Dual topographic representation of neostriatum in the globus pallidus of rats.

Two spatially separate strio-pallidal axonal arborizations were demonstrated autoradiographically. One was restricted to an approximately 100 micrometer thick strio-pallidal border zone of pallidal neuropil and displayed a 2-dimensional topographical relationship with neostriatum. The second exhibited a 3-dimensional neostriatal representation throughout the remainder of the pallidal neuropil. Comparison to the axonal branching pattern of single strio-pallidal neurons suggests that these represent the two pallidal collateral arborizations made by axons of spiny neostriatal neurons.