Learn More
The distribution volume ratio (DVR), which is a linear function of receptor availability, is widely used as a model parameter in imaging studies. The DVR corresponds to the ratio of the DV of a receptor-containing region to a nonreceptor region and generally requires the measurement of an arterial input function. Here we propose a graphical method for(More)
A graphical method of analysis applicable to ligands that bind reversibly to receptors or enzymes requiring the simultaneous measurement of plasma and tissue radioactivities for multiple times after the injection of a radiolabeled tracer is presented. It is shown that there is a time t after which a plot of integral of t0ROI(t')dt'/ROI(t) versus integral of(More)
Understanding the changes in the brain which occur in the transition from normal to addictive behavior has major implications in public health. Here we postulate that while reward circuits (nucleus accumbens, amygdala), which have been central to theories of drug addiction, may be crucial to initiate drug self-administration, the addictive state also(More)
Decreased dopaminergic function has been postulated to underlie cocaine addiction. To examine the possibility that dysfunction of brain regions subserved by the dopamine system could promote cocaine self-administration, positron emission tomography and a dual-tracer approach was used to examine dopamine D2 receptor availability and regional brain glucose(More)
BACKGROUND The cerebral mechanisms underlying the behaviours that lead to pathological overeating and obesity are poorly understood. Dopamine, a neurotransmitter that modulates rewarding properties of food, is likely to be involved. To test the hypothesis that obese individuals have abnormalities in brain dopamine activity we measured the availability of(More)
Methamphetamine is a popular drug of abuse that is neurotoxic to dopamine (DA) terminals when administered to laboratory animals. Studies in methamphetamine abusers have also documented significant loss of DA transporters (used as markers of the DA terminal) that are associated with slower motor function and decreased memory. The extent to which the loss of(More)
OBJECTIVE The therapeutic effects of methylphenidate in the treatment of attention deficit disorder have been attributed to its ability to increase the synaptic concentration of dopamine by blocking the dopamine transporters. However, the levels of dopamine transporter blockade achieved by therapeutic doses of methylphenidate are not known. This study(More)
Cocaine is believed to work by blocking the dopamine transporter (DAT) and thereby increasing the availability of free dopamine within the brain. Although this concept is central to current cocaine research and to treatment development, a direct relationship between DAT blockade and the subjective effects of cocaine has not been demonstrated in humans. We(More)
OBJECTIVE Methamphetamine is a popular and highly addictive drug of abuse that has raised concerns because it has been shown in laboratory animals to be neurotoxic to dopamine terminals. The authors evaluated if similar changes occur in humans and assessed if they were functionally significant. METHOD Positron emission tomography scans following(More)
Methylphenidate (Ritalin) is the most commonly prescribed psychoactive drug in children for the treatment of attention deficit hyperactivity disorder (ADHD), yet the mechanisms responsible for its therapeutic effects are poorly understood. Whereas methylphenidate blocks the dopamine transporter (main mechanism for removal of extracellular dopamine), it is(More)