Deoxyglucose analysis of the specific topographic functional interrelations between substantia nigra and globus...

The response of the ipsilateral globus pallidus (GP) to unilateral electrical stimulation of the substantia nigra reticulata (SNr) was studied in the rat, by the autoradiographic [14C]-deoxyglucose method. Different compartments within the GP were metabolically activated, depending on the localization of the electrically stimulated subregions within the SNr. Computer generated, quantified colour coded glucograms were used for the analysis of specific topographic organization of the pallido-nigral functional system. Stimulation of the medial or lateral segments within the SNr induced activation in the medial or lateral compartments of the GP, respectively. Stimulation of the dorsal or ventral subregions within the SNr elicited activation in the ventral or dorsal compartments of the GP, respectively. Activation of the medial or lateral GP compartments was independent of stimulation in the dorsal or ventral SNr segments and vice versa. These results suggest that the topographic interrelations between the substantia nigra and the globus pallidus are characterized by preservation of the mediolateral and inversion of the dorsoventral functional correspondence. The neuronal territory involved into this topographic organization is suggested to consist of the subthalamic and striatal nerve cells projecting collateral axons to both the SNr and the GP.