Development of defensive burying in Rattus norvegicus: experience and defensive responses

Rats (Rattus norvegicus) deprived of the opportunity to interact with particulate matter until they were young adults engaged in defensive burying after they were shocked by a wire-wrapped dowel in a test chamber that held bedding material. Interacting with a particulate substrate during development is not necessary for the expression of defensive burying in adulthood. However, interacting with a particulate substrate early in the rats' lives did have a substantial effect on the emergence and maintenance of burying behavior. Defensive burying developed at a later age and declined at an earlier age in rats maintained on wire mesh from birth until testing than it did in rats raised until weaning on bedding and housed on mesh thereafter. Because defensive burying is a complex, flexible, yet reliable response sequence that cannot be performed without the appropriate substrate, it has considerable potential as a model for the study of the development of species-specific defense responses.