Quantification of Drosophila melanogaster Grooming Behavior for Evaluation of Excessive Grooming Phenotypes

Observable changes in stereotyped grooming are applied translationally in model organisms. These changes are representative of pathologies that elicit similar deviations in human behavior; for example, excessive grooming acts as a proxy for obsessive and compulsive behaviors present in conditions like Tourette Syndrome or obsessive-compulsive disorder. The grooming assay presented allows for the evaluation of abnormal self-grooming phenotypes in Drosophila melanogaster. Flies are recorded for a period of 10 min, and these recordings are observed and annotated blind for previously defined grooming behaviors. Quantitative measures of both grooming bout frequency and the time spent engaging in self-grooming can be obtained by manually annotating the footage. The assay is relatively inexpensive, requires few materials not already available in laboratory environments, and is easily adaptable to fit the specific needs of any given study aiming to observe grooming. Additionally, the low level of skill needed to perform the assay, as compared to computer science-heavy automated methods, makes the protocol well-suited for small labs and students. We discuss in detail the steps required to perform this assay and its present limitations.