The neural correlates of individual differences in self-regulation

Datum: 5 oktober 2015

Locatie: University of Antwerp - Campus Drie Eiken - Building Q - Promotiezaal - Universiteitsplein 1 - 2610 Wilrijk

Tijdstip: 16 uur

Organisatie / co-organisatie: Faculty of Medicine and Health Sciences

Promovendus: Anja Waegeman

Promotor: Prof C. Declerck, Prof P. Parizel & Prof C. Boone

Korte beschrijving: PhD defence Anja Waegeman - Faculty of Medicine and Health Sciences



Abstract

Self-regulation, the ability to monitor and modulate attention, thought, affect and behaviour, is essential to achieve fulfilling relationships and good mental health. Failures of self-regulation are an important cause of medical and societal problems. Successful self-regulation is characterized by both overcoming prepotent impulsive responses (self-control), and adjusting performance whenever necessary (behavioural flexibility). Together with working memory capacities, self-control and behavioural flexibility make it possible to balance the pursuit of a long term-goal while maintaining the flexibility to be open to alternative courses of actions, should the former prove to be no longer adaptive.

This doctoral dissertation thesis investigates, by means of functional magnetic resonance imaging (fMRI), the neural correlates of these two aspects of self-regulation in one and the same population of healthy young men. Using two validated experimental paradigms, a time discounting task (assessing self-control) and a probabilistic reversal learning task (assessing behavioural flexibility), this research reveals the underlying neural mechanisms that are uniquely recruited during each task and commonly recruited by both tasks. We furthermore show how self-regulatory brain activation patterns relate to individual differences in task performance and independent measures of self-reported self-regulation.

In the first chapter, we assess the construct validity of self-report self-regulation questionnaires and investigate their predictive validity to actual self-regulatory behaviour. By analyzing the convergent validity of the Effortful Control scale of the Adult Temperament Questionnaire, the Temperament and Character Inventory and the Locus of Control (LOC) scale, we note that the construct validity of self-reported cognitive self-regulation questionnaires is robust. However, linking the self-report scores to actual performance scores on two self-regulatory tasks (the time discounting task and the probabilistic reversal learning task) shows that their predictive validity is rather poor.

In chapter two we corroborate by means of fMRI that, being able to prefer a larger reward provided later in time over a small but early reward (i.e., impulse control), recruits lateral prefrontal brain regions. This chapter adds to the literature on temporal discounting by showing that the dorsolateral prefrontal cortex (DLPFC, Brodmann Area (BA) 45) is more activated in self-controlled individuals while medial brain regions (medial PFC (BA8) and rostral anterior cingulate cortex, (rACC, BA32)) are more activated in individuals who favor earlier rewards.

In chapter three we show that successful behavioural flexibility during probabilistic reversal learning depends on the activation of a broader brain network including mostly frontal and parietal brain regions. We furthermore show that the perseveration of erroneous choices correlates with increasing activation of the dorsal ACC (BA 32/24) and the caudate head, signaling the need to change. Finally, we find that better performance on this probabilistic reversal learning task is associated with increased activation of the rACC (BA32) and insula/ventrolateral PFC (insula/VLPFC, BA13), two brain regions that have previously been shown to be involved in emotion regulation and conflict resolution, especially in conditions of uncertainty.

In the final chapter we perform a conjunction analysis on data merged from both tasks in order to identify the regions that are commonly recruited during both self-regulation tasks. Results reveal activation in brain regions that have previously been identified as integration zones, located laterally and modulating the more medially located brain regions involved in motivation.

Specifically, we found the dorsal premotor cortex (PMd, BA6), the insula/VLPFC (BA13), the inferior frontal gyrus (IFG, BA46) and the dorsal (BA32/24) and rostral ACC (BA32) to be commonly shared by both tasks. This common brain network can be seen as representing four basic functions that are necessary for “generalized” self-regulation across several different domains: (1) conflict detection and monitoring (ACC, BA32/24), (2) internal goal representation (PMd, BA6), (3) controlling impulses by modulating the motivational system (IFG, BA46) and (4) controlling frustration by regulating emotions (insula/VLPFC, BA13). Interestingly, PMd (BA6) and insula/VLPFC (BA13) activations correlate with an internal LOC, a generalized measure of self-regulation, suggesting that indeed a generalized ability to self-regulated behaviour may be traced back to neural markers in the brain.

Together, these four chapters replicate previous findings on the neural correlates of self-control and behavioural flexibility, corroborating the significance of the lateral prefrontal cortex in successful self-regulation. This dissertation is novel in showing that differential activation of certain brain regions may in part explain individual differences in self-regulatory capacities.