Disorders afflicting the nervous system account for more hospitalizations, more long term care and more suffering than all other disorders combined (JAMA 285, 594-600, 2001). In most cases prevention and effective treatment are hampered by a lack of know ledge of the underlying pathogenetic mechanisms and how the various genetic, biochemical and physiological processes are interconnected. The present proposal concerns the hippocampal formation, wich is great importance and which is frequently involved in disease. Our consortium brings together a broad range of expertise, but in order to release our potential and make major advances in our research, we need access to transgenic animals, which have become a central tool for understanding biological functi ons of genes and gene products. Here we apply for funding to make use of The Norwegian Transgenic Animal Facility (which is organized by Stefan Kraus and Arne Klungland). We plan to make animals with genetic modifications in a number of genes to ablate select cell populations or alter the expression of potassium channels, glutamate transporters and growth factors. The effects of these modifications will be studied during development to senescence by applying imaging techniques, advanced databasing and 3-D reconstruction, electrophysiological techniques and studies of behaviour.