Date of Award

Spring 5-2020

Document Type

Undergraduate Honors Thesis

Degree Name

Bachelor of Arts in Behavioral Neuroscience


Psychological Sciences


Dr. Veronica Galván


Understanding the neural processes that mediate decision making is a relatively new field of investigation in the scientific community. With the ultimate goal of understanding how humans decide between one path and another, simpler models such as Drosophila Melanogaster, the common fruit fly, are often utilized as a way of determining the neural circuits involved in these decision-making processes. One of the most important decisions flies make is the decision of where to lay their eggs (oviposit). Choosing the proper substrate upon which to lay eggs is a crucial decision that can ultimately impact their fecundity. This paper investigates the field of decision-making neuroscience research previously conducted in order to provide background information and point out the void that my research is attempting to fill. In conducting research, I first began by collecting data on the number of eggs laid by wildtype flies on each substrate type (sucrose, yeast, combination, or plain) within the 20 chamber two-choice preference assay. Following this, the same procedure was conducted using dopamine knockout flies created by crossing KIR2.1 genetically encoded flies with specific dopamine output neurons which inhibited their function. Our lab found that wildtype flies prefer yeast and avoid sucrose. They also tend to choose a plain substrate in Plain vs. Sucrose-Yeast. Though the genetically altered flies also prefer plain, a significant decrease in preference was observed in four of the mushroom body output neuron lines (057B, 027C, 542B, 543B) indicating that these lines may play a more significant role in determining this preference for Plain over Sucrose-yeast. These neurons that mediate crucial decisions for fruit flies can hopefully one day be correlated to the dopamine neurons in the human brain that help us make simple, everyday decisions and even life-changing decisions such as where to settle down someday and lay our own eggs.