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1.

001-es BibID:BIBFORM018030
Első szerző:Budd, Julian M. L.
Cím:Neocortical Axon Arbors Trade-off Material and Conduction Delay Conservation / Julian M. L. Budd, Krisztina Kovács, Alex S. Ferecskó, Péter Buzás, Ulf T. Eysel, Zoltán F. Kisvárday
Dátum:2010
ISSN:1553-734X
Megjegyzések:The brain contains a complex network of axons rapidly communicating information between billions of synaptically connected neurons. The morphology of individual axons, therefore, defines the course of information flow within the brain. More than a century ago, Ramo'n y Cajal proposed that conservation laws to save material (wire) length and limit conduction delay regulate the design of individual axon arbors in cerebral cortex. Yet the spatial and temporal communication costs of single neocortical axons remain undefined. Here, using reconstructions of in vivo labelled excitatory spiny cell and inhibitory basket cell intracortical axons combined with a variety of graph optimization algorithms, we empirically investigated Cajal's conservation laws in cerebral cortex for whole three-dimensional (3D) axon arbors, to our knowledge the first study of its kind. We found intracortical axons were significantly longer than optimal. The temporal cost of cortical axons was also suboptimal though far superior to wire-minimized arbors. We discovered that cortical axon branching appears to promote a low temporal dispersion of axonal latencies and a tight relationship between cortical distance and axonal latency. In addition, inhibitory basket cell axonal latencies may occur within a much narrower temporal window than excitatory spiny cell axons, which may help boost signal detection. Thus, to optimize neuronal network communication we find that a modest excess of axonal wire is traded-off to enhance arbor temporal economy and precision. Our results offer insight into the principles of brain organization and communication in and development of grey matter, where temporal precision is a crucial prerequisite for coincidence detection, synchronization and rapid network oscillations.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Egészség- és Környezettudomány
Megjelenés:PloS Computational Biology. - 6 : 3 (2010), p. e1000711. -
További szerzők:Kovács Krisztina Ferecskó, Alex S. Buzás Péter Eysel, Ulf T. Kisvárday Zoltán (1957-) (biológus, neurobiológus)
Pályázati támogatás:PEOPLE-2007-2-2.ERG/TOOTH/223834
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TÁMOP-4.2.1/B-09/1/KONV-2010-0007
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A gerincvelő felületes hátsó szarvi neuronhálózatok szerveződése és plaszticitása krónikus gyulladásos és neuropátiás fájdalom állapotokban
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2.

001-es BibID:BIBFORM033344
Első szerző:Buzás Péter
Cím:Axonal topography of cortical basket cells in relation to orientation, direction, and ocular dominance maps / Péter Buzás, Ulf T. Eysel, Péter Adorján, Zoltán F. Kisvárday
Dátum:2001
ISSN:0021-9967
Megjegyzések:Abstract The axonal (bouton) distributions of a layer 4 clutch cell (CC), two layer 3 medium-sized basket cells (MBC), and a layer 3 large basket cell (LBC) to orientation, direction, and ocular dominance maps were studied quantitatively. 1) The CC provided exclusively local projections (<380 microm from the soma) and contacted a narrow "niche" of functional representations. 2) The two MBCs emitted local projections (75% and 79% of all boutons), which were engaged with isoorientations (61% and 48%) and isodirections, and long-range projections (25% and 21%, >313 microm and >418 microm), which encountered cross-orientation sites (14% and 12%) and isoorientation sites (7% and 5%). Their direction preferences were mainly perpendicular to or opposite those of local projections. 3) The LBC provided the majority (60%) of its boutons to long-range distances (>437 microm). Locally, LBC boutons showed a rather balanced contribution to isoorientations (19%) and cross-orientations (12%) and preferred isodirections. Remotely, however, cross-orientation sites were preferred (31% vs. 23%) and the directional output was balanced. 4) Monte Carlo simulations revealed that the differences between the orientation specificity of local and long-range projections cannot be explained by a homogeneous lateral distribution of the boutons. 5) There was a similar eye preference in the local and long-range projection fields of the MBCs. The LBC contacted both contra- and ipsilateral eye domains. 6) The basket axons showed little laminar difference in orientation and direction topography. The results suggest that an individual basket cell can mediate a wide range of effects depending on the size and termination pattern of the axonal field.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:The Journal of Comparative Neurology. - 437 : 3 (2001), p. 259-285. -
További szerzők:Eysel, Ulf T. Adorján Péter Kisvárday Zoltán (1957-) (biológus, neurobiológus)
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3.

