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1.

001-es BibID:BIBFORM029495
Első szerző:Birinyi András (anatómus, neurobiológus)
Cím:The extent of the dendritic tree and the number of synapses in the frog motoneuron / Birinyi A., Antal M., Wolf E., Székely G.
Dátum:1992
ISSN:0953-816X
Megjegyzések:Frog motoneurons were intracellularly labelled with cobaltic lysine in the brachial and the lumbar segments of the spinal cord, and the material was processed for light microscopy in serial sections. With the aid of the neuron reconstruction system NEUTRACE, the dendritic tree of neurons was reconstructed and the length and surface area of dendrites measured. The surface of somata was determined with the prolate - oblate average ellipsoid calculation. Corrections were made for shrinkage and for optical distortion. The mean surface area of somata was 6710 microm2; lumbar motoneurons were slightly larger than brachial motoneurons. The mean length of the combined dendritic tree of brachial neurons was 29 408 microm and that of lumbar neurons 46 806 microm. The mean surface area was 127 335 microm2 in brachial neurons, and 168 063 microm2 in lumbar neurons. The soma - dendrite surface area ratio was 3 - 5% in most cases. Dendrites with a diameter of </= 1.0 microm constituted approximately 75% of the combined dendritic length in most of the neurons. Unlike in the cat, there was no correlation between the size of stem dendrites and the extent of daughter branches. From the synaptic density estimated in earlier electron microscope investigations of frog motoneuron dendrites (Antal et al., J. Neurocytol., 15, 303 - 310, 1986; 21, 34 - 49, 1992), and from the present data, the number of synapses on the dendritic tree was calculated. The calculations indicated 26 949 synapses on the smallest and 61 519 synapses on the largest neuron if the synaptic density was multiplied by the length of the dendritic tree. If the synaptic density was multiplied by the surface area of the dendritic tree the calculation yielded 23 337 synapses for the smallest and 60 682 synapses for the largest neuron. More than 60% of the combined surface area of dendrites was >600 microm from the soma. This suggests that about two-thirds of the synapses impinged upon distant dendrites >600 microm from the soma. The efficacy of synapses at these large distances is investigated on model neurons in the accompanying paper
Tárgyszavak:Orvostudományok Természettudományok Biológiai tudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:European Journal Of Neuroscience. - 4 : 11 (1992), p. 1003-1012. -
További szerzők:Antal Miklós (1951-) (orvos, anatómus) Wolf Ervin (1961-) (fizikus, neurobiológus) Székely György (1926-2017) (neurobiológus)
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2.

001-es BibID:BIBFORM020247
Első szerző:Li, Wen-Chang
Cím:Persistent responses to brief stimuli : feedback excitation among brainstem neurons / Wen-Chang Li, Stephen R. Soffe, Ervin Wolf, Alan Roberts
Dátum:2006
ISSN:0270-6474
Megjegyzések:The ability of brief stimuli to trigger prolonged neuronal activity is a fundamental requirement in nervous systems, common to motor responses and short-term memory. Bistable membrane properties and network feedback excitation have both been proposed as suitable mechanisms to sustain such persistent responses. There is now good experimental evidence for membrane bistability. In contrast, the long-standing hypotheses based on positive feedback excitation have yet to be supported by direct evidence for mutual excitatory connections between appropriate neurons. In young frog tadpoles (Xenopus), we show that a small region of caudal hindbrain and rostral spinal cord is sufficient to generate prolonged swimming in response to a brief stimulus. We used paired whole-cell patch recordings to identify hindbrain neurons in this region that actively excite spinal neurons to drive sustained swimming. We show directly that some of these hindbrain neurons make reciprocal excitatory connections with each other. We use a population model of the hindbrain network to illustrate how feedback excitation can provide a robust mechanism to generate persistent responses. Our recordings provide direct evidence for feedback excitation among neurons within a network that drives a prolonged response. Its presence in a lower brain region early in development suggests that it is a basic feature of neuronal network design.
Tárgyszavak:Orvostudományok Természettudományok Klinikai orvostudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:The Journal of Neuroscience. - 26 : 15 (2006), p. 4026-4035. -
További szerzők:Wolf Ervin (1961-) (fizikus, neurobiológus) Soffe, Stephen R. Roberts, Alan
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3.

001-es BibID:BIBFORM097650
035-os BibID:(cikkazonosító)721773 (Scopus)85118322206
Első szerző:Somogyi Attila
Cím:Increased Signal Delays ad Unaltered Synaptic Input Pattern Recognitio in Layer III Neocortical Pyramidal Neurons of the rTg4510 Mouse Model of Tauopathy : a Computer Simulation Study With Passive Membrane / Attila Somogyi, Ervin Wolf
Dátum:2021
ISSN:1662-453X
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Frontiers in Neuroscience. - 15 (2021), p. 721773. -
További szerzők:Wolf Ervin (1961-) (fizikus, neurobiológus)
Pályázati támogatás:TÁMOP 4.2.4. B/2-11-1-2012-0001
TÁMOP
TÁMOP 4.2.4. A/2- 11-1-2012-0001
TÁMOP
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4.

