J. Voogd

Vestibular afferents of the inferior olive and the vestibulo-olivo-cerebellar climbing fiber pathway to the flocculus in the cat

The projection of the vestibular nuclei to the inferior olive was investigated by means of anterograde transport of tritiated leucine. Following injections in the medial and descending vestibular nuclei, terminal labeling was found ipsilaterally in the dorsomedial cell column, subnucleus beta and the caudal medial accessory olive, while the latter also received afferents from the nucleus prepositus hypoglossi. At the contralateral side termination in the dorsomedial cell column and the medial accessory olive was found after injections in the nucleus vestibularis superior and group Y. The ventrolateral outgrowth and different parts of the principal olive also received afferents from these two nuclei and also from ventral parts of the lateral cerebellar nucleus. The dorsal cap was labeled exclusively from the contralateral nucleus prepositus hypoglossi. The termination in the inferior olive of the vestibular afferents is compared with the projection from a number of pretectal nuclei. Furthermore the consequences of the divergence and convergence of both types of projections at the level of the inferior olive is discussed in relation to the subsequent climbing fiber projection to the flocculus.

Reciprocal connections between the caudal vermis and the vestibular nuclei in the rabbit

The termination of secondary vestibulocerebellar mossy fibers and the localization of Purkinje cells giving rise to corticovestibular projections were visualized simultaneously in lobules IX and X after injections of wheat germ agglutinin-horseradish peroxidase in the vestibular nuclei of the rabbit. Vestibulocerebellar mossy fibers from the medial, descending and superior vestibular nuclei terminate in longitudinal strips in the granular layer, which coincide exactly with the localization of the labeled Purkinje cells.

Vestibular nuclear efferents to the nucleus raphe pontis, the nucleus reticularis tegmenti pontis and the nuclei pontis in the cat

The projection of the vestibular nuclei to the pontine tegmentum was investigated by means of anterograde transport of tritiated leucine. Dense patches of terminal labeling were observed in the contralateral nucleus raphe pontis and the nucleus reticularis tegmenti pontis in cases where the injection involved the medial and descending vestibular nuclei. Following injections in the superior vestibular nucleus and group Y, weaker termination, also patchlike, was observed in the same tegmental nuclei, and in addition in the dorsomedial pontine nuclei proper. The results are discussed in relation to the position of the nucleus raphe pontis and the nucleus reticularis tegmenti pontis in the oculomotor pathways.

Hypertrophy of neurons in the inferior olive after cerebellar ablations in the cat

Olivary hypertrophy, a combined retrograde and transneuronal reaction, is found in cells of the inferior olive after cerebellar ablation in the cat. Its chief features are central chromatolysis and hypertrophy of the peripherally located granular endoplasmatic reticulum with accumulation of electron-dense material in its often vacuolarly distended cisterns. Hypertrophy is restricted to subdivisions of the inferior olive included in recurrent cerebello-mesencephalic-olivary circuits.

Cerebellar cortical afferents from the dorsal column nuclei in sheep, demonstrated with retrograde transport of horseradish peroxidase.

Following horseradish peroxidase injections in the cortex of the sheep cerebellum (except the ventral part of the anterior lobe, the flocculus and ventral paraflocculus), labeled cells were found in nucleus gracilis, medial cuneate and lateral cuneate. The present findings provide evidence that the projection of the dorsal column nuclei to the cerebellum in the sheep is more extensive than has been reported for the common laboratory animals. Projections to the vermis are bilateral, projections to the hemisphere are mainly ipsilateral.

The localization of acetylcholinesterase (ache) in the developing cerebellum of the rabbit

The postnatal development of nicotine-like binding sites in discrete areas of mouse brain was studied using labelled nicotine /,3H-Nic) and two nicotinic antagonists tubocurarine (3H-TC) and ~-bungarotoxin (3H-Bt~0 respectively.Binding studies in adult mouse brain have indicated for these ligan(is a common binding site but also an additional site for nicotine and tubocurarine. In this study mice were killed at 3,7,12, 17 and 30 days of age.The brain was dissec~d into four areas namely cerebell~n,hippoca~ous,cortex and midbrain.A crude synapto~-~m~l P2 fraction was prepared for in vitro binding studies. The 3H-Btx binding increased up to day 712 in all regions (except the cerebell~n) followed by a decrease.The number of 3H-TC binding sites was in general higher and showed an early max~ followed by an age related decline. The 3H-Nic binding ,on the other hand, inc: ~eased gradually with age.The time course was somewhat different for the discrete ar~as of the brain showing a continous increase in number of 3H-Nic sites in the midbrain from day 3 to 30 (threefold increase) while in the cortex the most marked increase in ;number of binding sites (fivefold) was observed from day 17 to day 30.