An autoradiographic study of the postnatal development of pericruciate cortical projections to the neostriatum and the claustrum of the cat

Abstract

The postnatal development of corticostriatal and corticoclaustral projections was traced by light-microscopic autoradiography following injections of tritiated proline and leucine into the pericruciate cortex of kittens, 2-56 days of age, and adult cats. A medial-lateral topography of the corticostriatal pathways was present at birth, with a smaller and more restricted projection arising from the lateral pericruciate region. During postnatal development, the volume of the ipsilateral caudate nucleus filled by labelled corticostriatal fibers was reduced by 30% and these projections became constricted within the dorsolateral head and body of the caudate nucleus. During the first postnatal week, terminal fields were diffuse but lacked homogeneity since irregular patches of intensely labelled elements clustered near the internal capsule. By the end of the first month, a fenestrated organization became apparent within the caudate nucleus where elongated clusters of intensely labelled fibers radiated from the internal capsule and partially or completely surrounded islands of neuropil virtually devoid of label. Pericruciate inputs were confined to the dorsal parts of the rostral putamen and claustrum and the patchy nature of these terminal fields was limited to small labelled clusters close to the capsular margins. Contralateral terminal fields were labelled less intensely and occupied areas symmetrical to those within the ipsilateral neostriatum and claustrum.