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The dopaminergic mechanisms that control reward-motivated behavior are the subject of intense study, but it is yet unclear how, in humans, neural activity in mesolimbic reward-circuitry and its functional neuroimaging correlates are related to dopamine release. To address this question, we obtained functional magnetic resonance imaging (fMRI) measures of(More)
It is currently hypothesized that adenosine is involved in the induction of sleep after prolonged wakefulness. This effect is partially reversed by the application of caffeine, which is a nonselective blocker of adenosine receptors. Here, we report that the most abundant and highly concentrated A1 subtype of cerebral adenosine receptors is upregulated after(More)
OBJECTIVE The study was aimed at the examination of the acute and cumulative impact of partial sleep deprivation (PSD) on architecture and quality of sleep, on circadian rhythm and on daytime fatigue. METHODS Time in bed for 16 healthy male volunteers was reduced from 8 to 5h during four consecutive nights, followed by two recovery nights. This scheme(More)
Evidence from animal studies suggests that the social attraction and bonding effects of the neuropeptide oxytocin (OXT) are mediated by its modulation of dopamine (DA) release in brain reward centers, but this has not yet been demonstrated in humans. DA release can be measured by positron emission tomography (PET) using the radioligand [11C]raclopride. Its(More)
Sleep deprivation increases the levels of extracellular adenosine and A1 receptor (A1R)mRNA in the cholinergic zone of the basal forebrain, a region involved in sleep homeostasis. To evaluate homeostatic control mechanisms, we examined the sleep deprivation-induced changes in the A1R density in rodent brain using [H]CPFPX receptor autoradiography. We also(More)
The cerebral A(1) adenosine receptor (A(1)AR) has recently become accessible for in vivo imaging using the selective A(1)AR ligand [(18)F]CPFPX and PET. For broad application in neurosciences, imaging at distribution equilibrium is advantageous to quantify stimulus-dependent changes in receptor availability and to avoid arterial blood sampling. Here we(More)
PURPOSE The goal of the present study was to evaluate the reproducibility of cerebral A1 adenosine receptor (A1AR) quantification using [18F]CPFPX and PET in a test-retest design. METHODS Eleven healthy volunteers were studied twice. Eight brain regions ranging from high to low receptor binding were examined. [18F]CPFPX was injected as a bolus with(More)
BACKGROUND Imaging of cerebral A(1) adenosine receptors (A(1)AR) with positron emission tomography (PET) has recently become available for neurological research. To date, it has still not been unraveled if there is a valid reference region without specific radioligand binding that may be used to improve image quantification. We conducted in vivo(More)
UNLABELLED 8-cyclopentyl-3-(3-18F-fluoropropyl)-1-propylxanthine (18F-CPFPX) is a novel PET ligand for in vivo quantification of cerebral A1 adenosine receptors. The present study investigated the applicability of voxelwise graphical analysis to the generation of parametric images of the total volume of distribution (DVt) of 18F-CPFPX as a prerequisite for(More)
PURPOSE The cerebral mechanisms underlying hepatic encephalopathy (HE) are poorly understood. Adenosine, a neuromodulator that pre- and postsynaptically modulates neuronal excitability and release of classical neurotransmitters via A(1) adenosine receptors (A(1)AR), is likely to be involved. The present study investigates changes of cerebral A(1)AR binding(More)