PubMed Health⌕ Search

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 1,261 records · Page 70Linked to original sources
PubMed1992

Somatosensory Trigeminal Projections to the Inferior Olive, Cerebellum and other Precerebellar Nuclei in Rabbits.

We have analysed the pathways through which somatosensory information from the face reaches the inferior olive and the cerebellum in rabbits. We used wheatgerm agglutinin - horseradish peroxidase (WGA - HRP) to trace projections from all parts of the somatosensory trigeminal system to the olive, cerebellar cortex, the cerebellar deep nuclei and the pontine nuclei. Projections to the cerebellar cortex and inferior olive were verified using retrograde transport of WGA - HRP. Two regions of the inferior olive-the medial dorsal accessory olive and the ventral leaf of the principal olive-receive inputs from pars interpolaris (Vi) and rostral pars caudalis (Vc) of the spinal trigeminal nucleus and from the principal trigeminal nucleus (Vp). Another area in the caudal medial accessory olive receives inputs from rostral Vo (pars oralis of the spinal trigeminal nucleus), caudal Vi and Vc. There are trigemino-olivo-cortical inputs to lobule HVI via all these olivary areas and to the paramedian lobe via the principal olive only. Cerebellar cortex-lobules HVI, crus I and II, paramedian lobe and IX-receives direct mossy fibre inputs from Vp, Vo and rostral Vi. The pontine nuclei receive an input only from rostral Vi. We saw no trigeminal projections to other precerebellar nuclei or to the deep cerebellar nuclei. The concentration of face somatosensory cortical inputs, via several pathways, upon lobule HVI may underlie its important role in the regulation of learned and unlearned eyeblinks.

Journal Article↗
PubMed1979

Neurochemical and morphological consequences of axon terminal degeneration in cerebellar deep nuclei of mice with inherited Purkinje cell degeneration.

The concentrations of free amino acids and the activities of transmitter-related enzymes, glutamic acid decarboxylase (GAD), choline acetylase (ChAC) and GABA-transaminase (GABA-t) were measured in cerebellar cortex and deep cerebellar nuclei from the mouse mutant Purkinje cell degeneration (pcd) at various times before and after Purkinje cell loss. Axosomatic synapses on target cells in pcd deep nuclei were quantified by electron microscopy during and after degeneration. The concentration of GABA (nmol/mg wet weight), the Purkinje cell transmitter, was normal in pcd cerebellar cortex and deep nuclei before onset of Purkinje cell degeneration on postnatal day 15. Just after the major period of Purkinje cell loss in cerebellar cortex, GABA concentration was unchanged in the cortical layers but fell to 50% of normal values in the deep nuclei of pcd animals killed either by decapitation or by microwave irradiation. No other measured free amino acid decreased. There were no long-term increases following Purkinje cell degeneration in the concentration of any transmitter amino acids or related enzymes, GAD, ChAC or GABA-t, and thus no indication of axonal sprouting reactions. Progressive losses occurred in wet weight and protein and in activity of GABA-t in both the cerebellar cortex and the deep nuclei of pcd animals. Electron microscopic analysis indicated that Purkinje cell axon terminals contact 30% or more of the somatic surface of principal neurons of the lateral nucleus of the normal cerebellum, but only about 2% of the corresponding sites in the pcd cerebellum. Glial leaflets, rather than other synaptic terminals take their place. Axon terminals may degenerate earlier than Purkinje somata in the pcd disease.

4-Aminobutyrate Transaminase↗
PubMed2005

A comparison between blood oxygenation level-dependent and cerebral blood volume contrast in the rat cerebral and cerebellar somatosensoric cortex during electrical paw stimulation.

PURPOSE: To implement and optimize cerebral blood volume (CBV)-weighted functional magnetic resonance imaging (fMRI) in the rat cerebral and cerebellar cortex during electrical paw stimulation. MATERIALS AND METHODS: fMRI of the cerebral and cerebellar cortex was performed during electrical paw stimulation on a 7-T MRI system (MRRS, Guilford, UK) comparing the blood oxygenation level-dependent (BOLD) and CBV-weighted contrast with different ultrasmall particles of iron oxide (USPIO) contrast doses (NC100150, 30 mg Fe/mL; Amersham Health, Oslo, Norway) and different TE. RESULTS: Doses of 15 and 20 mg/kg USPIO at TE = T*2 or TE = 14 msec almost doubled the contrast-to-noise ratio (CNR) of the activated areas in the cerebral cortex without affecting the overall signal-to-noise ratio (SNR) or the incidence of activation (100%). In the cerebellum the SNR decreased significantly with an increasing contrast dose. At a dose of 15 mg/kg, the CNR was slightly smaller than the CNR measured in the BOLD images, but the activation incidence seemed to be doubled. At 20 mg/kg, the CNR was slightly increased, but the activation incidence was lower. At both contrast doses the venous artifacts disappeared. CONCLUSION: A USPIO contrast dose of 20 mg/kg proved to be beneficial for fMRI in the rat, even though it affected the CNR and SNR in the cerebral and the cerebellar cortex differentially.

