Adolescence, defined as the transition phase between childhood and adulthood, is a time of many physical, cognitive and social-emotional changes. It is a natural time of exploring, thrill seeking,... Show moreAdolescence, defined as the transition phase between childhood and adulthood, is a time of many physical, cognitive and social-emotional changes. It is a natural time of exploring, thrill seeking, and for eventually setting long-term goals and aspirations. One of the most prominent findings is that adolescents take more risks than children or adults. The focus of this thesis is on adolescent risk taking behavior. The goal is to identify individual difference factors that are related to risk taking behavior and assess how these variables change over development. Adolescence is associated with major changes in hormonal levels, brain function and social environment. In this thesis it is tested how changes in pubertal development, brain function and social environment together influence real life risk taking. The studies in this thesis show that neural responses to rewards in the striatum are elevated during adolescence. This response is influenced by chronological age, pubertal development, personality and the social context. Importantly, the striatum response to rewards is related to real life risk taking behavior and therefore has functional relevance. The results of this thesis provide vital insight in the complex relationship between reward processing and real life risk taking behavior. Show less
This dissertation explores the involvement of the locus-coeruleus-noradrenaline (LC-NE) system in both temporal attention and uncertainty processing. To this end, a number of cognitive tasks are... Show moreThis dissertation explores the involvement of the locus-coeruleus-noradrenaline (LC-NE) system in both temporal attention and uncertainty processing. To this end, a number of cognitive tasks are used (Stroop, passive viewing, attentional blink, accessory stimulus, auditory oddball) and a number of techniques are utilized (electroencephalogram [EEG], pupillometry, phsychopharmacology). Show less
Children and adolescents who are chronically rejected by their peers suffer from widespread impairments in daily life, ranging from poor academic achievement and dropping out of school, to... Show moreChildren and adolescents who are chronically rejected by their peers suffer from widespread impairments in daily life, ranging from poor academic achievement and dropping out of school, to delinquency and the development of mental health problems. To gain a better understanding of the developmental processes that give rise to such impairments, the research described in this dissertation examined the neurocognitive underpinnings of processes that play a role in the emergence and maintenance of peer group rejection and acceptance. The first part of this dissertation focuses on neurocognitive processes underlying reactions to social exclusion. The second part concentrates on the neurocognitive processes involved in sharing valuable resources, based on the widely established finding that frequent displays of prosocial behaviors, such as cooperating, helping, and sharing, are associated with both gaining and maintaining acceptance among peers. The empirical work in this dissertation demonstrates that a developmental cognitive neuroscience approach provides unique insights into the emotional, regulatory, and socio-cognitive processes thought to play a role in the emergence and maintenance of peer group acceptance and rejection. Show less
This thesis aimed to investigate the neurobiological mechanisms of adolescent onset depression and anxiety disorders. A longitudinal fMRI study design was used that included both task related brain... Show moreThis thesis aimed to investigate the neurobiological mechanisms of adolescent onset depression and anxiety disorders. A longitudinal fMRI study design was used that included both task related brain activation and resting state functional connectivity. All participants were scanned three times in a six-month period. In between scan sessions the adolescents from the clinical group received treatment as usual. Adolescents from the control group were scanned within the same time interval but did not receive treatment. During a scan session several MRI parameters were collected including task based fMRI (emotional face processing task) and resting state fMRI. We also administered several questionnaires about derpession and anxiety symptomatology. It was demonstrated that adolescents with depressive and anxiety disorders show differentiating patterns of amygdala reactivity and connectivity compared to a healthy control group. Furthermore, using a dimensional approach and taking individual differences in self-reported depression and anxiety symptoms into account highlighted the role of self-reported anxiety symptoms in amygdala reactivity during emotional faces processing. These findings indicate that the amygdala indeed is an important region involved in emotional face processing and that focusing on this region can provide further insights in the development and persistence of depressive and anxiety disorders in adolescents. Show less
Although much research effort has been put into the development of new antidepressant drugs, the process of developing a drug often fails at the stage of large randomized controlled trials (RCTs)... Show moreAlthough much research effort has been put into the development of new antidepressant drugs, the process of developing a drug often fails at the stage of large randomized controlled trials (RCTs) in which an initially promising compound appears to lack efficacy after all. Several experimental medicine models have been proposed as preclinical tools in order to predict drug efficacy before the stage large RCTs. Among the various experimental medicine models, the cognitive neuropsychological model has been proposed as a tool to predict the efficacy of antidepressant drug even before the stage of large scale and expensive RCTs. We applied the cognitive neuropsychological model of drug action to test antidepressant effects of a novel compound (ARA290) and a well-known compound (L-tryptophan). We further investigated the model by tapping into HPA-axis reactivity and social decision making as additional outcomes, and investigated their interaction with a genetic marker. Show less
Depressie en angststoornissen, zoals major depressive disorder, paniekstoornis, sociale angststoornis en gegeneraliseerde angststoornis, vallen onder de meest voorkomende psychiatrische... Show moreDepressie en angststoornissen, zoals major depressive disorder, paniekstoornis, sociale angststoornis en gegeneraliseerde angststoornis, vallen onder de meest voorkomende psychiatrische ziektebeelden. Door middel van neuroimaging onderzoek zoals structurele en functionele MRI (fMRI) is het mogelijk om op een non-invasieve manier de onderliggende neurobiologie van deze stoornissen in kaart te brengen. Op basis van dergelijk onderzoek werden ruim 15 jaar geleden enkele neurobiologische modellen opgesteld waarin werd voorgesteld dat het goed of juist niet goed hersengebieden een belangrijke bijdrage leverde aan het ontstaan en/of instandhouden van depressie en angst. In de loop der jaren zijn nieuwe MRI technieken ontwikkeld. Met behulp van structurele MRI en resting-state fMRI, waarmee connectiviteit tussen hersengebieden onderzocht kan worden, heb ik gekeken naar anatomische en functionele hersenafwijkingen bij volwassenen en jongeren met depressie en/of angststoornissen. Doel was te bepalen of de reeds bestaande neurobiologische modellen bevestigd danwel aangepast of aangevuld zouden kunnen worden met recent ontwikkelde onderzoeksmethoden. De resultaten van mijn studies bevestigden grotendeels de betrokkenheid van de hersengebieden in de modellen, maar wezen tevens op een rol voor uitgebreidere netwerken van hersengebieden dan in de modellen werd verondersteld. Show less
