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Purkinje fibre

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https://www.readbyqxmd.com/read/29589816/modulation-of-complex-spike-activity-differs-between-zebrin-positive-and-negative-purkinje-cells-in-the-pigeon-cerebellum
#1
Rebecca M Long, Janelle M P Pakan, David J Graham, Peter L Hurd, Cristian Gutierrez-Ibanez, Douglas R Wylie
The cerebellum is organized into parasagittal zones defined by its climbing and mossy fibre inputs, efferent projections, and Purkinje cell (PC) response properties. Additionally, parasagittal stripes can be visualized with molecular markers, such as the heterogeneous expression of the isoenzyme zebrin II (ZII), where sagittal stripes of high ZII expression (ZII+) are interdigitated with stripes of low ZII expression (ZII-). In the pigeon vestibulocerebellum, a ZII+/- stripe pair represents a functional unit, insofar as both ZII+ and ZII- PCs within a stripe pair respond best to the same pattern of optic flow...
March 28, 2018: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29571876/normal-tendon-reflexes-despite-absent-sensory-nerve-action-potentials-in-canvas-a-neurophysiological-study
#2
David Burke, G Michael Halmagyi
CANVAS is a recently defined progressive ataxic syndrome with impairment of vestibular, somatosensory and cerebellar function due to atrophic degeneration of dorsal root ganglia and dorsal columns, of cranial nerve somatosensory ganglia, of vestibular ganglia and vestibular nerves and of cerebellar Purkinje cells. While all patients eventually develop sensory impairment in a non-length dependent pattern and lose sensory nerve action potentials, some retain their tendon reflexes. Here we study 5 CANVAS patients with absent sensory nerve action potentials but intact, even brisk Achilles tendon reflexes and, in 4, preserved H reflexes in the upper and lower limbs...
April 15, 2018: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/29460990/beta-gamma-burst-stimulations-of-the-inferior-olive-induce-high-frequency-oscillations-in-the-deep-cerebellar-nuclei
#3
Julian Cheron, Guy Cheron
The cerebellum displays various sorts of rhythmic activities covering both low- and high-frequency oscillations. These cerebellar high-frequency oscillations were observed in the cerebellar cortex. Here, we hypothesised that not only is the cerebellar cortex a generator of high-frequency oscillations but also that the deep cerebellar nuclei may also play a similar role. Thus, we analysed local field potentials and single-unit activities in the deep cerebellar nuclei before, during and after electric stimulation in the inferior olive of awake mice...
February 20, 2018: European Journal of Neuroscience
https://www.readbyqxmd.com/read/29403069/genetic-targeting-of-purkinje-fibres-by-sema3a-creert2
#4
Yan Li, Xueying Tian, Huan Zhao, Lingjuan He, Shaohua Zhang, Xiuzhen Huang, Hui Zhang, Lucile Miquerol, Bin Zhou
The maintenance of the heart rhythm and the conduction of excitatory signals require changing excitatory signals via electrical activity and coordination by communication between working and conductive cardiomyocytes. Understanding how the ventricular conduction system is established provides novel insights into the pathophysiological progress of cardiac arrhythmias. However, the major hurdle in this field is the lack of a specific genetic tool that targets the Purkinje fibres of the ventricular conduction system and no other types of cardiomyocytes or coronary vessels...
February 5, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29067911/syncope-in-a-young-man-role-of-purkinje-fibres-in-idiopathic-ventricular-fibrillation
#5
Claire A Martin, Laurence Nunn, Pier D Lambiase
A young man suffered cardiac arrests with polymorphic ventricular tachycardia (PVT) and ventricular fibrillation (VF) triggered by ventricular premature contractions (PVCs). The arrhythmia was resistant to anti-arrhythmics, so after ICD implantation he underwent successful ablation of the triggering VE beat, which was pace-mapped to the left posterior hemi-fascicle. We review the evidence for the role of the Purkinje network in the initiation and maintenance of PVT and VF, postulating a channelopathy as a possible underlying cause, and provide recommendations for PVC ablation...
