CCL

Összesen 6 találat.
#/oldal:
Részletezés:
Rendezés:

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)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
DOI
Borító:

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
Internet cím:Szerző által megadott URL
DOI
Intézményi repozitóriumban (DEA) tárolt változat
Borító:

3.

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
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
DOI
Borító:

4.

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
Borító:

5.

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
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
DOI
Borító:

6.

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
Borító:
Rekordok letöltése1 
Corvina könyvtári katalógus v8.2.27 © 2023 Monguz kft. Minden jog fenntartva.