ABSTRACT
RATIONALE: An increasing number of investigators utilize the marble-burying assay despite the paucity of information available regarding what underlies the behavior. OBJECTIVES: We tested the possibility that a genetic component underlies marble burying in mice and if there is a genetic correlation with other anxiety-like traits. Since findings reported in the literature indicate that marble-burying behavior reflects an anxiety-like response, we explored the assumption that the novel nature of a marble induces this anxiety. Finally, we investigated how the natural response of a mouse to dig relates to the marble-burying phenomenon. METHODS: We examined ten different inbred mouse strains to determine if marble-burying behavior is genetically regulated and correlated with anxiety-like traits in two other assays. We employed multiple variants of the "traditional" marble-burying assay to address how issues such as the novelty of marbles and digging behavior contribute to marble burying. RESULTS: Marble-burying behavior varied across strain and did not correlate with anxiety measures in other assays. Multiple tests conducted to reduce the novelty of marbles failed to alter burying behavior. Additionally, digging behavior correlated with marble burying, and the presence of marbles did not significantly impact the digging response. CONCLUSIONS: Our results indicate that mouse marble burying is genetically regulated, not correlated with other anxiety-like traits, not stimulated by novelty, and is a repetitive behavior that persists/perseveres with little change across multiple exposures. Marble burying is related to digging behavior and may in fact be more appropriately considered as an indicative measure of repetitive digging.
