The representational-hierarchical view of amnesia: translation from animal to human

Animal research has, in our opinion, made an invaluable contribution to our understanding of human amnesia. In this article we summarise our and others' work in this area, focusing on a new view of amnesia we refer to as the representational-hierarchical view. According to this view-and in contrast to the prevailing paradigm in the field-the brain is best understood as a hierarchically organized continuum of representations, each of which is useful for a variety of cognitive functions. We focus our review on four visual discrimination paradigms that have been successfully translated into the human arena: configural concurrent discriminations, pair-wise "morph" discriminations, oddity discriminations, and configural oddity discriminations. The data from the animal studies are first reviewed, followed by illustrations of how the tasks have been utilized in human research. We then turn to the canonical impairment in animal models of amnesia, object recognition, and show how impairments in object recognition can be understood within the representational-hierarchical framework. This is followed by a discussion of predictions of the view related to classic issues in amnesia research, namely whether amnesia is due to a deficit of encoding, storage or retrieval, and the related issue of the role of interference in amnesia. Finally, we provide evidence from animal and human studies that even the hippocampus-almost universally regarded as a module for memory-may be better understood within the representational-hierarchical paradigm.