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  • Plasticity  (4)
  • Immunocytochemistry  (3)
  • Deoxyglucose  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Unusually large receptive fields in cats with restricted visual experience (1976)
    Springer
    Experimental brain research 26 (1976), S. 171-184 
    Details
    ISSN: 1432-1106
    Keywords: Cat striate cortex ; Spatial interactions ; Selective visual experience ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The receptive fields of striate cortex neurons were analyzed in cats which had restricted or no visual experience. Two groups of animals were investigated: 1. cats which were deprived from contour vision over variable periods of time up to 1 year and 2. kittens whose visual experience was restricted to vertically oriented gratings of constant spatial frequency which moved unidirectionally at a fixed distance in front of the restrained animals. In both preparations exceedingly large receptive fields (up to 20° in diameter) were encountered, especially in cells located in supragranular layers. These large receptive fields never extended over more than 2° into the ipsilateral hemifield. Their sensitivity profile was frequently asymmetric and contained discontinuities. Many of these large receptive fields consisted of several excitatory subregions which were separated from each other by as much as 15°. Often but not always the most sensitive area was located where the retinotopic map predicted the receptive field center. The orientation and direction selectivity and also the angular separation of such multiple excitatory bands often matched precisely the orientation, direction and spatial frequency of the experienced moving grating. In other fields with multiple excitatory subregions such a correspondence could not be established; the various subregions could even have different orientation and direction selectivities. From these unconventional receptive fields it is concluded that the function of cat striate cortex is not confined to a point by point analysis of the visual field in retinotopically organized and functionally isolated columns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238281
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  • 2
    Electronic Resource
    Electronic Resource
    Experience-dependent modifications of kitten striate cortex are not prevented by thalamic lesions that include the intralaminar nuclei (1988)
    Springer
    Experimental brain research 70 (1988), S. 627-631 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Development ; Plasticity ; Intralaminar nuclei ; Kitten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It has been shown previously that surgical lesions of the antero-medial thalamus interfere with ocular dominance modifications that normally result from monocular deprivation in young kittens (Singer 1982). The aim of the present study was to determine whether this effect was due specifically to the destruction of the visual cortical projections of the anterior intralaminar nuclei. We report here that large excitotoxin lesions of the anterior dorsal thalamus have no effect on the cortical response to monocular deprivation. These data indicate that the intralaminar projection is not essential for ocular dominance plasticity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247611
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure and synaptic relations of neural elements containing glutamic acid decarboxylase (GAD) in the perigeniculate nucleus of the cat (1984)
    Springer
    Experimental brain research 56 (1984), S. 115-125 
    Details
    ISSN: 1432-1106
    Keywords: Visual system ; Perigeniculate nucleus ; GAD ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The perigeniculate nucleus of the cat (PGN) was examined at light and electron microscopic levels after immunocytochemical labeling for the gamma-aminobutyric acid (GABA) synthesizing enzyme, glutamic acid decarboxylase (GAD). In light microscopic sections, virtually all perikarya were found to be labeled (GAD+), as well as proximal dendrites, fibres and punctiform elements. Cells in the thalamic reticular nucleus (TRN) dorsal to PGN were also labeled. Ultrastructural analysis of PGN showed immunoreactivity in all somata, in dendrites and in the following vesicle containing profiles: 1.) F1 terminals, which are characterized by large size, dark mitochondria, and pleomorphic vesicles. These terminals form symmetrical synaptic contacts with somata, somatic spines and with dendrites of GAD+ PGN cells. 2.) F2 terminals, which are smaller than F1 terminals, contain also pleomorphic vesicles and frequently make serial synapses of the symmetric type with other F2 terminals. Presumably, F1 terminals are formed by collaterals of PGN-cell axons and F2 terminals by vesicle containing dendrites of PGN cells. Terminals devoid of immunoreactivity included: 1.) RLD terminals characterized by large size, round vesicles, dark mitochondria, and by asymmetric synaptic contacts with somata, especially with somatic spines, and with dendrites of GAD+ perigeniculate neurons; 2.) RSD terminals, characterized by small size, round vesicles and dark mitochondria, which make asymmetric synapses with GAD+ dendrites of medium and small size; 3.) Multivesicular (MV) terminals with variably shaped vesicles including dense core vesicles synapsing on GAD+ dendrites. There are reasons to believe that RSD terminals belong to corticofugal axons and RLD terminals to collateral axons of LGN relay cells. The origin of MV terminals remains to be determined. The GABAergic nature of the PGN cells conforms with the presumed function of these cells as mediators of inhibition of LGN relay cells. The complex synaptic relations observed between GAD+ elements in the PGN would allow for reciprocal inhibition between perigeniculate cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237447
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  • 4
    Electronic Resource
    Electronic Resource
    Localization of isoenzymes II/III of protein kinase C in the rat visual cortex (area 17), hippocampus and dentate gyrus (1988)
