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Mind wandering (MW) is a heterogeneous construct involving task-unrelated thoughts. Recently, the interest in modulating MW propensity via non-invasive brain stimulation techniques has increased. Single-session transcranial direct current stimulation (tDCS) in healthy controls has led to mixed results in modulating MW propensity, possibly due to methodological heterogeneity. Therefore, our aim was to conduct a systematic meta-analysis to examine the influence of left dorsolateral prefrontal cortex (lDLPFC) and right inferior parietal lobule (rIPL) targeted tDCS on MW propensity. Importantly, by computational modeling of tDCS-induced electric fields, we accounted for differences in tDCS-dose across studies that varied strongly in their applied methodology.Fifteen single-session, sham-controlled tDCS studies published until October 2021 were included. All studies involved healthy adult participants and used cognitive tasks combined with MW thought-probes. Heterogeneity in tDCS electrode placement, stimulation polarity and intensity were controlled for by means of electric field simulations, while overall methodological quality was assessed via an extended risk of bias (RoB) assessment.We found that RoB was the strongest predictor of study outcomes. Moreover, the rIPL was the most promising cortical area for influencing MW, with stronger anodal electric fields in this region being negatively associated with MW propensity. Electric field strength in the lDLPFC was not related to MW propensity. We identified several severe methodological problems that could have contributed to overestimated effect sizes in this literature, an issue that needs urgent attention in future research in this area. Overall, the evidence for tDCS influencing MW in the healthy is not very convincing. Based on our findings, research aiming for reducing MW propensity should focus on increasing neural excitability in the rIPL. In addition, stimulating medial and frontopolar prefrontal regions (rather than the lDLPFC) should also be explored more systematically.

Chronic pain is known to impair decision-making in patients while also altering their sensitivity to reward and punishment (Phelps, Navratilova & Porreca, 2021). Defective cognitive and affective responses in chronic pain have been associated with patients’ own perceived control over environmental outcomes, which is related to the generalized effects of their perceptual pain symptoms to areas of life that are not directly affected by pain itself (Samwel, Evers, Crul & Kraaimaat, 2006). Previous research on value-based decision-making (VBDM) and absence of control has lead us to believe that when healthy participants are facing intermittent absence of control over outcomes, decision-making shifts towards less optimal choice strategies under motivational conflict (Csifcsák, Melsæter, Mittner, 2020; Csifcsák, Bjørkøy, Kuyateh, Reithe & Mittner, 2021). Motivational conflict is conceptualized as a requirement to approach an aversive stimulus or to remain passive (inhibit approach) when faced with potential rewards. Since our natural predisposition to approach reward and withdraw from punishment has been associated with the so-called Pavlovian valuation system, this system alters task performance in certain stimulation, introducing "Pavlovian bias over instrumental responding". In individuals with strong Pavlovian bias, decision-making can be maladaptive and lead to worse task performance under motivational conflict. Based on research literature on value-based decision-making, in our lab we have developed an experimental paradigm in which we manipulate both action-feedback contingency and the frequency of rewards/losses ("IAC" manipulation), leading to stronger maladaptive Pavlovian biases in conflict trials. In the current study, we hypothesize that experimental heat pain (EHP) applied to the skin of the lower arm would further worsen task performance when paired with IAC in healthy adults. Worse task performance is primarily anticipated in conflict trials, accompanied by increased Pavlovian bias, which will be quantified using a special index, "Pavlovian Performance bias Index (PPI)", described later. We will also test whether repetitive transcranial magnetic stimulation (rTMS) over the medial prefrontal cortex (mPFC), targeting the dorsal anterior cingulate cortex (dACC) can alleviate the detrimental effect of either IAC in itself, or IAC combined with heat pain. Therefore, we will adopt a 2x2 between-subject experimental design, whereby 4 groups of participants will receive either 1) no pain + sham rTMS; 2) no pain + real rTMS; 3) EHP + sham rTMS; 4) EHP + real rTMS. Each participant will perform the task for 3 block, whereby blocks 1 and 3 (baseline and post-intervention) will be identical for every participant. In the crucal, 2nd block, all participants will undergo the IAC manipulation, and in addition, participants will either receive non-painful warm stimulation of the skin of the arm, or EHP. Sham or real rTMS will be applied both preceding and after block 2. In this study, we address the following questions: Q1. Is EHP when combined with IAC in a reinforcement learning task associated with worse response accuracy and increased Pavlovian bias over instrumental learning in healthy adults? Q2. Will rTMS (intermittent theta-burst stimulation; iTBS) above the mPFC reduce Pavlovian bias over instrumental learning during and after stimulation (blocks 2 and 3) and increase response accuracy in conflict trials after the stimulation (in block 3)? Q3. Can we reverse the deleterious effect of EHP (when combined with IAC) on choice behavior by applying active iTBS above the mPFC relative to sham stimulation?