001-es BibID:BIBFORM063917
Első szerző:Somogyi Attila
Cím:A novel form of compensation in the Tg2576 amyloid mouse model of Alzheimer disease / Attila Somogyi, Zoltán Katonai, Alán Alpár, Ervin Wolf
Dátum:2016
ISSN:1662-5102
Megjegyzések:One century after its first description, pathology of Alzheimer's disease (AD) is still poorly44 understood. Amyloid-related dendritic atrophy and membrane alterations of susceptible brain45 neurons in AD, and in animal models of AD are widely recognized. However, little effort has46 been made to study the potential effects of combined morphological and membrane47 alterations on signal transfer and synaptic integration in neurons that build up affected neural48 networks in AD. In this study spatial reconstructions and electrophysiological measurements49 of layer II/III pyramidal neurons of the somatosensory cortex from wild-type (WT) and50 transgenic (TG) human amyloid precursor protein (hAPP) overexpressing Tg2576 mice were51 used to build faithful segmental cable models of these neurons. Local synaptic activities were52 simulated in various points of the dendritic arbors and properties of subthreshold dendritic53 impulse propagation and predictors of synaptic input pattern recognition ability were54 quantified and compared in modeled WT and TG neurons.55 Despite the widespread dendritic degeneration and membrane alterations in mutant mouse56 neurons, surprisingly little, or no change was detected in steady-state and 50Hz sinusoidal57 voltage transfers, current transfers, and local and propagation delays of PSPs travelling along58 dendrites of TG neurons. Synaptic input pattern recognition ability was also predicted to be59 unaltered in TG neurons in two different soma-dendritic membrane models investigated. Our60 simulations predict the way how subthreshold dendritic signaling and pattern recognition are61 preserved in TG neurons: Amyloid-related membrane alterations compensate for the62 pathological effects that dendritic atrophy has on subthreshold dendritic signal transfer and63 integration in layer II/III somatosensory neurons of this hAPP mouse model for AD. Since64 neither propagation of single PSPs nor integration of multiple PSPs (pattern recognition)65 changes in TG neurons, we conclude that AD-related neuronal hyperexcitability cannot be66 accounted for by altered subthreshold dendritic signaling in these neurons but67 hyperexcitability is related to changes in active membrane properties and network connectivity
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Alzheimer's disease
human amyloid precursor protein
computer 28 simulations
mouse somatosensory cortex
compensation
electrotonic analysis
29 conservation of dendritic signaling
synaptic integration
Megjelenés:Frontiers in Cellular Neuroscience. - 10 : 152 (2016), p. [38]. -
További szerzők:Katonai Zoltán Alpár Alán Wolf Ervin (1961-) (fizikus, neurobiológus)
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5.

001-es BibID:BIBFORM037166
Első szerző:Stelescu András
Cím:Somato-dendritic morphology and dendritic signal transfer properties differentiate between fore- and hindlimb innervating motoneurons in the frog Rana esculenta / Stelescu András, Sümegi János, Wéber Ildikó, Birinyi András, Wolf Ervin
Dátum:2012
ISSN:1471-2202
Megjegyzések:BACKGROUND: The location specific motor pattern generation properties of the spinal cord along its rostrocaudal axis have been demonstrated. However, it is still unclear that these differences are due to the different spinal interneuronal networks underlying locomotions or there are also segmental differences in motoneurons innervating different limbs. Frogs use their fore- and hindlimbs differently during jumping and swimming. Therefore we hypothesized that limb innervating motoneurons, located in the cervical and lumbar spinal cord, are different in their morphology and dendritic signal transfer properties. The test of this hypothesis what we report here.RESULTS: Discriminant analysis classified segmental origin of the intracellularly labeled and threedimensionally reconstructed motoneurons 100% correctly based on twelve morphological variables. Somata of lumbar motoneurons were rounder; the dendrites had bigger total length, more branches with higher branching orders and different spatial distributions of branch points. The ventro-medial extent of cervical dendrites was bigger than in lumbar motoneurons. Computational models of the motoneurons showed that dendritic signal transfer properties were also different in the two groups of motoneurons. Whether log attenuations were higher or lower in cervical than in lumbar motoneurons depended on the proximity of dendritic input to the soma. To investigate dendritic voltage and current transfer properties imposed by dendritic architecture rather than by neuronal size we used standardized distributions of transfer variables. We introduced a novel combination of cluster analysis and homogeneity indexes to quantify segmental segregation tendencies of motoneurons based on their dendritic transfer properties. A segregation tendency of cervical and lumbar motoneurons was detected by the rates of steady-state and transient voltageamplitude transfers from dendrites to soma at all levels of synaptic background activities, modeled by varying the specific dendritic membrane resistance. On the other hand no segregation was observed by the steady-state current transfer except under high background activity.CONCLUSIONS: We found size-dependent and size-independent differences in morphology and electrical structure of the limb moving motoneurons based on their spinal segmental location in frogs. Location specificity of locomotor networks is therefore partly due to segmental differences in motoneurons driving fore-, and hindlimbs.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Bmc Neuroscience [electronic resource]. - 13 : 1 (2012), p. 68. -
További szerzők:Sümegi János Wéber Ildikó (1972-) (biológus, neurobiológus) Birinyi András (1960-) (anatómus, neurobiológus) Wolf Ervin (1961-) (fizikus, neurobiológus)
Pályázati támogatás:K67747
OTKA
Internet cím:DOI
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6.

