Medial Caudate Research Articles

Topographical projections of the prestriate cortex to the pulvinar nuclei in the macaque monkey: An autoradiographic study

Localized microinjections of tritiated amino acids were made in the prestriate cortex (areas 18 and 19) of macaque monkeys in order to determine the topography of the subcortical projections. It was found that the prestriate cortex projected to the entire inferior pulvinar (PI), lateral pulvinar (PL), dorsolateral nucleus, the lateral posterior nucleus, the reticular nucleus, a portion of the medial pulvinar, superior colliculus, and caudate nucleus but not to the dorsal lateral geniculate nucleus. The projections to the PI were organized according to the topographical representation of the contralateral visual hemifield. The ventral portion of the PL which is immediately adjacent to the PI also received a parallel topographical projection in register with the representation of the visual hemifield and thus is distinguished from the remainder of the PL. The dorsal and caudal portions of the PL (which extend to form the lateral portion of the caudal pole of the pulvinar and are located away from PI) also received projections from prestriate cortex which often appeared as several bands of grains. However, although dorsal prestriate cortex seemed to project to the dorsal portion of caudal PL and ventral prestriate cortex seemed to project to the ventral portion of caudal PL, any further topography in the projections to the dorsal and caudal PL as well as any to the other dorsal group nuclei was difficult to determine. The results point to the conclusion that the PI and the immediately adjacent portion of PL are distinguished from the remainder of the pulvinar by their connectional organization, and each region contains a representation of the visual hemifield. Furthermore, the prestriate projections to these and other regions of the pulvinar form the corticothalamic half of visual and visuomotor cortico-thalamocortical projections which involve all the occipital cortices (areas 17, 18 and 19) as well as inferotemporal, parietal and frontal cortices.

Medial forebrain bundle lesions: blockade of effects of light on rat gonads and pineal.

When adult female rats are exposed to continuous illumination, there is a decrease in the activity of the pineal enzyme, hydroxyindole- O-methyl transferase, which synthesizes meiatonin. There is also an increase in ovarian weight and in the proportion of daily vaginal smears which show estrous phases. These effects of light are blocked by central lesions bilaterally transecting the medial forebrain bundle in the lateral hypothalamus. Lesions in the medial hypothalamus or caudate nucleus do not interfere with these responses to light. (Endocrinology 81: 509,1967)

Topical distribution of the striatal efferents in the monkey

Single or multiple electrolytic lesions were placed in various parts of the head of the caudate nucleus and in the putamen. The degenerated fibers were impregnated with the Nauta technique and followed to their destination. It was found that the lateral areas of the caudate nucleus project to the external segment of the globus pallidus and in lesser degree to the internal segment. Fibers from the middle part of the caudate nucleus end in both segments equally. The most medial caudate regions are connected mainly to the internal segment. The caudatonigral fibers end in the rostral substantia nigra, pars reticulata, and have a similar distribution pattern mediolaterally. This topical organization seems to exist also in the anteroposterior direction. The putamen projects to both segments of the globus pallidus and to the substantia nigra, pars reticulata, posterior to a frontal level through the oculomotor roots. There is a topical arrangement also in the putaminonigral connections anteroposteriorly. The double striatal influence from the caudate nucleus and putamen exerted upon the pallidum and substantia nigra does not overlap since the caudate fibers are distributed in the mediodorsal pallidum, while its ventrolateral remaining part receives connections from the putamen. In the substantia nigra the caudate fibers end in parts rostral to the oculomotor roots and the putaminonigral fibers terminate in areas posterior to this level.