Browsing by Author "Stednitz, Sarah"
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Item Open Access The Social Brain of Zebrafish(University of Oregon, 2020-02-27) Stednitz, Sarah; Washbourne, PhilipSocial behavior is arguably one of the most complex forms of behavior exhibited by animals. It requires active attention to dynamic multisnsory cues, recall of past experiences, and the generation of situationally appropriate responses. Given the swath of different cognitive systems required, it is unsurprising that social behavior is disrupted in many neurological disorders. Autism spectrum disorders (ASD) are particularly notable, as social impairment is a required diagnostic criteria. Efforts using animal models to both understand the etiology and improve behavioral outcomes for human ASD patients are complicated by the difficulty of replicating the genetic environmental causes. Similarly, measuring deficits in complex behaviors like social interaction is challenging and their neuroanatomical correlates are not yet fully described. To address these issues, I utilized the highly social and genetically tractable zebrafish (Danio rerio) as a model system. I developed a novel assay that shows social engagement requires a behavioral visual stimulus provided by another socially-engaged fish. I demonstrated that both pharmacological manipulation of dopaminergic systems and ablation of a portion of the ventral telencephalon produce predictable deficits in social behavior. Our results also provide evidence that an as yet uncharacterized population of cholinergic neurons in the ventral forebrain are critical for social interactions in zebrafish. This region corresponds to mammalian forebrain regions implicated in social behavior, suggesting an evolutionarily conserved population of cells may drive social orienting in zebrafish and mammals. Further, I identified the time points in early development when specific social behaviors are first observed, suggesting a progressive acquisition of increasingly complex social behaviors over a rapid timescale. This highly variable and early stage in development represents an opportunity to further understand how genetic and environmental factors affect the assembly of the neural circuits underlying complex behaviors.Item Open Access The Influence of Sensory Conditions on Social Behavior and Brain Activity of Zebrafish(University of Oregon, 2020) Fecker, Adeline; Stednitz, Sarah; Washbourne, Phil; Washbourne, PhilDisruption in social behavior is characteristic of Autism Spectrum Disorder, a neurodevelopmental disorder that appears in early childhood. Previous experiments in zebrafish showed lesioning of the ventral forebrain reduced social engagement. Results also suggested subjects must be able to see each other to socialize (Stednitz, 2018). Subsequent experiments demonstrated that zebrafish can interact without vision, perhaps using their other senses like the water-pressure mechanosensory and olfactory systems. Our study investigates how sensory modalities contribute to social behavior. Measuring behavior in an open field allows for quantification of complex social behaviors like orienting, following, and dispersing. We manipulated sensory modalities by recording behavior in the dark and mechanosensory ablated conditions. Our results show the loss of the visual input causes a significant 43.3% reduction in orienting behaviors and a 52% reduction in following behavior. When we ablate visual input and mechanosensation, we do not observe a reduction in orienting or following behaviors. Another outstanding question is which brain regions are activated during social behavior by the contributing senses. We use whole brain immunolabeling with neuronal activity markers as an unbiased approach to identifying and quantifying active brain regions in social and alone conditions. We found the posterior pallium of the forebrain is more active in social than alone conditions. Visual ablated fish had a 44.1% decrease in total telencephalon activity compared to controls. Our study of behavior and corresponding brain activity sheds light on the importance of vision in social behavior and forebrain activity of zebrafish.