Habenular connections in the brain of the newt, Triturus cristatus carnifex Laurenti

The connections of the habenular complex have been studied in the crested newt (Amphibia Urodela) by means of degeneration and HRP transport techniques. With the Fink-Heimer method, habenular efferents have been traced to the basal telencephalon, the pallium, the stria medullaris, the dorsal and ventral thalamus, the preoptic and anterior hypothalamus, the fasciculus retroflexus, the tegmentum and the interpeduncular neuropil. Anterograde transport of HRP by habenular neurons reveals fibers projections to the thalamus, the fasciculus retroflexus and the interpeduncular neuropil. After HRP injections in the habenulae, retrograde labelling of cells and fibres was observed, in the striatum, the posterior pole of the telencephalon, the thalamus, the preoptic area, the tegmentum and the raphe. The present results indicate that the habenular complex of the newt receives inputs of various sources (striatum, thalamus, hypothalamus, tegmentum) and is less directly involved in the olfactory functions.