Blood Supply by the Superior Cerebellar Artery and Posterior Inferior Cerebellar Artery to the Motor and Nonmotor Domains of the Human Dentate Nucleus.

BACKGROUND: The human cerebellum plays an important role in motor and nonmotor coordination. Any functional loss of the dentate nucleus can result in interruption of the cerebellar efferent pathway based on its somatotopy. However, understanding of the vascular supply to the dentate nucleus remains inadequate. METHODS: The origin of the perforators to the dentate nucleus was investigated by microscopic anatomic dissection of 14 human cerebellar hemispheres. The dentate nuclei were divided dorsoventrally, rostrocaudally, and mediolaterally to identify which cerebellar artery dominated which part of the dentate nucleus. RESULTS: The average number of perforators from the superior cerebellar artery (SCA) to the dentate nucleus was 2.2 ± 0.9. The average number of perforators from the posterior inferior cerebellar artery (PICA) was 1.8 ± 0.7. The anterior inferior cerebellar artery did not provide perforators to the dentate nucleus. The dorsal, rostral, and lateral halves of the dentate nucleus were more frequently dominated by the SCA than by the PICA. The ventral and medial halves of the dentate nucleus were more frequently dominated by the PICA than by the SCA. The dorsal rostrolateral and the ventral caudomedial sections were mainly supplied by the SCA and PICA, respectively. CONCLUSIONS: These findings in combination with findings of previous imaging studies suggest that the SCA is mainly associated with the motor activity and the PICA is mainly associated with the nonmotor activity of the dentate nucleus.

Cerebellar lobules and dentate nuclei mirror cortical force-related-BOLD responses: Beyond all (linear) expectations.

The relationship between the BOLD response and an applied force was quantified in the cerebellum using a power grip task. To investigate whether the cerebellum responds in an on/off way to motor demands or contributes to motor responses in a parametric fashion, similarly to the cortex, five grip force levels were investigated under visual feedback. Functional MRI data were acquired in 13 healthy volunteers and their responses were analyzed using a cerebellum-optimized pipeline. This allowed us to evaluate, within the cerebellum, voxelwise linear and non-linear associations between cerebellar activations and forces. We showed extensive non-linear activations (with a parametric design), covering the anterior and posterior lobes of the cerebellum with a BOLD-force relationship that is region-dependent. Linear responses were mainly located in the anterior lobe, similarly to the cortex, where linear responses are localized in M1. Complex responses were localized in the posterior lobe, reflecting its key role in attention and executive processing, required during visually guided movement. Given the highly organized responses in the cerebellar cortex, a key question is whether deep cerebellar nuclei show similar parametric effects. We found positive correlations with force in the ipsilateral dentate nucleus and negative correlations on the contralateral side, suggesting a somatotopic organization of the dentate nucleus in line with cerebellar and cortical areas. Our results confirm that there is cerebellar organization involving all grey matter structures that reflect functional segregation in the cortex, where cerebellar lobules and dentate nuclei contribute to complex motor tasks with different BOLD response profiles in relation to the forces. Hum Brain Mapp 38:2566-2579, 2017. © 2017 Wiley Periodicals, Inc.

The veins of the nucleus dentatus: anatomical and radiological findings.

The veins of the dentate nucleus are composed of several channels draining the external surface and one single vein draining the internal surface. We analyzed specimens of the human cerebellum and described the central vein of the nucleus dentatus as the main venous outflow of the nucleus. The central vein of the nucleus dentatus is formed by a network of smaller vessels draining the sinuosities of the gray matter; it emerges from the hilum of the nucleus and runs along the superior cerebellar peduncle, opening in the anterior vermian vein. We looked for this structure and for the surrounding veins on ultra-high-field (7 Tesla) MR, using susceptibility-weighted imaging. An anatomical and radiological description of the veins of the dentate nucleus is provided, with some remarks on the future clinical applications that these findings could provide.

Extracellular amino acid levels in the interpositus nucleus during classical eyeblink conditioning in alert cats.

