Paradigms for Behavioral Assessment in <i>Drosophila</i> Model of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) encompasses a heterogeneous group of neurodevelopmental disorders with common behavioral symptoms including deficits in social interaction and ability for communication, enhanced restricted or repetitive behaviors, and also, in some cases, learning disability and motor deficit. Drosophila has served as an unparalleled model organism for modeling a great number of human diseases. As many genes have been implicated in ASD, fruit flies have emerged as a powerful and efficient way to test the genes putatively involved with the disorder. As hundreds of genes, with varied functional roles, are implicated in ASD, a single genetic fly model of ASD is unfeasible; instead, individual genetic mutants, gene knockdowns, or overexpression-based studies of the fly homologs of ASD-associated genes are the common means for gaining insight regarding molecular pathways underlying these gene products. A host of behavioral techniques are available in Drosophila which provide easy readout of deficits in specific behavioral components. Social space assay and aggression and courtship assays in flies have been shown to be useful in assessing defects in social interaction or communication. Grooming behavior in flies is an excellent readout of repetitive behavior. Habituation assay is used in flies to estimate the ability for habituation learning, which is found to be affected in some ASD patients. A combination of these behavioral paradigms can be utilized to make a thorough assessment of the human ASD-like disease state in flies. Using Fmr1 mutant flies, recapitulating Fragile-X syndrome in humans, and POGZ-homolog row knockdown in fly neurons, we have shown quantifiable deficits in social spacing, aggression, courtship behavior, grooming behavior, and habituation. These behavioral paradigms are demonstrated here in their simplest and straightforward forms with an assumption that it would facilitate their widespread use for research on ASD and other neurodevelopmental disorders in fly models.