SEARCH · PubMed Health

Results for “CEREBELLAR CORTEX”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

PubMed1978

Accumulation of cyclic adenosine 3',5'-monophosphate in human cerebellar cortex slices: effect of monoamine receptor agonists and antagonists.

Noradrenaline, isoproterenol, adrenaline or clonidine stimulate cyclic AMP formation in human cerebellar cortex 15-20 fold and serotonin or dopamine 3-fold. The increase by noradrenaline or clonidine is dose-dependent. Propranolol completely blocks the increase induced by noradrenaline or isoproterenol but not that by clonidine. Phentolamine was ineffective in blocking cyclic AMP formation induced by noradrenaline, isoproterenol, adrenaline or clonidine. Chlorpromazine completely blocked the increase induced by noradrenaline, isoproterenol, clonidine, serotonin or dopamine.

Adolescent↗

PubMed1997

Learning-dependent synaptic modifications in the cerebellar cortex of the adult rat persist for at least four weeks.

Several experiments have demonstrated increased synapse number within the cerebellar cortex in association with motor skill learning but not with motor activity alone. The persistence of these synaptic changes in the absence of continued training was examined in the present experiment. Adult female rats were randomly allocated to either an acrobatic condition (AC) or a motor activity condition (MC). The AC animals were trained to traverse a complex series of obstacles, and each AC animal was pair-matched with an MC animal that traversed an obstacle-free runway. These animals were further assigned to one of three training conditions. Animals in the EARLY condition were trained for 10 consecutive days before being killed, animals in the DELAY, condition received the same 10 d of training followed by a 28 d period without training, and animals in the CONTINUOUS condition were trained for the entire 38 d. Unbiased stereological techniques were used to obtain estimates of the number of synapses per Purkinje cell within the cerebellar paramedian lobule. Results showed the AC animals to have significantly more synapses per Purkinje cell than the MC animals in all three training conditions. There were no differences in the number of synapses per Purkinje cell among the EARLY, DELAY, and CONTINUOUS conditions. These data demonstrate that both the motor skills and the increases in synapse number presumed to support them persist in the absence of continued training.

Animals↗

PubMed1996

[The patterns of focal reorganization of the synaptic pool at the molecular level of the cerebellar cortex in the ischemic period].

A comparative analysis of intraneuronal relationship between Purkinje cells and granule cells zones of the cerebellar cortex molecular layer with different extent of expression of destructive and compensatory-adaptive processes was performed in rats in the dynamics of postischemic period. The ischemia was modelled by the 10 minutes long compression of the heart vascular bundle under the ethereal narcosis, Dependence between type and extent of the synaptic profile and functional state of the synapse was shown. Dynamics of changes of the synapse numerical density was demonstrated so as the regularities of the axo-spinous synapses structural organization changes during their dysfunction, destruction and interneuronal contact repair within and outside the nidi of interneuronal interrelations during 30 days of postischemic period.

Animals↗

PubMed2005

Neuroscience and learning: lessons from studying the involvement of a region of cerebellar cortex in eyeblink classical conditioning.

How the nervous system encodes learning and memory processes has interested researchers for 100 years. Over this span of time, a number of basic neuroscience methods has been developed to explore the relationship between learning and the brain, including brain lesion, stimulation, pharmacology, anatomy, imaging, and recording techniques. In this paper, we summarize how different research approaches can be employed to generate converging data that speak to how structures and systems in the brain are involved in simple associative learning. To accomplish this, we review data regarding the involvement of a particular region of cerebellar cortex (Larsell's lobule HVI) in the widely used paradigm of classical eyeblink conditioning. We also present new data on the role of lobule HVI in eyeblink conditioning generated by combining temporary brain inactivation and single-cell recording methods, an approach that looks promising for further advancing our understanding of relationships between brain and behavior.

Animals↗

PubMed2001

Muscarinic cholinergic receptors subtypes in rat cerebellar cortex: light microscope autoradiography of age-related changes.

