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K Brauer

Publications and source records attributed to K Brauer.

At least 91 records · Page 5Linked to original sources
PubMed1984

Neuron types in the rat dorsal lateral geniculate nucleus identified in Nissl and deimpregnated Golgi preparations.

To identify geniculo-cortical relay neurons (GCR-neurons) and interneurons (I-neurons) in Nissl stained sections of the albino rat's (Wistar strain) dorsal lateral geniculate nucleus (dLGN) we combined a Golgi deimpregnation technique (Fairén et al. 1977) with the Nissl staining. The two types of neurons show numerous characteristic features in Golgi preparations (Brauer and Schober 1973, Grossman et al. 1973, Brauer et al. 1974, Winkelmann et al. 1976, 1979). After application of the combined method it is obvious that neuronal somata exhibit also features which make it possible to identify these types of neurons in Nissl stained series. GCR-neurons are characterized by a very broad cytoplasmic portion, whereas a particularly thin cytoplasm rim is typical of I-neurons. Our findings confirm former results obtained by analysis of Nissl material (Werner and Kruger 1973, Werner et al. 1975, Werner and Winkelmann 1976, Werner et al. 1984). In these investigations, special attention was paid to cytoplasmic and nuclear characteristics in order to elucidate the ratio of GCR-/I-neurons (13:1) and the internal dLGN topography. It is still discussed if the described cytological features can be taken as basis for the classification of GCR- and I-neurons in other species.

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

The localization of AChE in the dorsal lateral geniculate nucleus of different mammals--a light and electron microscopical study.

AchE has been histochemically demonstrated in the dLGN of different mammals. In the rat dLGN the enzyme is light microscopically localized in fibres only. This reaction is somewhat higher in the superficial than in the innermost region of the dLGN. The same distribution has been observed in other rodents like hamster, mouse, and guinea pig. Reaction products have been found electron microscopically in afferent fibres of the rat's dLGN with characteristic vesicle types and synaptic contacts to dendrites. We concluded that these fibres originate from the formatio reticularis of the brain stem. Nerve cells show a very weak reaction in the nuclear envelope and in the endoplasmatic reticulum. In the rabbit dLGN cell bodies with strong AchE-reaction are demonstrable. The AchE-activity in the laminae of the dLGN of tree shrew, cat and monkey is compared with the morphologically characterized cell types. It is discussed that X-cells in the mammalian dLGN are more influenced by AchE-containing afferent axons than other types of geniculo-cortical relay cells. Light microscopic results of AchE-localization in the visual cortex of rodents, tree shrew, and cats are described.

Acetylcholinesterase↗
PubMed1983

[Degenerative changes in the occipital neocortex in chronically amphetamine treated rats].

Neurons of the Wistar-rats' occipital cortex were morphologically investigated after chronical application of amphetamine. The nerve cells impregnated according to the Golgi-Kopsch technique showed in part changes on both the dendrites and in the axonal region. Besides a partial reduction of spines and of peripheral dendritic arborizations round varicosities of different density could be observed on the dendrites and on the axon, either, which were discussed to be due to a neurotoxic effect of amphetamine.

Amphetamine↗
PubMed1982

Identification of geniculo-tectal relay neurons in the rat's ventral lateral geniculate nucleus.

In the rat's ventral lateral geniculate nucleus (vLGN), geniculo-tectal relay neurons (GTR-neurons) could be identified by the retrograde transport of horseradish peroxidase (HRP) after injection in the superior colliculus (SC). GTR-neurons correspond to class III cells described by Brauer and Schober (1973) in Golgi preparations of the rat's LGN. The distribution of GTR-neurons is restricted to the lateral subnucleus of vLGN. According to Swanson et al. (1974), the axons of these cells terminate in lower Stratum griseum superficiale and in Stratum opticum, Stratum griseum intermedium and Stratum album intermedium of SC. The GTR-neurons are characterized by very thick and long proximal dendritic segments which have a smooth surface. Dendrites branch preponderantly in their distal regions and only in this part form many multiform protrusions. There is some evidence that retinal axons terminate on these dendritic surface structures. The supposed differences in the afferent patterns between GTR-neurons in the vLGN and geniculo-cortical relay neurons in the dorsal lateral geniculate nucleus are discussed.

Animals↗
PubMed1982

A comparative light microscopic investigation on geniculo-cortical relay neurons in rat, tree shrew and cat.

The morphology of geniculo-cortical relay neurons (GCR-neurons) of tree shrew, rat and cat differs intraspecifically and interspecifically from each other. Intraspecific differences in the cat have been explained functionally by the W-, X-, and Y-characteristics of cells (Wilson et al. 1976). Analogous morpho-functional correlations may also explain the morphological differences in tree shrew and rat. The interspecific differences in the morphology of GCR-neurons seem to be closely correlated to the levels of visual specialization in the three species in which the rat represents a basal developmental stage.

