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Modern functional imaging methods, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT), provide non-invasive, quantitative tools for the direct measurement of neurotransmitter function in the living human brain. The dopamine system has been of key interest; first, because it has a prominant role in several(More)
BACKGROUND Brain dopamine neurons code rewarding environmental stimuli by releasing endogenous dopamine, a transmission signal that is important for reinforcement learning. Human reward-seeking gambling behavior, and especially pathological gambling, has been presumed to be modulated by brain dopamine. METHODS Striatal dopamine release was studied with(More)
Previous imaging studies in Parkinson's disease have focused mainly on the striatum, a region with very high dopaminergic activity. Using modern high-sensitivity 3D [(18)F]fluorodopa (Fdopa)-PET, mesocortical monoamine projections can be studied. To study the frontal monoaminergic system in unmedicated early Parkinson's disease in vivo, we examined 20 early(More)
A distinctive personality type, characterized by introversion, inflexibility, and low novelty seeking, has been suggested to be associated with Parkinson's disease. To test the hypothesis that Parkinson's disease is associated with a specific dopamine-related personality type, the personality structures of 61 unmedicated Parkinson's disease patients and 45(More)
Dopamine is known to regulate food intake by modulating food reward via the mesolimbic circuitry of the brain. The objective of this study was to compare the effects of high energy input (i.v. glucose) on striatal and thalamic dopamine release in overweight and lean individuals. We hypothesized that glucose would induce dopamine release and positive ratings(More)
Loss of dopamine D2-like receptors in the striatum has been associated with both normal human aging and impairment of cognitive and motor functions in the elderly. To investigate whether there are age-associated changes in dopamine D2 and D3 receptor subtypes (D2/3Rs) outside the striatum, a D2/3R selective high-affinity radioligand [11C]FLB 457 was used in(More)
Recent data from animal experiments suggest an important role for the basal ganglia in the processing and sensorimotor gating of nociceptive information. However, very little is known about their possible participation in human pain. Because of our previous finding of increased excitability of the blink reflex (a brainstem reflex under dopaminergic(More)
Donepezil and rivastigmine are acetylcholinesterase (AChE) inhibitors used to improve cholinergic neurotransmission and cognitive function in Alzheimer's disease (AD). This study examined direct effects of these drugs on AChE activity in the frontal, temporal, and parietal cortices in AD. Six AD patients were scanned with positron emission tomography before(More)
CONTEXT AND OBJECTIVE Obesity is associated with several metabolic abnormalities. Recent studies suggest that obesity also affects brain function and is a risk factor for some degenerative brain diseases. The objective of this study was to examine the effects of weight gain and weight loss on brain gray and white matter structure. We hypothesized that(More)
BACKGROUND Early stage patients with Parkinson's disease (PD) show cognitive impairment in frontal lobe functions and memory tests. Hippocampal atrophy is seen in medicated patients with advanced PD. OBJECTIVES To examine whether prefrontal or hippocampal atrophy are already present in early stage PD, and whether such atrophy is associated with cognitive(More)