Using mice as a model organism for the study of communication and social behavior
Date
2020
Authors
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Publisher
University of Delaware
Abstract
Communication is vital for the success of numerous animal species. Animals communicate about predators, to coordinate behavior, and to indicate fitness and reproductive interest to potential partners. As the neural circuitry underlying communication is thought to be well conserved between humans and other animals, animal models have become a means by which to study the mechanisms underlying communication and communication impairments in humans. Mice are an ideal model, as they are highly social creatures that emit vocalizations while engaged in social encounters. Mice are also highly tractable, meaning that we can alter mice genetically in ways to match humans with communication disorders, and subsequently determine the exact role of individual genetic alterations in producing communication deficits. Leveraging this ability, our lab records groups of mice during unrestrained social interaction to measure both individual behavior and group dynamics. This method of recording allows us to assess how mice interact in a naturalistic group setting, and whether that behavior is perturbed in mouse models of disorder. ☐ Chapter 1 of this dissertation provides background on social communication, as well as the utility of studying mice as a model of social communication. Specifically, this chapter outlines the foundation for the use of mouse models as genetic models of autism spectrum disorders. This chapter also outlines our current knowledge about the role of mouse vocalizations in coordinating behavior in mice. ☐ As both studies contained within this document used the same behavioral setup and recording equipment, Chapter 2 of this dissertation outlines the methodology used in both Chapters 3 and 4. ☐ Chapter 3 of this dissertation outlines our study of mouse models of autism in while mice are allowed to freely socialize. This chapter elucidates the role of our novel paradigm as a tool to provide a thorough quantification of well-established facets of autism-like behaviors in two different genetic mouse models of autism. Using traditional metrics of autism-like behavior in mice, we found that one model showed a strong autism-like behavioral phenotype; the other did not. However, we next generated a metric to quantify the autism-like behavior of individual mice. This showed that individual mice of both autism-like models showed strong autism-like behavioral phenotypes. We also found that engagement in other, non-autism associated behaviors was impacted by these genetic alterations. However, regardless of a male’s behavioral profile, we found that all four genotypes of mouse emitted the same types of vocalizations while engaged in the same behavioral contexts. Thus, the chapter outlines a novel methodology for assessing autism-like behavior in mice, allowing us to quantify autism-like behavior at the level of individual animals, while also indicating a ubiquity in context-dependent vocal emissions across mice. ☐ Chapter 4 of this dissertation outlines our study on the role of mouse ultrasonic vocal emission in coordinating and changing behavior between pairs of mice. While previous research is mixed on the role of USVs in mouse behavior, our lab has shown that mice emit specific vocalization types while engaged in specific behaviors, and that hearing these vocalizations is tied to immediate changes in a mouse’s speed. This chapter extends these findings by assessing the role of hearing vocalizations on coordinating behavior: if vocalizations are necessary to alter instantaneous behavior, then deaf mice should not show immediate speed changes that are tied to vocalizations. However, we found that this was not the case. Mice, irrespective of hearing ability, showed similar patterns of behavior when a vocalization was emitted by a social partner. Thus, the findings of this chapter indicate that USVs are not sufficient to alter the instantaneous behavior of mice while engaged in numerous types of social behavior. ☐ Chapter 5 elucidates the findings, limitations, and possible implications of the data collected and analyses applied for this dissertation. ☐ The data presented here have provided a framework to evaluate the role of mouse vocal activity as a means of communication in social engagements. Together, these studies work to progress the use of mice as models of communication and communication disorders.
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Keywords
Autism, Mouse models, Vocal emissions, Mouse ultrasonic, Mice