Importance of strain differences in evaluations of learning and memory processes in null mutants

Complex behaviors such as learning and memory are regulated by multigenic systems. The advent of new animal models created by recombinant DNA technology has provided a set of genetic tools whereby the role of specific candidate genes in acquisition and retention of new information can be examined. These techniques include the creation of null mutant mice. Because of the polygenic nature of complex behaviors, the impact of single gene manipulations will in part depend on the genetic background of the mouse. This review addresses the relationship of endogenous strain differences in complex learning performance using a number of learning and memory paradigms to the analyses of null mutants. Limitations to the current technology and possible future advances are discussed.