PROJECT SUMMARY
Visual system dysfunction is a common and debilitating comorbidity for individuals diagnosed with a variety of
neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD), schizophrenia, and
attention deficit hyperactivity disorder. The microbiome is emerging as an important determinant of brain
development, and recent research links these NDDs to intestinal dysbiosis, suggesting that a normal
microbiome is a necessary component of typical brain neurodevelopment and function. To further connect
these issues, microbial dysbiosis is also frequently associated with visual system dysfunction, yet practically
nothing is known about the mechanisms by which the microbiota impacts visual system development.
Therefore, a greater understanding of the dynamics between host and microbiome, including the specific
cellular pathways and microbial products influencing neurodevelopment, is needed before effective treatments
can be pursued. In this proposal, I will test the hypothesis that normal development of the visual system
depends on sensing of specific secreted bacterial factors by specific cell types that mediate
communication between the intestinal microbiome and the brain. To accomplish this, I will use the
gnotobiotic zebrafish model to investigate how the microbiome interacts with intestinal cells and peripheral
neurons to impact early visual neurodevelopment. This is a simple but powerful model system because it
allows us to test the role that individual bacterial species and their byproducts play in neurodevelopment. I will
use three approaches to determine the role specific host cell types and secreted bacterial products play in
visual system development and its downstream behavioral output. Aim 1 tests the hypothesis that the
microbiota is required for the normal development and function of a set of superficial interneurons involved in
prey capture behavior. Aim 2 investigates the role of gut epithelial sensory cells and the vagus nerve in
sensing bacterial products and relaying this information to promote visual system development. In Aim 3, I will
identify the active product secreted from a gut bacterium that is sufficient to promote visual system
development. These approaches allow an unbiased identification of the anatomical locations, cell types, and
signaling pathways that relay microbial cues required for normal development of the visual system and its
behavioral outputs. This work is significant because it lays the foundation for understanding mechanisms
behind visual comorbidities associated with neurodevelopmental disorders like ASD, and ultimately serves to
better inform intervention and treatment, and to one day prevent these complex NDDs and their associated
comorbidities.