Rostral Putamen Research Articles

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

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.

Widespread corticostriate projections from temporal cortex of the rhesus monkey.

The corticostriate projections of temporal areas TA, TE, TF, TG, 35, and 28 were studied in the rhesus monkey with the use of autoradiography. Widespread projections were observed to rostral as well as caudal parts of the striatum for all areas except area 28. For example, areas TA and TG have sizable projections to the medial or periventricular part of the head of the caudate nucleus, as well as to the medial part of the tail of this structure and the dorsally adjacent putamen. Areas TE and TF also were observed to send strong projections to the head of the caudate nucleus. In addition, they project to the rostral putamen. Both have projections to the tail of the caudate nucleus and caudal putamen. The widespread distribution of temporostriate axons to the rostral striatum suggests strongly that previous silver impregnation studied have not only underestimated the strength of the temporal cortical contribution to the corticostriate system, but also failed to identify the major projection zone of temporostriate axon terminals. For example, while all temporal cortical areas contribute projections to an organized topography in the tail of the caudate nucleus and the ventrocaudal putamen, they were observed consistently to have larger projections to the head of the caudate nucleus and rostral putamen. These results add to a growing body of evidence which demonstrates the existence of widespread nonmotor cortical input to the basal ganglia, and an organization of this input far greater in complexity than that demonstrated by earlier suppressive silver impregnation methods.

The nigrostriatal projection in the cat: Part 1. Silver impregnation study

The course and destination of the degenerating nigrostriatal fibers were studied by selective silver impregnation methods in 37 cats with unilateral lesions in the substantia nigra. The nigrostriatal fibers ascend along the dorsomedial border of the substantia nigra to the prerubral area; they proceed for a short distance through the lateral hypothalamus, enter the medial part of the internal capsule and run in a dorsorostral direction to reach the head of the caudate nucleus and the rostral portion of the putamen. A smaller number of degenerating fibers obliquely cross the peduncular part of the internal capsule and traverse the entopeduncular nucleus and the pallidum to terminate in the central and caudal portions of the putamen. Some features of the topical distribution of the nigrostriatal tract are described. Apparently, the more anterior part of the pars compacta sends axons primarily to the head of the caudate nucleus and to the most rostral putamen. The most medially situated nigral neurons project to the fundus striati. The posteromedial cell groups of the pars compacta innervate primarily the central putamen and the caudal part of the caudate nucleus. The projection of the lateral cell group of the posterior zona compacta to the caudal putamen is sparser than from the other nigral groups, suggesting that a part of them has another destination, possibly lower in the neuraxis. The contribution of the pars reticulata to the nigrostriatal connections seems to be modest, according to the small number of neurons; they project to the lateral caudate and putamen. Thus, the ascending nigrostriatal fibers mirror the distribution of the descending striatonigral fibers. No convincing evidence for the existence of a nigroentopeduncular and nigropallidal projection was found.

EFFERENT CONNECTIONS OF THE SUPRA-GENICULATE NUCLEUS IN THE ALBINO RAT.

AbstractUsing the experimental method of retrograde cell degeneration efferent connections of the supra‐geniculate nucleus to the caudal part of the ipsilateral putamen were demonstrated in rats. Following lesions in the cortex, rostral putamen and caudate nucleus the supra‐geniculate nucleus remains intact, but following lesions in the caudal part of the putamen this nucleus shows retrograde cell degeneration.The supra‐geniculate nucleus belongs to the intermediate nuclei of the thalamus, where it constitutes the caudal part. The connections suggest that this nucleus contributes in some way to opto‐motor or auditivo‐motor functions.