| dc.description.abstract | This dissertation aimed to investigate behavioral symptoms commonly encountered in conditions that present with motor symptoms. These studies primarily focused on the pathophysiology of impulsive and compulsive behaviors in Parkinson disease and frontal behaviors in Essential Tremor. The theme was linking cerebellar function and the networks it subserves in behavior regulation. This includes investigations into measurable levels of dopamine receptors. To investigate these problems, I used a combination of patient reported outcomes of health status, anatomical and functional magnetic resonance imaging (MRI), and positron emission tomography (PET) imaging with the dopamine receptor ligand [18F] fallypride. Results show that persons with Parkinson disease show significantly higher impulsivity than age- and sex- matched controls. Specific deficits in attentional control are noted in this population, and those with impulsive-compulsive behaviors have changes to cognitive control and complexity. Further, those with impulsive and compulsive behaviors patients showed greater dAMPH-induced elevations in positive mood, indicating an overall elevation in physical perception of benefit to amphetamine administration and subsequent affective changes. Overall, the data show that acute modification of dopamine levels in mesocorticolimbic structures results in differing emotional and physical perceptions between ICB+ and ICB- PD populations. these investigations were also performed in Essential Tremor population, and I note clinically elevated disinhibited behavior. This behavior relates to atrophy in the cerebellum, particularly in Crus I and Crus II, which are thought to relate to behavioral control. To determine if dopamine release in Crus I-II is present, I applied an amphetamine challenge and are correlated changes in BPND to impulsivity scores. Findings indicate that impulsivity is present in multiple “motor movement” disorders and is related to dopamine receptor expression not just in mesocorticolimbic areas, but the cerebellum as well. Future research is needed to fully elucidate the role of dopamine regulation in the cerebellum. | |
