David Elmenhorst

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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)
Current perspectives on the pathophysiology of schizophrenia direct attention to serotonergic (serotonin, 5-HT) dysregulation in the prodrome or at-risk mental state (ARMS). To study the cerebral 5-HT2A receptor (5-HT2AR) in the ARMS with [18F]altanserin positron emission tomography (PET) and a bolus-infusion paradigm. We quantified the spatial distribution(More)
Adenosine, increasing after sleep deprivation and acting via the A(1) adenosine receptor (A(1)AR), is likely a key factor in the homeostatic control of sleep. This study examines the impact of sleep deprivation on A(1)AR density in different parts of the rat brain with [(3)H]CPFPX autoradiography. Binding of [(3)H]CPFPX was significantly increased in(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)
Cerebral A(1) adenosine receptors (A(1)AR) fulfill important neuromodulatory and homeostatic functions. The present study examines possible age-related A(1)AR changes in living humans by positron emission tomography (PET) and the A(1)AR ligand [(18)F]CPFPX. Thirty-six healthy volunteers aged 22-74 years were included. The apparent binding potential (BP'2)(More)
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. 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 subsequent infusion over(More)
The A1 adenosine receptor positron emission tomography (PET) ligand 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propylxanthine ([18F]CPFPX, ) undergoes a fast hepatic metabolism. An optimal design of PET quantitation approaches (e.g., bolus/infusion studies) necessitates the knowledge of factors that influence this metabolism. Metabolites of were separated by(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)
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)
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)