Degree Name

Department

Plant and Wildlife Sciences

College

Life Sciences

Defense Date

2023-03-10

Publication Date

2023-03-17

First Faculty Advisor

Arminda Suli

First Faculty Reader

Jonathon Hill

Honors Coordinator

Craig Coleman

Keywords

optic tectum, zebrafish, optogenetics, multisensory, deep brain photoreceptor, neuroscience

Abstract

Deep brain photoreceptors (DBPs) are light sensing neurons present in mammals and non-mammalian vertebrates. In non-mammalian vertebrates, studies have shown DBP involvement in various time and light dependent behaviors including circadian rhythm, phototaxis, and seasonal reproduction. In adult teleosts, DBPs are present throughout the brain, including the optic tectum (OT), a multilaminated midbrain structure responsible for multisensory integration. While their approximate location in teleosts is known, little is known about DBP’s functionality. In this study, we focused on DBPs present in the larval zebrafish OT. Single-cell RNA sequencing of the larval zebrafish OT showed the presence of several opsins. We focused on opsins that respond to the violet-blue light range - one typical of optogenetic studies. To identify neurons with similar activation patterns following light stimulation, we used live calcium imaging to detect brain activity, followed by watershed segmentation and k-means clustering. Preliminary data comparing

the activity patterns following presentation of light stimuli to control and larvae whose eyes have been removed indicate the presence of two different groups of opsin responding neurons: one that activates independently of retinal innervation consistent with a DBP identity, and another that activates more frequently when the visual system is intact, suggesting they receive both retinal and DBP inputs.