Effect of tDCS Over the Right Inferior Parietal Lobule on Mind-Wandering Propensity

Abstract

Mind-wandering is associated with switching our attention to internally directed thoughts and is by definition an intrinsic, self-generated cognitive function. Interestingly, previous research showed that it may be possible to modulate its propensity externally, with transcranial direct current stimulation (tDCS) targeting different regions in the default mode and executive control networks (ECNs). However, these studies used highly heterogeneous montages (targeting the dorsolateral prefrontal cortex (DLPFC), the right inferior parietal lobule (IPL), or both concurrently), often showed contradicting results, and in many cases failed to replicate. Our study aimed to establish whether tDCS of the default mode network (DMN), via targeting the right IPL alone, could modulate mind-wandering propensity using a within-subjects double-blind, counterbalanced design. Participants completed sustained attention to response task (SART) interspersed with thought-probes to capture their subjective reports of mind-wandering before and after receiving anodal, cathodal, or sham tDCS over the right IPL (with the reference over the left cheek). We found evidence for the lack of an effect of stimulation on subjective reports of mind-wandering (JZS-BF 01 = 5.19), as well as on performance on the SART task (errors (JZS-BF 01 = 6.79) and reaction time (JZS-BF 01 = 5.94). Overall, we failed to replicate previous reports of successful modulations of mind-wandering propensity with tDCS over the IPL, instead of providing evidence in support of the lack of an effect. This and other recent unsuccessful replications call into question whether it is indeed possible to externally modulate spontaneous or self-generated cognitive processes.

The interplay between executive control, behavioural variability and mind wandering: Insights from a high‐definition transcranial direct‐current stimulation study

“…Initially, several studies reporting successful modulation of mind‐wandering propensity using traditional non‐focal, low‐intensity tDCS over the DLPFC provided an optimistic outlook (Axelrod et al., 2015; Kajimura et al., 2016; Kajimura & Nomura, 2015). However, as several studies have failed to replicate this effect (Boayue et al., 2019; Coulborn et al., 2020) including a large‐scale, pre‐registered direct replication study (Boayue et al., 2019), suggesting that the initial positive results that were based on very low sample‐sizes might have been a false positive (but see Axelrod et al., 2018; Csifcsák et al., 2019, for a discussion). Furthermore, those studies that did find an effect of tDCS on mind wandering were inconsistent with respect to the directionality of the effect, some finding an increase (e.g.…”

DLPFC-tDCS unable to modulate mind-wandering propensity nor underlying functional or effective brain connectivity

“…Specifically, the thought probes require participants to subjectively identify whether they were on or off-task, and this is known to be problematic for some 55 , given the sometimes vague and all-encompassing classification of 'mind-wandering' thoughts 56 . Despite this, the SART remains the most typically used task in studies investigating mind wandering 18,24,57,58 , and in particular in conjunction with tDCS 1,4,5,[8][9][10][11] . It is worth noting that we (and others) also analysed objective measures that do not rely on participants' self-report (i.e., commission errors and reaction times) and can be used as proxies for mind-wandering propensity, but these also failed to elicit the expected brain activation or to be modulated by our tDCS montage.…”

“…Research investigating the use of transcranial direct current stimulation (tDCS) as a tool to modulate self-generated cognitive processes, such as mind-wandering, is becoming increasingly popular [1][2][3][4][5][6][7][8][9][10][11] . Mind-wandering is an internally directed process which is typically associated with the activation of the default mode network (DMN) 12,13 .…”

The effect of transcranial direct current stimulation on the interplay between executive control, behavioral variability and mind wandering: A registered report

“…In addition to studies elucidating the nature of MW on a behavioral level using cognitive tasks, there has been an increase in research focusing on the role of neural networks in MW (Andrews-Hanna et al, 2010;Dixon et al, 2018;Fox et al, 2013), and in methods for manipulating their activity with non-invasive brain stimulation (NIBS) techniques (Axelrod et al, 2015(Axelrod et al, , 2018Boayue et al, 2019;Coulborn et al, 2020;Csifcsak et al, 2019;Csifcsák et al, 2018;Filmer et al, 2021). To identify these networks, researchers have attempted to locate neural markers of mind wandering, such as electrophysiological signatures recorded by electroencephalography (EEG; Braboszcz & Delorme, 2011;Kawashima & Kumano, 2017), functional magnetic resonance imaging (fMRI; Chou et al, 2017;Christoff et al, 2009;Mittner et al, 2014) or both (Groot et al, 2021).…”

“…Some studies provide evidence for tDCS to induce neuroplastic effects when applied for longer stimulation periods (Lefaucheur et al, 2014 Initially, several studies reporting successful modulation of mind wandering propensity using traditional bipolar tDCS over the DLPFC provided an optimistic outlook (Axelrod, Rees, Lavidor, & Bar, 2015;Kajimura, Kochiyama, Nakai, Abe, & Nomura, 2016;Kajimura & Nomura, 2015). However, several subsequent studies have failed to replicate this effect (Coulborn et al, 2020), including a large-scale, pre-registered direct replication study (Boayue et al, 2019). This suggests that the initial positive results that were based on very low sample-sizes might have been overly optimistic (but see Axelrod, Zhu, & Qiu, 2018;Csifcsak et al, 2019).…”