Animals↗
PubMed1982

[Comparative volumetric studies of the lateral geniculate body of mammals].

Volumetric investigations of the dorsal and ventral nucleus of the lateral geniculate body (dLGN and vLGN) in 16 mammalian species showed that forms with a high level of neocorticalization are characterized by a high quotient of dLGN and vLGN volumina. This result may be explained by the very different fibre connections of these two nuclei and the close relationship of the dLGN to the visual cortex. Compared with terrestric forms of the same body size tree living forms belonging to the same mammalian order have a larger LGN. The dLGN of these arboreal species exhibits additionally a higher level of histological differentiation (lamination). So we can conclude that there is a correlation between LGN volumina and the occurrence of dLGN lamination in members of the same order. This rule cannot be applied generally to species belonging to different orders.

Animals↗
PubMed1982

Topographical distribution of neuronal types in the albino rat's area 17. A qualitative and quantitative Nissl study.

1. Using Nissl preparations of adult male albino rats the topographical distributions of 10 neuronal types of the area 17 were ascertained in medio-lateral and dorso-ventral direction. 2. Two groups of neuronal types and one intermediate type are distinguished: (i) neurons rich in cytoplasm: pyramidal cells in L II-VI, stellate cells in L IV, one type each in L I and L VII, and a particularly large neuronal type in L II-VI; (ii) neurons poor in cytoplasm: one type in L I, three types in L II-VII and (iii) the intermediate type in L II-VI. 3. In the area 17, 93% of neurons are rich in cytoplasm (except the particularly large neuronal type B, 3.5%) (category-I-neurons = projection neurons), 2.9% of neurons are poor in cytoplasm (category-II-neurons = interneurons), and 0.6% are of the intermediate type. The latter may correspond with the Martinotti cell. At present we can only speculate, which cell type in Golgi preparations corresponds with the type B. 4. Taking into account the shrinkage of histologically treated tissue the number of neurons within a fresh volume of area 17 can be estimated. There are about 40,000 neurons within a volume of 1,000 microns x 1,000 microns basis. 5. Each layer is characterized by a specific amount of certain neuronal types, which are intermingled. 6. The distribution pattern of neuronal types change considerably in dorso-ventral direction. Medio-laterally there are only random deviations. 7. There are much more neurons poor in cytoplasm in superficial layers than in deeper layers. 8. In L I and L Va the highest and in L VII the smallest percentage of neurons poor in cytoplasm could be found. 9. L IV is characterized by its high number of stellate cells, the relatively high portion of the particularly large neuronal type B and small portions of pyramidal cells and neurons poor in cytoplasm. 10. As far as possible the functional aspects of the presented findings are discussed.

Animals↗
PubMed1982

Perineuronal nets of glia.

Perineuronal nets could be visualized with some Golgi methods in the rat's brain. Nets were seen in telencephalic, diencephalic and mesencephalic structures covering somata and proximal dendrites of different neuronal types. Some nets could be found originating from microglia cells. In most cases their origin is not recognizable. These perineuronal nets seem to be identical with "Golgi nets" of late anatomists, which played an important role in the discussion between recticularists and neuronists. Some aspects of their possible functional significance are discussed.

Animals↗
PubMed1981

The dorsal lateral geniculate nucleus of Tupaia glis: a Golgi, Nissl and acetylcholinesterase study.

Morphology of neurons and afferent axons in the dorsal lateral geniculate nucleus (dLGN) of the tree shrew (Tupaia glis) was studied using Golgi-Kopsch impregnated and Nissl stained material. Staining of acetylcholinesterase (AChE) could inform about the distribution of this enzyme in the tree shrew's dLGN. The results can be summarized as follows: 1. Two classes of neurons can be identified: class-I-neurons and class-II-neurons. Class-I-neurons correspond to geniculo-cortical relay neurons (GCR-neurons) and class-II-neurons correspond to local interneurons (I-neurons). 2. Class-I-neurons differ in their morphology depending on their laminar position. Tufted neurons with clusters of grape-like appendages in their branching zones resembling X-cells in the cat's dLGN are localized in the external laminae 5 and 4. In the superficial lamina 6 the dendrite domains of GCR-neurons are flattened and elongated. Dendrites seem not to penetrate laminar borders. The cells in layer 3 have the smallest soma and radiate dendrites. There is some evidence that GCR-neurons in this lamina represent W-cells (Carey et al., 1979). GCR-neurons in laminae 2 and 1 (innermost laminae) have the biggest somata. Their dendritic branching patterns make it difficult to classify the cells into tufted or radiate. Branching zones are rather smooth. These cells seem to be good candidates for Y-cells. 3. I-neurons could be identified in all laminae. Their dendrites preferentially take a dorso-ventral course. Only axon initial segments of these neurons were visible in Golgi preparations. 4. GCR-neurons and I-neurons could also be identified in Nissl preparations. The ratio GCR-neurons: I-neurons is about 10:1, i.e. 10% of all neurons are I-neurons. 5. In Golgi preparations some types of axons were impregnated. Type-1-axons resemble cortical afferents of other mammalian species. Type-2-axons (2a, 2b, 2c) do not leave single laminae in our material. Considering branching characteristics of their terminal zones, this finding could be a reference for their retinal origin. 6. Laminae 5, 4, 2, and 1 have a remarkable higher content of AChe than the laminae 6 and 3. The low level of ACHE in lamina 3 of the tree shrew's dLGN corresponds to the less activity of ACHE in the laminae 4 and 5 of Galago senegalensis (Fitzpatrick and Diamond, 1979), which like lamina 3 in Tupaia's dLGN project to layer I of the visual cortex (Carey et al., 1979).

