Dopamine-containing neurons have been shown to make direct contact with enkephalin-like immunoreactive neurons in the striatum of rat brain (Kubota et al., 1986). Chronic blockade of dopaminergic neurotransmission with the neuroleptic drug haloperidol has been reported to increase the striatal concentration of methionineenkephalin and proenkephalin m R N A (ENK mRNA) (Tang et al., 1983). We inv...

Dopamine (DA) losses are associated with various aging-related cognitive deficits. Typically, higher moment-to-moment brain signal variability in large-scale patterns of voxels in neocortical regions is linked to better cognitive performance and younger adult age, yet the physiological mechanisms regulating brain signal variability are unknown. We explored the relationship among adult age, DA a...

UNLABELLED 123I-Labeled radiotracers are suitable for in vivo imaging of the dopaminergic system by SPECT. However, precise measurement of striatal uptake is limited by scatter, attenuation, and the finite spatial resolution of the camera. We studied the quantitative accuracy that can be achieved with (123)I SPECT of the dopaminergic neurotransmission system. METHODS Using a Monte Carlo simul...

INTRODUCTION Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most prevalent cause of familial and sporadic Parkinson's disease (PD). Because most pathogenic LRRK2 mutations result in enhanced kinase activity, it suggests that LRRK2 inhibitors may serve as a potential treatment for PD. To evaluate whether LRRK2 inhibitors are effective therapies for PD, it is crucial to know whether LR...