This project is an attempt to replicate the findings of Axelrod et al. (2015) who found an increase using anodal stimulation of the DLPFC. Axelrod, V., Rees, G., Lavidor, M., & Bar, M. (2015). Increasing propensity to mind-wander with transcranial direct current stimulation. Proceedings of the National Academy of Sciences, 112(11), 3314-3319.

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Transcranial direct current stimulation (tDCS) has been proposed to be able to modulate different cognitive functions. However, recent meta- analyses conclude that its efficacy is still in question. Recently, an increase in subjects’ propensity to mind-wander has been reported as a consequence of anodal stimulation of the left dorsolateral prefrontal cortex (Axelrod et al., 2015). In addition, an independent group found a decrease in mind wandering after cathodal stimulation of the same region. These findings seem to indicate that high-level cognitive processes such as mind wandering can reliably be influenced by non-invasive brain stimulation. However, these previous stud- ies used low sample sizes and are as such subject to concerns regarding the replicability of their findings. In this registered report, we implement a high- powered replication of Axelrod et al. (2015)’s finding that mind-wandering propensity can be increased by anodal tDCS. We used Bayesian statistics and a pre-registered sequential-sampling design resulting in a total sample size of N=192 participants collected across three different labs. Our findings show support against a stimulation effect on self-reported mind-wandering scores. The effect was small, in the opposite direction as predicted and not reliably different from zero. Using a Bayes Factor specifically designed to test for replication success, we found strong evidence against a successful replication of the original study. Finally, even when combining data from both the origi- nal and replication studies, we could not find evidence for an effect of anodal stimulation. Our results underline the importance of designing studies with sufficient power to detect evidence for or against behavioral effects of non- invasive brain stimulation techniques, preferentially using robust Bayesian statistics in pre-registered reports.

Here we use a non specific feedback after every block in the experimental phase. We plan on using an encouraging "thumbs up" emoji. Everything else is kept the same as in the baseline, study 2. Meaning we still use the specific performance feedback during the training phase.

We add a progress bar to our Finger-Tapping Random Sequence Generation Task and measure if this reduce mind wandering compared to a our baseline study (off.io/f48ya)

We add camera monitoring to our Finger-Tapping Random Sequence Generation Task and measure if this reduce mind wandering compared to a our baseline study (off.io/f48ya)

Mind wandering is a mental state that is typically characterized as attention drifting away from external tasks to internal thoughts (i.e., task-unrelated thought). The goal of this project is to reduce the propensity to mind wandering using continuous theta burst stimulation (cTBS) over the left angular gyrus (AG). cTBS is an repetitive transcranial magnetic stimulation (rTMS) technique developed to create long-lasting inhibitory effects in the stimulated brain regions (Rounis & Huang, 2020). In an accelerated protocol participants will be stimulated three times in a single session. The target region is the left angular gyrus (AG), an area that is part of the default mode network. By using inhibitory cTBS over the AG, we aim to reduce the propensity to mind wander by reducing the activity of the DMN. The rationale for this approach is that the DMN is commonly shown to be more active during mind wandering (Christoff et al., 2009; Mason et al., 2007), and a reduction of its activity and/or functional connectivity can therefore be hypothesized to result in a decrease of MW. If this approach is effective, it should make the participants able to stay more on task and to direct their attention better to the primary task, and therefore reduce mind wandering frequency. The outcome variables for this study will be self-reported mind wandering, and two behavioral features related to mind wandering (behavioral variability and randomness in sequence response). These behavioral features will be captured using a finger-tapping random-sequence generation task developed in our group (FT-RSGT; Boayue, et al., 2020). We expect that self-reported mind wandering and the behavioral measures will differ depending on whether the person received a real or fake stimulation.

We want to investigate whether stimulating the dorso-lateral prefrontal cortex (DLPFC) with an intermittent theta-burst stimulation (iTBS) protocol is able to reduce mind wandering propensity. To this end, we will use a novel finger-tapping random sequence generation task (FT-RSGT) by Boayue et al. (2020). We will use a within-subject crossover design. Furthermore, following an accelerated design, participants will be stimulated in between blocks of the FT-RSGT. Lastly, we will engage in a triple blinding procedure.

Hovedoppgave Høst 2020

This study is number 4 in our experimental series (https://osf.io/wjvk2) This is a control study checking whether the feedback applied to our Finger Tapping Random Sequence Generation Task needs to be specific in order to improve the behavioral measures (AE and BV). This study implements a non-specific feedback after every block during the experimental session.

Performance feedback (in training only)

Online experiment with performance feedback in training- and experimental session Using the Finger-Tapping Random Sequence Generation Task (FT-RSGT)