July 2017: Indian Pacing and Electrophysiology Journal
https://www.readbyqxmd.com/read/29060697/a-generic-cardiac-biventricular-fluid-electromechanics-model
#6
Azam Ahmad Bakir, Amr Al Abed, Nigel H Lovell, Socrates Dokos
We present a fully-coupled fluid-electromechanics model of the heart using a generic biventricular structure to provide a tool for future multiphysics interaction studies. A simplified Purkinje fibre structure was embedded within the myocardium along with transmural variation of action potential duration to obtain realistic activation and relaxation sequences. To ease computational requirements, phenomenological action potential and excitation-contraction formulations were chosen, and coupled to transverse isotropic hyperelastic myocardial material physics...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28941245/nonclinical-cardiovascular-safety-of-pitolisant-comparing-international-conference-on-harmonization-s7b-and-comprehensive-in-vitro-pro-arrhythmia-assay-initiative-studies
#7
Xavier Ligneau, Rashmi R Shah, Isabelle Berrebi-Bertrand, Gary R Mirams, Philippe Robert, Laurent Landais, Pierre Maison-Blanche, Jean-François Faivre, Jeanne-Marie Lecomte, Jean-Charles Schwartz
BACKGROUND AND PURPOSE: We evaluated the concordance of results from two sets of nonclinical cardiovascular safety studies on pitolisant. EXPERIMENTAL APPROACH: Nonclinical studies envisaged both in the International Conference on Harmonization (ICH) S7B guideline and Comprehensive in vitro Pro-arrhythmia Assay (CiPA) initiative were undertaken. The CiPA initiative included in vitro ion channels, stem cell-derived human ventricular myocytes, and in silico modelling to simulate human ventricular electrophysiology...
December 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28795396/synaptic-excitation-by-climbing-fibre-collaterals-in-the-cerebellar-nuclei-of-juvenile-and-adult-mice
#8
Marion Najac, Indira M Raman
KEY POINTS: The inferior olive sends instructive motor signals to the cerebellum via the climbing fibre projection, which sends collaterals directly to large premotor neurons of the mouse cerebellar nuclei (CbN cells). Optogenetic activation of inferior olivary axons in vitro evokes EPSCs in CbN cells of several hundred pA to more than 1 nA. The inputs are three-fold larger at younger ages, 12 to 14 days old, than at 2 months old, suggesting a strong functional role for this pathway earlier in development...
November 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28794450/serial-processing-of-kinematic-signals-by-cerebellar-circuitry-during-voluntary-whisking
#9
Susu Chen, George J Augustine, Paul Chadderton
Purkinje cells (PCs) in Crus 1 represent whisker movement via linear changes in firing rate, but the circuit mechanisms underlying this coding scheme are unknown. Here we examine the role of upstream inputs to PCs-excitatory granule cells (GCs) and inhibitory molecular layer interneurons-in processing of whisking signals. Patch clamp recordings in GCs reveal that movement is accompanied by changes in mossy fibre input rate that drive membrane potential depolarisation and high-frequency bursting activity at preferred whisker angles...
August 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/28677370/neuronal-vacuolation-and-spinocerebellar-degeneration-associated-with-altered-neurotransmission
#10
Aggeliki Giannakopoulou
<i>Inherited neurodegenerative disorders are debilitating diseases that occur across different species, such as the domestic dog (Canis lupus familiaris), and many are caused by mutations in the same genes as corresponding human conditions. In the present study, we report an inherited neurodegenerative condition, termed 'neuronal vacuolation and spinocerebellar degeneration' (NVSD) which affects neonatal or young dogs, mainly Rottweilers, which recently has been linked with the homozygosity for the RAB3GAP1:c...
2017: Folia Neuropathologica
https://www.readbyqxmd.com/read/28634887/aberrant-connections-between-climbing-fibres-and-purkinje-cells-induce-alterations-in-the-timing-of-an-instrumental-response-in-the-rat
#11
Lorena Gaytán-Tocavén, Miguel Ángel López-Vázquez, Miguel Ángel Guevara, María Esther Olvera-Cortés
Cerebellar participation in timing and sensory-motor sequences has been supported by several experimental and clinical studies. A relevant role of the cerebellum in timing of conditioned responses in the range of milliseconds has been demonstrated, but less is known regarding the role of the cerebellum in supra-second timing of operant responses. A dissociated role of the cerebellum and striatum in timing in the millisecond and second range had been reported, respectively. The climbing fibre-Purkinje cell synapse is crucial in timing models; thus, the aberrant connection between these cellular elements is a suitable model for evaluating the contribution of the cerebellum in timing in the supra-second range...