Muscarinic cholinergic M1-M5 receptor subtypes were investigated in the cerebellar cortex of Fischer 344 rats aged 6 (young), 15 (adult) and 22 months (senescent) by combined kinetic and equilibrium binding and light microscope autoradiography. In young rats the rank order of receptor density was M5<M4<M3 and M3<M5<M4 in the molecular and granular layers, respectively. M1, M2, M4 and M5 receptors were also observed within Purkinje neurons. M1 receptor did not show age-related changes as well as the M2 receptor in the molecular layer. In this layer, M3-M5 receptors were increased in senescent compared to younger rats. In the granular layer the expression of M2 and M5 muscarinic receptors was similar in young and senescent rats and higher in adult rats. M3 and M4 receptors were more in adult and senescent rats compared to young animals. In Purkinje neurons, a slight-to-moderate age-related increase of M1 and M5 receptor expression was observed.

Aging↗

PubMed1989

The arrangement of actin filaments in the postsynaptic cytoplasm of the cerebellar cortex revealed by quick-freeze deep-etch electron microscopy.

The cytoskeletal architecture of the postsynaptic cytoplasm in the cerebellar cortex of mice and rats was observed by quick-freeze, deep-etch electron microscopy. The postsynaptic cytoplasm was mainly filled with a network of actin filaments (approximately 8 nm in width). The tips of the actin filaments were closely associated with the true inner side of the postsynaptic membranes. However, the organization of the actin filaments was distinct depending on the types of synapses. In axosomatic synapses the actin filaments tended to run randomly and form a network while in the postsynaptic spine, such as Purkinje cell dendritic spines, the actin filaments were mainly arranged parallel to the stalk of the spines. Only a few actin filaments were found in the postsynaptic cytoplasm of some axodendritic synapses such as mossy fiber-granule cell synapses. In most cases a mesh of fine strands (approximately 6 nm in width) and granular substances was observed just underneath the postsynaptic membranes which also associated with actin filaments. The arrangement of actin filaments in the spine does not support the possibility of constriction of spines as a basis for long-term depression (LTD).

Actins↗

PubMed1981

Localization of high affinity [3H]glycine transport sites in the cerebellar cortex.

A study was made of [3H]glycine uptake sites in a preparation greatly enriched in large pieces of the cerebellar glomeruli (glomerulus particles) and in morphologically well preserved slices of rat cerebellum. Electron microscopic autoradiography revealed that of the neurones in the cerebellar cortex only Golgi cells transported [3H]glycine at the low concentration used. Glial cells also took up [3H]glycine but to a lesser extent than the Golgi neurons. It was also confirmed that under comparable conditions Golgi cells transport [3H]GABA. Kinetic studies utilizing the Golgi axon terminal-containing glomerulus particles showed that glycine is a weak non-competitive inhibitor of [3H]GABA uptake (Ki over 600 microM vs the Kt of about 20 microM) and that GABA is an even weaker inhibitor of [3H]glycine uptake. These observations indicated that glycine and GABA do not share the same carrier. Quantitative electron microscopic autoradiography showed that the uptake of the two amino acids, in terms of the unit area of labelled Golgi axon terminals, was not additive. In contrast, their uptake in terms of unit protein was strictly additive. These observations, the first relating to unit volume and the latter to the total volume of Golgi terminals, are consistent with the view that there are two biochemically separate populations of Golgi neurons, one transporting glycine the other GABA. Saturable [3H]strychnine binding was detected in the preparations of glomerulus particles, but in comparison with those from the spinal cord the affinity was lower and [3H]strychnine was not displaced by glycine. Available information on glycine receptors, however, suggest that this should not exclude the possibility of strychnine resistant glycine receptors in the rat cerebellum.

Animals↗

PubMed1989

Distribution of nuclear pores and chromatin organization in neurons and glial cells of the rat cerebellar cortex.