Acetylcholinesterase↗
PubMed1980

[Ultrastrastructural and histochemical examinations of afferent pathways of the geniculate-cortical relay cells].

On the basis of ultrastructural and ultrahistochemical studies in the dorsal part of lateral geniculate nucleus (d LGN) of albino rat a topistical model of geniculo-cortical relay cell (GCR-cell) afferentiation is proposed. Retinal afferent terminals of type 2a and 2b and their synaptic properties are discussed in connection with slow and fast conducting retinofugal channels. Interneuronal contacts are represented by presynaptic dendritic specializations (P-bouton) and by axonal terminals (F-bouton) (LIEBERMAN and WEBSTER, 1974). These findings suggest that the function of interneurons may be dualistic. Cortical afferents are represented by small terminals with round agranular vesicles. Using the "false" transmitter 5-OH-DA we succeeded in demonstrating degenerating terminals with dense core vesicles. There is evidence that noradrenergic axons originating in the Locus coeruleus may contact with the distal dendritic parts of GCR-neurons.

Acetylcholinesterase↗
PubMed1979

[Variability of the relay neurons in the corpus geniculatum laterale, pars dorsalis in the albino rat].

38 Golgi-impregnated relay cells from the Wistar rat's dLGN were investigated considering their possible differentiation into 2 types using camera lucida drawings with a magnification of 800. The following criteria were taken into account: 1. size of neurons (perikarya, size of dendritic domains) 2. structure of dendrites (number of dendrites, branching points, distribution of dendritic density in relation to the perikaryon, surface structures of dendrites). It was tried to correlate the investigated parameters quantitatively and qualitatively. The results showed that inspite of a missing clear subdivision into 2 types there exists a trend towards developing a second type of relay cells.

Animals↗
PubMed1979

[Fluorescence histochemical identification of axons using the GOLGI method].

Using fluorescence histochemical and GOLGI-methods afferent fibers in the albino rat's dorsal lateral geniculate nucleus (d LGN) have been investigated. We considered the following parameters: diameters of the axons, diameters of boutons, number of the boutons by 100 micrometers axon length. From comparison of the data from histochemical material with the data of the GOLGI-material follows that the noradrenergic terminals are identical with the type-4- and 5-axons. The terminal branching and synaptic contacts of the type-4- and 5-axons are discussed in connection with the aminergic innervation of this nucleus.

Afferent Pathways↗
PubMed1979

[Identification of nerve cells in the visual cortex of the rat using Nissl and Golgi-Kopsch methods].

The neurons of the visual cortex of the albino rat were studied using both the Nissl- and Golgi-Kopsch methods. In Nissl preparations we can distinguish between a group of neurons rich in cytoplasm, a group of neurons poor in cytoplasm and an intermediate group. In the Golgi preparations the neurons can be subdivided according to the shape of their cell bodies, dendrites and axons. Spiny cells with long axonal main trunks are pyramidal cells, multiangular cells and stellate cells of layer IV. Cells with spineless dendrites and short axonal arborization are basket cells, neuroglioform cells and small double bouquet cells. Due to its spines and the short axonal arborization, the coarse fusiform cell (Martinotti cell) is an intermediate type. We assume cells having long axons and dendritic spines are category I neurons and cells having short axons and no or a few spines are category II neurons (according to SZENTAGOTHAI 1973). On the basis of homological criterions and taxonomically relevant features references for identifying the cell group rich in cytoplasm and category I neurons, on the one hand, and the cell group poor in cytoplasm and category II neurons, on the other hand, were found. The group of cells rich in cytoplasm is related to pyramidal cells, multiangular cells and stellate cells of lamina IV. The group of cells poor in cytoplasm is discussed as corresponding to cells of lamina I, round or oval forms as basket cells and neuroglioform cells, fusiform cells as double bouquet cells. The intermediate cell form in the Nissl preparations is according to the Martinotti cell in Golgi material. These findings allow quantitative studies about particular cell populations and can, completed with electron microscopical date, instruct computer models to simulate the complicate neuronal network of the visual cortex.

Animals↗