THE PREGLOMERULAR NUCLEUS OF GYMNOTIFORM FISH - RELAY STATION FOR CONVEYING INFORMATION BETWEEN TELENCEPHALON AND DIENCEPHALON

The preglomerular nucleus of teleost fishes, believed to be a lateral part of the posterior tuberculum in the diencephalon, receives input f rom several sensory areas. By employing an in vitro technique, the pat tern of connectivity between this cell group and the telencephalon has been explored through retrograde and anterograde tracing in the gymno tiform fish Apteronotus leptorhynchus. Neurons of the preglomerular nu cleus project to the following telencephalic areas: central division o f dorsal forebrain, dorsal subdivision of dorsolateral telencephalon, posterior subdivision of dorsolateral telencephalon, dorsal posterior telencephalon, and probably, also subdivision 2 of dorsomedial telence phalon. Experiments in which tracer application was restricted to the lateral subdivision of the preglomerular nucleus, or in which tracer s ubstance was placed into various regions of the telencephalon revealed a differential projection pattern of cells in the lateral and the med ial subdivision of the preglomerular nucleus. Neurons in the central d ivision of the dorsal forebrain, the dorsal posterior telencephalon, a nd likely, also in the subdivision 2 of the dorsomedial telencephalon and the ventricular zone of the intermediate subdivision of the ventra l telencephalon project back to the preglomerular nucleus. Thus, a maj or function of the preglomerular nucleus appears to be to act as a rel ay station for conveying information between diencephalon and telencep halon. (C) 1997 Elsevier Science B.V.