Nuclear pores were assessed on freeze-fracture replicas from different neuronal and glial cell types of the rat cerebellar cortex. Nuclear diameter and perimeter were measured on semithin sections, and nuclear surface area and volume were calculated from these data. The proportion of inner nuclear membrane in apposition to condensed chromatin was measured on thin sections. The values of nuclear pore numerical density (number/micron2) were as follows (mean +/- S.D.): Purkinje cells, 22 +/- 3; Golgi cells 17 +/- 3; granule cells, 6 +/- 4; stellate and basket cells, 6 +/- 1; protoplasmic astrocytes, 11 +/- 1; Bergmann glia, 10 +/- 1; oligodendrocytes, 6 +/- 1. The total number of nuclear pores per nucleus varied from 18,451 +/- 2,336 (Purkinje cells) to 621 +/- 394 (granule cells) among neurons, and from 1,782 +/- 162 (protoplasmic astrocytes) to 402 +/- 67 (oligodendrocytes) among glial cells. The number of nuclear pores per unit nuclear volume (number/micron3), a parameter related to nucleocytoplasmic transport capacity, varied from 15 +/- 2 in Purkinje cells to 6 +/- 4 in granule cells. The proportion of nuclear membrane free of condensed chromatin was significantly (P less than 0.01) correlated to pore numerical density and total number of pores per nucleus. Some nuclear pores were associated in clusters of two or more pores. The amount of pore clustering was measured by counting the proportion of pores associated in clusters. This proportion varied among the different cell types from 82% in Purkinje cells to 44% in stellate and basket cells. The amount of pore clustering showed a positive linear correlation to pore numerical density and pore number per nucleus. However, the proportion of pores in clusters was not significantly correlated with the amount of condensed chromatin applied against the inner nuclear membrane.

Animals↗

PubMed1989

Blood-derived phagocytes in the cerebellar cortex of the rat after chronic alcohol consumption.

Past work showed that chronic alcohol consumption induces massive degeneration in the rat cerebellar cortex. To study the subsequent process of nervous tissue repair, followed itself by a remodelling activity, groups of alcohol-treated rats for 3 and 6 months were used and the results compared with the respective age-matched controls. From the wide variety of cells which display phagocytic activity in the mammalian brain it was found, based on qualitative observations, that two types were clearly involved in the removal of the alcohol-induced degenerated debris: the resident microglial cells and the non-resident brain macrophages. This assumption was corroborated by the study of their origin, using carbon particles and latex beeds intravenously injected, which showed that brain macrophages were the sole population to be labelled. These observations fit with the multiple origin concept for neural phagocytosis which postulates that different cell types can be recruited for the removal of the damaged neural tissue depending on the severity of the lesions and on the extension of the blood vessels damage.

Alcoholism↗

PubMed1984

A micrometric and cytophotometric study of the simultaneous development of the cerebellar cortex and dental function in the rat during the early post-natal period.

A study was made of the growth of two cerebellar lobules receiving trigeminal afferents, crus 1 (C1) and uvula (U) and another lobule which receives only vestibular afferents, nodulus (N). Growth factors were determined using micrometry and histophotometry. Times of growth end were compared with first masticatory movements. The end of the maturation period of U and the beginning of absorption of tough diet appeared on the 15th post-natal day (PND). The end of growth of C1 on the 18th PND coincided with functional appearance of molars. It was suggested that, in the rat, maturity of the cerebellar cortex in certain lobules could be related to the early stage of weaning.

Aging↗

PubMed1985

Classical conditioning of the nictitating membrane response of the rabbit. II. Lesions of the cerebellar cortex.

The nictitating membrane response (NMR) of 20 rabbits was conditioned to light and white noise conditional stimuli (CSs) using a periorbital shock unconditional stimulus (US). Unilateral lesions of the cerebellar cortex, sparing the underlying deep nuclei, were then made. Small lesions of cerebellar cortical lobule HVI abolished conditioning on the side of the lesion to both CSs leaving unconditional responses to the US intact. Larger lesions of the posterior lobe which spared HVI did not impair NMR conditioning. We conclude that cerebellar lobule HVI is essential for NMR conditioning in the rabbit. Degeneration following critical lesions of HVI was seen in a restricted region of the inferior olive - the medial part of the dorsal accessory olive and the adjoining medial part of the dorsal leaf of the principal olive. This region of the olive provides somatosensory information from the face to HVI. We suggest that HVI receives information related to the US via climbing fibres from the olive and CS information via mossy fibres from the pontine nuclei. The critical changes underlying NMR conditioning may be the association of these two inputs at the Purkinje cells of cortical lobule HVI.

Animals↗

PubMed2006

Retrograde endocannabinoid signaling in the cerebellar cortex.