001-es BibID:BIBFORM033341
Első szerző:Buzás Péter
Cím:Independence of visuotopic representation and orientation map in the visual cortex of the cat / Péter Buzás, Maxim Volgushev, Ulf T. Eysel, Zoltán F. Kisvárday
Dátum:2003
ISSN:0953-816X
Megjegyzések:The representations of visual space and stimulus orientation were mapped in the cat primary visual cortex using electrophysiological recordings supplemented with intrinsic signal optical imaging. The majority of units displaced up to 600 micro m laterally had overlapping RFs both in orientation domains and around singularities of the orientation map. Quantitative comparison of these units revealed only a weak, positive correlation between the difference in their preferred orientations and RF separations (area 17: r = 0.09; area 18: r = 0.15). The occurrence of nonoverlapping RFs could be accounted for by random RF position scatter rather than by orientation difference between the units. Monte Carlo analysis showed that our findings are compatible with a locally smooth and linear representation of visual space that is not coupled to the representation of stimulus orientation. An important functional implication of the above map relationships is that positional information captured by the retina is faithfully transmitted into the cortex.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:The European Journal of Neuroscience. - 18 : 4 (2003), p. 957-968. -
További szerzők:Volgushev, Maxim Eysel, Ulf T. Kisvárday Zoltán (1957-) (biológus, neurobiológus)
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4.

001-es BibID:BIBFORM033349
Első szerző:Buzás Péter
Cím:Functional topography of single cortical cells : an intracellular approach combined with optical imaging / Péter Buzás, Ulf T. Eysel, Zoltán F. Kisvárday
Dátum:1998
ISSN:1385-299X
Megjegyzések:Pyramidal cells mediating long-range corticocortical connections have been assumed to play an important role in visual perceptual mechanisms [C.D. Gilbert, Horizontal integration and cortical dynamics, Neuron 9 (1992) 1-13]. However, no information is available as yet on the specificity of individual pyramidal cells with respect to functional maps, e.g., orientation map. Here, we show a combination of techniques with which the functional topography of single pyramidal neurons can be explored in utmost detail. To this end, we used optical imaging of intrinsic signals followed by intracellular recording and staining with biocytin in vivo. The axonal and dendritic trees of the labelled neurons were reconstructed in three dimensions and aligned with corresponding functional orientation maps. The results indicate that, contrary to the sharp orientation tuning of neurons shown by the recorded spike activity, the efferent connections (axon terminal distribution) of the same pyramidal cells were found to terminate at a much broader range of orientations.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Brain Research Protocols. - 3 : 2 (1998), p. 199-208. -
További szerzők:Eysel, Ulf T. Kisvárday Zoltán (1957-) (biológus, neurobiológus)
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5.

001-es BibID:bibEBI00019271
Első szerző:Buzás Péter
Cím:Model-based analysis of excitatory lateral connections in the visual cortex / Buzás P., Kovács K., Ferecskó A. S., Budd J. M. L., Eysel U. T., Kisvárday Z.F.
Dátum:2006
Megjegyzések:Excitatory lateral connections within the primary visual cortex are thought to link neurons with similar receptive field properties. Here we studied whether this rule can predict the distribution of excitatory connections in relation to cortical location and orientation preference in the cat visual cortex. To this end, we obtained orientation maps of areas 17 or 18 using optical imaging and injected anatomical tracers into these regions. The distribution of labeled axonal boutons originating from large populations of excitatory neurons was then analyzed and compared with that of individual pyramidal or spiny stellate cells. We demonstrate that the connection patterns of populations of nearby neurons can be reasonably predicted by Gaussian and von Mises distributions as a function of cortical location and orientation, respectively. The connections were best described by superposition of two components: a spatially extended, orientation-specific and a local, orientation-invariant component. We then fitted the same model to the connections of single cells. The composite pattern of nine excitatory neurons (obtained from seven different animals) was consistent with the assumptions of the model. However, model fits to single cell axonal connections were often poorer and their estimated spatial and orientation tuning functions were highly variable. We conclude that the intrinsic excitatory network is biased to similar cortical locations and orientations but it is composed of neurons showing significant deviations from the population connectivity rule.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:The Journal of comparative neurology. - 499 : 6 (2006), p. 861-881. -
További szerzők:Kovács Krisztina Ferecskó, Alex S. Budd, Julian M. L. Eysel, Ulf T. Kisvárday Zoltán (1957-) (biológus, neurobiológus)
Internet cím:DOI
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6.

