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W Schober

Publications and source records attributed to W Schober.

At least 37 records · Page 2Linked to original sources
PubMed1990

Development of visual callosal projection in the microphthalmic stain of mice 944.

The strain of mice 944 produces a recessive microphthalmy. The microphthalmic mice were compared with phenotypically healthy animals of the same litter and with 944-mice bilaterally enucleated at 1. postnatal day (pd). Comparison was done at the 5., 10., 15. and 20. pd after lesion of the right visual cortex 24 hours before. Therefore Nissl- and Fink-Heimer-series were prepared. The results are the following: At 20. pd microphthalmic mice show both retrograde and anterograde degeneration after lesion. Enucleated and control mice produce destroyed fibres only. This evidence of callosal projection in visual cortex is possible exclusive at pd 20 with satisfying results. The neurons of laminae II and III project in the animals with a normal visus exactly to the contralateral 17/18a borderline. Enucleated mice show in area 18a two or three stripes more reaching laterally. Microphthalmic mice have terminals in both area 17 and 18a.

Animals↗
PubMed1990

Different laminar distribution of flash evoked potentials in cortical areas 17 and 18 b of freely moving rats.

The laminar distribution of flash evoked field potential (VEP) was investigated in the visual cortical areas 17 and 18 b in freely moving rats. Averaged VEPs were recorded during stable relaxed wakefulness characterized behaviorally and polygraphically. The depth profiles of the main VEP components displayed polarity reversals in lamina V in every electrode track through area 17 while no polarity reversal was observed in any track through area 18 b. The primary negative component (N30) had an amplitude maximum in lamina IV in both areas. Current source-density analysis (CSD) in connection with amplitude depth profiles indicated that the surface-negative component N30 is generated mainly by the synaptic excitatory inputs in lamina IV. The negative peak of the flash-evoked afterdischarges in area 17 are generated the same way. The data imply a more concentrated field generator in area 17 with densely packed cellular elements responding synchronously to the flash. In area 18 b, either the anatomical distribution or the temporal relationship of the responding elements seems to be different.

Animals↗
PubMed1989

[Projection of the mesencephalic raphe nuclei to the magnocellular nuclei of the basal forebrain of the rat: a horseradish peroxidase study].

In 15 rats the projection of the mesencephalic raphe nuclei to the magnocellular nuclei of the basal forebrain (b.f.) were investigated by using the HRP-method. In 5 other rats the distribution of serotoninergic fibers in the b.f. was analyzed immunocytochemically. The most important results are: The projection courses ipsilaterally only. The number of labelled cells comprehends only 5-30% of the number of cells estimated in the raphe nuclei that were studied. In the Ncl. r. linearis oralis only a few cells were labelled after injection of HRP into the subnuclei of the diagonal band. More cells were labelled after injection of HRP into the more caudal lying nuclei of the b.f. In the Ncl. r. centralis superior, more labelled cells could be observed after HRP-injection into the rostral nuclei of the b.f. (Ncl. tr. diagonalis with pars septalis, pars verticalis and pars horizontalis; Ncl. praeopticus magnocellularis) than after injection into the caudal nuclei. The labelled cells were of all the types described in the literature. In the Ncl. r. dorsalis, most of the labelled cells were observed in the medial part of this nucleus. In the lateral part there were only a few labelled cells. After injection of HRP into the caudal nuclei of the b.f. (Subst. innominata, medial and ventral boundary of the Gl. pallidus) more cells were labelled than after injection into the more rostral nuclei of the b.f. Of the cell types of the Ncl. r. dorsalis, the medium-sized and large multipolar types and the medium-sized fusiform cells were most frequent labelled. The Ncl. r. centralis superior tended to project more to the rostral nuclei, and the Ncl. r. dorsalis more to the caudal nuclei of the magnocellular b.f. The serotinergic fibers appeared more or less loosely distributed in the nuclei of the b.f. We could not differentiate between subtypes of the serotoninergic axons.

Animals↗
PubMed1988

Topographic differences in retinal axons in the dorsal lateral geniculate nucleus of the rat: a quantitative reexamination using anterograde transport of horseradish peroxidase.