Animals↗
PubMed1996

Comparative study of the pattern of expression of calmodulin messenger RNAs in the mouse brain.

Calmodulin is a major calcium-binding protein in the mammalian brain, playing an important role in neuronal cell function. Its amino acid sequence is highly conserved and the protein is encoded by multiple genes. In the mouse brain, as well as in the rat and the human brain, three different genes have been detected for calmodulin, CaM I, CaM II and CaM III, all of which encode an identical protein. We studied the pattern of expression of the three calmodulin genes and the pattern of calmodulin distribution in the mouse brain by in situ hybridization histochemistry and immunohistochemistry. We found that calmodulin messenger RNAs from the three calmodulin genes were widely expressed in the mouse brain. Nevertheless, there were differences in their patterns of distribution. In general, all calmodulin messenger RNAs were preferentially distributed in hippocampus, cerebral cortex and cerebellar cortex, and CaM II messenger RNA also in caudate-putamen. However, all messenger RNAs showed clearly differentiated patterns of distribution in the hippocampus and the cerebellar cortex. Calmodulin immunoreactivity was present in all cells so far examined. Immunostaining was observed both in the cell nucleus, where it was especially strong, and in the cytoplasm. Our results suggest that the three calmodulin genes are differentially regulated in the mouse brain and also that, although all calmodulin genes have a basal expression, precise regulation of calmodulin levels might be attained through the different contribution of the three calmodulin genes.

Animals↗
PubMed1989

Controlled hypotension during anesthesia for otologic operations. An ultrastructural study of the brain in an experimental animal model.

We have studied the fine structure of the cerebral cortex, the cerebellar cortex, the thalamus, the caudate nucleus, the amygdala, the putamen, the vestibular nuclei, the substantia nigra, the hippocampus and the centrum semiovale in a canine model following 20 min controlled hypotension by the administration of sodium nitroprusside. The neurons and the astrocytes of all structures were intact morphologically. The synapses in the cerebral and cerebellar cortex were all unremarkable. Sensitive areas such as the molecular layer of the cerebellum did not demonstrate any ultrastructural alterations. We believe that carefully controlled sodium-nitroprusside-induced hypotension might be applied in middle ear microsurgery in otherwise healthy patients as an effective and innocuous method without causing any anoxic insult to sensitive areas of the central nervous system.

Animals↗
PubMed1999

Cerebellar lesions and prism adaptation in macaque monkeys.

If a laterally displacing prism is placed in front of one eye of a person or monkey with the other eye occluded, they initially will point to one side of a target that is located directly in front of them. Normally, people and monkeys adapt easily to the displaced vision and correct their aim after a few trials. If the prism then is removed, there is a postadaptation shift in which the subject misses the target and points in the opposite direction for a few trials. We tested five Macaque monkeys for their ability to adapt to a laterally displacing prism and to show the expected postadaptation shift. When tested as normals, all five animals showed the typical pattern of adaptation and postadaptation shift. Like human subjects, the monkeys also showed complete interocular transfer of the adaptation but no transfer of the adaptation between the two arms. When preoperative training and testing was complete, we made lesions of various target areas on the cerebellar cortex. A cerebellar lesion that included the dorsal paraflocculus and uvula abolished completely the normal prism adaptation for the arm ipsilateral to the lesion in one of the five monkeys. The other four animals retained the ability to prism-adapt normally and showed the expected postadaptation shift. In the one case in which the lesion abolished prism adaptation, the damage included Crus I and II, paramedian lobule and the dorsal paraflocculus of the cerebellar hemispheres as well as lobule IX, of the vermis. Thus in this case, the lesion included virtually all the cerebellar cortex that receives mossy-fiber visual information relayed via the pontine nuclei from the cerebral cortex. The other four animals had damage to lobule V, the classical anterior lobe arm area and/or vermian lobules VI/VII, the oculomotor region. When tested postoperatively, some of these animals showed a degree of ataxia equivalent to that of the case in which prism adaptation was affected, but prism adaptation and the postadaptation shift remained normal. We conclude that in addition to its role in long-term motor learning and reflex adaptation, the region of the cerebellum that was ablated also may be a critical site for a short-term motor memory. Prism adaptation seems to involve a region of the cerebellum that receives a mossy-fiber visual error signal and probably a corollary discharge of the movement.