    Springer
    Experimental brain research 72 (1988), S. 443-449 
    Details
    ISSN: 1432-1106
    Keywords: Protein kinase C subspecies ; Immunocytochemistry ; Visual cortex ; Hippocampus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Monoclonal antibodies against type II and type III subspecies of protein kinase C PkC(II/III) were used to map the distribution of these isoenzymes in the visual cortex (area 17), hippocampus and dentate gyrus of the rat. PkC(II/III)-immunocytochemistry resulted in a specific staining of neuropil and of neuronal somata with their proximal dendrites. The majority of immunopositive cells exhibited a punctate distribution of reaction product, while only a few neurons were homogeneously labeled. In the visual cortex stained neurons were distributed throughout all laminae and reached a particularly high density in layers II/III. Moreover, PkC(II/III)-positive neurons were found within the strata pyramidale and radiatum of the hippocampus proper and in the stratum granulosum, the subgranular zone and the hilar region of the dentate gyrus. The present results suggest that PkC(II/III)-positive neurons constitute a distinct population of both projection and local circuit neurons that are not exclusively associated with any one neurotransmitter system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250589
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  • 5
    Electronic Resource
    Electronic Resource
    Developmental changes of the distribution of binding sites for organic Ca2+-channel blockers in cat visual cortex (1988)
    Springer
    Experimental brain research 70 (1988), S. 266-275 
    Details
    ISSN: 1432-1106
    Keywords: Calcium ; Plasticity ; Visual cortex ; Organic Ca2+-channel blockers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary There are indications that during a critical period of visual cortex development Ca2+-fluxes from extra- to intracellular compartments serve as a trigger signal for experience-dependent changes of neuronal response properties. In this study we investigate the possibility of a relation between the time course of the critical period and age-dependent changes in the density and topographical distribution of Ca2+-channels. As a marker for the latter we used Ca2+-channel blockers of the 1,4-Dihydropyridine (1,4-DHP) class since these are supposed to bind to voltage-dependent Ca2+-channels. We used the tritiated 1,4-DHP derivative 3H-PN 200 110 for autoradiographic determination of 1,4-DHP binding sites in the visual cortex of adult cats and kittens ranging in age from two to ten weeks. The binding of 3H-PN 200 110 to slide-mounted tissue sections was saturable and of high affinity. The overall density of specific 3H-PN 200 110 binding sites decreased during development and their laminar distribution underwent marked changes: in young kittens specific binding was accentuated in lower layer IV, whereas in adult cats the supragranular layers were most intensely labeled. Dark rearing did not affect these developmental changes of 3H-PN 200 110 binding sites. The time course of the reduction of 1,4-DHP binding sites correlates well with that of the age-dependent decrease of the susceptibility to experience-dependent modifications. We consider this result as compatible with the hypothesis that use-dependent modifications of the response properties of cortical neurons involve changes in the Ca2+-fluxes from extra- to intracellular compartments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248352
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructural identification of somata and neural processes immunoreactive to antibodies against glutamic acid decarboxylase (GAD) in the dorsal lateral geniculate nucleus of the cat (1985)
    Springer
    Experimental brain research 59 (1985), S. 151-165 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; GAD ; GABA ; Inhibition ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cat dorsal lateral geniculate nucleus (LGN) was examined at the light- and electron-microscopic level after immunocytochemistry for GAD (the synthesizing enzyme of the inhibitory neurotransmitter GABA), to identify cells and processes with GAD-like immunoreactivity. GAD-positive perikarya were distributed throughout the A and C laminae, constituting a moderate proportion of cells in the LGN. Labeled cells were characterized by small size, scant cytoplasm, relatively large nuclei with common indentations, small mitochondria, few organelles and few strands of rough endoplasmic reticulum. Unlabeled cells were of large, medium and small size. GAD-positive terminals were identified as F1 and F2 types (Guillery's nomenclature) on the basis of their synaptic relations and ultrastructure. Labeled F2 terminals were postsynaptic to retinal (RLP) boutons and presynaptic to unlabeled dendrites in synaptic glomeruli. Labeled F1 terminals made synapses on unlabeled somata and dendrites, and on labeled dendrites and F2 terminals. Presumably, most labeled F1 terminals originate from GABAergic perigeniculate axons. Retinal (RLP) and cortico-geniculate (RSD) boutons remained unlabeled in the reative zone. These terminals made synapses with labeled and unlabeled dendrites and with labeled F2 boutons. In conjunction with previous studies on GAD-positive cells in the perigeniculate nucleus, these results provide immunocytochemical and morphological evidence suggesting that the GABAergic intrinsic and extrinsic (perigeniculate) interneurons mediate the different inhibitory phenomena which occur in relay cells of the cat LGN. The ultrastructural features and synaptic relations of GABAergic cells and processes in the cat LGN are similar to those of equivalent neural elements in the LGN of rat and monkey, suggesting general principles of organization and morphology for GABAergic neurons in the thalamus of different mammals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237675
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  • 7
    Electronic Resource
    Electronic Resource
    Topographic organization of orientation columns in the cat visual cortex (1981)
    Springer
