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001-es BibID:	BIBFORM033347
Első szerző:	Yousef, Tagrid
Cím:	Topography of orientation centre connections in the primary visual cortex of the cat / Tagrid Yousef, Éva Tóth, Martin Rausch, Ulf T. Eysel, Zoltán F. Kisvárday
Dátum:	2001
ISSN:	0959-4965
Megjegyzések:	The functional topography of lateral connections to orientation-centre zones was studied by optical imaging of intrinsic signals in combination with tracer injections (fluorescent beads and biocytin) and electrophysiological recordings. Three-dimensional reconstruction of anterogradely labelled axon terminals and retrogradely labelled somata revealed a uniform distribution across all orientations in a non-patchy manner. The overall lateral extent of the labelling was 3-4 mm in layer 3, that is about half of the extent observed for orientation domain connections in the same layer. These bulk injection data are in contrast with the reportedly sharp orientation tuning of neurons of centre zones and suggest that orientation specificity here does not require highly specific connections. Nonetheless, another plausible scenario is that orientation centre connections are orientation specific but their specificity present at the single cell level cannot be revealed by bulk labelling due to their large spatial overlap.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	Neuroreport. - 12 : 8 (2001), p. 1693-1699. -
További szerzők:	Tóth Éva Rausch, Martin Eysel, Ulf T. Kisvárday Zoltán (1957-) (biológus, neurobiológus)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM033353
Első szerző:	Yousef, Tagrid
Cím:	Orientation topography of layer 4 lateral networks revealed by optical imaging in cat visual cortex (area 18) / Tagrid Yousef, Tobias Bonhoeffer, Dae-Shik Kim, Ulf T. Eysel, Éva Tóth, Zoltán F. Kisvárday
Dátum:	1999
ISSN:	0953-816X
Megjegyzések:	The functional specificity of corticocortical connections with respect to the topography of orientation selectivity was studied by optical imaging of intrinsic signals and bulk injections of fluorescent latex beads (green and red) and biocytin into layer 4. The distributions of retrogradely labelled cells and anterogradely labelled axon terminals were histologically reconstructed from all cortical laminae, and the resulting anatomical maps compared with the optically imaged functional maps. Layer 4 injections produced extensive horizontal labelling up to 2-3 mm from the injection centres albeit without the clear patchy pattern described after layer 2/3 injections (Gilbert & Wiesel 1989, J. Neurosci., 9, 2432-2442; Kisvárday et al. 1997, Cerebral Cortex, 7, 605-618). The functional (orientation) distribution of the labelled projections was analysed according to laminar location and lateral spread. With regard to the former, no major difference in the orientation topography between supragranular- (upper tier), granular- (middle tier) and infragranular (lower tier) layers was seen. Laterally, proximal and distal projections were distinguished and further dissected into three orientation categories, iso- (+/- 30 degrees ), oblique- (+/- 30-60 degrees ) and cross-orientations (+/- 60-90 degrees ) with respect to the orientation preference at the injection sites. The majority of distal connections (retrograde and anterograde) was equally distributed across orientations (35.4% iso-, 33.7% oblique-, and 30.9% cross-orientations) that are equivalent with a preponderance to dissimilar orientations (oblique- and cross-orientations, 64.6%). In one case, distal excitatory and inhibitory connections could be morphologically distinguished. For both categories, a marked bias to dissimilar orientations was found (excitatory, 63.7%; inhibitory, 86.6%). Taken together, these results suggest that the long-range layer 4 circuitry has a different functional role from that of the iso-orientation biased (52.9%, Kisvárday et al. 1997, Cerebral Cortex, 7, 605-618) layer 2/3 circuitry, and is perhaps involved in feature difference-based mechanisms, e.g. figure ground segregation.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	The European Journal of Neuroscience. - 11 : 12 (1999), p. 4291-4308. -
További szerzők:	Bonhoeffer, Tobias Kim, Dae-Shik Eysel, Ulf T. Tóth Éva Kisvárday Zoltán (1957-) (biológus, neurobiológus)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
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