Origin and topography of thalamocaudate projections in the opossum

The origins of the thalamocadaute projections in the North American opossum include the intralaminar nuclei (parafascicular complex, the paracentral, centralis and central lateral nuclei) and the intermedial dorsal, medial dorsal and interanterior dorsal nuclei. Of these, portions of the intralaminar nuclei exhibit rudimentary elements of a topographically organized projection. However, it is obvious that the patterns observed here are much less specific than those reported in other mammalian species. We suggest that the question of topographic specificity may relate to the overlapping of sensory and motor representations in the neocortex.