidence interval = -1.77 to -0.12). We also found a significant interaction between hypothalamus-related yielding and perceived social support on baseline heart rate variability ( β = 0.51, SE = 0.23, z = 2.19, p = .028, 95% confidence interval = 0.05 to 0.97).

CONCLUSIONS

Greater perceived social support was associated with lower C-reactive protein levels and greater baseline heart rate variability among individuals who were more likely to yield to social support in the dorsal anterior cingulate cortex and hypothalamus years earlier. The current study highlights the construct of yielding in the link between social support and physical health.

Prefrontal transcranial direct current stimulation over the right prefrontal cortex reduces proactive and reactive control performance towards emotional material in healthy individuals

The prefrontal cortex plays a crucial role in cognitive processes, both during anticipatory and reactive modes of cognitive control. Transcranial Direct Current Stimulation (tDCS) can modulate these cognitive resources. However, there is a lack of research exploring the impact of tDCS on emotional material processing in the prefrontal cortex, particularly in regard to proactive and reactive modes of cognitive control. In this study, 35 healthy volunteers underwent both real and sham tDCS applied to the right prefrontal cortex in a counterbalanced order, and then completed the Cued Emotion Control Task (CECT). Pupil dilation, a measure of cognitive resource allocation, and behavioral outcomes, such as reaction time and accuracy, were collected. The results indicate that, as compared to sham stimulation, active right-sided tDCS reduced performance and resource allocation in both proactive and reactive modes of cognitive control. These findings highlight the importance of further research on the effects of tDCS applied to the right prefrontal cortex on cognitive engagement, particularly for clinical trials utilizing the present electrode montage in combination with cognitive interventions.

Altered Associations Between Task Performance and Dorsolateral Prefrontal Cortex Activation During Cognitive Control in Schizophrenia

BACKGROUND

Dysfunctional cognitive control processes are now well understood to be core features of schizophrenia (SZ). A body of work suggests that the dorsolateral prefrontal cortex (DLPFC) plays a critical role in explaining cognitive control disruptions in SZ. Here, we examined relationships between DLPFC activation and drift rate (DR), a model-based performance measure that combines reaction time and accuracy, in people with SZ and healthy control (HC) participants.

METHODS

One hundred fifty-one people with recent-onset SZ spectrum disorders and 118 HC participants performed the AX-Continuous Performance Task during functional magnetic resonance imaging scanning. Proactive cognitive control-associated activation was extracted from left and right DLPFC regions of interest. Individual behavior was fit using a drift diffusion model, allowing DR to vary between task conditions.

RESULTS

Behaviorally, people with SZ showed significantly lower DRs than HC participants, particularly during high proactive control trial types ("B" trials). Recapitulating previous findings, the SZ group also demonstrated reduced cognitive control-associated DLPFC activation compared with HC participants. Furthermore, significant group differences were also observed in the relationship between left and right DLPFC activation with DR, such that positive relationships between DR and activation were found in HC participants but not in people with SZ.

CONCLUSIONS

These results suggest that DLPFC activation is less associated with cognitive control-related behavioral performance enhancements in SZ. Potential mechanisms and implications are discussed.

Repetitive Transcranial Magnetic Stimulation (rTMS) in Mild Cognitive Impairment: Effects on Cognitive Functions-A Systematic Review

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique also used as a non-pharmacological intervention against cognitive impairment. The purpose of the present review was to summarize what is currently known about the effectiveness of rTMS intervention on different cognitive domains in patients with mild cognitive impairment (MCI) and to address potential neuromodulation approaches in combination with electroencephalography (EEG) and neuroimaging, especially functional magnetic resonance imaging (fMRI). In this systematic review, we consulted three main databases (PubMed, Science Direct, and Scopus), and Google Scholar was selected for the gray literature search. The PRISMA flowchart drove the studies' inclusion. The selection process ensured that only high-quality studies were included; after removing duplicate papers, explicit ratings were given based on the quality classification as high (A), moderate (B), or low (C), considering factors such as risks of bias, inaccuracies, inconsistencies, lack of direction, and publication bias. Seven full-text articles fulfilled the stated inclusion, reporting five double-blind, randomized, sham-controlled studies, a case study, and a randomized crossover trial. The results of the reviewed studies suggested that rTMS in MCI patients is safe and effective for enhancing cognitive functions, thus making it a potential therapeutic approach for MCI patients. Changes in functional connectivity within the default mode network (DMN) after targeted rTMS could represent a valuable indicator of treatment response. Finally, high-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) has been shown to significantly enhance cognitive functions, such as executive performance, together with the increase of functional connectivity within frontoparietal networks. The main limitations were the number of included studies and the exclusion of studies using intermittent theta-burst stimulation, used in studies on Alzheimer's disease. Therefore, neuroimaging techniques in combination with rTMS have been shown to be useful for future network-based, fMRI-guided therapeutic approaches.