September 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28513836/facilitation-of-mossy-fibre-driven-spiking-in-the-cerebellar-nuclei-by-the-synchrony-of-inhibition
#12
Yeechan Wu, Indira M Raman
KEY POINTS: Large premotor neurons of the cerebellar nuclei (CbN cells) integrate synaptic inhibition from Purkinje neurons and synaptic excitation from mossy fibres to generate cerebellar output. We find that mossy fibre inputs to CbN cells generate unitary AMPA receptor EPSCs of ∼1 nS that decay in ∼1 ms and mildly voltage-dependent NMDA receptor EPSCs of ∼0.6 nS that decay in ∼7 ms. A few hundred mossy fibres active at a few tens of spikes s(-1) must converge on CbN cells to generate physiological CbN spike rates (∼60 spikes s(-1) ) during convergent inhibition from spontaneously active Purkinje cells...
August 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28495974/long-term-depression-of-intrinsic-excitability-accompanied-by-synaptic-depression-in-cerebellar-purkinje-cells
#13
Hyun Geun Shim, Dong Cheol Jang, Jaegeon Lee, Geehoon Chung, Sukchan Lee, Yong Gyu Kim, Da Eun Jeon, Sang Jeong Kim
Long-term depression (LTD) at the parallel fiber (PF)-to-cerebellar Purkinje cell (PC) synapse is implicated in the output of PCs, the sole output of the cerebellar cortex. In addition to synaptic plasticity, intrinsic excitability is also one of the components that determines PC output. Although long-term potentiation of intrinsic excitability (LTP-IE) has been suggested, it has yet to be investigated how PF-PC LTD modifies intrinsic excitability of PCs. Here, we show that pairing of the PF and climbing fiber (CF) for PF-PC LTD induction evokes LTD-IE in cerebellar PCs from male C57BL/6 mice...
June 7, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28433554/catheter-ablation-to-prevent-sudden-cardiac-death
#14
Josef Kautzner, Petr Peichl
Since ventricular arrhythmias are a common cause of sudden cardiac death (SCD), treatment for ventricular arrhythmias is the target area of interest in research field. Among different means to prevent ventricular arrhythmias, catheter ablation (CA) has emerged as an effective therapeutic method. CA can decrease the likelihood of SCD in the following arrhythmia categories: 1) idiopathic ventricular fibrillation (VF) that is usually triggered by premature ventricular beats originating in the Purkinje fibres; 2) VF in subjects with structural heart disease, especially after myocardial infarction, that is triggered by premature ventricular beats from surviving Purkinje fibres; 3) Brugada syndrome in which modification of an epicardial substrate in the right ventricular outflow tract might be the most promising strategy; 4) recurrent monomorphic ventricular tachycardias in the setting of structural heart disease; 5) ventricular preexcitation in which CA appears to be a method of choice in high risk patients, regardless of the presence or absence of symptoms...
June 15, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/27832106/the-effect-of-a-novel-highly-selective-inhibitor-of-the-sodium-calcium-exchanger-ncx-on-cardiac-arrhythmias-in-in-vitro-and-in-vivo-experiments
#15
Zsófia Kohajda, Nikolett Farkas-Morvay, Norbert Jost, Norbert Nagy, Amir Geramipour, András Horváth, Richárd S Varga, Tibor Hornyik, Claudia Corici, Károly Acsai, Balázs Horváth, János Prorok, Balázs Ördög, Szilvia Déri, Dániel Tóth, Jouko Levijoki, Piero Pollesello, Tuula Koskelainen, Leena Otsomaa, András Tóth, István Baczkó, István Leprán, Péter P Nánási, Julius Gy Papp, András Varró, László Virág
BACKGROUND: In this study the effects of a new, highly selective sodium-calcium exchanger (NCX) inhibitor, ORM-10962 were investigated on cardiac NCX current, Ca2+ transients, cell shortening and in experimental arrhythmias. The level of selectivity of the novel inhibitor on several major transmembrane ion currents (L-type Ca2+ current, major repolarizing K+ currents, late Na+ current, Na+/K+ pump current) was also determined. METHODS: Ion currents in single dog ventricular cells (cardiac myocytes; CM), and action potentials in dog cardiac multicellular preparations were recorded utilizing the whole-cell patch clamp and standard microelectrode techniques, respectively...
