Emotional Distraction and Bodily Reaction: Modulation of Autonomous Responses by Anodal tDCS to the Prefrontal Cortex.

Philipp A Schroeder,Christian Plewnia,Ann-Christine Ehlis,Larissa Wolkenstein,Andreas J Fallgatter

doi:10.3389/fncel.2015.00482

Abstract

Prefrontal electric stimulation has been demonstrated to effectively modulate cognitive processing. Specifically, the amelioration of cognitive control (CC) over emotional distraction by transcranial direct current stimulation (tDCS) points toward targeted therapeutic applications in various psychiatric disorders. In addition to behavioral measures, autonomous nervous system (ANS) responses are fundamental bodily signatures of emotional information processing. However, interactions between the modulation of CC by tDCS and ANS responses have received limited attention. We here report on ANS data gathered in healthy subjects that performed an emotional CC task parallel to the modulation of left prefrontal cortical activity by 1 mA anodal or sham tDCS. Skin conductance responses (SCRs) to negative and neutral pictures of human scenes were reduced by anodal as compared to sham tDCS. Individual SCR amplitude variations were associated with the amount of distraction. Moreover, the stimulation-driven performance- and SCR-modulations were related in form of a quadratic, inverse-U function. Thus, our results indicate that non-invasive brain stimulation (i.e., anodal tDCS) can modulate autonomous responses synchronous to behavioral improvements, but the range of possible concurrent improvements from prefrontal stimulation is limited. Interactions between cognitive, affective, neurophysiological, and vegetative responses to emotional content can shape brain stimulation effectiveness and require theory-driven integration in potential treatment protocols.

Highlights

Non-invasive brain stimulation has been shown to be effective in the modulation of cognitive control (CC) in healthy subjects and various psychiatric disorders (De Raedt et al, 2014; Kuo et al, 2014; Plewnia et al, 2015b)
We further focus on the interrelations of CC over emotional stimuli in a working memory task, in case of the modulation of skin conductance responses (SCRs) to neutral and emotional distraction by prefrontal activity-enhancing, anodal transcranial direct current stimulation (tDCS)
For emotional stimuli, there was no effect of tDCS, ps > 0.59

Summary

Introduction

Non-invasive brain stimulation has been shown to be effective in the modulation of cognitive control (CC) in healthy subjects and various psychiatric disorders (De Raedt et al, 2014; Kuo et al, 2014; Plewnia et al, 2015b). Transcranial direct current stimulation (tDCS) has been demonstrated to reduce emotional biases in major depression under controlled conditions (Wolkenstein and Plewnia, 2013; Brunoni et al, 2014a). By augmenting cortical activity in prefrontal regions, anodal tDCS can counteract disorder-specific CC deficits with. Specific activation of prefrontal regions can modulate and subordinate emotional responses to irrelevant distraction. In this context, PFC activity corresponds with the preservation of goal-directed cognitive performance (Anticevic et al, 2010; Wessa et al, 2013). If a CC task requires the suppression of distracting emotional information, effective behavior is possibly deflected by arousing emotional information already on a vegetative level

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