Anterior thalamic nucleus projections to the dorsal pallium in ranid frogs

Wheat germ agglutinin-horseradish peroxidase (WGA-HRP) applied in the anterior thalamic nucleus of ranid frogs was anterogradely transported to both the medial pallium and a ventral part of the dorsal pallium. Applications of WGA-HRP in the medial pallium labeled cells in the ipsilateral and contralateral anterior nucleus, including those considered to receive retinal input. An identical pattern of labeled cells was found in the anterior nucleus after WGA-HRP applications in the dorsal pallium. These results, combined with those of others, suggest that (1) the dorsal pallium has at least two subfields, (2) the dorsal pallium may receive a variety of non-olfactory sensory information, and (3) receipt of a disynaptic pathway from the retina may not determine isocortical homology among pallial fields in anurans.