The regulation of Purkinje cell activity is important for motor behavior and motor learning. As the sole output cell of the cerebellar cortex, Purkinje cell firing is controlled by parallel fibers and climbing fiber synapses, and by inhibitory interneurons. Depolarization of Purkinje cells evokes endocannabinoid release that activates cannabinoid CB1 receptors expressed on boutons of its synaptic inputs to transiently decrease neurotransmitter release. In addition, associative activation of the excitatory inputs can liberate endocannabinoids to decrease synaptic strength for a prolonged duration. Here we review the different mechanisms of evoking endocannabinoid release and discuss the physiological role of endocannabinoids in mediating global modulation of synaptic strength, localized short-term associative plasticity and cerebellar long term depression.

Animals↗

PubMed2000

GM1 ganglioside treatment protects against long-term neurotoxic effects of neonatal X-irradiation on cerebellar cortex cytoarchitecture and motor function.

Exposure of neonatal rats to a 5 Gy dose of X-irradiation induces permanent abnormalities in cerebellar cortex cytoarchitecture (disarrangement of Purkinje cells, reduction of thickness of granular cortex) and neurochemistry (late increase in noradrenaline levels), and motor function (ataxic gait). The neuroprotective effects of gangliosides have been demonstrated using a variety of CNS injuries, including mechanical, electrolytic, neurotoxic, ischemic, and surgical lesions. Here, we evaluated whether systemically administered GM1 ganglioside protects against the long-term CNS abnormalities induced by a single exposure to ionizing radiation in the early post-natal period. Thus, neonatal rats were exposed to 5 Gy X-irradiation, and subcutaneously injected with one dose (30 mg/kg weight) of GM1 on h after exposure followed by three daily doses. Both at post-natal days 30 and 90, gait and cerebellar cytoarchitecture in X-irradiated rats were significantly impaired when compared to age-matched controls. By contrast, both at post-natal days 30 and 90, gait in X-irradiated rats that were treated with GM1 was not significantly different from that in non-irradiated animals. Furthermore, at post-natal day 90, cerebellar cytoarchitecture was still well preserved in GM1-treated, X-irradiated animals. GM1 failed to modify the radiation-induced increase in cerebellar noradrenaline levels. Present data indicate that exogenous GM1, repeatedly administered after neonatal X-irradiation, produces a long-term radioprotection, demonstrated at both cytoarchitectural and motor levels.

Animals↗

PubMed1991

[A quantitative evaluation of the reactive and dystrophic changes in the cerebellar cortex of mice during malnutrition and subsequent food rehabilitation].

Neurones with chromatolysis, hyperchromatism and numerous nucleus have been counted of the paraffin cerebellar cortex sections coloured with kresil-violet and metil-green pironin. The alimentary deficiency has been shown to result in increase of cell number with chromatolysis and hyperchromatism and decrease of the number of numerous nucleus. The food rehabilitation doesn't take off completely damages caused by malnutrition. The use of carnitine leads to the complete rehabilitation that is due to the normalization of protein metabolism in cerebellum.

Animals↗

PubMed2002

Surface-based atlases of cerebellar cortex in the human, macaque, and mouse.

This study describes surface reconstructions and associated flat maps that represent the highly convoluted shape of cerebellar cortex in three species: human, macaque, and mouse. The reconstructions were based on high-resolution structural MRI data obtained from other laboratories. The surface areas determined for the fiducial reconstructions are about 600 cm(2) for the human, 60 cm(2) for the macaque, and 0.8 cm(2) for the mouse. As expected from the ribbon-like pattern of cerebellar folding, the cerebellar flat maps are elongated along the axis parallel to the midline. However, the degree of elongation varies markedly across species. The macaque flat map is many times longer than its mean width, whereas the mouse flat map is only slightly elongated and the human map is intermediate in its aspect ratio. These cerebellar atlases, along with associated software for visualization and for mapping experimental data onto the atlas, are freely available to the neuroscience community (see http:/brainmap.wustl.edu).

Animals↗

PubMed1985

Evidence of a direct projection from the medial terminal nucleus of the accessory optic system to lobule IX of the cerebellar cortex in the tree shrew (Tupaia glis).

Injections of a wheat germ agglutinin-horseradish peroxidase conjugate were placed in representative areas of the cerebellar cortex of adult tree shrews. Retrogradely labeled cells were found in the medial terminal nucleus (MTN) of the accessory optic system (AOS) when ventral portions of the uvula were involved in the injection site. These labeled cells are small to medium sized and have round or oval somata and few primary dendrites. The AOS functions to stabilize the eyes and head in space. The present observations provide evidence of a direct projection from the MTN of the tree shrew AOS to regions of the posterior vermal cortex (ventral uvula) which, through interconnections with the vestibular nuclei, are involved in the regulation of eye movement.

