Selective perturbation of cognitive conflict in the human brain–A combined fMRI and rTMS study

Abstract

We investigated if single and double conflicts are processed separately in different brain regions and if they are differentially vulnerable to TMS perturbation. Fifteen human volunteers performed a single (Flanker or Simon) conflict task or a double (Flanker and Simon) conflict task in a combined functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS) study. The fMRI approach aimed at localizing brain regions involved in interference resolution induced by single Flanker (stimulus-stimulus, S-S) and Simon (stimulus-response, S-R) conflicts as well as regions involved in the double conflict condition. The data revealed a distinct activation in the right intraparietal sulcus (IPS) for Flanker interference and in the right middle frontal gyrus (MFG) for the double interference condition. The causal functional role of these brain regions was then examined in the same volunteers by using offline TMS over right IPS and right MFG. TMS perturbation of the right IPS increased the Flanker effect, but had no effect in the Simon or double conflict condition. In contrast, perturbation of the right MFG had no effect on any of the conflict types. These findings suggest a causal role of the right IPS in the processing of the single conflict of Flanker (stimulus-stimulus) interference.

The neurocognitive underpinnings of the Simon effect: An integrative review of current research

“…Activity in right MFG has been linked to interference resolution (e.g., Tang, Critchley, Glaser, Dolan, & Butterworth, 2006). However, it might not be necessary to actively resolve conflict in the Simon task, given that a study perturbating right MFG with transcranial magnetic stimulation (TMS) found no effects on the Simon effect in a double-conflict task (Peschke et al, 2016). Indeed, their targeted region was located more anterior and inferior compared to our results.…”

“…We included one study using an incompatible > neutral contrast (Forstmann, van den Wildenberg, Wery, & Ridderinkhof, 2008a) and one study reporting a main effect of the incompatible condition (Forstmann et al, 2008b), while all other studies used the incompatible > compatible contrast. One study did not find any activation related to the Simon interference (Peschke et al, 2016). As the Simon interference should be assessed with fMRI throughout the whole brain, all studies solely examining specific regions of interest (ROIs) or using a restricted search volume that did not provide data on a whole brain level were excluded.…”

The effect of feature-based attention on flanker interference processing: An fMRI-constrained source analysis

“…The results are therefore compatible with our a priori hypothesis of overlapping activity in dorsal fronto-parietal regions. However, it is also conceivable that MFG is more generally involved in focusing attention, given that temporarily disrupting MFG had no deteriorating effect on different conflict manipulations in a recent TMS study 89 .…”

Age differences in the principal temporo-spatial components of EEG activity during a proactive interference task

“…Similarly, the middle frontal gyrus has also been found to be activated in tasks that induce response conflict, such as the Flanker paradigm (Hoffman et al, 2021;Peschke et al, 2016) as well as during judgements of how recently items were memorised in an episodic memory task (Zorrilla et al, 1996). Additionally, a meta-analysis by Gavazzi and colleagues (2023), found the right middle frontal gyrus to be one of the key right PFC nodes involved in varying levels of reactive inhibitory control.…”