摘要:

AbstractThe morphology and organisation of the central projections of tactile hair afferents from the hind leg of the locust,Schistocerca gregaria, were examined by staining individual hair afferents. Each tactile hair on the femur, tibia, and tarsus is innervated by a single sensory afferent, which projects to the ipsilateral half of the metathoracic ganglion. Afferents arborize in the ventralmost and lateral ventral association centres (vVAC and lVAC). The projections are organised somatotopically in a map with three axes, according to the position of the hair on the leg. First, proximo‐distal: afferents from hairs on the proximal leg segments project more anteriorly than do those from hairs on distal leg segments. Moreover, on any given segment the afferents from the more proximal hairs project more anteriorly than do the afferents from the distal hairs. Second, antero‐posterior: afferents from hairs on the posterior surface of the leg project more medially than do afferents from anterior hairs. Third, dorso‐ventral: afferents from hairs on ventral parts of the leg project more ventrally than do afferents from the dorsal hairs. The afferents from posterior and anterior hairs project to an area between the central projections from dorsal hairs and ventral hairs The position of a projection within the map is dependent upon the location of the hair on the leg and not the peripheral routes taken by the axon of its afferent to reach the gan

ISSN:0092-7317    

DOI:10.1002/cne.903120402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe corticothalamic projections to the prefrontal cortex have been shown to be topographically organized. However, the underlying basis for this topography as it relates to the organization of the different architectonically defined areas of the prefrontal cortex has not been systematically studied. In the present investigation we have reassessed the thalamic projections from the different architectonic areas of the prefrontal cortex by using the technique of autoradiography in the rhesus monkey. The results show that the prefrontomediodorsal projections are organized according to the architectonic differentiation of the prefrontal cortices. Thus architectonically less differentiated medial and orbital prefrontal regions project to the medial sector of the mediodorsal nucleus, the magnocellular subdivision. In contrast, highly differentiated prefrontal area 8 projects to the most lateral sector of the mediodorsal nucleus, the multiformis subdivision. Lateral prefrontal areas with intermediate architectonic features project to the central parvocellular sector of the mediodorsal nucleus. Additionally, these projections also reveal a dorsoventral topography. Thus areas in the medial and dorsolateral cortices project to the dorsal part of the mediodorsal nucleus. In contrast, areas in orbital and ventrolateral cortices project to the ventral part of the mediodorsal nucleus.The topographic organization of the corticothalamic connections described in this study corresponds to the progressive elaboration and differentiation of the architectonic features of the different prefrontal areas. This successive and dichotomous organization of prefrontothalamic connections may provide the basis for the observed differential functions of the prefrontal cortex and the mediodorsal nucleus.

ISSN:0092-7317    

DOI:10.1002/cne.903120403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe distribution of acetylcholinesterase (AChE) was examined in the subiculum and hippocampus of the adult mouse (Mus musculus domesticus). A distinctly stratified AChE pattern was observed in both areas and was compared in detail with the cytoarchitectural fields and layers.In the subiculum, the lateral plexiform layer was lightly stained superficially and moderately stained at depth, where it abutted the lateral, moderately stained cell layer. Medially, a moderately stained deep plexiform layer separated the darkly stained superficial plexiform layer from the equally AChE‐intense cell layer. At depth, the subicular cell layer was delimited by a band of very high AChE activity. In regio superior of the hippocampus, AChE‐intense bands delimited the moderately stained strata moleculare, radiatum, and oriens toward the subjacent layers. In the stratum pyramidale, precipitate insinuated between the cell bodies gave a dark appearance to the deep part of the layer. The homologous strata of regio inferior appeared darker, but the relative staining intensities corresponded largely to those in regio superior. AChE activity in the layer of mossy fibers was almost absent septally but increased gradually to very high levels temporally.The AChE staining pattern, in conjunction with cytochemical and morphological evidence, strongly suggests a division of the pyramidal cell layer of the mouse and rat into superficial and deep substrata and discourages the definition of a prosubiculum in rodents. A comparative analysis of the AChE pattern reveals that: (1) in the subiculum, differences between species are observed within a generalized pattern of medial darkly staining and lateral lightly staining portions; (2) in the hippocampus, a conservation of the AChE pattern is seen in strata associated with intrinsic hippocampal connections; while (3) numerous interspecific differences are found in the stratum molecul

