WHISKER-RELATED NEURONAL PATTERNS FAIL TO DEVELOP IN THE TRIGEMINAL BRAIN-STEM NUCLEI OF NMDAR1 KNOCKOUT MICE

Sensory pathways of the brain generally develop from crudely wired net works to precisely organized systems. Several studies have implicated neural activity-dependent mechanisms, including N-methyl-D-aspartate ( NMDA) receptors, in this refinement process. We applied the gene targe ting to the NMDAR1 gene and created a mutant mouse that lacks function al NMDA receptors. The development of whisker-related patterns in the trigeminal nuclei of the mutant mice and their normal littermates was compared. We show that in the mutant mice pathfinding, initial targeti ng, and crude topographic projection of trigeminal axons in the brains tem are unaffected, but that whisker-specific patches fail to form. Ou r results provide a direct demonstration of the involvement of the NMD A receptor in the formation of periphery-related neural patterns in th e mammalian brain.