001-es BibID:BIBFORM033407
035-os BibID:PMID:8734604 WOS:A1996UK80900026
Első szerző:Crook, John M.
Cím:GABA-induced inactivation of functionally characterized sites in cat visual cortex (area 18) : effects on direction selectivity / John M. Crook, Zoltán F. Kisvárday, Ulf T. Eysel
Dátum:1996
Megjegyzések:1. Microiontophoresis of gamma-aminobutyric acid was used to reversibly inactivate small sites of defined orientation and direction specificity at a horizontal distance of 400-700 microns from single cells recorded in cat area 18. There was extensive or complete overlap between the receptive fields of cells at the recording and inactivation sites. A cell's directionality index [DI: 1 - (response to nonpreferred direction/response to preferred direction)], the response to the preferred direction, and orientation tuning width (measured at half the maximum response) were compared before and during inactivation of either iso-orientation sites (where the orientation preference was within 22.5 degrees) or cross-orientation sites (where it differed by 45-90 degrees). 2. During iso-orientation inactivation, 40 (73%) of 55 cells showed a significant (> 0.20) change in DI; the mean change in DI for these cells was 0.59. An additional cell showed a marked increase in response to the preferred direction that did not result in a change in DI. With one exception, the effects occurred in the absence of a significant (> 25%) change in orientation tuning width. 3. In most cases, the results were broadly predictable in the sense that iso-orientation inactivation predominantly affected a cell's response to the direction of motion of an optimally oriented bar that was closest to the preferred direction at the inactivation site: viz., a decrease in response to the preferred direction and an increase in response to the preferred or nonpreferred direction. 4. It is argued that the decreases in response were due to a reduction in the strength of intracortical iso-orientation excitatory connections made primarily between cells with similar direction preferences, whereas the increases in response involved a loss of iso-orientation inhibition. 5. In cases where remote inactivation caused an increase in response to the nonpreferred direction, comparable effects could be elicited when a mask left exposed only the excitatory subregion of the receptive field in S cells or the most responsive part of the excitatory discharge region in C cells. This implies extensive or complete spatial overlap between the profiles of excitation and inhibition in a cell's nonpreferred direction. 6. During cross-orientation inactivation, a significant change in DI was seen in only 14 (19%) of 73 cells and, with one exception, these changes were accompanied by increases in response to non-optimal orientations and significant broadening of orientation tuning. The effects of cross-orientation inactivation on directionality were presumably due to the loss of cross-orientation inhibition, which contributes primarily to orientation tuning. 7. Inactivation of the same site could cause an increase in response to the nonpreferred direction in cells recorded at iso-orientation sites and an increase in response to nonoptimal orientations and broadening of orientation tuning in cells recorded at cross-orientation sites. This is consistent with the notion that a single inhibitory neuron can contribute to the directionality or orientation tuning of different target cells depending on their location in the orientation map. 8. The results provide evidence for a major contribution of intrinsic mechanisms to the orientation tuning and direction selectivity of cells in cat area 18. It is proposed that two different intracortical processes are involved in the enhancement of orientation and direction selectivity: 1) suppression of responses to nonoptimal orientations and directions as a result of cross-orientation inhibition and iso-orientation inhibition; and 2) facilitation of responses to optimal orientations/directions via iso-orientation excitatory connections.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Journal of Neurophysiology. - 75 : 5 (1996), p. 2071-2088. -
További szerzők:Kisvárday Zoltán (1957-) (biológus, neurobiológus) Eysel, Ulf T.
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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7.

