An Autoradiographic Study of Visual Pathways of the Australian Rodents Notomys Alexis, Pseudomys Australis and Rattus Villosissimus.

Abstract

In three species of Australian rodents, Notomys alexis, Pseudomys australis and Rattus villosissimus, primary optic centres were mapped by observing the distribution of autoradiographic label in the brain following injection of one eye with 3*H-proline or 3*H-leucine. Five regions receive a primary optic input in the three species: the lateral geniculate complex, the pretectum, the superior colliculus, the hypothalamus and the three terminal nuclei of the accessory optic system. The retinal projections are generally similar in the three species, except that in N. alexis and P. australis the dorsal lateral geniculate nucleus (LGNd) is subdivided into two, and the pattern of ipsilateral retinal input to it is similar; but in R. villosissimus the LGNd is not apparently subdivided, and the pattern is slightly different. It is concluded that the pattern of primary optic inputs is likely to be similar in other Australian rodents. Two secondary optic centres were shown in Notomys alexis, using the method of transneuronal transport of 3*H-proline. Autoradiographic label was observed in the visual cortex and in the parabigeminal nucleus 20-25 days after eye injection.