IMPAIRED HIPPOCAMPAL REPRESENTATION OF SPACE IN CA1-SPECIFIC NMDAR1 KNOCKOUT MICE

To investigate the role of synaptic plasticity in the place-specific f iring of the hippocampus, we have applied multiple electrode recording techniques to freely behaving mice with a CA1 pyramidal cell-specific knockout of the NMDAR1 gene. We have discovered that although the CA1 pyramidal cells of these mice retain place-related activity, there is a significant decrease in the spatial specificity of individual place fields. We have also found a striking deficit in the coordinated firi ng of pairs of neurons tuned to similar spatial locations. Pairs have uncorrelated firing even if their fields overlap. These results demons trate that NMDA receptor-mediated synaptic plasticity is necessary for the proper representation of space in the CA1 region of the hippocamp us.