001-es BibID:BIBFORM029496
Első szerző:Székely György (neurobiológus)
Cím:Spatial distribution of pre- and postsynaptic sites of primary afferent cutaneous terminals in the frog spinal cord / Székely G., Nagy I., Wolf E., Nagy P.
Dátum:1989
ISSN:0306-4522
Megjegyzések:Axon terminals which could be interpreted as dorsal root boutons, were photographed from a series of 98 ultrathin sections with a Jeol 100B electron microscope. A total of 13 boutons were recovered for computer reconstruction. Two of them were terminal boutons, eight en passant boutons and three boutons were only partially recovered. All boutons contained multiple synaptic sites (maximum 33 and minimum seven) at which axodendritic and axoaxonic synapses were established. Axodendritic synapses were of the asymmetric type and they were directed toward adjacent dendrites. In axoaxonic synapses, which were of the symmetric type, the boutons were invariably on the postsynaptic side. Among the presynaptic profiles axons with spherical and pleomorphic vesicles and dendrites with flattened vesicles could be discerned. On average, each 2.67-mikrom2 bouton surface area contained one presynaptic site at which an axodendritic synapse was established, and each 7-mikrom2 surface area contained one postsynaptic site for an axoaxonic (or dendroaxonic) contact. A tendency of grouping of synaptic sites was observed. Distance measurements between the closest neighbours of all synaptic sites were made in four combinations in boutons with the original and with a random distribution of synaptic sites. The arithmetic mean of distances measured between the presynaptic and the closest postsynaptic sites was almost twice as big as that measured in the reverse direction. The difference between these values became greatly reduced in the case of random distribution. The arithmetic mean of distances between the closest neighbours of presynaptic sites was about the same as that between the closest neighbours of postsynaptic sites. This latter value was considerably increased with randomly distributed synaptic sites. The results suggest a non-random distribution of synaptic sites on the surface of boutons. The analysis of cluster formation of synaptic sites performed with a numerical taxonomy technique revealed that the majority of the 153 synaptic sites were comprised in 27 clusters containing both pre- and postsynaptic sites within the 1-mikrom similarity level. All postsynaptic sites were within 1-mikrom of one or more presynaptic sites.
Tárgyszavak:Orvostudományok Természettudományok Biológiai tudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Neuroscience. - 29 : 1 (1989), p. 175-188. -
További szerzők:Nagy I. (orvos) Wolf Ervin (1961-) (fizikus, neurobiológus) Nagy Péter
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7.

001-es BibID:BIBFORM029487
Első szerző:Wolf Ervin (fizikus, neurobiológus)
Cím:A fast 3-dimensional neuronal tree reconstruction system that uses cubic polynomials to estimate dendritic curvature / Wolf E., Birinyi A., Pomahazi S.
Dátum:1995
ISSN:0165-0270
Megjegyzések:The main goal of this work was to develop and test the accuracy of our 3DARBOR neuronal tree reconstruction system by comparing it with a very precise but time-consuming method of reconstruction (NEUTRACE). Comparison was performed by reconstructing 18 dendritic trees of frog spinal motoneurons from serial sections with both methods and comparing several morphological summaries of the two reconstructions. In 3DARBOR the planar projection of the dendritic trees was drawn and fed into an IBM-compatible PC through a graphic tablet. Dendritic coordinates along the perpendicular (focus) axis on the plane of drawing were estimated by an interpolation method. The interpolation was based on the lengths of projected dendrites and the coordinates of points where dendrites entered the next section. Focus axis coordinates of these points could automatically be calculated from the serial numbers and thicknesses of sections. 3DARBOR was tested by comparison of the distributions of characteristic points of dendritic trees, segment lengths and branching angles. Product moment analysis on dendritic trees was also performed. It was concluded that 3DARBOR is a fast enough reconstruction system without any systematical error of interpolation that can correctly supply the most morphological parameters and visualize the natural arborizations.
Tárgyszavak:Orvostudományok Természettudományok Biológiai tudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Journal Of Neuroscience Methods. - 63 : 1-2 (1995), p. 137-145. -
További szerzők:Birinyi András (1960-) (anatómus, neurobiológus) Pomaházi Sándor
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8.