    Experimental brain research 44 (1981), S. 431-436 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Visual cortex ; Orientation columns ; Deoxyglucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three-dimensional reconstructions of the orientation column system were obtained from the visual cortex of four cats using the deoxyglucose technique. One cat had normal visual experience, one was monocularly deprived and two had selective experience with vertical and horizontal contours, respectively. In areas 17 and 18 orientation columns form a remarkably regular system of equally spaced parallel bands whose trajectory is orthogonal to the borderline between areas 17 and 18. This topographic organization is resistant to manipulations of early visual experience.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238836
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  • 8
    Electronic Resource
    Electronic Resource
    Central core control of developmental plasticity in the kitten visual cortex: II. Electrical activation of mesencephalic and diencephalic projections (1982)
    Springer
    Experimental brain research 47 (1982), S. 223-233 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Development ; Plasticity ; Central core ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fifteen dark-reared, 4- to 5-week-old kittens were stimulated monocularly with patterned light while they were anesthetized and paralyzed. Six of these kittens were exposed to the light stimuli only, in four kittens the light stimuli were paired with electric stimulation of the mesencephalic reticular formation and in five kittens with electric activation of the medial thalamic nuclei. Throughout the conditioning period, the ocular dominance of neurons in the visual cortex was determined from evoked potentials that were elicited either with electric stimulation of the optic nerves or with phase reversing gratings of variable spatial frequencies. In two kittens, ocular dominance changes were assessed after the end of the conditioning period by analyzing single unit receptive fields. Monocular stimulation with patterned light induced a marked shift of ocular dominance toward the stimulated eye, when the light stimulus was paired with electric activation of either the mesencephalic reticular formation or of the medial thalamus. Moreover, a substantial fraction of cells acquired mature receptive fields. No such changes occurred with light or electric stimulation alone. It is concluded that central core projections which modulate cortical excitability gate experience-dependent modifications of connections in the kitten visual cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239381
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  • 9
    Electronic Resource
    Electronic Resource
    Restriction of visual experience to a single orientation affects the organization of orientation columns in cat visual cortex (1981)
    Springer
    Experimental brain research 41 (1981), S. 199-215 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Development ; Orientation columns ; Deoxyglucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary and Conclusions In six dark reared, 4-weak-old kittens visual experience was restricted to contours of a single orientation, horizontal or vertical, using cylindrical lenses. Subsequently, the deoxyglucose method was used to determine whether these artificial raising conditions had affected the development of orientation columns in the visual cortex. After application of the deoxyglucose pulse one hemifield was stimulated with vertical, the other with horizontal contours. Thus, from interhemispheric comparison, changes in columnar systems corresponding to experienced and inexperienced orientations could be determined. The following results were obtained: (1) Irrespective of the restrictions in visual experience, orientation columns develop in areas 17, 18, 19 and in the visual areas of the posterior suprasylvian sulcus. (2) Within area 17, spacing between columns encoding the same orientations is remarkably regular (1 mm), is not influenced by selective experience and shows only slight interindividual variation. (3) In non-striate areas the spacing of columns is less regular and the spatial frequency of the periodicity is lower. (4) The modifiability of this columnar pattern by selective experience is small within the granular layer of striate cortex but substantial in non-granular layers: Within layer IV columns whose preference corresponds to the experienced orientation are wider and more active than those encoding the orthogonal orientation but the columnar grid remains basically unaltered. Outside layer IV the columnar system is maintained only for columns encoding the experienced orientations. The deprived columns by contrast frequently fail to extend into non-granular layers and remain confined to the vicinity of layer IV. (5) These modifications in the columnar arrangement are more pronounced in striate cortex than in non-striate visual areas and, within the former, more conspicuous in the central than in the peripheral representation of the visual field. It is concluded that within layer IV the blue print for the system of orientation columns is determined by genetic instructions: first order cells in layer IV develop orientation selectivity irrespective of experience whereby the preference for a particular orientation is predetermined by the position in the columnar grid. Dependent on experience is, however, the expansion of the columnar system from layer IV into non-granular layers. It is argued that all distortions following selective rearing can be accounted for by competitive interactions between intracortical pathways, the mechanisms being identical to those established for competitive processes in the domain of ocular dominance columns. It is proposed that such experience dependent modifiability of connections between first and second order cells is a necessary prerequisite for the development of orientation selectivity in cells with large and complex receptive fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238877
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