Mind the social feedback: effects of tDCS applied to the left DLPFC on psychophysiological responses during the anticipation and reception of social evaluations

Abstract

<jats:title>Abstract</jats:title> <jats:p>The left dorsolateral prefrontal cortex (lDLPFC) is implicated in anticipatory (i.e. during anticipation of emotional stimuli) and online (i.e. during confrontation with emotional stimuli) emotion regulatory processes. However, research that investigates the causal role of the lDLPFC in these processes is lacking. In this study, 74 participants received active or sham transcranial direct current stimulation (tDCS) over the lDLPFC. Participants were told strangers evaluated them. These (rigged) social evaluations were presented, and in 50% of the trials, participants could anticipate the valence (positive or negative) of the upcoming social feedback. Pupil dilation (a marker of cognitive resource allocation) and skin conductance responses (a marker of arousal) were measured. The results indicate that active (compared to sham) tDCS reduced arousal during the confrontation with anticipated feedback but only marginally during the confrontation with unanticipated feedback. When participants were given the opportunity to anticipate the social feedback, tDCS reduced arousal, irrespective of whether one was anticipating or being confronted with the anticipated feedback. Moreover, tDCS reduced cognitive resource allocation during anticipation, which was associated with resource allocation increases during the subsequent confrontation. Altogether, results suggest that the lDLPFC is causally implicated in the interplay between anticipatory and online emotion regulatory processes.</jats:p>

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

“…This estimated a total sample size of N = 74 to detect with 80% power the hypothesized betweenwithin interaction effect of a small to moderate magnitude (Cohen's f = 0.15) using a mixed ANOVA F-test. Participants were recruited in the context of a larger research project investigating the effects of left prefrontal tDCS on the interplay between anticipatory and online emotion regulatory processes to social evaluations (Allaert et al, 2020). They were recruited from the general community via internet postings on social media and posters in public places.…”

“…First, based on the self-regulation theories proposing adaptive SET reactivity consists of both decreased self-attention and increased otherattention (Hess and Pickett, 2010;Durlik and Tsakiris, 2015), and given the wide array of research showing adaptive left prefrontal tDCS effects on attention processes and emotional reactivity (Mondino et al, 2015;Smits et al, 2020), we expected that active (in contrast to sham) left prefrontal tDCS would be associated with attenuated self-attention (i.e., slower first fixation to and less total fixation time on this information) and increased other-attention (i.e., faster first fixation to and more total fixation time on this information). We had no clear expectations whether these effects would be modulated by valence, as previous prefrontal tDCS research has shown both valence-independent (Sanchez-Lopez et al, 2018;Allaert et al, 2020), and valence-dependent tDCS effects (Mondino et al, 2015;Nejati et al, 2021). Second, based on the proposed association between prefrontal-mediated attentional processes and emotional reactivity, we expected the attentional processes that are modulated by tDCS to be more strongly associated with attenuated emotional reactivity (assessed via SCRs) among participants receiving active (versus sham) tDCS.…”

“…Studies have shown that the causal modulation of the prefrontal cortex and its associated neural networks, via transcranial direct current stimulation (tDCS), can facilitate processes involved in cognitive flexibility (e.g., selective attention, working memory), modulate the interplay between anticipatory and online self-regulatory processes, and produces a wide array of adaptive cognitive and psychological effects in both depressed and healthy populations (Mondino et al, 2015;Dedoncker et al, 2016;Allaert et al, 2020;Smits et al, 2020). TDCS is a low cost and easy to use form of non-invasive brain stimulation that operates through the delivery of a weak electrical current to the scalp, which modulates the membrane potentials of the underlying neurons and thereby influences cortical excitability (Stagg and Nitsche, 2011).…”

“…TDCS is a low cost and easy to use form of non-invasive brain stimulation that operates through the delivery of a weak electrical current to the scalp, which modulates the membrane potentials of the underlying neurons and thereby influences cortical excitability (Stagg and Nitsche, 2011). For example, it has been shown that left prefrontal tDCS can transiently (a) reduce attentional biases to threat (Ironside et al, 2016), (b) improve attentional disengagement abilities from emotional information (Sanchez-Lopez et al, 2018), and (c) attenuate emotional reactivity to SET (Allaert et al, 2020). However, ecologically valid research that investigates the effects of prefrontal tDCS on the interplay between selective attention processes toward self-referential stimuli and emotional reactivity, and how prior expectations may influence this, is non-existent.…”

“…During each exposure to an evaluation, a photograph of the participant and of the supposed evaluator is shown, along with the explicit positive or negative evaluation, while participants' gaze behavior (time to first fixation and total fixation time) to these is measured. Concurrently, emotional reactivity is assessed via the measurement of autonomic changes in skin conductivity (skin conductance responses; SCRs), as SCRs are mediated by amygdala activity and index emotional arousal (Wood et al, 2014;Christopoulos et al, 2019;Allaert et al, 2020). First, based on the self-regulation theories proposing adaptive SET reactivity consists of both decreased self-attention and increased otherattention (Hess and Pickett, 2010;Durlik and Tsakiris, 2015), and given the wide array of research showing adaptive left prefrontal tDCS effects on attention processes and emotional reactivity (Mondino et al, 2015;Smits et al, 2020), we expected that active (in contrast to sham) left prefrontal tDCS would be associated with attenuated self-attention (i.e., slower first fixation to and less total fixation time on this information) and increased other-attention (i.e., faster first fixation to and more total fixation time on this information).…”