001-es BibID:BIBFORM033440
Első szerző:Crook, John M.
Cím:Intracortical mechanisms underlying orientation and direction selectivity studied with the GABA-inactivation technique / John M. Crook, Zoltán F. Kisvárday, Ulf T. Eysel
Dátum:2002
ISBN:0-19-850893-X
Tárgyszavak:Orvostudományok Elméleti orvostudományok könyvfejezet
Megjelenés:Virtual lesions : examining cortical function with reversible deactivation / ed. by Stephen G. Lomber, Ralf A. W. Galuske. - p. 3-40. -
További szerzők:Kisvárday Zoltán (1957-) (biológus, neurobiológus) Eysel, Ulf T.
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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8.

001-es BibID:BIBFORM033354
Első szerző:Crook, John M.
Cím:Evidence for a contribution of lateral inhibition to orientation tuning and direction selectivity in cat visual cortex : reversible inactivation of functionally characterized sites combined with neuroanatomical tracing techniques / John M. Crook, Zoltan F. Kisvárday, Ulf T. Eysel
Dátum:1998
ISSN:0953-816X
Megjegyzések:We have previously reported that cells in cat areas 17 and 18 can show increases in response to non-optimal orientations or directions, commensurate with a loss of inhibition, during inactivation of laterally remote, visuotopically corresponding sites by iontophoresis of gamma-aminobutyric acid (GABA). We now present anatomical evidence for inhibitory projections from inactivation sites to recording sites where 'disinhibitory' effects were elicited. We made microinjections of [3H]-nipecotic acid, which selectively exploits the GABA re-uptake mechanism, < 100 microm from recording sites where cells had shown either an increase in response to non-optimal orientations during inactivation of a cross-orientation site (n = 2) or an increase in response to the non-preferred direction during inactivation of an iso-orientation site with opposite direction preference (n = 5). Retrogradely labelled GABAergic neurons were detected autoradiographically and their distribution was reconstructed from series of horizontal sections. In every case, radiolabelled cells were found in the vicinity of the inactivation site (three to six within 150 microm). The injection and inactivation sites were located in layers II/III-IV and their horizontal separation ranged from 400 to 560 microm. In another experiment, iontophoresis of biocytin at an inactivation site in layer III labelled two large basket cells with terminals in close proximity to cross-orientation recording sites in layers II/III where disinhibitory effects on orientation tuning had been elicited. We argue that the inactivation of inhibitory projections from inactivation to recording sites made a major contribution to the observed effects by reducing the strength of inhibition during non-optimal stimulation in recurrently connected excitatory neurons presynaptic to a recorded cell. The results provide further evidence that cortical orientation tuning and direction selectivity are sharpened, respectively, by cross-orientation inhibition and iso-orientation inhibition between cells with opposite direction preferences.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:The European Journal of Neuroscience. - 10 : 6 (1998), p. 2056-2075. -
További szerzők:Kisvárday Zoltán (1957-) (biológus, neurobiológus) Eysel, Ulf T.
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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9.