ISSN:0092-7317    

DOI:10.1002/cne.903120404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractMedial and lateral rectus motoneurons of frogs were localized after retrograde labeling with horseradish peroxidase (HRP) injected in the medial rectus muscle or applied on the cut end of the abducens nerve. Coordinates of these cell columns were used as target areas for the injection of small amounts of HRP (20–60 nl) and [3H]leucine (25–40 nl) and as search areas for retrogradely and anterogradely labeled internuclear neurons (INT) in in vivo and in vitro experiments.HRP injection in the medial rectus subdivision of the oculomotor nucleus (n = 6) resulted in retrograde labeling of ‐cell bodies in the contralateral principal abducens nucleus. On the average about 16 cells per animal were found. Somatic diameters were about 13.5 ± 2.8 μm (n = 32). The number and the size of these abducens internuclear neurons (AbINT) are smaller than those of lateral rectus motoneurons (n = 75; diameter: 19 ± 3.2 μm).A crossed projection of AbINT to medial rectus motoneurons in the contralateral oculomotor nucleus is further supported by autoradiographic results. Following injection of [3H]leucine into the abducens nucleus, a high density of silver grains was visible within the contralateral oculomotor nucleus, mainly in the caudal part of the oculomotor nucleus, where medial rectus motoneurons are located. Injection of [3H]leucine in vivo (n = 4) and in vitro (n = 3) resulted in a similar high density of silver grains within the contralateral oculomotor nucleus, but the background level of silver grains was significantly higher after in vitro (264 ± 38/2,500 μm2) than after in vivo injections (195 ± 17/2,500 μm2).HRP injection in the principal abducens nucleus (n = 9) resulted in retrograde labeling of cell bodies in the medial rectus subdivisions of the bilateral oculomotor nuclei. Ipsilateral projections predominated, with about 10 (±8) labeled cells over contralateral projections (about 3 ± 2). Average diameters of these oculomotor internuclear neurons (OcINT) were again smaller (10.8 ± 2 μm; n = 18) than those of medial rectus motoneurons (14.4 ± 3 μm; n = 52).In addition, retrogradely labeled cells were consistently encountered in the bilateral vestibular nuclei, the cerebellar nuclei, the dorsal brainstem caudal to the abducens nuclei, and ipsilaterally in the pretectum. Most of the vestibular neurons were located in the rostral part of the vestibular nuclear complex. These neurons might constitute part of the three‐neuronal arc of the vestibulo‐ocular reflex in the frog.Labeled cells in the pretectum were restricted to the ipsilateral posterior thalamic nucleus (P). After abducens injections the number of retrogradely labeled neurons in the P differed on the average by a factor of ten, depending on the micropipette's direction to the injection site. A ventral approach through the medial longitudinal fasciculus (MLF) resulted (as in other studies) in a false‐positive over estimation of the number of P neurons projecting to the abducens nucleus, probably due to labeling of fibers of passage in the MLF. Many axons of these P neurons descend more caudally and project to an area where retrogradely labeled neurons are found after oculomotor or abducens HRP injections. Location and input‐output relations of these neurons are compatible with a prepositus

ISSN:0092-7317    

DOI:10.1002/cne.903120405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractAntisera directed against the 48 kDa and 50 kDa cytoskeletal antigens were used to examine changes in the astroglial fabric of the goldfish visual pathways following optic nerve crush. Several major‐ observations are described. First, an optic nerve crush lesion in these animals appears to be devoid of glial cells for at least the first month after surgery. As acorollary, regenerating axons that grow acrossthe lesion may do so over an aglial substrate. Once the axons cross the lesion, their growth is confined to the astroglial domains of the proximal nerve stump. In the optic nerve, gliosis comprises hypertrophy of astrocytic processes such that the open framework characterizing the normal nerve is obscured. In addition, during regeneration, optic nerve glia express large amounts of the 50 kDa cytoskeletal protein, which they ordinarily express at only minimal levels. In the optic tract, gliosis is reflected in a markedly increased expression of the 50 kDa protein as well as an apparent increase in the number and complexity of glial processes. In addition, optic tract glia begin to express the 48 kDa antigen during regeneration. This protein is ordinarily confined for the most part to the optic nerve and is not seen in the tract glia. Finally, no obvious changes were seen in the glia of the optic tectum.These results demonstrate many points of similarity between gliosis in the goldfish and in mammals. However, in some particulars the two responses differ, and it is possible that these differences are related to the differing ability of central axons to regenerate in the two groups of organism