The extracellular levels of selected amino acids in the cerebellar posterior interpositus nucleus (PIN) during classical eyeblink conditioning was analyzed in alert cats using a delay paradigm. Animals were prepared for the chronic recording of eyelid movements (with the magnetic search-coil technique) and the electromyographic activity of the orbicularis oculi muscle. With the help of a guide and push-pull cannulae, selected PIN sites were perfused daily during classical eyeblink conditioning. The perfusate was sampled at intervals of 5 min and analyzed with a high-pressure liquid chromatography- electrochemical detection (HPLC-EC) method. The analysis of push-pull perfusate revealed a significant increase in the release of glycine, taurine, and glutamate across the successive conditioning sessions, in parallel with the acquisition of eyelid conditioned responses (CRs). Both CRs and extracellular levels of these three amino acids returned to control values during extinction. Other amino acids (alanine, GABA, glutamine, serine, and threonine) did not undergo modifications in their extracellular concentrations across the training. Results are discussed with regard to the role of PIN in this type of associative learning.

Vascularisation of the cerebellar nuclei in Akkaraman sheep.

This study reports an anatomical study of the vascular supply in 20 Akkaraman sheep cerebelli from adult subjects of both sexes. The origin and branching pattern of the cerebellar artery vascularising the cerebellar nuclei were studied by gross dissection and vascular injection. Then dissection was performed and vessels nourishing the cerebellar nuclei were documented. Four bilaterally symmetrical cerebellar nuclei were determined as nucleus lateralis cerebelli, nucleus interpositus lateralis cerebelli, and nucleus interpositus medialis cerebelli and nucleus fastigii from lateral to medial side. It has been previously confirmed that vascularisation of the cerebellar nuclei is carried out by intermediary branches of the rostral cerebellar artery and the caudal cerebellar artery. However, this study has confirmed that the caudal cerebellar artery has no contribution in the vascularisation of the cerebellar nuclei.

The medullary cerebrovascular vasodilator area mediates cerebrovascular vasodilation and electroencephalogram synchronization elicited from cerebellar fastigial nucleus in Sprague-Dawley rats.

We investigated whether the medullary cerebrovasodilator area (MCVA), a region of ventral medulla mediating elevations of regional cerebral blood flow (rCBF) and electroencephalogram (EEG) synchronization elicited in cerebral cortex from stimulation of reticulospinal neurons of rostral ventrolateral medulla (RVLM), also mediates comparable responses from the cerebellar fastigial nucleus (FN). In spinalized rats, electrical stimulation of MCVA, RVLM or FN elevated rCBF and synchronized the EEG. The FN-evoked responses were significantly attenuated or blocked by bilateral lesions of MCVA. The MCVA is a novel region of medullary reticular formation mediating actions of medullary and cerebellar centers on rCBF and EEG to link visceral centers of brainstem and cerebral cortex.

Cerebellum implicated in sensory acquisition and discrimination rather than motor control.

Recent evidence that the cerebellum is involved in perception and cognition challenges the prevailing view that its primary function is fine motor control. A new alternative hypothesis is that the lateral cerebellum is not activated by the control of movement per se, but is strongly engaged during the acquisition and discrimination of sensory information. Magnetic resonance imaging of the lateral cerebellar output (dentate) nucleus during passive and active sensory tasks confirmed this hypothesis. These findings suggest that the lateral cerebellum may be active during motor, perceptual, and cognitive performances specifically because of the requirement to process sensory data.

SPECT abnormalities in generalized dystonia.

A patient with severe, generalized dystonia and 6 age range-matched controls were studied with the regional cerebral blood flow tracer technetium-99m hexamethylpropyleneamine oxime by single-photon emission computed tomography to test the hypothesis that cerebellar function is abnormal in dystonia. Analysis was performed by drawing regions of interest around the caudate head nuclei, hemithalami, deep cerebellar nuclei, and cerebellar hemicortices. The counts in each region of interest were normalized to whole brain cerebral blood flow in an identical manner for each subject. The dystonic patient had a difference in regional cerebral blood flow between the right and left deep cerebellar nuclei, increased regional cerebral blood flow in subcortical motor structures, and an abnormal relationship between right cerebellar cortical and right deep cerebellar nuclear regional cerebral blood flow. The findings in this patient provide evidence that the cerebellum may play a role in the pathophysiology of motor signs in some patients with dystonia.

