In the realm of cognitive science, the quest to understand cognitive control has persisted for decades. Traditional notions of cognitive control have focused on inhibition through the prefrontal... Show moreIn the realm of cognitive science, the quest to understand cognitive control has persisted for decades. Traditional notions of cognitive control have focused on inhibition through the prefrontal cortex, but this dissertation challenges that perspective with a more comprehensive framework: The Metacontrol State Model (MSM). The MSM proposes that cognitive control emerges from the interplay between two opposing systems – one promoting flexibility and the other promoting persistence. These systems interact to shape our cognitive processing styles, thereby influencing our ability to effectively regulate our actions. This dissertation explores questions such as why individuals exhibit differences in cognitive control capacity and how state-related changes and trait-related predispositions impact cognitive control function. The overarching goal of this dissertation is to empirically test the MSM model and shed light on the factors that influence cognitive control. Through a series of experiments, it seeks to understand how altered states of consciousness, achieved through meditation techniques or serotonergic psychedelics, affect the balance between intentional and habitual processes. Additionally, it examines the extent to which individual trait biases serve as trans-diagnostic markers in various psychopathologies. This work comprises a literature review and six empirical articles. By integrating theory and empirical research, this dissertation takes us on a journey into the intricate world of cognitive control, shaping our understanding of how it influences our lives. Show less
Marschall, J.C.; Fejer, G.; Lempe, P.; Prochazkova, L.; Kuchar, M.; Hajkova, K.; Elk, M. van 2022
IntroductionTaking microdoses (a mere fraction of normal doses) of psychedelic substances, such as truffles, recently gained popularity, as it allegedly has multiple beneficial effects including... Show moreIntroductionTaking microdoses (a mere fraction of normal doses) of psychedelic substances, such as truffles, recently gained popularity, as it allegedly has multiple beneficial effects including creativity and problem-solving performance, potentially through targeting serotonergic 5-HT2A receptors and promoting cognitive flexibility, crucial to creative thinking. Nevertheless, enhancing effects of microdosing remain anecdotal, and in the absence of quantitative research on microdosing psychedelics, it is impossible to draw definitive conclusions on that matter. Here, our main aim was to quantitatively explore the cognitive-enhancing potential of microdosing psychedelics in healthy adults.MethodsDuring a microdosing event organized by the Dutch Psychedelic Society, we examined the effects of psychedelic truffles (which were later analyzed to quantify active psychedelic alkaloids) on two creativity-related problem-solving tasks: the Picture Concept Task assessing convergent thinking and the Alternative Uses Task assessing divergent thinking. A short version of the Ravens Progressive Matrices task assessed potential changes in fluid intelligence. We tested once before taking a microdose and once while the effects were expected to be manifested.ResultsWe found that both convergent and divergent thinking performance was improved after a non-blinded microdose, whereas fluid intelligence was unaffected.ConclusionWhile this study provides quantitative support for the cognitive-enhancing properties of microdosing psychedelics, future research has to confirm these preliminary findings in more rigorous placebo-controlled study designs. Based on these preliminary results, we speculate that psychedelics might affect cognitive metacontrol policies by optimizing the balance between cognitive persistence and flexibility. We hope this study will motivate future microdosing studies with more controlled designs to test this hypothesis. Show less
The aging brain undergoes several anatomical changes that can be measured with Magnetic Resonance Imaging (MRI). Early studies using lower field strengths have assessed changes in tissue properties... Show moreThe aging brain undergoes several anatomical changes that can be measured with Magnetic Resonance Imaging (MRI). Early studies using lower field strengths have assessed changes in tissue properties mainly qualitatively, using T 1 T1 - or T ∗ 2 T2∗ - weighted images to provide image contrast. With the development of higher field strengths (7 T and above) and more advanced MRI contrasts, quantitative measures can be acquired even of small subcortical structures. This study investigates volumetric, spatial, and quantitative MRI parameter changes associated with healthy aging in a range of subcortical nuclei, including the basal ganglia, red nucleus, and the periaqueductal grey. The results show that aging has a heterogenous effects across regions. Across the subcortical areas an increase of T 1 T1 values is observed, most likely indicating a loss of myelin. Only for a number of areas, a decrease of T ∗ 2 T2∗ and increase of QSM is found, indicating an increase of iron. Aging also results in a location shift for a number of structures indicating the need for visualization of the anatomy of individual brains. Show less