Studying additive effects of combining rTMS with cognitive control training: a pilot investigation

Background

Repetitive transcranial magnetic stimulation (rTMS) on the dorsolateral prefrontal cortex (DLPFC) is an effective treatment for depression that has been proposed to work via the enhancement of cognitive control. Cognitive control training (CCT) can also alleviate depression by relying on DLPFC activation. As the additive effects of rTMS and CCT are unclear, we set out to conduct a within-subject pilot study in healthy controls.

Methods

Seventeen participants received two sessions of individualized resting-state connectivity-guided high-frequency rTMS, while randomly performing CCT or a control task. After each session, a negative mood was induced.

Results

We found effects on mood and cognitive control after rTMS + CCT as well as rTMS + control, which were indiscriminative between conditions. Based on the statistical evidence for the absence of an additive effect of CCT, we did not perform a full study.

Conclusion

Our results demonstrate no differential effects of single sessions combining rTMS and CCT in a healthy population, even with the methodological improvement of individualized neuronavigation. The improvement in cognitive control seen in both conditions could indicate that a simple cognitive task is sufficient when studying additive rTMS effects. Future studies should focus on augmenting the effects of various cognitive tasks and compare the present interventions with rTMS or cognitive tasks alone.

High frequencies (HF) repetitive transcranial magnetic stimulation (rTMS) increase motor coordination performances in volleyball players

INTRODUCTION

It is widely demonstrated that high frequency (HF) repetitive transcranial magnetic stimulation (rTMS) has facilitative effects and is therefore capable to inducing changes in motor responses. One of the most investigated areas is the dorsolateral prefrontal cortex (DLPFC) as it plays a special executive attention role in actively preserving access to stimulus representations and objectives in environments with plenty of distraction such as those of team sports. Volleyball is a team sport in which the attention and coordination components are essential for achieving performance. Thus, the aim of this study was to investigate if HF rTMS at DLPFC in volleyball players can improve homolateral motor coordination and cortical excitability.

RESULTS

This study was a double-blinded (participant and evaluator) matched-pair experimental design. Twenty right-handed female volleyball players were recruited for the study and were randomly assigned either the active rTMS (n = 10) or the sham stimulation group (n = 10). The stimulation was performed in one session with 10 Hz, 80% of the resting motor threshold (RMT) of the right first dorsal interosseous muscle, 5 s of stimulation, and 15 s of rest, for a total of 1500 pulses. Before and after stimulation, the coordination and the cortical excitability were evaluated. The significant finding of this paper was that HF-rTMS of the DLPFC improved performance in terms of the homolateral interlimb coordination, with a significantly decreased in resting motor threshold and MEP latency of the ipsilateral motor cortex. It seem that HF-rTMS could increase coordination performances when the velocity of the execution is higher (120 bpm and 180 bpm).

CONCLUSION

Moreover, in active rTMS group significant differences emerged after stimulation in RMT and in MEP latency, while no differences emerged after stimulation in MEP amplitude. In conclusion we believe that these results may be of great interest to the scientific community and may also have practical implications in the future.

Stimulation of the dorsolateral prefrontal cortex modulates brain cue reactivity to reward (un)availability

Brain imaging studies have shown that stimulation of the left dorsolateral prefrontal cortex (dlPFC), which plays a pivotal role in high-order cognitive control processes, modulates brain reactivity to reward-related cues. Nevertheless, the impact of contextual factors such as reward availability (the reward that is depicted in the cue exposure task) on such modulation effect remains unclear. Here we tested whether a single session of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) over the left dlPFC differently impacts brain reactivity to cues signalling either availability or unavailability of a sports betting opportunity. Employing a within-subject design (verum versus sham HF-rTMS) among thirty-two frequent sports bettors, we first observed that, as compared to the sham condition, verum HF-rTMS modulated brain reactivity to game cues prior to being made (un)available for betting, through simultaneous increases (posterior insula and caudate nucleus) and decreases (occipital pole) in brain activation. Second, verum HF-rTMS led to increased ventral striatal activity towards cues available for betting but did not modulate brain response to cues unavailable for betting. Taken together, these findings demonstrate that transient stimulation of the left dlPFC led to a general modulation in brain activity in responses to cues, and that this effect is only partly dependent on cues signalling for reward (un)availability.

