Thesis title: Cognitive control for conflict resolution: causative and behavioural investigations on the link between conflict monitoring and body representations
During my doctoral studies, I focused on the field of cognitive control and, in particular, its sub-processes namely conflict monitoring and response inhibition. My research primarily investigated conflicting body-related representations and pursued two main objectives: (i) the study, through non-invasive brain stimulation (NIBS) methods, such as Transcranial Magnetic Stimulation (TMS), of the interacting neural regions involved in perceptual encoding, conflict monitoring and response inhibition and (ii) the exploration of the relationships between cognitive control and implicit body-related attitudes and stereotypes.
Chapter 1 is dedicated to the application of repetitive TMS to explore the functional role of the Medial Frontal Cortex (MFC), a key-node of the Cognitive Control Network (CCN), and of the right Extrastriate Body Area (rEBA), a category-selective occipitotemporal region, during the processing of representational conflicts in two versions of the Flanker task, in which the target and the flankers were represented either by letters or human whole-body silhouettes. As a matter of fact, recent evidence highlighted the possible involvement of the rEBA, interacting with the MFC, in resolving cognitive conflict in a content-specific manner. Further, the MFC functional role in conflict resolution and, specifically, its potential involvement in the earliest stages of conflict processing, such as encoding or monitoring, is still a topic of debate. The current study aimed, therefore, to interfere with the activity of these cortical regions to identify their individual causal contribution in the stream of information processing during task performance.
Chapter 2 introduces a behavioural study in which we investigated whether implicit attitudes and stereotypes toward the biological gender and the body weight could influence and be recognized in the processing of conflicting body-related representations in the flanker task. For this purpose, we examined the performance of 40 healthy male and female volunteers who were asked to process body-related stimuli associated with gender (Gender-Flanker, GF) or body size (Weight-Flanker, WF, in two versions, WF-male and WF-female). Additionally, we administered both the Implicit Association Test (IAT) and the Affective Misattribution Procedure (AMP) in a gender-related version (IAT-G and AMP-G) and in a weight-related version (IAT-G and AMP-G) to collect independent measures of implicit cognitive biases associated with these two dimensions.
In particular, we hypothesized that individuals’ implicit attitudes may be reflected in the way they handle conflicting body-related stimuli.
While being one of the first investigations probing how attitudes can affect and be measured in a cognitive control task, this experimental study aimed to demonstrate that the flanker task could be used, in turn, as a sensitive and reliable implicit measure to investigate these biases.
Chapter 3 regards an investigation, which I have collaborated on, of the causal role of the right Inferior Frontal Gyrus (rIFG) in response inhibition processes during a variant of the Flanker Task including NoGo trials (i.e., a certain number of trials where the participants were instructed not to respond at all). The idea of investigating the causal role of the rIFG in a Go/NoGo Flanker is based on several behavioural evidence showing that the ability to inhibit prepotent responses may depend on the degree of competition between response alternatives, and on a TMS investigation showing that the stimulation of the rIFG impairs the behavioural performance in a Stop-Signal Task specifically under conditions of heightened response competition, suggesting that response inhibition and conflict processing may directly interrelate on this common neural substrate.
On the same line of the TMS study introduced in Chapter 1, a further aim of this investigation was to elucidate a possible role of the rEBA in supporting the CCN also during response inhibition. For this purpose, we employed on-line 10Hz rTMS while specifically targeting the rIFG and the rEBA during two variants of a Go/NoGo Flanker task, with stimuli representing letters or human hands.
Finally, Chapter 4 reports a mini-review, currently published in Frontiers in Integrative Neuroscience (16, 2022), in which recent evidence showing how transcranial direct and alternate current stimulations (i.e., tDCS and tACS, respectively) modulate the performance monitoring network in neurotypical samples. The review focused overall to studies using behavioural tasks tapping conflict and error processing such as the Stroop, the Flanker, and the Simon tasks. These studies have highlighted the significant role played by the MFC, the Anterior Cingulate Cortex (ACC) and the theta synchronization in errors and conflict processing. The review also mentions the limitations of current technology and the specific strategies that could be employed to effectively target and modulate cortical and subcortical regions.