Adaptation, Physiological↗
PubMed1985

[Electrical activity of the cerebellum during the sleep-wakefulness cycle].

Spontaneous electrical activity of the cerebellar cortex and fastigial nuclei was studied in unrestrained cats with implanted electrodes. Rhythmic (4-8/s) electrical activity was recorded in the fastigial nuclei of the cerebellum in paradoxical sleep as well as during some fragments of active wakefulness. A weak correlation between these processes was revealed by means of cross-correlation analysis of electrical activity in the fastigial nuclei and dorsal hippocampus. During wakefulness and in different phases of sleep some high-amplitude waves occur in the cortex of cerebellar vermis, their frequency sharply increasing with the onset of the paradoxical sleep. Functional significance of the changes in electrical activity of the cerebellum in sleep-wakefulness cycle and their possible mechanisms are discussed.

Animals↗
PubMed1991

Metabolism and release of glutamate in cerebellar granule cells cocultured with astrocytes from cerebellum or cerebral cortex.

Cerebellar granule cells were cocultured with astrocytes from either cerebral cortex or cerebellum in two different systems. In one system the cells were plated next to each other only sharing the culture medium (separated cocultures) and in the other system the granule cells were plated on top of a preformed layer of astrocytes (sandwich cocultures). Using astrocytes from cerebellum, granule cells developed morphologically and functionally showing a characteristic high activity of the glutamate synthesizing enzyme aspartate aminotransferase (AAT) as well as a high stimulus-coupled transmitter release regardless of the culture system, i.e., granule cells could grow on top of cerebellar astrocytes as well as next to these cells. In the case of cerebral cortex astrocytes it was found that cerebellar granule cells did not develop (11% survival) when seeded on top of these astrocytes. This was indicated by the morphological appearance of the cultures as well as by a negligible difference between the AAT activity in sandwich cocultures and astrocytes cultured alone. On the other hand, granule cells in separated cocultures with cerebral cortex astrocytes exhibited a normal morphology and a high activity of AAT as well as a large stimulus-coupled transmitter release. Cerebellar and cortical astrocytes expressed the astrocyte specific enzyme glutamine synthetase in a glucocorticoid-inducible form regardless of the culture system. The results show that under conditions of direct contact between granule cells and astrocytes, regional specificity exists with regard to neuron-glia contacts. This specificity does not seem to involve soluble factors present in the culture medium because in separated cocultures the cerebellar granule cells developed normally regardless of the regional origin of the astrocytes.

Animals↗
PubMed1996

Changes in rabbit cerebellar cortical and interpositus nucleus activity during acquisition, extinction, and backward classical eyelid conditioning.

Multiple- and single-unit neuronal activities were recorded from cerebellar cortex (Larsell's lobule HVI and adjacent ansiform cortex) and the cerebellar interpositus nucleus during forward (CS-US), backward (US-CS), and explicitly unpaired classical eyeblink conditioning in several rabbits. Whereas learning-related activity was observed in the interpositus nucleus only during forward pairing of the conditioning stimuli, a variety of patterns of learning-related neuronal firings were observed in cerebellar cortex during forward, backward, and even unpaired presentations of the conditioning stimuli. These data suggest that the cerebellar cortex and the deep cerebellar nuclei play different roles during classical eyeblink conditioning.

Animals↗
PubMed1996

The cerebellum: a neuronal learning machine?

Comparison of two seemingly quite different behaviors yields a surprisingly consistent picture of the role of the cerebellum in motor learning. Behavioral and physiological data about classical conditioning of the eyelid response and motor learning in the vestibulo-ocular reflex suggests that (i) plasticity is distributed between the cerebellar cortex and the deep cerebellar nuclei; (ii) the cerebellar cortex plays a special role in learning the timing of movement; and (iii) the cerebellar cortex guides learning in the deep nuclei, which may allow learning to be transferred from the cortex to the deep nuclei. Because many of the similarities in the data from the two systems typify general features of cerebellar organization, the cerebellar mechanisms of learning in these two systems may represent principles that apply to many motor systems.

Animals↗
PubMed1990

Human brain sulphotransferase and glucuronyltransferase.

