Analysis of the Conduction of Information and Its Integration in the Projection Systems Connecting the Basal Ganglia and the Rostromedial Tegmental Nucleus of the Dog Brain

Abstract

Analysis of retrograde axonal transport studies of the projections between individual parts of the rostral and caudal sectors of the rostromedial tegmental nucleus (RMTg) and functionally diverse segments of striatal and pallidal structures was used to study the structural basis of information processing in the morphofunctional system of the basal ganglia. Topical elements were seen in the organization of the projections between these structures in the dog brain, suggesting the possibility of segregated conduction of information between the limbic segments of the RMTg and the limbic areas of the striopallidum. However, most striopallidal structures showed convergence of projection fibers running from neurons in functionally diverse parts of the RMTg, which may be evidence that functionally diverse information is integrated within these structures. Labeled sparsely branching, long-axon, “reticular” neurons of the RMTg projecting to striopallidal structures also provided evidence of the integrative function of the nucleus of interest. We evaluate data on the possible pathways conducting specific motor and limbic information and its integration in the structures of this system and the possibility of using them to create new models promoting our understanding of the functioning of the basal ganglia in health and disease.