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Query: UMLS:C0153640 (Cerebellum)
 1,777 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Presynaptic terminals occur along unmyelinated axons in specialized compartments called axonal varicosities or synaptic boutons. Since the first descriptions of varicose axons by Cajal and others, the spatial organization of varicosities along axons has attracted the attention of neuroscientists. Quantitative light- and electron-microscopic analyses of varicosity spacing in the cerebellum and elsewhere have recently provided a clearer picture of this organization, and theoretical analyses now incorporate varicosity spacing as an essential parameter in structural models of neural connectivity. Here we review the salient features of varicosity spacing, with emphasis on cerebellar parallel fibers as a model system. Measured globally across the entire approximately 5 mm lengths of parallel fibers, the overall mean spacing of varicosities is 5.2 microm. Measured locally, however, mean spacing follows a proximodistal gradient, increasing with distance from the point of bifurcation from the ascending axon. Measured at the level of individual varicosities, parallel fiber varicosity distributions follow a distinct pattern characterized by a fixed relationship between the spacing variability and mean. This pattern equally describes varicosity distributions in a number of other brain regions, and therefore appears to constitute a general scaling relationship for excitatory varicose axons. We further discuss evidence for common principles underlying the placement of both varicosities and synapses along axons.
Cerebellum 2003
PMID:Axonal varicosity distributions along parallel fibers: a new angle on a cerebellar circuit. 1288 Jan 78

The cellular and synaptic organization of new born mouse cerebellum maintained in organotypic slice cultures was investigated using immunohistochemical and patch-clamp recording approaches. The histological organization of the cultures shared many features with that observed in situ. Purkinje cells were generally arranged in a monolayer surrounded by a molecular-like neuropil made of Purkinje cell dendritic arborizations. Purkinje cell axons ran between clusters of small round cells identified as granule cells by Kv3.1b potassium channel immunolabelling. The terminal varicosities of the Purkinje cells axons enwrapped presumptive neurons of the cerebellar nuclei whereas their recurrent collaterals were in contact with Purkinje cells and other neurons. Granule cell axons established contacts with Purkinje cell somata and dendrites. Parvalbumin and glutamine acid decarboxylase (GAD) immunohistochemistry revealed the presence of presumptive interneurons throughout the culture. The endings of granule cell axons were observed to be in contact with these interneurons. Similarly, interneurons endings were seen close to Purkinje cells and granule cells. Whole cell recordings from Purkinje cell somata showed AMPA receptor-mediated spontaneous excitatory post-synaptic currents (sEPSCs) and GABAA receptor-mediated spontaneous inhibitory post-synaptic currents (sIPSCs). Similar events were recorded from granule cell somata except that in this neuronal type EPSPs have both a NMDA component and an AMPA component. In addition, pharmacological experiments demonstrated a GABAergic control of granule cell activity and a glutamatergic control of GABAergic neurons by granule cells. This study shows that a functional neuronal network is established in such organotypic cultures even in the absence of the two normal excitatory afferents, the mossy fibers and the climbing fibers.
Cerebellum 2006
PMID:Synaptic organization of the mouse cerebellar cortex in organotypic slice cultures. 1713 87

Our understanding of GABAergic and glutamatergic neurotransmission in the CNS has been greatly influenced with the discovery and subsequent investigations of the metabotropic gamma-aminobutyric acid (B) (GABA(B)) receptors. These G-protein coupled receptors mediate slow inhibitory neurotransmission and are widely expressed and distributed in the cerebellum, where they play critical roles in neuronal excitability and modulation of synaptic neurotransmission. Their function is modulated by interaction with effector ion channels, notably inwardly rectifying K(+) channels and voltage-gated Ca(2+) channels. The receptors are encoded by two distinct subunits, GABA(B1) and GABA(B2), both of which are required in order to function normally in vivo, as shown in recombinant expression systems and in GABA(B1) -/- mice. The GABA(B1) and GABA(B2) subunits exhibit overlapping distributions in the cerebellar cortex, both at pre- and postsynaptic sites, during development and adulthood. They are in particular abundant in Purkinje cells prior to synaptogenesis and throughout postnatal development. Using high-resolution immunohistochemical techniques at the electron microscopic level in combination with quantitative analysis and three-dimensional reconstructions, it has recently been demonstrated that GABA(B) receptors undergo changes in localization on the surface of Purkinje cell dendrites and spines during postnatal development in association with the establishment and maturation of excitatory synapses. Due to this dynamic regulation, the highest densities of GABA(B1) and GABA(B2) subunits occur around the glutamatergic synapses between Purkinje cell spines and parallel fibre varicosities. This review highlights recent studies that have shed further light on the subcellular localization during postnatal development and the cell surface dynamics of GABA(B) receptors.
Cerebellum 2007
PMID:Subcellular regulation of metabotropic GABA receptors in the developing cerebellum. 1751 Sep 12

Venous malformations are the most common cerebral vascular malformation, frequently associated with cavernous malformation, and rarely accompanied by a varix. We report the case of a 67-year-old woman with tinnitus, whose cranial magnetic resonance images and selective catheter angiograms showed extensive cerebellar venous malformation with cavernous malformations and varix. Injury of vessel walls by increased blood flow in the draining vein of the malformation may have led to the development of cavernous malformations and a varix. To our knowledge, such association with an extensive cerebellar venous malformation has not been reported.
Cerebellum 2012 Sep
PMID:Extensive cerebellar venous malformation associated with a varix and cavernous malformations: a case report. 2228 66

Thanks to their flexibility, optical techniques could be the key to explore anatomy, plasticity, and functionality of the cerebellum. As an example, an in vivo analysis of the dynamic remodeling of cerebellar axons by nonlinear microscopy can provide fundamental insights of the mechanism that promotes neuronal regeneration. Several studies showed that damaged climbing fibers are capable of regrowing also in adult animals. The investigation of the time-lapse dynamics of degeneration and regeneration of these axons within their complex environment can be performed by time-lapse two-photon fluorescence (TPF) imaging in vivo. Here, we show that single axonal branches can be dissected by laser axotomy, thus avoiding collateral damage to the adjacent dendrite and the formation of a persistent glial scar. Despite the very small denervated area, the injured axons consistently reshaped the connectivity with surrounding neurons and sprouted new branches through the intact surroundings. Correlative light and electron microscopy revealed that the sprouted branch contains large numbers of vesicles, with varicosities in the close vicinity of Purkinje dendrites. By using an RNA interference approach, we found that downregulating GAP-43 causes a significant increase in the turnover of presynaptic boutons and hampers the generation of reactive sprouts. Further, we report how nonlinear microscopy in combination with novel voltage sensitive dyes or transgenic mice allow optical registrations of action potential across a population of neurons opening promising prospective in understanding brain functionality. Finally, we describe novel implementations of light-sheet microscopy to resolve neuronal anatomy in whole cerebellum with cellular resolution. The understanding gained from these complementary optical methods may provide a deeper comprehension of the cerebellum.
Cerebellum 2016 Feb
PMID:Multi-Modal Optical Imaging of the Cerebellum in Animals. 2647 52