ISSN:0092-7317    

DOI:10.1002/cne.903120406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe organization of visual callosal projections was studied in (1) normal adult rabbits; (2) adult rabbits which had undergone monocular enucleation (ME) or binocular enucleation (BE) at birth; and (3) adult rabbits which had been deprived of normal visual experience during development by dark rearing (DR) or strobe rearing (SR). Previously published observations (Murphy and Grigonis, Behav Brain Res 30:151, 1988) on callosal organization in adult rabbits in which retinal ganglion cell activity was eliminated during development by intraocular tetrodotoxin (TTX) injections, are also summarized for comparison with these data.The tangential extent of the callosal cell zone was significantly larger than normal in DR, TTX, and ME rabbits, was unchanged in BE rabbits, and was significantly reduced in SR rabbits. An analysis of the laminar distribution of the callosal cells revealed a significant increase in the percentage of callosal cells in lamina IV in ME, DR, and TTX animals. Measurements of density of callosal cells showed a significant increase in the density of the callosal projection in ME and SR rabbits and a decrease in density in BE rabbits compared with normal.The data suggest that the mechanisms involved in the development of the tangential and laminar organization of the callosal cell zone are different. In addition, the data suggest that the mechanisms involved in the maintenance of callosal projections are different from the mechanisms involved in the elimination of callosal projections during development.The effects of these developmental manipulations on callosal organization in other mammals are reviewed and compared with the effects in rabbits. The data suggest that species differences in the degree of maturity of the visual system at birth and in the extent of callosal development at the time of eye opening, may underlie species differences in the effects of these manipulations on the organization of visual callosal projections during development.

ISSN:0092-7317    

DOI:10.1002/cne.903120407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis morphological and biochemical study examines the cytoplasmic synaptic determinant recognized by a monoclonal antibody (B16). This antibody was generated by using an immunosuppression protocol that generates antibodies to relatively rare antigens. The B16 antibody labels structures in the brain that are dot‐shaped and in the retina that resemble synaptic ribbons in their location, size, developmental emergence, and biochemical composition. The antigen is apparently conserved across species as it is found in retinas from lizards, frogs, fish, birds, mice, rats, rabbits, cats, and monkeys. This paper focuses on observations in the murine retina.Labeling in the outer plexiform layer of the retina is confined to the margin between the outer plexiform layer (OPL) and the outer nuclear layer. The labeled structure resembles a semiellipse or an arc with the open end facing the OPL and the top facing the outer nuclear layer. Overall, the arc is approximately 1 μm in length and less than 0.5 μm thick. Approximately 10% of the labeled arcs occur in a proximal stratum of the OPL and form a planar cluster that resembles a flat plaque parallel to the OPL. Five to ten arcs are found in each plaque. The arcs found within the plaques are approximately 50% smaller than the larger isolated arcs. Counterstaining with peanut agglutinin (PNA), a lectin that recognizes cone photoreceptors and their associated processes, demonstrates that the plaques are associated with the cone pedicles. Animals that have a higher ratio of cones/rods than mice demonstrate a much higher ratio of plaques/isolated arcs in the OPL. The structure labeled in the inner plexiform layer resembles a short bar (0.8 μm long by<0.5 μm wide) that is confined to the inner half of the inner plexiform layer in mice.The relative mobility (Mr) of the B16 antigen obtained from mouse retinal and brain tissue is 88 kD, as determined by SDS‐PAGE followed by Western blotting. The mouse 88 kD protein is relatively soluble (precipitates at 70% ammonium sulphate) and elutes at a pH of 7.3 from an isoelectric focusing column. It appears that the determinant recognized by the B16 antibody is a previously undescribed synaptic protein that is associated with the synaptic ribbons in photoreceptor and bipolar terminals of most vertebrate