The activities of cytosolic sulphotransferase (ST) and microsomal glucuronyltransferase (GT) were measured with 1-naphthol as the substrate in three frontal cortex, three temporal cortex, one parietal cortex, one occipital cortex and two cerebellar cortex specimens from human brain. The average activity was 11.7 +/- 4.2 pmol/min/mg protein/(ST) and 26.8 +/- 13.6 pmol/min/mg protein (GT). The kinetics of ST were studied varying the concentration of 1-naphthol in five brain specimens (temporal cortex, temporal subcortex, occipital cortex, cerebellum cortex and frontal cortex) whereas those of GT were studied in a sample obtained by pooling the microsomal fractions from the following eight brain tissues: one frontal cortex, four temporal cortex, one parietal cortex and two cerebellar cortex specimens. The Km of the first and second enzyme was 1.55 +/- 0.47 microM (mean +/- s.d.) and 121 microM, respectively. The Vmax values were 13.70 +/- 8.16 (mean +/- s.d.) pmol/min/mg protein (ST) and 103 pmol/min/mg protein (GT). Vmax/Km was ten times higher for ST than GT. These data suggest that ST is the predominant pathway at low concentrations of 1-naphthol whereas at higher concentrations, GT becomes the predominant pathway.

Aged↗
PubMed1997

Cerebellar circuits and synaptic mechanisms involved in classical eyeblink conditioning.

There is increasing evidence that, in addition to its major functional role in the regulation of fine motor control, the cerebellum is involved in other important functions, such as sensory-motor learning and memory. Classical conditioning of the eyeblink or nictitating membrane response (and other discrete behavioral responses) is a form of sensory-motor learning that depends crucially upon the cerebellum. Within the cerebellum, however, the relative importance of the cerebellar cortex and the deep cerebellar nuclei in eyeblink conditioning is unclear and disputed. Recent studies employing various mutant mice provide an effective approach to resolving this controversy. Eyeblink conditioning in spontaneous mutant mice deficit in Purkinje cells, the exclusive output neurons of the cerebellar cortex, indicate that both the cerebellar cortex and the interpositus nucleus are important. Furthermore, studies involving gene knockout mice suggest that long-term depression, a process of synaptic plasticity occurring in Purkinje cells, might be involved in eyeblink conditioning.

Animals↗
PubMed2002

Immunohistochemical study on the distribution of nitrotyrosine and neuronal nitric oxide synthase in aged rat cerebellum.

In the present study, we examined age-related changes in 3-nitrotyrosine (NT) and neuronal nitric oxide synthase (nNOS) in rat cerebellum using immunohistochemistry. No immunoreactivity for NT was found in any layers of adult cerebellar cortex. In aged cerebellar cortex, the most prominent labeling of NT was found in the Purkinje cell layers and molecular layers. In aged cerebellar nuclei, NT immunoreactivity was observed in the surrounding neuropil. In aged rat cerebellum, nNOS immunoreactivity was significantly decreased in the molecular layer, while it was slightly increased in the granular layer. Image analysis showed no significant age-related changes in nNOS immunoreactivity in the cerebellar nuclei. In summary, this report has demonstrated that NT increases with age in the cerebellum, and suggests that NO production by the neuronal form of NOS may not be the rate limiting step in NT formation in the aged brain. Further work is needed to examine the mechanisms underlying the increased immunoreactivity for NT, and the functional implications of this increase.

Aging↗
PubMedDate not supplied

Effect of nicardipine treatment on the expression of neurofilament 200 KDa immunoreactivity in the brain of spontaneously hypertensive rats.

Neurofilaments (NFP) are components of neuronal cytoskeleton involved primarily in axonal transport and in the regulation of dynamic activities of nerve cells. NFP consist of three subunits denominated high- (200 kDa, NFP-H), intermediate- (160 kDa, NFP-I), and low-molecular weight (68 kDa, NFP-L) neurofilament proteins. Their function and polymerization depends on phosphorylation status, and is regulated by Ca2+ influx. Ca2+ overload enhances degradation of NFP and may compromise axonal transport. An increased susceptibility to ischemia occurs in hypertension, which is also a cause of brain damage. In this study, the expression of phosphorylated NFP (P-NFP) was investigated in the brain of spontaneously hypertensive rats (SHR) using immunohistochemical techniques with antibodies against the phosphorylated epitope of NFP RT-97. Microanatomical analysis included frontal cortex, occipital cortex, hippocampus and cerebellar cortex. The effect of long-term treatment with the dihydropyridine-type Ca2+ antagonist nicardipine on the expression of P-NFP was investigated as well. In hypertension a decreased P-NFP immunoreactivity was observed in frontal and occipital cortex, in the CA1 subfield of hippocampus and in the dentate gyrus, but not in the CA3 subfield of hippocampus or in the cerebellar cortex. Treatment with a daily dose of 3 mg/kg of nicardipine and 10 mg/kg of hydralazine significantly reduced systolic pressure in SHR. The above dose of nicardipine and to a lesser extent a non-hypotensive dose of the compound (0.1 mg/kg/day), but not hydralazine, increased P-NFP immunoreactivity in the cerebral cortex and hippocampus, except the CA3 subfield. The possibility that rescued P-NFP immunoreactivity by treatment with nicardipine depends on improved brain perfusion caused by the compound and/or by countering neuronal Ca2+ overload is discussed.