[Morphologic characteristics of the vascular network of the dentate nucleus during development]. / Morfoloske karakteristike krvne mreze zupcastog jedra u toku razvoja.

The development of the blood network of the dentate nucleus was studied on 20 human fetal brains of different crown-rump length (CRL). In the stage of 17 to 20 weeks, the blood network of the dentate nucleus consisted of moderate spiral blood vessels. They anastomosed each other and made irregular elongated polyhedral meshes. From this meshwork, blood vessels of a greater volume arose and extended to the hilum of the nucleus. Between 23 and 25 weeks, a clear segmental vascular pattern was noticed. The capillary network was very dense. Along the outer surface of the nucleus the blood vessels which connected two secondary wrinkles of the gray matter were observed. In all the stages investigated the blood vessels were moderately spiral.

Muscarinic cholinergic receptors mediate the cerebrovasodilation elicited by stimulation of the cerebellar fastigial nucleus in rat.

We have investigated the effects of systemic administration of atropine sulfate on the global cerebrovascular vasodilation elicited by electrical stimulation of the cerebellar fastigial nucleus (FN) in chloralose-anesthetized rat. Atropine (0.3 mg/kg, i.v.) abolished the cerebrovasodilation elicited from FN but did not affect the concomitant elevation in arterial pressure and the EEG changes. We conclude that the cerebrovascular effect of FN stimulation, but not the peripheral cardiovascular or EEG changes, are mediated by cholinergic muscarinic receptors associated with cerebral vessels and/or intrinsic neural pathways.

[Vocal cord myoclonus. A case report on the posterior inferior cerebellar artery syndrome]. / Stimmbandmyoklonus. Ein kasuistischer Beitrag zum Syndrom der Arteria cerebelli inferior posterior.

The present article describes a patient with ischemia in the vascular territory of the posterior inferior cerebellar artery, who developed, in addition to other typical signs of the dorsolateral medulla oblongata, myoclonic movements of the ipsilateral vocal cord. The essential neuropathological lesion is considered to be an impairment of the dentato-olivary system. In this respect there is a close relationship to other types of rhythmical myoclonus due to lesions of the brain-stem and cerebellum.

The cerebellar arteries: cortical patterns and vascularization of the cerebellar nuclei.

This paper reports an anatomical study of the vascular supply in 60 human cerebelli from subjects of both sexes, aged between 20 and 60 years, who had died of various accidental causes. The origin, branching pattern and cortical and central distributions of the cerebellar arteries have been studied by gross dissection, vascular injection and corrosion procedures. Variations of the normal pattern of the cerebellar arteries in both origin and cortical distribution are frequently found, the anterior inferior and the posterior inferior cerebellar arteries being the arteries showing the highest number of variations. The anomalies most frequently found are duplication in the origin, abnormal origin, and the presence of hypoplastic vessels. The cerebellar nuclei were supplied by the rhomboidal artery, a collateral branch of the superior cerebellar artery. The formation of a precise segmentary vascular pattern into the dentate nucleus by branches arising from the rhomboidal artery is described. The results are discussed in the light of other anatomical studies.

[Comparative characteristics of the cyto- and angioarchitectonics of the inferior olives and the dentate nuclei of the cerebellum during human prenatal ontogenesis]. / Sravnitel'naia kharakteristika tsito- i angioarkhitektoniki nizhnikh oliv i zubchatykh iader mozzhechka v prenatal'nom ontogeneze cheloveka.

The development of the inferior olives and the denticulate nuclei of the cerebellum and their capillary network were studied in human fetuses 4--10 months old. General regularities in the formation of the inferior olives and the denticulate nuclei of the cerebellum were stated. During prenatal ontogenesis, nuclear cytoarchitectonics becomes more complex that is especially evident after 7th month of the intrauterine development: the density of the neural cells arrangement decreases, while the density of the glia arrangement and that of the glial index increases. At the same time, essential alterations occur in the capillary network: int acquires three-dimensional structure, becomes longer with more complicated interrelations between the neural cells and the capillaries.