Graduation Date

Summer 2021

Document Type



Master of Arts degree with a major in Psychology, option Academic Research

Committee Chair Name

Dr. Ethan Gahtan

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Amanda Hahn

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Christopher Aberson

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories



Parkinson’s disease (PD) is a neurodegenerative disease that progressively decreases dopaminergic function. Lower amounts of dopamine may cause an innate motivational shift that decreases movement vigor when performing difficult tasks. In PD patients, bradykinesia, the slowing of movement, is characteristic of this decrease in vigor. The movement vigor hypothesis proposes that dopamine neurons modulate performance aspects of movement, like speed and persistence. This paper proposes a series experiments utilizing neuron recording techniques in zebrafish that would test the movement vigor hypothesis by determining whether in fact there is a distinct group of dopamine neurons that modulate movement vigor. Core elements of the human dopamine motor system are shared by all vertebrates, so zebrafish are a valid model system for studying dopamine’s role in controlling movement vigor. The zebrafish behavior used to study vigor in the proposed experiments is a dive response to a sudden decrease in ambient illumination (dark flash evoked dive). This behavior is remarkably persistent, and its duration, speed and distance will be used to quantify the vigor components of movement. In humans, dopamine deficits affect movement vigor particularly when there is an expectation that the required movement will be difficult. Therefore, zebrafish will be trained to perform easy (short) or difficult (longer) dives, and dopamine neuron activation will be compared across those conditions to identify neurons whose activity correlates with vigor level. If vigor related neurons are identified, subsequent experiments will test whether they are necessary for normal modulation of movement vigor.

Citation Style