Understanding how people control their actions

Parkinson's disease (PD) is a neurodegenerative disorder involving a part of the brain that is responsible for motor control, which not only results in changes or disruptions in movement, but also cognitive dysfunctions. Given that the decline of muscle control such as tremors, with difficulty walking or the ability to switch tasks once in movement, greatly affects the quality of daily life. Action regulation is a critical executive function (cognitive control over behavior), which includes actions such as suppressing activity when selecting between options, making decisions about stopping unwanted or inappropriate actions, and switching to new actions in response to environmental changes. Parkinson's disease (PD) has been shown to disrupt action inhibition which can be considered a measure to the progression of PD. The purpose of this research study is to better understand the mechanism of action regulations in PD patients and how action regulations in PD can be improved using dopaminergic treatment, which is a drug that either releases or involves dopamine, which is a neurotransmitter involved in sending signals to nerve cells. You are asked to participate in this research study because you are receiving a dopaminergic medication for treatment of your Parkinson's disease. There is currently no theory that integrates the mechanisms of action regulation into a unified framework, which this study aims to address. The researchers hope to learn more about the mechanisms of action regulation in PD patients and to help decrease action regulation disruptions in PD patients. This study will help characterize the motor behavior of PD patients.