Right dorsolateral prefrontal cortex regulates default prosociality preference

The dorsolateral prefrontal cortex has been shown to be associated with prosocial behavior. However, the direction of this relationship remains controversial. To resolve inconsistencies in the existing literature, we introduced the concept of default prosociality preference and hypothesized that this preference moderates the relationship between gray matter volume in the dorsolateral prefrontal cortex and prosocial behavior. This study analyzed the data of 168 participants obtained from voxel-based morphometry, 4 types of economic games, and 3 different measures of social value orientation that represent default prosociality preference. Here we show that, in individuals who were consistently classified as proself on the 3 social value orientation measures, gray matter volume in the right dorsolateral prefrontal cortex was positively associated with prosocial behavior. However, in individuals who were consistently classified as prosocial, the direction of this association was vice versa. These results indicate that the right dorsolateral prefrontal cortex regulates default prosociality preference.

Abnormal behavioral and neural responses in the right dorsolateral prefrontal cortex during emotional interference for cognitive control in pedophilic sex offenders

Studies within the last decade have reported neural and behavioral differences in cognitive control between men with the pedophilic disorder who commit (CSO+) and do not commit (CSO-) child sexual abuse. Prior studies reported a higher number of errors in Go/Nogo task and lower activity of the prefrontal cortex in NoGo trials, in CSO+ compared with CSO-. Moreover, negative mood was reported as a risk factor for child sexual abuse in pedophilic men. We aimed to examine differences in brain function and behavior between CSO+ and CSO- patients regarding emotional interference on cognitive processes and inhibition. We recruited CSO+ (n = 11) and CSO- (n = 14) patients as well as matched healthy controls (HC) (n = 17). Participants performed the affective Go/NoGo task in a block-design functional magnetic resonance imaging experiment. The task comprised the following four conditions: Negative Go, including only Go stimuli and negatively valenced pictures; Negative NoGo, including 50% of Go and 50% of NoGo trials as well as negatively valenced pictures; and two corresponding conditions with neutral pictures. Brain analysis was restricted to the dorsolateral prefrontal (DLPFC), orbitofrontal, and anterior cingulate cortices. The HC and CSO- groups, but not the CSO+ group, showed significantly slower reactions in negative blocks compared with neutral blocks. Brain analysis revealed increased activation in the right DLPFC during emotional interference contrast (Negative > Neutral) in the HC and CSO- groups; however, there was decreased activation in the CSO+ group. In the CSO+ group, negative distractors did not increase cognitive control processes, which was observed in the CSO- and HC groups at the behavioral and neural levels. These results support previous reports indicating offender status is associated with cognitive and emotional impairments.

Effect of Cognition by Repetitive Transcranial Magnetic Stimulation on Ipsilesional Dorsolateral Prefrontal Cortex in Subacute Stroke Patients

Objective

To demonstrate the efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the ipsilesional dorsolateral prefrontal cortex (DLPFC) on neurological recovery in patients with subacute phase stroke.

Methods

Patients with supratentorial hemispheric stroke who were hospitalized for intensive rehabilitation in the subacute phase were enrolled for this retrospective analysis. Two groups of patients were selected: the rTMS group who received high-frequency (20 Hz) rTMS ≥ 5 times over the ipsilesional DLPFC, and a control group who did not receive any rTMS. The patients were further divided into groups with right- or left-side brain lesions. Functional measurements for cognitive ability, mood, speech, and activities of daily living, which were assessed at baseline and at the 1-month follow-up as a routine clinical practice, were used for analyses.

