First, the information represented in the primate hippocampus, and what is computed by the primate hippocampus, are considered. Then a theory is described of how the information represented in the hippocampus is able to influence the cerebral cortex by a hierarchy of hippocampo-cortical and cortico-cortical backprojection stages. The recalled backprojected information in the cerebral neocortex could then be used by the neocortex as part of memory recall, including that required in spatial working memory; to influence the processing that each cortical stage performs based on its forward inputs; to influence the formation of long-term memories; and/or in the selection of appropriate actions.