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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)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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001-es BibID:	BIBFORM001438
Első szerző:	Halasi Gábor (neurobiológus)
Cím:	The effect of vestibular nerve section on the expression of the hyaluronan in the frog, Rana esculenta / Halasi G., Wolf E., Bácskai T., Székely Gy., Módis L., M. Szigeti Zs., Mészár Z., Felszeghy Sz., Matesz K.
Dátum:	2007
Tárgyszavak:	Orvostudományok Természettudományok Biológiai tudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban egyetemen (Magyarországon) készült közlemény
Megjelenés:	Brain Structure and Function. - 212 : 3-4 (2007), p. 321-334. -
További szerzők:	Wolf Ervin (1961-) (fizikus, neurobiológus) Bácskai Tímea (1974-) (biológus, neurobiológus) Székely György (1926-2017) (neurobiológus) Módis László (1939-) (anatómus, kötőszövetbiológus) Máthéné Szigeti Zsuzsa (1976-) (biológus-ökológus) Mészár Zoltán Mihály (1977-) (agrármérnök) Felszeghy Szabolcs Béla (1972-) (fogorvos, anatómus, kötőszövetbiológus) Matesz Klára (1949-) (anatómus, neurobiológus)
Internet cím:	elektronikus változat DOI
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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
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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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)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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