The medial temporal lobe (MTL) memory system consists of the hippocampus and adjacent cortical structures (i.e., entorhinal, perirhinal, and parahippocampal cortices) that are critical for forming and retrieving long-term declarative memories. As a convergence site for highly processed, multimodal input the hippocampus is ideally suited to bind together the relations among perceptually distinct items. Conventional theories suggest that the hippocampus does not contribute to working memory maintenance, but recent research suggests that the hippocampus may be necessary for short-term maintenance of relational information. A second unresolved issue in the literature is whether different MTL subregions make qualitatively different contributions to memory. The proposed experiments use event-related functional magnetic resonance imaging to test: (1) whether the hippocampus is recruited when memory for arbitrary relations must be maintained in working memory, and (2) whether different MTL subregions are involved in encoding of item and relational memory, respectively. ? ? ?