One of the most prominent changes in adolescence is social reorientation. In other words, adolescents develop more intimate relationships with peers, they discover what it is like to be involved in... Show moreOne of the most prominent changes in adolescence is social reorientation. In other words, adolescents develop more intimate relationships with peers, they discover what it is like to be involved in a romantic relationship, and they take (social) risks by for example showing risky driving in the presence of friends. Given that social networks with peers become central elements in the adolescent’s life, investigating the role of individual differences related to the development of social reorientation seems highly relevant. This dissertation contributes to a better understanding of stability and change in social reorientation during adolescence by explaining the crucial role of empathy in social interactions from a brain and behavioral perspective. Future research can benefit from the presented studies by applying it to a more detailed analysis of individual differences in this important period in life, which may help to explain why some adolescents are successful in developing social competencies and relationships, whereas others experience difficulties. Eventually, this may lead to the development of interventions for youth who do not cope well with the social requirements from the environments, and help to improve their lives and the lives of individuals around them Show less
The aim of this thesis was to identify the neural mechanisms that enable a person to adaptively respond to, and recover from stress, which was studied in healthy controls, in people with increased... Show moreThe aim of this thesis was to identify the neural mechanisms that enable a person to adaptively respond to, and recover from stress, which was studied in healthy controls, in people with increased vulnerability or resilience to stress-related disorders, and in people with depression or PTSD, using magnetic resonance imaging (MRI). In most of the studies, a specific MRI method was employed, with which it is possible to assess how different brain regions communicate with each other (i.e., functional connectivity) when the brain is initiating or regulating stress responses. Structure, activity, and connectivity of the amygdala, a small brain region important for stress reactivity, was of main interest. The results show how stress influences information processing, and causes changes in the communication between brain areas, even long after the stressful event ended. Furthermore, personality dimensions associated with increased vulnerability or resilience to affective disorders were associated with changes in brain networks involved in emotion processing and regulation. Finally, smaller amygdala volumes were found in women with PTSD, while reduced integrity of affective brain networks was demonstrated in depression. Together, these results open important new avenues for future research into the short and long term effects of stress on the brain. Show less
Self-control abilities are crucial for successful functioning in daily life. At the core of self-control lies the ability to intentionally inhibit one__s actions. Intentional inhibition differs... Show moreSelf-control abilities are crucial for successful functioning in daily life. At the core of self-control lies the ability to intentionally inhibit one__s actions. Intentional inhibition differs from externally driven inhibition in that it is driven by an internal thought process rather than an external stimulus that tells one to stop. The goal of this thesis was to examine the development of intentional inhibition and compare this with externally driven inhibition. In order to investigate the covert process of intentional inhibition, the research described in this thesis made use of neurobiological measures such as phasic heart rate changes and functional magnetic resonance imaging (fMRI). In addition, to learn more about self-control in context, the final empirical chapter examined intentional and externally driven inhibition in the context of relevant and irrelevant emotions. Show less
What motivates people, and when do they perform optimally at work? In this dissertation, a regulatory focus perspective is taken (RFT, Higgins, 1997) to provide answers to these important questions... Show moreWhat motivates people, and when do they perform optimally at work? In this dissertation, a regulatory focus perspective is taken (RFT, Higgins, 1997) to provide answers to these important questions. The results of multiple studies, conducted in complex organizational environments are reported. In many of those environments, there is a clear preference for promotion oriented employees and leaders. Yet, many jobs contain both promotion and prevention tasks. The results show that the use of the prevention orientation contributes importantly to both individual and organizational performance. Show less
Unexplained Chronic Fatigue (CF) is of unknown aetiology, but research suggests a multifactorial nature in which biological/physical, psychological and social fators interact. Treatment approaches... Show moreUnexplained Chronic Fatigue (CF) is of unknown aetiology, but research suggests a multifactorial nature in which biological/physical, psychological and social fators interact. Treatment approaches for CF target mainly perpetuating factors of fatigue chronicity, such as lack of physical activity. This thesis describes a brief self-regulation-based intervention targeting physical activity for patients with CF. Prior to this intervention study we conducted a series of studies that were important for the development of the trial: (1) a validation of a measure of fatigue severity for the language and population in which we intended to implement the intervention, (2) a comparison of clinical characteristics and behavioural and cognitive determinants of CFS in a Dutch and a Portuguese patient sample, and (3) a systematic review and meta-analysis of behavioural interventions with a graded activity component conducted with CF patients. In a randomized controlled trial (n=91), the self-regulation based intervention led to significant sustained effects (1 year) on fatigue severity, quality of life and physical activity. Sustained benefits on fatigue severity were partially explained by progress on a personal physical activity goal, and use of self-regulation skills. Findings are discussed in terms of its implications for practice, methodological considerations and avenues for future research. Show less
