Since its inception in 2002, the Centre for the Biology of Memory has provided insights into how spatial location and spatial memory are computed in the brain. Some of these insights confirmed and extended hypotheses outlined in the original Research Plan , but the most exciting discoveries were unexpected and only came about after modifications in the Research Plan that could not be envisaged when the proposal was written in 2001-02. For the second part of the Centre's lifetime, the ultimate goals remain unaltered, but priorities have changed and a number of new questions and techniques have surfaced. The Research Plan is meant to reflect these developments. The plan contains two main sections. The first pursues the original long-term aim of understanding the computational functions of hippocampal networks. Understanding the computational functions of the dentate gyrus and neurogenesis in this region will receive particular attention. New technology like viral transfection and gene silencing will be used to understand the function of specific cell classes in dentate gyrus and other hippocampal-entorhinal regions. The second section aims to establish the dynamics of the cortical network involved in the ongoing representation of location, based on the disco very of grid cells in the medial entorhinal cortex. The representation of spatial location has appeared as one of the first cognitive functions to be understood in mechanistic detail, and we wish to use the opportunities emerging from our recent discoveri es to understand general principles of computation in cortical microcircuits.