Repeated noninvasive stimulation of the ventromedial prefrontal cortex reveals cumulative amplification of pleasant compared to unpleasant scene processing: A single subject pilot study

Abstract

The ventromedial prefrontal cortex (vmPFC) is a major hub of the reward system and has been shown to activate specifically in response to pleasant / rewarding stimuli. Previous studies demonstrate enhanced pleasant cue reactivity after single applications of transcranial direct current stimulation (tDCS) to the vmPFC. Here we present a pilot case study in which we assess the cumulative impact of multiple consecutive vmPFC-tDCS sessions on the processing of visual emotional stimuli in an event-related MEG recording design. The results point to stable modulation of increased positivity biases (pleasant > unpleasant stimulus signal strength) after excitatory vmPFC stimulation and a reversed pattern (pleasant < unpleasant) after inhibitory stimulation across five consecutive tDCS sessions. Moreover, cumulative effects of these emotional bias modulations were observable for several sourcelocalized spatio-temporal clusters, suggesting an increase in modulatory efficiency by repeated tDCS sessions. This pilot study provides evidence for improvements in the effectiveness and utility of a novel tDCS paradigm in the context of emotional processing.

Noninvasive stimulation of the ventromedial prefrontal cortex modulates rationality of human decision-making

“…More positive feedback ratings overall following excitatory vmPFC-tDCS also dovetail with our previous findings of a relative reduced negativity-bias of emotional face and emotional scene processing after excitatory compared to inhibitory stimulation (Junghofer et al, 2017; Winker et al, 2020, 2019, 2018). Indeed, losses in the ‘keep’ option in particular were rated as less negative after excitatory compared to inhibitory stimulation, which fits with the hypothesis that vmPFC-excitation reduces loss-aversion.…”

“…Changes of cortical excitability can last up to one hour after a single stimulation (Poreisz et al, 2007). We implemented the tDCS-montage as used in our previous studies to non-invasively stimulate the vmPFC (Junghofer et al, 2017;Roesmann et al, 2021;Winker et al, 2020Winker et al, , 2019Winker et al, , 2018. The active electrode was placed on the forehead (3 x 3 cm) and the extracephalic reference under the chin (5 x 5 cm).…”

“…Here we combined the financial gambling paradigm developed by Kahneman and Tversky (1983) - and adopted by De Martino and coworkers (2006) as well as Pujara and colleagues (2015) - with the vmPFC stimulation and MEG neuroimaging approach as used in our previous studies (Junghofer et al, 2017; Winker et al, 2020, 2019, 2018). Within this paradigm, participants decided to either accept a safe amount of an initial stake or gamble for the whole amount with variable risks to win or lose.…”

“…modulation of valence biases such as loss-aversion). In fact, a series of fMRI and MEG studies from our lab recently revealed that excitatory stimulation of the vmPFC attenuated behavioral and neural negativity-biases to emotional scenes and emotional facial expressions in healthy participants (Junghofer et al, 2017;Winker et al, 2020Winker et al, , 2019Winker et al, , 2018.…”

Effects of Transcranial Direct Current Stimulation on Cognition, Mood, Pain, and Fatigue in Multiple Sclerosis: A Systematic Review and Meta-Analysis

“…For instance, in studies measuring fatigue, the number of stimulation sessions varied across trials, with a range from single session to 20 sessions. Previous studies have reported that repeated sessions of tDCS can result in cumulative effects ( 74 , 75 ). Although trials applied 20 sessions of tDCS ( 34 ) did not show a larger ES (0.95) compared to trials with five or six sessions of stimulation (ES ranging from −0.7 to 1.91), the influence of heterogeneity across the studies on the effect estimation cannot be ruled out.…”