Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Anatomy and Cell Biology

Supervisor

Allman, Brian L.

Abstract

To perceive the environment, the brain naturally merges related visual and auditory signals. The neural mechanisms underlying this ability remain elusive, in part, due to a lack of suitable animal models to conduct translational studies. Thus, we set out to develop and validate rat models of audiovisual temporal perception; important first steps toward conducting mechanistic studies. Rats were trained to report whether an auditory or visual stimulus was presented first (i.e., temporal order judgment; TOJ task), or whether auditory and visual stimuli were synchronous or asynchronous (i.e., synchrony judgment; SJ task). Afterward, rats were tested for perceptual malleability and susceptibility to disruption, important characteristics in human literature. While both models showcased those characteristics, the TOJ task appeared more consistent with humans. To conclude, the present behavioural tasks are the only complete and valid animal models in the field of audiovisual perception, which will lay the foundation for future mechanistic studies.

Summary for Lay Audience

To perceive the environment, the brain naturally combines related visual and auditory signals. The brain circuits responsible for this process are relatively unknown due to the limitations of research on humans. Therefore, to gain a better understanding of these circuits, animal models are needed to carry out invasive studies. Thus, we set out to develop and validate rat models of behaviour that show the rats' perception of visual and auditory signals; important first steps towards uncovering the brain circuits through invasive studies. To do so, rats were trained to report whether a sound or light was presented first (i.e., temporal order judgment; TOJ task), or whether a sound and a light were presented at the same time or at two different times (i.e., synchrony judgment; SJ task). Then, the rats' performance on these tasks was tested to examine if their perception was malleable and can be disrupted through external factors; two characteristics commonly seen in human studies. Based on our results, both models showed these characteristics; however, the rat TOJ task was more consistent with what is observed in human studies. To conclude, the behavioural tasks developed and presented in this thesis are the first of their kind to assess an animal’s perception of how the brain combines visual and auditory signals. Looking forward, these models will provide the foundation for investigating the brain circuits responsible for combining visual and auditory information.

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