001-es BibID:BIBFORM029497
Első szerző:Wolf Ervin (fizikus, neurobiológus)
Cím:Simulation of the effect of synapses : the significance of the dendritic diameter in impulse propagation / Wolf E., Birinyi A., Székely G.
Dátum:1992
ISSN:0953-816X
Megjegyzések:The effectiveness of synapses at various sites of the dendritic tree was studied using a segmental cable model with a program developed by Hines (Int. J. Biomed. Comput., 24, 55 - 68, 1989). The model rendered possible a high-fidelity simulation of the dendritic geometry of a frog motoneuron described in the accompanying paper (Birinyi et al., Eur. J. Neurosci., 1003 - 1012, 1992). The model was used in the passive membrane mode and the synaptic activity was simulated with current injections into large and small diameter dendrites at proximal and distal locations. Synaptic efficiency was defined by the charge transfer ratio expressed as the proportion of the injected current which appeared at the soma. The charge transfer ratio was determined with uniform and non-uniform distribution of specific membrane resistance over the soma - dendrite surface while the diameter of selected dendrite segments changed. The best charge transfer ratio was found with the largest dendrite membrane resistance, and the maximum efficiency of synaptic activity appeared at the original size of the dendrite segment stimulated. The amount of current that flowed in the proximal and distal directions from the segment stimulated depended on the diameter of that segment. The increase in diameter of proximal dendrites increased synaptic efficiency on distal dendrites, whereas the reverse caused a decline in synaptic efficiency on proximal dendrites. In addition to the diameter of dendrites, the arborization pattern also played a significant role in this mechanism. It is concluded that the cellulipetal increase in dendrite diameter greatly increases synaptic efficiency.
Tárgyszavak:Orvostudományok Természettudományok Biológiai tudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:European Journal Of Neuroscience. - 4 : 11 (1992), p. 1013-1021. -
További szerzők:Birinyi András (1960-) (anatómus, neurobiológus) Székely György (1926-2017) (neurobiológus)
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9.

001-es BibID:BIBFORM029498
Első szerző:Wolf Ervin (fizikus, neurobiológus)
Cím:The influence of premotor interneurone populations on the frequency of the spinal pattern generator for swimming in Xenopus embryo: a simulation study / Wolf E., Roberts A.
Dátum:1995
ISSN:0953-816X
Megjegyzések:Our aim was to test the hypothesis that the frequency of neuronal rhythm-generating networks is partly controlled by the size of the active premotor interneuron population. We have tested possible mechanisms for frequency changes in a population model of the Xenopus laevis embryo spinal rhythm-generating networks for swimming. After initiation by a brief sensory excitation, the frequency of swimming activity decreases to a steady level determined by the properties of the 24 interneurons and their connections. The initial frequency decrease was dependent on the time-course of initiating sensory synaptic excitation. When some premotor excitatory interneurons were given weaker synaptic connections to reflect the variability in the spinal cord, they could drop out and stop firing during the initial frequency decrease while swimming activity continued. If the synaptic input of such weak excitatory interneurons was graded finely, they could drop out consecutively. This led to further decreases in the level of tonic excitation and in network frequency which depended on the number, type and distribution of excitatory interneurons that stopped firing. Silent weak excitatory interneurons could be recruited by a second sensory excitation and cause an increase in tonic depolarization and frequency which outlasted the sensory input. Such recruitment could occur on both sides after local sensory stimulation to only one region or one side of the model. We conclude that these computer simulations support the hypothesis that premotor interneuron drop-out and recruitment is one mechanism which can control frequency in a locomotor central pattern generator.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:European Journal Of Neuroscience. - 7 : 4 (1995), p. 671-678. -
További szerzők:Roberts, Alan
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10.

001-es BibID:BIBFORM008786
Első szerző:Wolf Ervin (fizikus, neurobiológus)
Cím:Longitudinal neuronal organization and coordination in a simple vertebrate : a continuous, semi-quantitative computer model of the central pattern generator for swimming in young frog tadpoles / Ervin Wolf, S. R. Soffe, Alan Roberts
Dátum:2009
Tárgyszavak:Orvostudományok Természettudományok Biológiai tudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Journal of Computational Neuroscience. - 27 : 2 (2009), p. 291-308. -
További szerzők:Soffe, Stephen R. Roberts, Alan
Internet cím:elektronikus változat
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