Retinal endings in the dorsal lateral geniculate nucleus (dLGN) of the rat were visualized by anterogradely transported horseradish peroxidase following injections in the optic tract. The morphological findings confirm the two types of retinal axons previously suggested by Golgi investigations. In the caudal third of the dLGN type 2b axons, with small dense clusters of boutons, are the only representatives of retinal fibres seen. In the rostral two thirds they are intermingled with the larger type 2a terminals, but tend to accumulate laterally, adjacent to the optic tract. This study supports the concept that large retinal ganglion cells probably give rise to 2a axons that may represent a Y-like channel, whereas 2b axons are derived from small ganglion cells, and may relay a W-like pathway.

Animals↗
PubMed1988

The brain of the raccoon (Procyon lotor) in stereotaxic coordinates. I. Macroscopic studies.

Comparative anatomical and physiological studies revealed that the different sensory modalities are represented in the neocortex in topographically determined areas. Comparison of the representation field of the forepaw in different species of carnivores reveals an exceptional enlargement of these area in the somatosensory cortex of the raccoon. In this species the forepaws are of primary importance for the exploration of the environment and of the food. The peculiar structural organization of the somatosensory area initiated detailed studies by physiologists. There are now sufficient maps obtained after stimulation of circumscript areas in the forepaw. In order to study the somatosensory cortex by morphological methods (espec. degeneration and tracer methods) the aim of the present study was to establish in a first step stereotaxic data for the raccoon brain, especially for the neocortex in the macroscopic level. We gave information about the fixation of the raccoon head in a David-Kopf-stereotaxic-instrument and about the position of the brain in the skull. At least the raccoon brain in a dorsal and lateral view related to stereotaxic coordinates is demonstrated. The zero-plane is positioned in the interaural line.

Afferent Pathways↗
PubMed1988

[Anatomy of the nucleus magnocellularis in the basal forebrain of rodents and rabbits].

1. We have investigated the topographic organization and the extend of the magnocellular nuclei in the basal forebrain in 7 species of rodents and in the hare and the rabbit. 2. These nuclei, extending in rostro-caudal direction and forming a more or less continuous complex, are termed as follows: Nc. tractus diagonalis with pars medialis septi, pars verticalis and pars horizontalis, Nc. praeopticus magnocellularis, Substantia innominata, Nc. basalis Meynert, large cells lying along the lateral, ventral and medial borders of the globus pallidus, within the nucleus ansae lenticularis and the nucleus entopeduncularis. 3. Despite the multiplicity of nomenclature used by several authors for the same or different species, the magnocellular basal forebrain complex is present in all mammalian species investigated up to now. 4. We found that the nucleus medialis septi is not a separate nucleus. As a part of the pars verticalis of the diagonal band it is a subdivision of this nucleus. Indications for this result are: Agreeing positions of the cells among the fibers of the diagonal band of Broca, identical types of neurons in Golgi-preparations, the same efferent projection regions (mainly hippocampus). 5. In most of the rodents the nucleus basalis of Meynert can not be recognized in Nissl-preparations. Large interdigitated, cells as well in the substantia innominata as in the boundaries of the globus pallidus may probably be homologous to those in this nucleus. 6. In the squirrel we observed an accumulation of large cells at the ventral border of the globus pallidus interpreting this as a nuclear formation homologous or analogous to the nucleus basalis of Meynert in primates. 7. The hare and the rabbit form also an accumulation of large cells interpreted as nucleus basalis of Meynert. A dense arrangement already can be seen in the magnocellular praeoptic nucleus. It continuous through the ventral pallidum and the substantia innominata to the ventral border of the globus pallidus. 8. To elucidate the interrelations between the formation of a distinct nucleus basalis of Meynert and the mesencephalization process in the mammalian phylogeny more comparative investigations are necessary.

Acetylcholinesterase↗
PubMed1988

Increased expression of adhesive proteins on leukocytes by TNF alpha.

To further elucidate the role of tumor necrosis factor alpha (TNF alpha) in cell adhesion, we investigated the effect of TNF alpha on the expression of surface adhesive protein. After treatment with TNF alpha for 1 h, the increased expression of surface adhesive proteins (beta subunit) was observed on granulocytes but not on monocytes or lymphocytes. The expression of Mac-1 (3,4-fold increase) was consistently enhanced more than p 150,95 (1.4-fold increase) and LFA-1 expression was unchanged. Dose-response and time course studies indicated a parallel relationship between TNF alpha-increased expression of surface adhesive proteins and TNF alpha-induced granulocyte adhesion. The anti-inflammatory drug Dexamethasone suppressed both TNF alpha-induced granulocyte adhesion and TNF alpha-induced expression of surface adhesive proteins. The inhibition of granulocyte adhesion correlated with the reduction of surface adhesive protein expression. The data suggest that one contributing factor in the mechanism by which Dexamethasone inhibited TNF alpha-induced granulocyte adhesion may be diminished expression of surface adhesive proteins.

