Three-dimensional organization of the recurrent axon collateral network of the substantia nigra pars reticulata neurons in the rat.

The substantia nigra pars reticulata (SNR) constitutes a major output nucleus of the basal ganglia where the final stage of information processing within this system takes place. In this study, using juxtacellular labeling and three-dimensional reconstruction methods, we investigated the spatial organization of the intranigral innervation provided by single GABAergic projection neurons from the sensory-motor subdivision of the rat SNR. Confirming previous observations, most labeled SNR cells were found to possess a local axonal network innervating the pars reticulata and pars compacta (SNC).