Results

Among 270 patients with available clinical data, 133 (women, 51; age, 61.0 ± 13.8 years) met the inclusion criteria and were enrolled for analysis. There were no differences in demographic data and functional scores at baseline between the rTMS (n = 49) and control (n = 84) groups. The rTMS group showed a higher gain in the mini-mental status examination (MMSE) total score and subscores of all domains, forward digit span, and FIM-cognition than the control group (P < 0.05). Among the patients with left hemispheric lesions (n = 57), the rTMS group showed better outcomes in cognition and depression through scores of total and “attention and concentration” subscores of MMSE, FIM-cognition, and the geriatric depression scale (P < 0.05). Among the patients with right hemispheric lesions (n = 76), the rTMS group showed better outcomes in cognition through the MMSE total score and subscores of “attention and concentration,” “registration,” and “recall,” and scores of both forward and backward digit spans (P < 0.05).

Conclusion

High-frequency rTMS over the ipsilesional DLPFC has beneficial effects on the recovery of cognition on both sides as well as mood in patients with left-sided hemispheric lesions.

Computerized Music-Reading Intervention Improves Resistance to Unisensory Distraction Within a Multisensory Task, in Young and Older Adults

Incoming information from multiple sensory channels compete for attention. Processing the relevant ones and ignoring distractors, while at the same time monitoring the environment for potential threats, is crucial for survival, throughout the lifespan. However, sensory and cognitive mechanisms often decline in aging populations, making them more susceptible to distraction. Previous interventions in older adults have successfully improved resistance to distraction, but the inclusion of multisensory integration, with its unique properties in attentional capture, in the training protocol is underexplored. Here, we studied whether, and how, a 4-week intervention, which targets audiovisual integration, affects the ability to deal with task-irrelevant unisensory deviants within a multisensory task. Musically naïve participants engaged in a computerized music reading game and were asked to detect audiovisual incongruences between the pitch of a song's melody and the position of a disk on the screen, similar to a simplistic music staff. The effects of the intervention were evaluated via behavioral and EEG measurements in young and older adults. Behavioral findings include the absence of age-related differences in distraction and the indirect improvement of performance due to the intervention, seen as an amelioration of response bias. An asymmetry between the effects of auditory and visual deviants was identified and attributed to modality dominance. The electroencephalographic results showed that both groups shared an increase in activation strength after training, when processing auditory deviants, located in the left dorsolateral prefrontal cortex. A functional connectivity analysis revealed that only young adults improved flow of information, in a network comprised of a fronto-parietal subnetwork and a multisensory temporal area. Overall, both behavioral measures and neurophysiological findings suggest that the intervention was indirectly successful, driving a shift in response strategy in the cognitive domain and higher-level or multisensory brain areas, and leaving lower level unisensory processing unaffected.

Prefrontal tDCS Attenuates Self-Referential Attentional Deployment: A Mechanism Underlying Adaptive Emotional Reactivity to Social-Evaluative Threat

Social-evaluative threat (SET) - a situation in which one could be negatively evaluated by others - elicits profound (psycho)physiological reactivity which, if chronically present and not adaptively regulated, has deleterious effects on mental and physical health. Decreased self-awareness and increased other-awareness are understood to be an adaptive response to SET. Attentional deployment - the process of selectively attending to certain aspects of emotional stimuli to modulate emotional reactivity - is supported by fronto-parietal and fronto-limbic networks, with the dorsolateral prefrontal cortex being a central hub. The primary aim of the current study was to investigate the effects of active (versus sham) prefrontal transcranial direct current stimulation (tDCS) on self and other-attentional deployment during the exposure to a SET context. Seventy-four female participants received active or sham tDCS and were subsequently exposed to a rigged social feedback paradigm. In this paradigm a series of social evaluations were presented together with a photograph of the supposed evaluator and a self- photograph of the participant, while gaze behavior (time to first fixation, total fixation time) and skin conductance responses (SCRs; a marker of emotional reactivity) were measured. For half of the evaluations, participants could anticipate the valence (negative or positive) of the evaluation a priori. Analyses showed that participants receiving active tDCS were (a) slower to fixate on their self-photograph, (b) spent less time fixating on their self-photograph, and (c) spent more time fixating on the evaluator photograph. During unanticipated evaluations, active tDCS was associated with less time spent fixating on the evaluation. Furthermore, among those receiving active tDCS, SCRs were attenuated as a function of slower times to fixate on the self-photograph. Taken together, these results suggest that in a context of SET, prefrontal tDCS decreases self-attention while increasing other-attention, and that attenuated self-referential attention specifically may be a neurocognitive mechanism through which tDCS reduces emotional reactivity. Moreover, the results suggest that tDCS reduces vigilance toward stimuli that possibly convey threatening information, corroborating past research in this area.