Antigens, Surface↗
PubMed1988

Neurons in the basal forebrain complex of the rat: a Golgi study.

Several types of neurons are coexistent in the basal forebrain nuclear complex of the rat. In the medial septum and vertical limb of the diagonal band 3 classes of neurons occur which are characterized by varicose dendrites. In the horizontal limb of the diagonal band neurons with smooth dendrites and those with varicose dendrites are intermingled. We found 3 classes of neurons in the nucleus preopticus magnocellularis. A giant type with smooth and varicose dendrites occurs in this nucleus, but also in the substantia innominata. In the substantia innominata-nucleus basalis complex 4 classes of neurons with varicose dendrites and 2 classes with spiny dendrites have been observed. Our findings suggest that the nucleus of the vertical limb of the diagonal band forms a unit with the nucleus septi medialis, but is separated from the nucleus of the horizontal limb of the diagonal band by different neuronal composition. The nucleus preopticus magnocellularis is a separate nuclear structure characterized by a content of neurons different from those in the horizontal limb of the diagonal band and in most components also from the substantia innominata-nucleus basalis complex. There is some evidence that the cholinergic neurons have to be searched among those with varicose dendrites.

Animals↗
PubMed1986

The rat cortex in stereotaxic coordinates.

On the basis of Nissl-preparations the cortex of albino rats has been mapped cytoarchitectonically. 13 frontal sections through the cortex are illustrated with coordinates. Therewith exists a stereotaxic atlas of the cortex of the rat and one can realize exactly experimental investigations in the different cortical areas.

Animals↗
PubMed1985

[The lateral geniculate body of the guinea pig (Cavia aperea f. domestica). Its organization with reference to retinal afferents].

The lateral geniculate nucleus (LGN) of the guinea pig was studied in order to investigate the existence of an alpha- and beta-sector. On the basis of the fibre arrangement and the cell distribution in its rostral third the LGd can be subdivided into an alpha- and beta-sector. The caudal half of the LGd comprises the alpha-sector only. In contrast to the alpha-sector, in which the cells are densely packed, the beta-sector is rich in fibre bundles and contains a scattering of medium-sized cells. Following unilateral enucleation we observed degenerating fibres in the contralateral beta-sector, too. This confirms the assumption that this sector is a part of the dorsal LGN. Like most of the alpha-sector, the beta-sector receives fibres from the contralateral retina, therefore the two sectors can not be interpreted like laminae. A cytoarchitectonical lamination could not be observed. The ipsilateral input is concentrated in a specific zone of the GdL (dorsomedial) but there is an overlapping with the contralateral input in the alpha-sector. In contrast to rat and mouse were the fibres of the Radiatio thalami are bordering the medial region of LGN the fibre bundles of the Radiatio thalami in the guinea pig and in the rabbit are scattered and pass through the medial part of the LGd. Therefore a beta-sector is formed. Parallel observations are reported from different species of marsupials. More investigations are necessary in order to solve the question whether the alpha- and beta-sectors--firstly described by Rose (1935) in the LGd of the rabbit--in lagomorphs, rodents and marsupials are homologous.

Animals↗
PubMed1984

Topography of cells responding with long latencies to flashes and cells projecting to layer I of area 17 in the rat dorsal lateral geniculate nucleus.

After deposition of horseradish peroxidase (HRP) crystals on the surface of cortical area 17 in 7 adult Wistar albino rats only relay cells were found to be labelled retrogradually in the caudal two thirds of the dorsal lateral geniculate nucleus (dLGN). From these results it can be concluded that cells projecting to the cortical layer I are concentrated in this part of the nucleus. Single cell recordings in the rat dLGN have shown that cells responding to light stimuli with long latencies are very frequent in this part of the dLGN, likewise. These findings support the idea that W-cells dominate in the caudal region of the rat dLGN, which is characterized by a population of relatively small geniculo-cortical relay neurons (GCR-neurons).

Animals↗
PubMed1984

The ventral lateral geniculate nucleus of the albino rat morphological and histochemical observations.

