The retina is composed of many neurons that pre-process light stimuli before synapsing to the brain. To understand the function of different neurons, tracing neurons on a scanned image of a retina by hand is necessary to identify the neuron’s locations and synapses. Thresholding is an image processing technique that separates an image into two or more classes of pixels, simplifying an image and targeting specific structures. My goal is to create a tool to make annotation easier. I am coding a threshold program to generate binary images that will separate neurons from other surrounding neurons and the background. After generating these regions, I find their centers and approximate the region as a circle to match the style of annotations done by humans. To compare accuracies between machine and human, I compare overlapping areas between the circles created by machine and circles annotated by humans. I aim to have 80 percent accuracy in areas between the neurons annotated by a machine and neurons annotated by human annotators. Thresholding is a computationally simple process that can be applied with ease. A highly accurate threshold would make annotating quick and efficient, allowing for related studies to be conducted. Future work includes applying a threshold to a larger image and tracing a single neuron throughout a z-stack instead of identifying individual sections of neurons in a single image. 

The retina possesses an intrinsic circadian clock that synchronizes directly to light without input from the brain or visual photoreceptors. Previous research has shown that removing this clock affects photoreceptor health as an animal ages. Furthermore, disruptions to these circadian rhythms, which are increasingly common in modern lifestyles, may exacerbate retinal degenerative diseases such as Retinitis Pigmentosa (RP), a condition that leads to progressive vision loss and affects millions worldwide. Examples of circadian rhythm disruptions include cross-time-zone travel, the use of backlit devices, and social and work obligations. This study investigates the impact of chronic circadian dysregulation (chronic jet lag) on the progression of retinal degeneration in two murine models of RP. We hypothesize that stably synchronized circadian clocks protect against progressive retinal degeneration, while chronic disruption accelerates disease progression. We used three mouse models: a healthy wildtype, mice heterozygous for mild RP, and mice exhibiting retinal white deposits and degeneration. These mice were subjected to either a control lighting schedule or chronic jet lag beginning at one month of age. We assessed retinal health at multiple time points using fundus imaging to quantify white deposit area, immunohistochemistry staining to measure the thickness and depth of the outer nuclear layer (ONL) of the retina, and qRT-PCR to quantify the abundance of Rhodopsin and Opsin transcripts. We used ANOVA and Tukey post-hoc analyses to compare measured values among groups. The results of this experiment provide preliminary data that can inform research into RP models in other organisms and contribute to understanding the implications of chronic circadian desynchronization in the progression of RP in humans.