Animals↗
PubMed1994

Single neurons in the ventral tegmental area that project to both the cerebral and cerebellar cortical areas by way of axon collaterals.

Recently, we have found that the ventral tegmental area of the rat sends dopaminergic and non-dopaminergic axons, respectively, to the cerebellar cortex and deep cerebellar nuclei [Ikai et al. (1992) Neuroscience 51, 719-728]. In the present study, employing fluorescent retrograde double labeling with Fast Blue and Diamidino Yellow, we examined whether individual neurons in the ventral tegmental area of the rat send their axons to both the cerebellum and other brain regions. The neurons projecting to the cerebellar cortex often issued axon collaterals to the cerebral cortical areas, including the prelimbic-anterior cingulate cortices and piriform-entorhinal cortices, but not so frequently to the subcortical regions, including the nucleus accumbens, lateral septum, amygdala, and lateral habenula. On the other hand, the neurons projecting to the deep cerebellar nuclei rarely sent axon collaterals to the cerebral cortical and subcortical regions.

Animals↗
PubMed1995

Existence of a putative specific postsynaptic density protein produced during Purkinje cell spine maturation.

This study identified a 140 kDa polypeptide as a putative specific component of Purkinje cell spines' postsynaptic densities and which began to appear during the critical period of cerebellar cortex synaptogenesis. Mouse cerebellar cortices at postnatal days 5, 7, 9, 11, 15 and young adult, between days 30 and 40, were used to purify subcellular fractions of synaptosomes, synaptic membranes and postsynaptic densities. The purity of the subcellular fractions was assessed by electron microscopy and the protein composition of the different fractions was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Polypeptides of apparent molecular weights of 25, 26, 27, 30, 33, 37, 43, 45, 52, 64, 74, 85, 94, 110, 125, 130, 165 and 174 kDa were found in the synaptosomal fractions of all the ages studied, even before the critical period of synaptogenesis, at postnatal day 7, when the postsynaptic densities were still nonexistent, indicating that the polypeptides are nonspecific constituents of these structures. On the other hand, a 140 kDa polypeptide was detected in the postsynaptic density fractions at postnatal day 11, immediately after postsynaptic structures began to appear, suggesting the possibility that this protein is a specific component of the cerebellar cortex postsynaptic densities. The 140 kDa polypeptide was electroeluted from the gel and analysed for its amino acid composition by reverse-phase high-pressure liquid chromatography. The analysis showed that this protein has a high content of nonpolar amino acid residues, such as leucine, isoleucine, glycine, phenylalanine and valine. A hypothetical model relative to the participation of the 140 kDa protein in the molecular organization of the postsynaptic density is suggested which may contribute to the understanding of the role played by this structure in synaptic function.

Aging↗
PubMed1997

P300 and cerebral blood flow before and after TRH in olivopontocerebellar atrophy.

Ten cases of olivopontocerebellar atrophy (OPCA) (mean age 56 +/- 9 years) and 8 healthy controls (mean age 58 +/- 9 years) were studied. The P300 was measured with a Synax 1100 evoked potential recorder and the regional cerebral blood flow was measured using the stable xenon computed tomography method. The P300 latency was significantly longer in the OPCA group than in the healthy control group. The P300 latency after the intravenous infusion of thyrotropin releasing hormone (TRH) in the OPCA group was significantly shorter than that before the intravenous infusion of TRH. The blood flows in all the measured areas (the cerebellar cortex, the cerebellar white matter, the brainstem, the thalamus, the basal ganglia, the frontal lobe cortex and the frontal lobe white matter) were significantly lower in the OPCA group than in the healthy control group. The blood flows in the cerebellar cortex and in the frontal lobe cortex after the intravenous infusion of TRH were significantly higher than those before the intravenous infusion of TRH. The prolongation of P300 latency in the OPCA group suggests that subclinical disturbance in recognition function is present in OPCA and may be related to the blood flow decrease outside the cerebellum.

Aged↗