An understanding of the fundamental behavioral and neural processing mechanisms underlying higher order memory depends critically on animal models of human amnesia, yet the development of a valid model has not been fully realized because of the differences in the conceptualizations of cognitive processes and in the neuroscientific approaches to memory research on humans and animals. In our view, these differences can be bridged through a comparative neuroscience approach. Our aim is to develop a rodent model of memory capacities heretofore generally recognized only in humans by identifying psychological processes that both characterize human performance and are observable in animal behavior. At the same time, our perspective addresses evolutionary differences in the expression of memory by animals and humans by exploiting the superb olfactory learning and memory abilities of rats. If successful, our approach may lead to modifications in memory assessments aimed towards understanding and, ultimately, treating disease conditions that have been associated with dysfunction of the hippocampal system, including Alzheimer's disease, schizophrenia, and autism. Guided by current theoretical conceptions of human amnesia, we will develop new behavioral paradigms that dissociate impaired and preserved learning capacities in animals with hippocampal-system damage. Our characterization of this dissociation is that the hippocampal system mediates declarative memory, a representation of significant relations among items in memory that supports a capacity for the flexible use of memories in novel situations. The proposed experiments will serve to further specify our working hypothesis. We will develop little-studied and new behavioral paradigms that test the capacity for relational judgements not dependent on memories for specific items, memory for relations among specific odor items, and learning and using organized odor-memory representations. We will use these paradigms to assess the extent to which normal rats and rats with hippocampal system damage can perform these tasks and can use their memory representations in novel situations. In other experiments designed to delineate the pathway required for odor learning and memory, we will compare the effects of selective lesions within the hippocampal system. In addition to testing our own views, the proposed work will provide new empirical data that will require an accounting by any successful theory of amnesia and hippocampal function. Our hope is to generate new results that will contribute to an account of memory that crosses the boundaries separating current descriptions of memory in different species.