View clinical trials related to Placebo.
Filter by:Incidental affective states, i.e., affective states can influence decision making and selective attention to threatening information. Acute stress is such an affective state and is a powerful contextual modulator of decision-making processes and selective attention to threat. In terms of physiological and neurohormonal changes, the stress response has been well characterized: Exposure to stress elicits an array of autonomic, endocrine, and behavioral responses. The physiological stress response is mediated by the hypothalamic-pituitary-adrenal (HPA) axis and the locus coeruleus noradrenergic (LC-NA) system with cortisol and norepinephrine (NE) as their end products. There is compelling evidence that the stress hormones cortisol and NE influence cognitive processes. However, only very few studies so far used pharmacological approaches to specify the role of stress neuromodulators on decision making and selective attention to threat and these studies are hardly comparable due to differences in the experimental design, e.g., the decision making task used. Furthermore, the neural underpinnings of stress effects on decision making and selective attention to threat are uninvestigated so far. The aim of the proposed project is to clarify the role of the major stress neuromodulators, NE and cortisol, in their contribution to different processes related to decision making under risk and selective attention to threat. To this end, combined precise pharmacological stimulation, behavioral modeling, and fMRI methods will be applied to systematically disentangle the effects of stress hormones on risk attitudes and loss aversion as well as their relation to neural correlates of processing subjective value and risk. Using pharmacological manipulation, the influence of noradrenergic and glucocorticoid activity on decision making under risk at the behavioral, computational, and neural level will be investigated. In addition, the influence of noradrenergic and glucocorticoid activity on selective attention to threat at the behavioural and neural level using a dot-probe paradigm with fearful and neutral faces will be examined. Participants are randomly assigned to one of four groups: (A) yohimbine, (B) hydrocortisone, (C) yohimbine and hydrocortisone, or (D) placebo.
To provide an initial test of the hypothesis that dopamine mediates the motivational salience of stimuli beyond simple stimulus-reinforcement associations, the researchers propose to undertake a study of the modulation of a) levels of agreement or disagreement with; b) the perceived self- relevance; and c) the perceived interest of propositions expressing beliefs and values in healthy male volunteers using Ii) a dopamine antagonist (the D2-blocker haloperidol), and (ii) a dopamine precursor L-Dopa to increase CNS dopamine transmission. The researchers will also administer the Salience Attribution Task (SAT) which will allow researchers to assess reward-learning processing of simple stimuli using a reaction-time game. This task was utilised by Roiser et al in order to explore whether delusions in medicated patients with schizophrenia were related to impairments in associative learning. The authors hypothesised that associative learning was influenced by D2 receptor blockade. The researchers extend this approach to examine the effect of dopamine modulation on the SAT as a measure of associative learning, a basic neuropsychological process that may be involved in the attribution of salience to beliefs. Finally, the researchers will ask participants to perform a within-subjects dictator game to understand the influence of dopaminergic manipulation of the live attribution of harm intention to partners. The task has been previously validated online. Participants will play against 3 partners in a random order in each drug condition. Each partner will play the participant for 6 trials. One partner will always be fair, one will always be unfair, and one will be 50% unfair. We aim to understand whether potentiating dopamine has an additive effect on the harm intention attributions toward partners, regardless of the behaviour of the partner.
The goal of this study is to determine whether a study medication (d-cycloserine) improves the ability of older adults to perform on tests of neuropsychological functioning. Tests of neuropsychological functioning assess attention, memory, and executive functioning skills (for example, problem-solving, planning and organizing skills). It was hypothesized that participants who received study medication would perform better on neuropsychological tests than would participants who received the sugar pill.
The objective of this study is to verify if there is a neurophysiologic reserve when caffeine and placebo perceived as caffeine are manipulated in closed- and opened-loop exercises. Parameters of excitability level of skeletal muscle and Central Nervous System (CNS), and peripheral metabolism will be measured
Positive social relationships have consistently been associated with better health, although the neurobiological underpinnings of these observed effects remain largely unknown. The overall goal of the proposed work is to explore novel biological pathways that may explain how social relationships influence health. Recent theorizing suggests that the oxytocin system may underlie some of the observed beneficial effects. Four hypotheses will be examined: 1. Oxytocin ameliorates the deleterious neuroendocrine, cardiovascular, and subjective effects of stress. 2. Oxytocin and social support have similar and additive stress-buffering effects. 3. Effects of oxytocin are evident among younger and older adults. 4. Effects of oxytocin are stronger in women vs men.
The study is aimed to evaluate the efficacy of antiglutamate anticonvulsants (topiramate, lamotrigine, and memantine) in the treatment of alcohol withdrawal syndrome