The ventral lateral geniculate nucleus (vLGN) of albino rats (Wistar strain) has been described histologically and histochemically. Special attention was paid to the identification of cell classes in Nissl and Golgi preparations, the afferent and efferent connections of vLGN cells and the demonstration of enzymes of energy and transmitter metabolism. Topographical aspects were taken into consideration, too. The main results can be summarized as follows: In the rat vLGN, three subnuclei can be distinguished: the lateral and medial subnucleus and the intergeniculate leaflet. In the rostral vLGN, the lateral and medial subnucleus is separated by a vertical fibre bundle which contains retinal axons. Our own experiments and findings of other groups revealed that the rat vLGN is connected with numerous brain structures. There is no efferent projection to cortical regions. Afferent fibres reach the vLGN from retina, visual cortex, superior colliculus, pretectal region, zona incerta, contralateral vLGN, dorsal raphe nucleus, locus coeruleus, mesencephalic reticular formation, vestibular and dorsal tegmental nuclei. An efferent projection has been found to superior colliculus, pretectal region, dorsal lateral geniculate nucleus, contralateral vLGN, zona incerta, pontine nuclei, suprachiasmatic nucleus, lateral terminal nucleus of the accessory optic system and intralaminar nucleus of thalamus. Comparative findings suggest that the lateral subnucleus is involved in "specific projections", whereas the medial subnucleus projects to "unspecific zones". For detailed information see text. Five classes of neurons can be distinguished in Golgi and Nissl preparations. Class 1 cells are medium-sized to large with smooth thick proximal but branched spiny distal dendrites. They are confined to the lateral subnucleus and the intergeniculate leaflet. In the lateral subnucleus, class 1 cells could be identified as geniculo-tectal relay neurons (Brauer and Schober, 1982). All other classes of neurons are spineless or sparsely spined. Class 2 cells (giant neurons) of unknown function could be found in the lateral and medial subnucleus. Class 3 cells (medium-sized multipolar neurons) can mainly be found in the medial subnucleus. They are good candidates for neurons projecting to the contralateral vLGN. Class 4 cells (bipolar neurons) occupy the ventromedial part of the medial subnucleus and are very similar to cells localized in the adjacent zona incerta. Cells belonging to this type could found to be labelled by the HRP reaction product after injection of this enzyme in the pontine region.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1983

[Afferent and efferent connections of lateral geniculate body pars ventralis in albino rats].

The afferent and efferent connections of the Corpus geniculatum laterale, pars ventralis (Cglv) of the albino rat were investigated lightmicroscopically by using either silver degeneration methods and the HRP-method as well. In contrast to the dorsal Cgl the results show remarkably different afferent connections in the ventral Cgl. The afferent fibres originate from the following areas: a) Retina: the terminal degeneration area of optic fibres includes the lateral part of the Cglv only. b) Regio praetectalis: degenerating fibres from these region can also be observed in the medial part of the Cglv. c) Colliculus superior: degenerating fibres terminate mainly in the lateral part of the Cglv. In the superior colliculus these fibres originate particularly from the cells of lamina III. d) Visual cortex: neurons of layer V of area 17 project mainly to the lateral half of the Cglv. There was no evidence for a projecting of the parastriate cortex (area 18 a) to the Cglv. The efferent fibres reach the following target areas: a) Nucleus lateralis posterior, Regio praetectalis and Colliculus superior. Evidence for a projection to the dorsal Cgl requires further investigation. b) Zona incerta, Formatio reticularis mesencephali and Nucleus medialis et lateralis pontis. Neurons in the medial half ot eh Cglv project to the pons region. c) Crossing the Commissura posterior and the Commissura suprachiasmatica, efferent fibres reach the contralateral Cglv, the Regio praetectalis and the Colliculus superior. The results obtained from the rat are compared with findings from other mammalian species. The functional importance of the Cglv in the visual processes is discussed taking into consideration the specific connections.

Afferent Pathways↗
PubMed1983

[Subcortical projections of the visual cortex in the adult albino rat and during postnatal development].

