Life Sciences Commons^™

Dopaminergic Modulation Of A Fast Visuomotor Pathway In Parkinson's Disease, Madeline C. Gilchrist

Electronic Thesis and Dissertation Repository

Parkinson’s disease (PD) is associated with reduced dopaminergic (DA) input to the dorsal striatum (DS). This study investigated the role of DA in modulating automatic, stimulus-driven reactions by assessing contextual control of stimulus-locked responses (SLRs) in 10 PD patients off and on DA medication. The SLR is the rapid recruitment of limb muscles that drives the arm towards suddenly appearing stimuli. Participants reached away from (anti-reach) or towards (pro-reach) a target on a screen, depending on instruction appearing 500 or 1000ms before target appearance. Modulation of SLRs was assessed by comparing SLR magnitude on anti- and pro-reach trials using surface …

Early Experience And The Functional Calibration Of The Stress-Response Systems, Niki Hosseini-Kamkar

Electronic Thesis and Dissertation Repository

Individuals exposed to adversities in childhood are at a greater risk of developing various diseases as adults, including cardiovascular disease and cancer (Felitti et al. 1998). These findings have sparked an interest in examining biological mechanisms that might explain the link between exposure to adversity and disease. To date, evidence has linked adversity to the function of the hypothalamic-pituitary-adrenal (HPA) axis. More recently, adversity has been associated with the function of the mesolimbic dopamine pathway as well.

This thesis uses a variety of techniques to explore the association between adversity and the function of the HPA axis and mesolimbic dopamine …

Cholinergic Modulation Of Behaviour, Ornela Kljakic

Electronic Thesis and Dissertation Repository

The cholinergic system is one of the most influential and essential signalling systems in the body. In the brain, cholinergic neurons innervate many brain regions where they influence a wide variety of behaviours. However, the precise role of each cholinergic region on distinct types of behaviour is not well known. Furthermore, in recent years there has been evidence that many cholinergic neurons in the brain have a capacity for co-transmission. Yet the functional significance of secreting two classical neurotransmitters from the same neuron is still largely unidentified. In this thesis, we investigated how different cholinergic nuclei modulate behavioural functions. To …

Neural Substrates Of Reward, Error, And Effort Processing Underlying Adaptive Motor Behaviour, Dimitrios J. Palidis

Electronic Thesis and Dissertation Repository

Human motor control is highly adaptive to new tasks and changing environments. Motor adaptation relies on multiple dissociable processes that function to increase attainment of reward and to reduce sensory error and physical effort as costs. This thesis tests the hypothesis that fronto-striatal and dopaminergic neural systems contribute to specific aspects of motor adaptation that occur through reinforcement of rewarding actions.

Behavioral tasks were designed to isolate learning in response to feedback conveying information about reward, error, and physical effort. We also measured behavioral effects of savings and anterograde interference, by which memories from previous motor learning can facilitate or …