2016: PloS One
https://www.readbyqxmd.com/read/27716829/analysis-of-microstructure-of-the-cardiac-conduction-system-based-on-three-dimensional-confocal-microscopy
#16
Daniel Romero, Oscar Camara, Frank Sachse, Rafael Sebastian
The specialised conducting tissues present in the ventricles are responsible for the fast distribution of the electrical impulse from the atrio-ventricular node to regions in the subendocardial myocardium. Characterisation of anatomical features of the specialised conducting tissues in the ventricles is highly challenging, in particular its most distal section, which is connected to the working myocardium via Purkinje-myocardial junctions. The goal of this work is to characterise the architecture of the distal section of the Purkinje network by differentiating Purkinje cells from surrounding tissue, performing a segmentation of Purkinje fibres at cellular scale, and mathematically describing its morphology and interconnections...
2016: PloS One
https://www.readbyqxmd.com/read/27661463/improved-hybrid-gpu-algorithm-for-solving-cardiac-electrophysiology-problems-on-purkinje-networks
#17
M Lange, S Palamara, T Lassila, C Vergara, A Quarteroni, A F Frangi
Cardiac Purkinje fibers provide an important pathway to the coordinated contraction of the heart. We present a numerical algorithm for the solution of electrophysiology problems across the Purkinje network that is efficient enough to be used in in silico studies on realistic Purkinje networks with physiologically detailed models of ion exchange at the cell membrane. The algorithm is on the basis of operator splitting and is provided with 3 different implementations: pure CPU, hybrid CPU/GPU, and pure GPU. Compared to our previous work, we modify the explicit gap junction term at network bifurcations to improve its mathematical consistency...
September 23, 2016: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/27651000/spatiotemporal-dynamics-of-lesion-induced-axonal-sprouting-and-its-relation-to-functional-architecture-of-the-cerebellum
#18
Matasha Dhar, Joshua M Brenner, Kenji Sakimura, Masanobu Kano, Hiroshi Nishiyama
Neurodegenerative lesions induce sprouting of new collaterals from surviving axons, but the extent to which this form of axonal remodelling alters brain functional structure remains unclear. To understand how collateral sprouting proceeds in the adult brain, we imaged post-lesion sprouting of cerebellar climbing fibres (CFs) in mice using in vivo time-lapse microscopy. Here we show that newly sprouted CF collaterals innervate multiple Purkinje cells (PCs) over several months, with most innervations emerging at 3-4 weeks post lesion...
September 21, 2016: Nature Communications
https://www.readbyqxmd.com/read/27586811/cathepsin-l-coexists-with-cytotoxic-t-lymphocyte-antigen-2-alpha-in-distinct-regions-of-the-mouse-brain
#19
Claudius Luziga, Bui Thi To Nga, Gabriel Mbassa, Yoshimi Yamamoto
Cathepsins B and L are two prominent members of cystein proteases with broad substrate specificity and are known to be involved in the process of intra- and extra-cellular protein degradation and turnover. The propeptide region of cathepsin L is identical to Cytotoxic T-lymphocyte antigen-2α (CTLA-2α) discovered in mouse activated T-cells and mast cells. CTLA-2α exhibits selective inhibitory activities against papain and cathepsin L. We previously demonstrated the distribution pattern of the CTLA-2α protein in mouse brain by immunohistochemistry, describing that it is preferentially localized within nerve fibre bundles than neuronal cell bodies...
September 2016: Acta Histochemica
https://www.readbyqxmd.com/read/27581745/dysfunctional-cerebellar-purkinje-cells-contribute-to-autism-like-behaviour-in-shank2-deficient-mice
#20
Saša Peter, Michiel M Ten Brinke, Jeffrey Stedehouder, Claudia M Reinelt, Bin Wu, Haibo Zhou, Kuikui Zhou, Henk-Jan Boele, Steven A Kushner, Min Goo Lee, Michael J Schmeisser, Tobias M Boeckers, Martijn Schonewille, Freek E Hoebeek, Chris I De Zeeuw
Loss-of-function mutations in the gene encoding the postsynaptic scaffolding protein SHANK2 are a highly penetrant cause of autism spectrum disorders (ASD) involving cerebellum-related motor problems. Recent studies have implicated cerebellar pathology in the aetiology of ASD. Here we evaluate the possibility that cerebellar Purkinje cells (PCs) represent a critical locus of ASD-like pathophysiology in mice lacking Shank2. Absence of Shank2 impairs both PC intrinsic plasticity and induction of long-term potentiation at the parallel fibre to PC synapse...
September 1, 2016: Nature Communications
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