Two thalamo-telencephalic pathways in a urodele, Triturus alpestris

Ascending thalamo-telencephalic projection systems have been investigated in an urodele, Triturus alpestris, using the horseradish peroxidase technique. Two separate dorsal thalamic projections onto the telencephalon have been identified; one arises from the posterior dorsal thalamus and terminates in the ipsilateral striatum, the other originates from anterior dorsal thalamic cells and reaches the medial pallium and a part of the dorsal pallium bilaterally. Both systems, which are spatially well segregated, might carry visual information to the telencephalon, as the posterior dorsal thalamus receives tectal, and the anterior dorsal thalamus direct retinal input. The urodele projection scheme as described here shows great similarities to the one described in anurans, although there are remarkable cytoarchitecture differences between the anuran and the urodele thalamus.