MICE EXPRESSING ACTIVATED CAMKII LACK LOW-FREQUENCY LTP AND DO NOT FORM STABLE PLACE CELLS IN THE CA1 REGION OF THE HIPPOCAMPUS

To relate different forms of synaptic plasticity to the formation and maintenance of place cells in the hippocampus, we have recorded place cells in freely behaving, transgenic mice that express a mutated Ca2+- independent form of CaM Kinase II. These mice have normal long-term po tentiation (LTP) at 100 Hz, but they lack LTP in response to stimulati on at 5-10 Hz and are impaired on spatial memory tasks. In these trans genic mice, the place cells in the CA1 region have three important dif ferences from those of wild types: they are less common, less precise, and less stable. These findings suggest that LTP in the 5-10 Hz range may be important for the maintenance of place-field stability and tha t this stability may be essential for the storage of spatial memory.