The present thesis contains five experimental studies into the effects of stress on memory I healthy males. Hydrocortisone (and propranolol) administration or the induction of social stress are... Show moreThe present thesis contains five experimental studies into the effects of stress on memory I healthy males. Hydrocortisone (and propranolol) administration or the induction of social stress are used to heighten cortisol levels, and consequently to study its effects on working memory performance and memory retrieval. In addition, by using neutral and emotional distraction during working memory, effects of cortisol on emotional distraction were investigated, also with use of functional imaging. Overall, it was consistently found that high cortisol levels, by hydrocortisone administration or induced by stress, reduced the distraction by emotional irrelevant stimuli, hence improving working memory. The current findings might be relevant for patients suffering from posttraumatic stress disorder, who typically suffer from trauma-related intrusions. Show less
The research described in this thesis aimed to gain insight in risky behavior in adolescence, by examining the development of decision-making in relation to brain development. Chapter 1 describes... Show moreThe research described in this thesis aimed to gain insight in risky behavior in adolescence, by examining the development of decision-making in relation to brain development. Chapter 1 describes two existing possible explanations for adolescent risky behavior, the first explanation focuses on the development of cognitive control, and states that adolescents’ immature ability to control their impulses may bias them to act risky. The second explanation focuses on emotional/motivational processes, and suggests that adolescents engage in risky behavior because they respond stronger to the possible rewards associated with risks than children and adults do. Chapters 2, 3, and 7 describe studies on developmental changes in the processes that form the building blocks of more complex decision-making under risk; probability estimation, reward processing and working memory. Chapters 4, 5, and 6 explore the relative contributions of reward sensitivity and cognitive control to decision-making across development. This thesis shows knowledge about brain maturation can inform models of adolescent risky behavior. And that adolescent risk-taking can be explained as the consequence of the earlier maturation of reward related relative to cognitive control related brain circuitry. Show less