We have investigated the subcortical projections of the rat striate cortex by using the silver-degeneration method and the HRP-technique too. Cortical lesions were made in 60 young animals (1, 4, 5, 6, 7, 10 and 14 days old) and in 6 adult rats. The terminal regions of projection occurred only ipsilateral to the lesions. After passing the internal capsule the degenerating pathway divides into 2 bundles. In the dorsal thalamus one of them runs in caudal direction. The other bundle turns ventrally, reaches the cerebral peduncle and terminates in the pons. The first fibre bundle terminates in the following structures: Nc. reticularis thalami, Nc. lateralis thalami, Nc. lateralis posterior thalami, Corpus geniculatum laterale, pars dorsalis (Cgld), Corpus geniculatum laterale, pars ventralis (Cglv), Nc. praetectalis anterior et posterior and Colliculus superior. The fibers of the second bundle innervate the Nc. lateralis pontis. Fibers from this bundle terminate probably in the Cglv and in the Zona incerta too. By using the HRP-technique it could be demonstrated that the axons terminating in the Cgld originate in layer VI of the area 17. In contrast, the projection to Cglv, Nc. lateralis posterior, Colliculus superior and Nc. lateralis pontis originates from pyramidal cells in layer V. The development of the projection in young animals indicates: Like in adults rats, terminal degeneration is present in all subcortical projection regions at postnatal day (PD) 10. At PD 4-7 we can observe heavily degenerating axons but the terminal degeneration is different. It is remarkable in the "visual" part of the reticular nucleus and iln the Cgld (decreasing from inside to outside). Only a weak terminal degeneration is visible in the pretectal region and in the superior colliculus. At PD 1 the trajectory of degenerating fibres is clearly visible. Signs of terminal degeneration can only be found in the reticular nucleus. It is discussed whether the date of generation of the cortical neurons and the time of the differentiation of the cortical layers is of importance for the time of innervation of the subcortical projection fields. The question when the axons arrive at their terminal region and form there synaptic contacts has not yet been exactly answered. To solve this problem electronmicroscopic investigations are necessary.

Aging↗
PubMed1983

Termination of geniculocortical afferents on bipolar neurons in area 17 of the albino rat: a Golgi/EM study.

Degenerating terminals of specific afferents to the primary visual cortex of the albino rat were identified by electron microscopy after electrolytic lesions of the lateral geniculate nucleus. Bipolar neurons were marked by Golgi impregnation. We observed smooth dendrites of two bipolar cells postsynaptic to degenerating geniculate terminals. We conclude that this cortical cell type is directly contacted by thalamic afferents.

Animals↗
PubMed1983

[Neuronal location of thalamic afferents in the cingulate area of the rat].

Lesions were placed in the rat anterior thalamus (nucleus mediodorsalis and nucleus anteromedialis) known to project to the cingulate cortex (area 24). Transneuronal degeneration signs were found at the apical and basal dendritic tree of lamina V- and lamina III-pyramidal neurons in Golgi-Kopsch preparations. The lesioned animals showed significant decreases in the dendritic spine-density of apical and basal single dendritic fields of lamina V- as well as lamina III-pyramids. The results suggest that in the area 24 of the rat the thalamic afferent fibres terminate at both these pyramidal neurons. The method used allowed no decision whether the thalamic afferents terminate directly at the pyramids or if interneurons are interconnected.

Afferent Pathways↗
PubMed1983

Geniculocortical synapses involving apical dendrites of layer V pyramidal cells in area 17 of the albino rat visual cortex: a combined Golgi/EM study.

Using the combined Golgi/EM technique (Fairén et al. 1977) we have investigated whether apical dendrites of layer V pyramidal cells with different diameters receive different numbers of geniculocortical synapses. An electrolytic lesion was made in the lateral geniculate nucleus (LGN) of albino rats. After a survival time of two days degenerating boutons of LGN afferents onto visual cortex (area 17) were identified by electron microscopy. Postsynaptic layer V pyramidal cells marked by Golgi impregnation were studied. The location of nine identified pyramids was determined by light microscopy. The diameter of the apical dendrites - ranging from 0.9 to 2.5 mum - was measured on electron micrographs. The dendrites of eight out of the nine pyramids make synaptic contacts with geniculocortical afferents in layer IV and lower layer III. The degenerative geniculocortical terminals were mostly of the electron dense type; one times the electron lucent type was observed. These axon terminals synapse mainly with asymmetrical synaptic junctions on spines. Occasionally synaptic contacts were found on dendritic shafts. Most degenerating synapses are localized on the pyramidal cell with the thinnest apical dendrite. There was also an other thin apical dendrite, which did not receive any degenerating bouton. All out of one apical dendrites of different size are involved in geniculocortical synapses without giving any preference to dendrites of a defined diameter.

Animals↗