001-es BibID:BIBFORM033352
Első szerző:Crook, John M.
Cím:GABA-induced inactivation of functionally characterized sites in cat striate cortex : effects on orientation tuning and direction selectivity / John M. Crook, Zoltan F. Kisvárday, Ulf T. Eysel
Dátum:1997
ISSN:0952-5238
Megjegyzések:Microiontophoresis of gamma-aminobutyric acid (GABA) was used to reversibly inactivate small sites of defined orientation/direction specificity in layers II-IV of cat area 17 while single cells were recorded in the same area at a horizontal distance of approximately 350-700 microns. We compared the effect of inactivating iso-orientation sites (where orientation preference was within 22.5 deg) and cross-orientation sites (where it differed by 45-90 deg) on orientation tuning and directionality. The influence of iso-orientation inactivation was tested in 33 cells, seven of which were subjected to alternate inactivation of two iso-orientation sites with opposite direction preference. Of the resulting 40 inactivations, only two (5%) caused significant changes in orientation tuning, whereas 26 (65%) elicited effects on directionality: namely, an increase or a decrease in response to a cell's preferred direction when its direction preference was the same as that at an inactivation site, and an increase in response to a cell's nonpreferred direction when its direction preference was opposite that at an inactivation site. It is argued that the decreases in response to the preferred direction reflected a reduction in the strength of intracortical iso-orientation excitatory connections, while the increases in response were due to the loss of iso-orientation inhibition. Of 35 cells subjected to cross-orientation inactivation, only six (17%) showed an effect on directionality, whereas 21 (60%) showed significant broadening of orientation tuning, with an increase in mean tuning width at half-height of 126%. The effects on orientation tuning were due to increases in response to nonoptimal orientations. Changes in directionality also resulted from increased responses (to preferred or nonpreferred directions) and were always accompanied by broadening of tuning. Thus, the effects of cross-orientation inactivation were presumably due to the loss of a cross-orientation inhibitory input that contributes mainly to orientation tuning by suppressing responses to nonoptimal orientations. Differential effects of iso-orientation and cross-orientation inactivation could be elicited in the same cell or in different cells from the same inactivation site. The results suggest the involvement of three different intracortical processes in the generation of orientation tuning and direction selectivity in area 17: (1) suppression of responses to nonoptimal orientations and directions as a result of cross-orientation inhibition and iso-orientation inhibition between cells with opposite direction preferences; (2) amplification of responses to optimal stimuli via iso-orientation excitatory connections; and (3) regulation of cortical amplification via iso-orientation inhibition.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Visual Neuroscience. - 14 : 1 (1997), p. 141-158. -
További szerzők:Kisvárday Zoltán (1957-) (biológus, neurobiológus) Eysel, Ulf T.
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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10.

001-es BibID:BIBFORM020539
Első szerző:Eckhorn, Reinhard
Cím:Visual resolution with retinal implants estimated from recordings in cat visual cortex / Reinhard Eckhorn, Marcus Wilms, Thomas Schanze, Marcus Eger, Lutz Hesse, Ulf T. Eysel, Zoltán F. Kisvárday, Eberhart Zrenner, Florian Gekeler, Helmut Schwahn, Keisuke Shinoda, Helmut Sachs, Peter Walter
Dátum:2006
ISSN:0042-6989
Megjegyzések:We investigated cortical responses to electrical stimulation of the retina using epi- and sub-retinal electrodes of 20-100 microm diameter. Temporal and spatial resolutions were assessed by recordings from the visual cortex with arrays of microelectrodes and optical imaging. The estimated resolutions were approximately 40 ms and approximately 1 degrees of visual angle. This temporal resolution of 25 frames per second and spatial resolution of about 0.8 cm at about 1m and correspondingly 8 cm at 10 m distance seems sufficient for useful object recognition and visuo-motor behavior in many in- and out-door situations of daily life.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Vision Research. - 46 : 17 (2006), p. 2675-2690. -
További szerzők:Wilms, Marcus Schanze, Thomas Eger, Marcus Hesse, Lutz Eysel, Ulf T. Kisvárday Zoltán (1957-) (biológus, neurobiológus) Zrenner, Eberhart Gekeler, Florian Schwahn, Helmut Shinoda, Keisuke Sachs, Helmut Walter, Peter
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11.

001-es BibID:BIBFORM033432
Első szerző:Eysel, Ulf T.
Cím:Struktur und Funktion der Nervenzellen im Gehirn / U. T. Eysel, Z. F. Kisvárday
Dátum:1994
Tárgyszavak:Orvostudományok Elméleti orvostudományok ismeretterjesztő, népszerűsítő cikk
külföldön készült közlemény
Megjelenés:Rubin : Wissenschaftsmagazin. - 4 : 2 (1994), p. 19-25. -
További szerzők:Kisvárday Zoltán (1957-) (biológus, neurobiológus)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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12.

001-es BibID:BIBFORM033433
Első szerző:Eysel, Ulf T.
Cím:Struktur und Funktion der Nervenzellen im Gehirn / Ulf Eysel, Zoltán Kisvárday
Dátum:1995
Tárgyszavak:Orvostudományok Elméleti orvostudományok ismeretterjesztő, népszerűsítő cikk
külföldön készült közlemény
Megjelenés:Praxis-Computer : Moderne Technologie für die Medizine. - 11 : 4 (1995), p. 50-55. -
További szerzők:Kisvárday Zoltán (1957-) (biológus, neurobiológus)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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