ISSN:0092-7317    

DOI:10.1002/cne.903120408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractAspartate has been reported to be a putative excitatory neurotransmitter in the retina, but little detailed information is available concerning its anatomical distribution. We used an antiserum directed against an aspartate‐albumin conjugate to analyze the anatomy, dendritic stratification, and regional distribution of cell types with aspartate‐like immunoreactivity in the turtle retina. The results showed dramatic differences in immunoreactivity in the peripheral versus the central retina. Strong aspartate‐like immunoreactivity was shown in the peripheral retina, with many well‐labeled processes in the inner plexiform layer. Many bipolar, horizontal, amacrine, and ganglion cells, some photoreceptors, and some unidentified cells were strongly immunoreactive in the peripheral retina. In contrast, although the central retina showed well‐labeled horizontal cells, there was only light labeling in the inner plexiform layer with weakly immunoreactive amacrine and ganglion cells and no labeled bipolar cells. There were several strongly immunoreactive efferent nerve fibers which left the optic nerve head and arborized extensively in the retina. At the electron microscopic level, electron‐dense reaction product was associated with synaptic vesicles at bipolar and amacrine cell synapses in the inner plexiform layer. These results suggest that aspartate may be involved in many diverse synaptic interactions in both the outer plexiform layer and the inner plexiform layer of the tu

ISSN:0092-7317    

DOI:10.1002/cne.903120409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe occurrence of acid phosphatase (AcPase)‐positive bodies, i.e., lysosomes, in lumbosacral alpha‐motor axons of kittens, 0–16 weeks of age, was analyzed by light and electron cytochemical methods under normal conditions and after intramuscular injection of horseradish peroxidase (HRP). Axonal lysosomes wore rare early postnatally. In 3‐week‐old animals, a few AcPase‐positive bodies appeared in the axoplasm at some nodes of Ranvier in the peripheral nervous system (PNS) and internodally in the intrafunicular motor axon parts within the central nervous system (CNS). From 6 weeks postnatally, a nodal concentration of AcPase‐positive bodies was also noted in the CNS. The number of AcPase‐positive bodies continued to increase gradually in the course of neuronal maturation. In 16‐week‐old animals, axonal AcPase activity was still at considerably lower levels than at adult stages. At all ages, acid hydrolase‐containing organelles were most commonly found at ventral root nodes. After injection of HRP in the medial gastrocnemius muscle, accumulations of AcPase‐positive bodies were seen in the axoplasm at some PNS nodes of the HRP‐injected sides of kittens aged 8, 12, and 16 weeks. Incubation for demonstration of both HRP and AcPase activity showed that some organelles at HRP‐transporting nodes contained both types of reaction product. The nodal AcPase activity in the intrafunicular, CNS parts of alpha‐motor axons of the HRP‐exposed sides did not differ from that of the contralateral, uninjected sides.In view of our previous observations in alpha‐motor neurons of adult cats in which a lysosome‐mediated degradation of axonally transported materials may take place at PNS nodes of Ranvier, the present study illuminates possible differences in the ability to interfere with axonal transport between developing and mature neurons. The infrequent presence of lysosomes in developing alpha‐motor axons and the implied disability of their nodal regions to interfere with axonally transported constituents in a way similar to that seen in adult animals may be of significance in that trophic and chemical signals can pass unhindered between the periphery and perikaryon. However, this could also have negative consequences for the vulnerable immature neuron in that various materials retrieved at the axon terminals outside the CNS are permitted a more

ISSN:0092-7317    

DOI:10.1002/cne.903120410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractPrimate cones maximally sensitive to short wavelength light (blue cones) have been previously identified by using indirect methods. We stained 7 wholemounted human retinas obtained from 6 female donors, using an affinity purified antibody to a 19 amino acid peptide sequence at the N‐terminus of blue opsin (Lerea et al., '89: Neuron3:367–376), standard PAP immunocytochemistry, and controls. Cones were counted where all outer segments could be traced to inner segments and were measured where cells were well aligned vertically.We find that: (1) 7% of cones within 4 mm of the foveal center are labeled by antiblue opsin; (2) compared to neighboring red/green cones, blue cone inner segments are 10% taller, have a larger cross‐sectional diameter near the junction with the outer segment, and a smaller diameter near the external limiting membrane, resulting in a more cylindrical shape, (3) foveal blue cones are sparse, irregularly spaced, and missing in a zone about 100 μm (0.35°) in diameter near the site of peak cone density, (4) the highest densities of blue cones (>2,000 cells/mm2) are found in a ring at 0.1–0.3 mm eccentricity, and (5) the shortest distances between neighboring cones are between blue and red/green cones, and the blue and red/green mosaics are statistically independent.These findings are consistent with psychophysical reports of foveal tritanopia and maximum sensitivity to blue light at 1° eccentricity. Blue cone spacing may limit resolution of the blue channel out to 20–30° eccentricity. The blue and red/green mosaics appear to be formed by separ

ISSN:0092-7317    

DOI:10.1002/cne.903120411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY