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PubMed1992

[Extrapyramidal manifestations in hereditary olivopontocerebellar atrophy--clinical study of 10 cases in three affected pedigrees].

We studied 3 pedigrees affected with autosomal dominant olivopontocerebellar atrophy (OPCA), and clinical features of 10 patients were reported. Clinically, 6 cases were dominated with cerebellar ataxia, one with Parkinsonism, and three with choreiform movements. Furthermore, they were characterized by slow eye movement and progressive loss of tendon reflexes. Generally, extrapyramidal manifestations, such as Parkinsonism or choreiform movements, are occasionally observed in dominant OPCA. However, the pathogeneses are different from each other. The choreiform movements are unique in dominant OPCA, and generally not observed in sporadic OPCA. In the distribution of degenerated foci, dominant OPCA is often associated with degeneration of not only substantia nigra, but also with other structures such as dentate nucleus, red nucleus, external segment of globus pallidus (GPe), and subthalamic nucleus. This dentatorubral and pallido-Luysian system degeneration are parts of neuropathological findings in hereditary DRPLA (Naito-Oyanagi form). In both disorders, choreiform movements is observed. Current theory indicates that hyperactivity of neostriatal dopamine neurons and degeneration of GPe play roles in the pathogenesis of chorea. Clinically, choreiform movements are common in hereditary DRPLA, but not in dominant OPCA. This difference could be explained by the nigral degeneration in dominant OPCA, which suppress the generation of choreiform movements.

Adult↗
PubMed1992

[Clinicopathological study of Joseph disease: report of 4 pedigrees and its nosological consideration].

Four pedigrees of Machado-Joseph disease (MJD) were reported. Main clinical features of 21 patients in these pedigrees were cerebellar ataxia, limb spasticity, gaze nystagmus, facio-lingual twitchings, and external ophthalmoparesis. Amyotrophy, hypokinesia, or dystonia were manifested with advance of the illness. In patients with younger onset age, such extrapyramidal signs were dominated. Neuropathological study of one autopsied case disclosed that there were degeneration of spinocerebellar tract, anterior horn cells, pontine nuclei, dentate nucleus, red nucleus, substantia nigra, internal segment of globus pallidus, subthalamic nucleus, and motor nuclei of brain stem; neurons of cerebellar cortex and inferior olivary nucleus were preserved. From these clinical and pathological features, these 4 pedigrees satisfied the criteria of MJD, and were differentiated from hereditary olivopontocerebellar atrophy. Currently, MJD is accepted as a new entity of hereditary spinocerebellar ataxias. However, there are still controversies as to whether Azores-Portuguese MJD and Japanese MJD are identical disorder. Furthermore, the nosological relationship between MJD and a number of similar cases, as reported historically under the diagnosis of Brown type ataxia or Marie's ataxia, has not been clearly established. From reviewing such cases critically, pathological and clinical features of our cases are so similar to those of the latter, indicating that the probably identical genetic disorder has been classified under the different categories.

Adult↗
PubMedDate not supplied

Prominent activation of the putamen during essential palatal tremor: a functional MR imaging case study.

Palatal tremor (PT), also known as palatal myoclonus, is defined by short rhythmic contractions of the palatal musculature. Functional MR imaging (fMRI) revealed prominent bilateral neuronal activation in the putamen associated with essential palatal tremor (EPT) in a 41-year-old man. This implies a central role of the putamen in EPT, most likely as a consequence of diminished inhibition in an afferent pathway. Because fMRI primarily detects activations, dysfunctional areas remain obscure. The present functional study complements previous pathologic studies, which associated PT with lesions to dentate nucleus, red nucleus, and the inferior olive (Guillain-Mollaret triangle).

Adult↗
PubMed1990

[Wilson's disease: computed tomography and magnetic resonance imaging].

Wilson's disease is an autosomal recessive hereditary disease in which the capacity of biliary copper excretion is reduced, resulting in a toxic accumulation of this metal in the liver, brain and other organs. The neuroimaging techniques, computed tomography (CT) and nuclear magnetic resonance (NMR), have been incorporated to the diagnostic workup in patients with suspected Wilson's disease (WD). We report two patients with WD in whom CT and NMR were carried out for the evaluation of the central nervous system (CNS). The lesions appeared as hypodense areas in CT or signal abnormalities in NMR over the involved structures: putamen, caudate nucleus, cerebellar dental nucleus, red nucleus and subcortical white matter. In one of the patients, hypointense signal areas were found over both putamen nuclei in T-2 times of NMR, which might correspond to cavitary necrosis or copper deposition. The lesion distribution suggests that vascular lesions might play a role in the mechanisms of tissue damage. These findings show that CT and NMR are very helpful to evaluate WD. NMR images are quite characteristic of this disorder.

Adolescent↗
PubMed1990

[The role of magnetic resonance imaging in the diagnosis of Hallervorden-Spatz disease].

A mentally-retarded 21-year-old female with narrowing of the visual field was admitted to our hospital because of dystonia in the body and extremities which appeared 6 months before and was gradually exacerbating. On admission, torsion dystonia, pyramidal tract sign, and retinitis pigmentosa with optic atrophy, urinary incontinence, hyperhidrosis and insomnia were noted. On the Wechsler Adult Intelligence Scale, she achieved less than 60 for verbal-IQ. Laboratory tests including serum copper and ceruloplasmin, were all normal. A computed tomography of the brain showed small hyperdense spot in the globus pallidus on the both sides. There was neither cortical atropy nor ventricular dilatation. A Magnetic Resonance Imaging was obtained using both moderate-field (0.5 Tesla) and high-field (1.5 Tesla) superconducting MR systems. T2-weighted spin echo images demonstrated markedly decreased signal intensity area restricted in the globus pallidus and substantia nigra on both system. Moreover, in the center of the globus pallidus, a small high signal spot was seen ("eye-of the-tiger" sign coined by Sethi et al). There was no abnormal signal in the putamen, caudate nucleus, red nucleus, and dentate nucleus. On the other hand, T1-weighted inversion recovery images were not remarkable. These striking low attenuation on T2-weighted findings suggests an increased iron deposition limited to the globus pallidus and substantia nigra which is characteristic of Hallervorden-Spatz disease/syndrome (H-S). Moreover, "eye-of-the-tiger" sign on T2-weighted MR images in the globus pallidus is previously described in H-S.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[The restructuring of the efferent activity of the generator of scratching during the electrical activation of the descending systems].

Rearrangement of the scratching generator activity evoked by phasic electrical stimulation of different descending systems has been investigated on decerebrated immobilized cats. This rearrangement heavily depends on the stimulation phase. Maximal increase of the scratching cycle duration by electrical stimulation of Deiters' nucleus, red nucleus and pyramidal tract takes place in the first half of an aiming phase. The electrical stimulation of structures mentioned above does not practically change duration of the scratching cycle in the second half of the aiming phase and at the beginning of the scratching phase. A maximal increase of the scratching cycle duration by electrical stimulation of reticular gigantocellular nucleus occurs in the second half of the aiming phase. The electrical activation of descending pathways during the aiming phase increases intensity of this phase and decreases intensity of the scratching phase. The electrical activation of descending pathways during the scratching phase increases its intensity and does not change practically the intensity of the aiming phase. Possible principles of the suprasegmental correction of the scratching generator activity are discussed.

Animals↗
PubMed1981

Decreased glutamate uptake in subcortical areas deafferented by sensorimotor cortical ablation in the cat.

Evidence that L-glutamate is a neurotransmitter of corticofugal fibers was sought by measuring changes in several biochemical markers of neurotransmitter function after pericruciate (sensorimotor) ablations in cats. Two weeks after cortical ablation, samples from various brain regions were analyzed for high affinity uptake of glutamate, gama-aminobutyric acid (GABA), glycine, alanine, and tyrosine. Amino acid levels and the activity of choline acetyltransferase (CAT) also were determined. High affinity glutamate uptake is decreased relative to the opposite side in areas of the nervous system which lost a predominantly unilateral corticofugal projection. These areas include the caudate nucleus, ventrolateral thalamic nucleus, red nucleus, basis pontis, and cervical and lumbar spinal cord. No significant changes were found in the uptake of other amino acids or in CAT in these regions. Changes in the levels of amino acids were significant only in ventrolateral thalamus where there was a 33% decrease in glutamate on the deafferented side. The data suggest that L-glutamate is a neurotransmitter of corticofugal fibers to many subcortical areas related to motor control.

Amino Acids↗
PubMed1993

Differential localization of phosphoinositide-linked metabotropic glutamate receptor (mGluR1) and the inositol 1,4,5-trisphosphate receptor in rat brain.

The type 1 metabotropic glutamate receptor (mGluR1) is through to act via the phosphoinositide (PI) system with the associated formation of inositol 1,4,5-trisphosphate (IP3) and Ca2+ release. Utilizing immunohistochemistry and in situ hybridization, we have localized protein and mRNA, respectively, for the mGluR1 and the IP3 receptor (IP3R). We have also localized glutamate-linked PI turnover by autoradiography with 3H-cytidine. We observe a striking contrast in localizations of mGluR1 and IP3R both for protein and mRNA. For instance, mGluR1 occurs in the apparent absence of IP3R in neurons of the stratum oriens of the CA1 hippocampus, islands of Calleja, anterodorsal nucleus of thalamus, lateral nucleus of hypothalamus, and the granular cell layer and the deep nuclei of cerebellum. mGluR1 actions in these brain regions may primarily be mediated through the protein kinase C limb of the PI system, as they contain moderate amounts of 3H-phorbol ester binding. The subthalamic nucleus, red nucleus, and Darkshevich's nucleus, which possess high levels of mGluR1, are devoid of both IP3R immunoreactivity and 3H-phorbol ester binding. These reciprocal localizations suggest that mGluR1 actions in many brain areas may not primarily involve IP3, reflecting instead influences on protein kinase C or other second messengers.

Animals↗
PubMedDate not supplied

Adult-onset motor neuron disease with basophilic intraneuronal inclusion bodies.

A 53-year-old man initially displayed muscle atrophy and weakness and a slight degree of pyramidal signs, which became more prominent with time. Later, gaze palsy, autonomic dysfunction, and bedsore developed. The total clinical course was 63 months. Pathologically, there was loss of upper and lower motor neurons and other regions, as well as degeneration of the anterior and lateral funiculi of the spinal cord. Round or irregularly-shaped basophilic inclusions were found not only in the motor neurons, but also in other regions such as the putamen, globus pallidus, thalamus, subthalamic nucleus, red nucleus, midbrain tegmentum, pontine nucleus, dentate nucleus, inferior olivary nucleus and others. The inclusions consisted of randomly arranged 12-25 nm thick filaments studded with granules. This patient with adult onset of the disease exhibited features resembling those of "juvenile amyotrophic lateral sclerosis" with basophilic inclusions. Clinically as well as pathologically, the disease manifestations involved many systems other than the motor neurons.

Age Factors↗
PubMed1996

Persistent c-fos expression in the brains of mice with chronic social stress.

The present study was conducted to demonstrate immunohistochemically, the sites of c-fos protein expression in the brains of mice subjected to acute and chronic social defeat stress. To induce social stress, mice were placed in situations of species-specific intermale aggression either only once or five times at 24 h intervals. Two hours after the single or fifth defeat stress, many c-fos immunoreactive neurons were observed in a variety of brain regions including the limbic system and sensory relay nuclei. The c-fos immunoreactive neurons in the brains of acute defeat mice decreased in number with time and the c-fos staining pattern of acute defeat mice became indistinguishable from that of normal control mice by 24 h after the single defeat stress. In contrast, chronic defeat stress induced persistent c-fos expression in the forebrain and brainstem even 24 h after the fifth defeat stress. In the forebrain of chronic defeat mice, the olfactory bulb, cingulate cortex, hippocampus, entire hypothalamus, septal nuclei and the amygdaloid complex, except for the central nucleus, were labeled intensely with c-fos antiserum. In the lower brainstem, nerve cells with c-fos immunoreactivity were seen mainly in ascending and descending sensory relay nuclei relevant to auditory and vestibular transmission, epicritic sensation (gracile and external cuneate nuclei), pain inhibition (central gray and raphe nuclei), and viscerosensory transmission (solitary tract nucleus). The differences in c-fos expression among the normal control, acute and chronic defeat mice were evaluated by an enumeration of the immunopositive neurons within each brain nucleus examined, and they were confirmed subsequently by statistical analysis. There was little c-fos expression in the nucleus putamen, lateral, ventral and posterior thalamic nuclei, pretectal nuclei, medial geniculate nucleus, red nucleus, substantia nigra, cerebellum, spinal cord, or cranial nerve nuclei. These findings suggest that chronic but not acute defeat stress causes persistent c-fos expression in more widespread brain regions than do any other stresses so far investigated. The present study may shed light on the central mechanisms by which behavioral abnormalities and/or chronic sociopsychological stress leads to the occurrence of abnormal behavior and/or psychosomatic disorders in experimental animals and humans.

Animals↗
PubMed1997

Expression of cadherin-8 mRNA in the developing mouse central nervous system.

The expression of cadherin-8 was mapped by in situ hybridization in the embryonic and postnatal mouse central nervous system (CNS). From embryonic day 18 (E18) to postnatal day 6 (P6), cadherin-8 expression is restricted to a subset of developing brain nuclei and cortical areas in all major subdivisions of the CNS. The anlagen of some of the cadherin-8-positive structures also express this molecule at earlier developmental stages (E12.5-E16). The cadherin-8-positive neuroanatomical structures are parts of several functional systems in the brain. In the limbic system, cadherin-8-positive regions are found in the septal region, habenular nuclei, amygdala, interpeduncular nucleus, raphe nuclei, and hippocampus. Cerebral cortex shows expression in several limbic areas at P6. In the basal ganglia and related nuclei, cadherin-8 is expressed by parts of the striatum, globus pallidus, substantia nigra, entopeduncular nucleus, subthalamic nucleus, zona incerta, and pedunculopontine nuclei. A third group of cadherin-8-positive gray matter structures has functional connections with the cerebellum (superior colliculus, anterior pretectal nucleus, red nucleus, nucleus of posterior commissure, inferior olive, pontine, pontine reticular, and vestibular nuclei). The cerebellum itself shows parasagittal stripes of cadherin-8 expression in the Purkinje cell layer. In the hindbrain, cadherin-8 is expressed by several cranial nerve nuclei. Results from this study show that cadherin-8 expression in the embryonic and postnatal mouse brain is restricted to specific developing gray matter structures. These data support the idea that cadherins are a family of molecules whose expression provides a molecular code for the regionalization of the developing vertebrate brain.

Animals↗
PubMed1978

[Convergence of reticulo-, vestibulo- and rubrospinal influences on motor neurons of the cervical region of the cat spinal cord].

Intracellular recording of synaptic potentials of 93 cervical motoneurons was performed in cats under stimulation of medial longitudinal fasciculus, Deiters vestibular nucleus and red nucleus. Under stimulation of medial longitudinal fasciculus and Deiters nucleus in motoneurons of the forelimb muscles distal groups excitatory reactions were predominant and in motoneurons of proximal extensors inhibitory reactions prevailed. When stimulating the red nucleus excitatory and inhibitory reactions were recorded almost in equal number of cells independently of functional significance of corresponding muscles. Monosynaptic EPSPs were recorded in 1/5 of motoneurons under stimulation of the medial longitudinal fasciculus and only in several cases during stimulation of vestibular and red nuclei. In the other cases stimulation of the structures investigated caused polysynaptic reactions in motoneurons which arose after a series of 2-3 stimuli. In 62% of motoneurons when stimulating different structures under study the reactions were of the same direction. The mutual facilitation of reactions was revealed under stimulation of different inputs. The data obtained show that interaction of influences of the studied structures occurs to a considerable extent at the level of spinal interneurons.

Animals↗
PubMed1998

Regional brain variations of cytochrome oxidase activity and motor coordination in Lurcher mutant mice.

Lurcher mutant mice are characterized by massive degeneration of cerebellar Purkinje cells and granule cells and by deficits in motor coordination. Regional brain variations of cytochrome oxidase (CO) activity were analyzed to identify those brain regions with abnormal metabolic activity as a secondary consequence of the cerebellar atrophy and to establish the relationship between CO activity and motor deficits. Lurcher mutants had higher CO activity in all three cerebellar deep nuclei than normal littermate controls of the same background strain. Higher CO activity was also found in Lurcher mutants in brain regions directly connected to the cerebellum, such as the lateral vestibular nucleus, the cochlear nucleus, the red nucleus, the ventrolateral thalamus, the dorsal raphe, the interpeduncular nucleus, and the inferior colliculus. By contrast, there was a sharp decrease in CO activity in the inferior olive. As for brain regions not directly connected to the cerebellum, higher CO activity was observed in the trigeminal motor nucleus and the CA1 molecular layer of the hippocampus, which highlights probable transsynaptic alterations as a secondary consequence of cerebellar atrophy. A positive correlation between CO activity in the red nucleus and latencies before falling in two motor-coordination tests indicates that a compensatory increase of metabolic activity in a cerebellar efferent region is associated with improved behavior.

Animals↗
PubMed1992

Spatial overlap of rubrospinal and corticospinal terminals with input to the inferior olive.

Somatosensory responses of cells in the dorsal accessory olive are suppressed following stimulation of the magnocellular red nucleus. Since the magnocellular red nucleus of the cat does not project directly to the dorsal accessory olive, the present experiments were designed to identify indirect pathways that might mediate suppression of olivary responsiveness. Wheat germ agglutinin-horseradish peroxidase was used to compare the location of magnocellular red nucleus terminals with the locations of cells providing input to the rostral dorsal accessory olive. Cells projecting to forelimb rostral dorsal accessory olive can be divided into two main groups: one group comprises a column of large cells located in the ventral caudal cuneate nucleus extending into lamina VI of C1 and C2, and a second group comprises smaller cells located in the ventral rostral cuneate nucleus. Terminations of fibers originating in the magnocellular red nucleus were found to target both groups of cells projecting to the dorsal accessory olive. Therefore, it is possible that the responsiveness of olivary cells is influenced via these terminations. Stimulation of sensorimotor cortex has also been shown to inhibit olivary responsiveness. Terminations from sensorimotor cortex target the same regions of cells that project to the dorsal accessory olive as those of the magnocellular red nucleus, and a similar, perhaps identical, anatomical substrate may serve to modulate olivary sensitivity by the two descending systems.

Animals↗
PubMed1994

Clusterin (SGP-2): a multifunctional glycoprotein with regional expression in astrocytes and neurons of the adult rat brain.

Clusterin (SGP-2) is a newly described glycoprotein associated with several putative functions including responses to brain injury. This study reports the regional and cell type expression of clusterin mRNA and its encoded glycoprotein in the rat brain; a limited comparison was also done with the human brain. Using in situ hybridization combined with immunocytochemistry, we found that astrocytes and neurons may express clusterin mRNA in the normal adult brain. While astrocytes throughout the brain contained clusterin mRNA, there was regional selectivity for neuronal clusterin expression. In the striatum, clusterin mRNA was not detected in neurons. Only a subset of substantia nigra dopaminergic neurons or locus ceruleus noradrenergic neurons (tyrosine hydroxylase immunopositive) contained clusterin mRNA. However, neuronal clusterin mRNA was prevalent in pontine nuclei and in the red nucleus of the midbrain tegmentum. Similarly, clusterin mRNA was prevalent in both rat and human hippocampal neuron-specific enolase immunopositive pyramidal neurons, although rat CA1 neurons had less mRNA than CA2-CA3 neurons. Monotypic primary cell cultures from the neonatal rat showed clusterin mRNA in both neurons and astrocytes, but not in microglia. By immunocytochemistry, no clusterin immunopositive glia were observed in any region of the rat brain, confirming previous studies. However, clusterin immunopositive cells (putative neurons) were observed in the Purkinje cell layer of the cerebellum, medial and interposed cerebellar nuclei, trigeminal motor nucleus, and red nucleus. Finally, in vitro studies suggest that astrocytes, but not neurons, secrete clusterin, which is pertinent to clusterin immunodeposits found after experimental lesioning.

Alzheimer Disease↗
PubMed1978

An autoradiographic study of midbrain-diencephalic projections to the inferior olivary nucleus in the opossum (Didelphis virginiana).

Techniques of intra-axonal transport were utlizied to elucidate the organization of diencephalic and midbrain projections to the inferior olivary nucleus of the Virginia opossum. Retrograde transport of horseradish peroxidase injected into the olive suggests that terminals within it arise from the subparafascicular nucleus of the caudal thalamus, the nucleus of Darkschewitsch, the fields of Forel, the interstitial nucleus of Cajal, the periaqueductal grey, the caudal pretectal nucleus, the tegmentum dorsomedial to the red nucleus, the red nucleus (minimal), the nucleus linearis, as well as the dorsolateral midbrain tegmentum and tectum (Henkel et al., '75). Tritiated leucine injections were made into each of the above-mentioned cell groups so that the olivary terminals of their axons could be demonstrated autoradiographically. In general, the projection systems show three basic patterns of organization. Ventromedial areas of the midbrain, including the ventral periaqueductal grey, the interstitial nucleus of Cajal, part of the red nucleus and the tegmentum dorso-medial to it, provide a substantial and topographically organized projection to the principal nucleus of the olive, as well as minor inputs to the accessory nuclei. Secondly, neurons within the subparafascicular nucleus, the nucleus of Darkschewitsch and the fields of Forel project most heavily to parts of the medial accessory nucleus, although they also provide input to the other major subdivisions of the olive. Third, axons from the dorsolateral tegmentum and tectum completely avoid the principal nucleus, while supplying small regions of the accessory nuclei.

Animals↗
PubMed1982

Descending projections to the inferior olive from the mesencephalon and superior colliculus in the cat. An autoradiographic study.

Descending projections from the mesencephalon and superior colliculus to the inferior olive were analyzed by an autoradiographic tracing method. Injections of tritium-labelled leucine were placed in regions which had previously been identified as sources of afferents to the olive. These were located adjacent to the central gray and extended from the rostral red nucleus to the posterior thalamus. Additional injections were made in the superior colliculus. Other injections were placed in the basal ganglia and thalamus. Injections restricted to one side of the central mesencephalon resulted in predominantly ipsilateral labelling of the olive. After injections in the caudo-medial parafascicular and subparafascicular nuclei and rostral nucleus of Darkschewitsch, deposits of grains were observed in the rostral pole of the medial accessory olive and adjacent ventral lamella of the principal olive. The medial accessory olive contained grains into its middle third. More caudal injections which involved the interstitial nucleus of Cajal as well as the nucleus of Darkschewitsch and rostral red nucleus resulted in the dense labeling of the entire principal olive (except the dorsal cap), the entire medial accessory olive (except subnucleus beta and the caudo-medial pole) and the caudo-dorsal accessory olive. Injections centered in the caudal magnocellular red nucleus and extending into the rostral parvocellular division labelled the dorsal lamella of the principal olive almost exclusively. When only the caudal part of the red nucleus was involved in the injection, the olive was entirely clear of grains. Minor contralateral distributions were observed in the dorsomedial cell column, the medial tip of the dorsal lamella and in the caudal medial accessory olive. The deep layers of the superior colliculus were found to project strongly to the contralateral medial accessory olive immediately beside subnucleus beta and weakly to the same area ipsilaterally. Four pathways were identified as contributing fibers to the olivary projections. These were the medial longitudinal fasciculus, the medial tegmental tract, the central tegmental tract and tectospinal or tectobulbar fibers. The rubrospinal tract did not contribute projections to the olive. Injections in the caudate nucleus, entopeduncular nucleus and ventral anterior and ventral lateral thalamic nuclei, did not result in any labeling in the olive.

Afferent Pathways↗
PubMed2000

Topography of cerebellar nuclear projections to the brain stem in the rat.

The organization of the cerebellum is characterized by a number of parallel and parasagittally ordered olivocorticonuclear modules; as such, the cerebellar nuclei basically function as output system of these modules. The present study provides a comprehensive and detailed description of the organization of the connections from the cerebellar nuclei to the brain stem in the rat. Thirteen small injections with the anterograde tracer Phaseolus vulgaris leucoagglutinin or biotinylated dextran amine which were centered on various aspects of the cerebellar nuclear complex are described and are illustrated with serial plots detailing the distribution of labeled varicosities throughout the brain stem. In every case at least 1,000 an up to 36,000 varicosities were plotted. All injections resulted in some or heavy labeling concentrated within specific regions of the contralateral inferior olivary complex and, usually, in some labeling of the contralateral ventrolateral thalamus. However, apart from these two areas it is shown that the cerebellar projections are generally very widespread and may be found throughout the entire brain stem. Below, only a survey of main projection areas will be given. Terminal arborizations originating from the rostral part of the medial cerebellar nucleus are mostly found in the caudal half of the brain stem with emphasis on the vestibular nuclear complex, whereas its caudal part rather connects to midbrain areas. Terminals that originate from the dorsolateral protuberance of the medial cerebellar nucleus are distributed more evenly throughout the brain stem and are mostly confined to reticular areas. The interstitial cell groups, interspersed between the medial and both interposed cerebellar nuclei, provide major projections to the ipsilateral vestibular nuclear complex and contralateral mesodiencephalic regions. However, reticular areas are also targeted over a large rostrocaudal range. The medial part of the posterior interposed nucleus sends most projections to the caudomedial red nucleus, prerubral regions and parvicellular reticular formation, all contralateral to the injection site. Projections that originate from more laterally placed injections are directed, apart from the inferior olivary complex, to the rostral half of the contralateral brain stem, where most labeled varicosities are found in the superior colliculus and zona incerta. The anterior interposed nucleus specifically targets the inferior olive, the red nucleus, the pontine reticulotegmental nucleus, the prectectum and the ventrolateral thalamic nucleus. More laterally placed injections also project to the ipsilateral parvicellular reticular formation and deep layers of the spinal trigeminal complex. The latter areas are more specifically targeted by the dorsolateral hump. In addition, its projections are found in the red nucleus and pretectum but do not seem to reach the ventrolateral thalamus. Projections from the lateral cerebellar nucleus are all characterized by a widespread distribution of terminals. Especially, the caudal aspect of the nucleus sends, apart from projections to the deep mesencephalic nucleus, red nucleus, periaquaductal gray, pretectum, prerubral area, and several thalamic regions, prominent projections to the caudal brain stem which terminate in the inferior olive and gigantocellular reticular formation. Projections from the ventral, parvicellular part of the nucleus are mostly, but not exclusively, directed to the rostral half of the brain stem and mainly terminate in the pararubral area, accessory oculomotor nuclei, pretectal areas, zona incerta, and in the parafascicular and ventrolateral thalamic nuclei. We conclude that the impact of the cerebellar nuclei on the brain stem is widespread; projections from different regions of the same cerebellar nucleus may show important differences in distribution of labeled terminals. On the other hand, injections placed in different cerebellar nuclei may result in a simila

Animals↗