Semester

Summer

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

Eric Horstick

Committee Co-Chair

Sadie Bergeron

Committee Member

Sadie Bergeron

Committee Member

Jennifer Gallagher

Abstract

Long-term internal states drive many behaviors in animals. Zebrafish is a common vertebrate model conducive to finding the neural coding to these behaviors. In the Horstick lab, the larval zebrafish light search behavior is central to our research. This behavior, which is the locomotor response to the loss of light in larval zebrafish, is controlled by multiple neural populations that drive different internal states. The sensory neurons initially responsible for this behavior are photosensitive due to the expression of light-absorbing proteins called opsins. Opsins vary in the ranges of wavelengths of light that they absorb, and are expressed in distinct photoreceptor populations in the retina and the central nervous system of the zebrafish. The presence of these discrete photoreceptor types and the fact that other light-mediated behaviors in zebrafish are modulated by wavelength presents the possibility that the zebrafish light search behavior is wavelength-sensitive. In this thesis, I present a series of experiments performed on larval zebrafish that ascertain the wavelength-sensitivity of the light search behavior, and discuss possible conclusions and significances of the project. Additionally, I showcase several other projects relating to zebrafish behavior I contributed to in the appendices at the end of the thesis. Overall, this thesis highlights how even subtle changes to sensory stimuli can have broad impacts to behavior, and espouses the usefulness of zebrafish in exploring visual behaviors and the neural anatomy that drives them.

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