Animals↗

PubMed1984

Variations in presynaptic grid size in the granular and molecular layer of the cerebellar cortex of the cat. I. A quantitative ultrastructural study on semithin E-PTA sections.

The size distribution of synapses in the cerebellar cortex of the cat was defined on 0.5-micron semithin sections stained with ethanolic phosphotungstic acid (E-PTA). The surface area (SA) of synaptic grids was measured and the number of dense projections per grid (NDP) was counted. The results show large differences in mean values between molecular and granular layer. Within the molecular layer the differences in mean values at different levels below the pial surface were small; however, the frequency distributions differed significantly. In the granular layer a confined unimodal frequency distribution of SA and NDP was observed (mean NDP, 7.02 +/- 0.10), in the molecular layer a considerable variation in the size of the synaptic discs was observed (mean NDP, 20.40 +/- 0.43). Only a small percentage of the synaptic discs have less than 5 or more than 47 DPs. The sharply defined differences in synaptic size between the granular and molecular layer and the smaller differences within the granular and molecular layer are discussed in the context of the congruity hypothesis of Chan-Palay.

Animals↗

PubMed1996

Morphological correlates of bilateral synchrony in the rat cerebellar cortex.

Simultaneous recordings of the left and right crus IIA of the cerebellar cortex in the rat have demonstrated that Purkinje cells of both sides can be activated synchronously by their climbing fibers. Because climbing fibers arise exclusively from the contralateral inferior olive (IO), this physiological finding seems to contradict the anatomy. To define the structural basis responsible for the bilateral synchrony, we examined the possibilities that bilateral common afferent inputs to the IO and interolivary connections form the underlying mechanisms. The bilaterality of the major afferents of the olivary regions that project to crus IIA was studied using Phaseolus vulgaris leucoagglutinin as an anterograde tracer. We found that the excitatory and inhibitory projections from the spinal trigeminal nucleus and dorsolateral hump of the interposed cerebellar nucleus to the transition area between the principal olive and dorsal accessory olive were bilateral. A second possible mechanism for bilateral synchrony, which is the possibility that axons of olivary neurons provide collaterals to the contralateral side, was investigated using biotinylated dextran amine as an anterograde tracer. Labeled axons were traced and reconstructed from the principal olive and dorsal and medial accessory olive up to the entrance of the contralateral restiform body. None of these axons gave rise to collaterals. The possibility that neurons in the left and right IO are electronically coupled via dendrodendritic connections was investigated by examining the midline region of the IO. The neuropil of the left and right IO is continuous in the dorsomedial cell column. Examination of Golgi impregnations of this subdivision demonstrated that (1) many dendrites cross from one side to the other, (2) neurons close to the midline give rise to dendrites that extend into both olives, and (3) dendrites of neurons in the dorsomedial cell column frequently traverse into adjacent olivary subdivisions such as the medial accessory olive and the transition area between the principal olive and dorsal accessory olive. Sections immunostained for dendritic lamellar bodies or GABAergic terminals showed the same pattern: the neuropils of the dorsomedial cell columns on both sides form a continuum with each other as well as with the neuropil of other adjacent olivary subdivisions. Ultrastructural examination of the dorsomedial cell column demonstrated that the midline area includes many complex glomeruli that contain dendritic spines linked by gap junctions. To verify whether the complex spike synchrony observed between left and right crus IIA could indeed be mediated in part through coupled neurons in the dorsomedial cell column, we recorded simultaneously from crus IIA areas and from left and right vermal lobule IX, which receives climbing fibers from the dorsomedial cell column. In these experiments we demonstrated that the climbing fibers of all four areas, i.e., the left and right crus IIA as well as the left and right lobule IX, can fire synchronously. The present results indicate that synchronous climbing fiber activation of the left and right crus IIA in the rat can be explained by (1) bilateral inputs to the transition areas between the principal olive and dorsal accessory olive and (2) dendrodendritic electrotonic coupling between neurons of the left and right dorsomedial cell column and between neurons of the dorsomedial cell column and adjacent olivary subdivisions.

Animals↗