bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of the release site of inhibitory synapses on the soma and dendrite of an identified neuron
Authors: Sur Cyrille , Triller Antoine , Korn Henri 
Published: January 2005

AbstractSynapse are complex arrangements of pre‐and postsynaptic differentiations involved in neural communication. A key element in this synaptic transmission is the presynaptic active zone where the release of neurotransmitter occurs. Active zones can be visualized and analyzed after staining with ethanolic phosphotungstic acid (EPTA) on semithin (0.5μm) sections. This staining has been used in association with postembedding immunogold labeling for the neurotransmitters glycine or GABA, to investigate the organization of chemically defined inhibitory active zones, viewed in their full extent, on different regions of the goldfish Mauthner (M−) cell.With this approach, a marked variability in size and shape was observed for the release sites contacting the different parts of the postsynaptic neuron. In the axon cap and on the soma, glycinergic afferent terminals have small presynaptic grids (0.066 ± 0.029 μm2, n = 30 and 0.076 ± 0.037 μm2, n = 46, respectively). These grids are quite circular and they include 12 to 13 presynaptic dense projections (PDPs). The situation is different on the lateral dendrite, where glycinergic and GABAergic active zones display a greater variability in their surface areas (mean = 0.147 ± 0.100 μm2, n =115 and 0.139 ± 0.080 μm2, n = 125, respectively), and their number of PDPs (mean = 19 ± 9) per individual grid. Similarly, the shape of the release sites over the dendrite is more complex (annular, horseshoe‐shaped) when compared to those on the soma. These differences of dendritic versus somatic release sites could represent a structural basis to maximize the shunting effect of glycinergic and GABAergic inhibitory junctions, i.e., close to excitatory inputs.We also observed that the proportion of endings containing 1 or more active zones also varies. More precisely, 96% and 82% of glycinergic terminals in the axon cap and on the soma, respectively, display only one active zone. On the dendrite, their proportion falls to 65.5% for both glycine‐ and GABA‐containing boutons. The remaining inhibitory terminals contain 2 (30%) and 3 to 4 (4.5%) presynaptic grids. These results reveal a greater variability of morphology and organization of the inhibitory release sites at dendritic versus somatic locations. The functional significance of this observation for the synaptic transmission is discussed. © 1995 Willy‐Liss, Inc.
Organization of somatosensory cortex in monotremes: In search of the prototypical plan
Authors: Krubitzer Leah , Manger Paul , Pettigrew Jack , Calford Mike 
Published: January 2005

AbstractThe present investigation was designed to determine the number and internal organization of somatosensory fields in monotremes. Microelectrode mapping methods were used in conjunction with cytochrome oxidase and myelin staining to reveal subdivisions and topography of somatosensory cortex in the platypus and the short‐billed echidna. The neocortices of both monotremes were found to contain four representations of the body surface. A large area that contained neurons predominantly responsive to cutaneous stimulation of the contralateral body surface was identified as the primary somatosensory area (SI). Although the overall organization of SI was similar in both mammals, the platypus had a relatively larger representation of the bill. Furthermore, some of the neurons in the bill representation of SI were also responsive to low amplitude electrical stimulation. These neurons were spatially segregated from neurons responsive to pure mechanosensory stimulation. Another somatosensory field (R) was identified immediately rostral to SI. The topographic organization of R was similar to that found in SI; however, neurons in R responded most often to light pressure and taps to peripheral body parts. Neurons in cortex rostral to R were responsive to manipulation of joints and hard taps to the body. We termed this field the manipulation field (M). The mediolateral sequence of representation in M was similar to that of both SI and R, but was topographically less precise. Another somatosensory field, caudal to SI, was adjacent to SI laterally at the representation of the face, but medially was separated from SI by auditory cortex. Its position relative to SI and auditory cortex, and its topographic organization led us to hypothesize that this caudal field may be homologous to the parietal ventral area (PV) as described in other mammals. The evidence for the existence of four separate representations in somatosensory cortex in the two species of monotremes indicates that cortical organization is more complex in these mammals than was previously thought. Because the two monotreme families have been separate for at least 55 million years (Richardson, B. J. [1987] Aust. Mammal. 11:71–73), the present results suggest either that the original differentiation of fields occurred very early in mammalian evolution or that the potential for differentiation of somatosensory cortex into multiple fields is highly constrained in evolution, so that both species arrived at the same solution independently. © 1995 Willy‐Liss, Inc.
Multiterminal proprioceptors in Squilla mantis (stomatopoda, crustacea)
Authors: Wales B. , Ferrero E. A. 
Published: January 2005

AbstractA series of morphologically simple multiterminal proprioceptors is described in the throacopods of the hoplocardian crustacean, Squilla mantis, which is a primitive offshoot of the main malacostracan evolutionary line. The description given here is primarily for the largest and most complex receptor that occurs in the second thoracopod, the raptorial limb. These stretch receptors, which lie distally in the coxopodite, consist of single multiterminal sensory neurones with widely branching dendrites innervating broad connective tissue strands. The single primary dendrite divides dichotomously or, occasionally, trichotomously to produce a large number of terminal dendrites. The terminal dendrites, which exhibit a beaded structure, run parallel to the connective tissue strands' longitudinal axis. Dendrites possess an elaborate connective tissue sheath consisting of a single inner glial layer and a multiple outer connective tissue layer. The presence of the beaded structure has been confirmed by transmission electron microscopy (EM), and, because microtubule density does not vary with dendrite diameter, the beads are not fixation artifacts. Beads have high numbers of mitochondria and glycogen deposits, which suggests that they have high metabolic activity. Dendritic tips are not associated with beads, arise from the terminals of smaller dendrites, and are embeded in the extracellular ground matrix of the connective tissue strand, where they lie parallel to and surround bundles of elastic fibrils. The different degree of development within the receptor series allows comparison between functionally different limbs, and comparison is made with other segmental receptor series. The evolution of multiterminal proprioceptors is discussed. © 1995 Willy‐Liss, Inc.
Convergence and divergence of ascending binaural and monaural pathways from the superior olives of the mustached bat
Authors: Vater Marianne , Casseday John H. , Covey Ellen 
Published: January 2005

AbstractThe lateral superior olive and medial superior olive give rise to pathways that terminate in the dorsal nucleus of the lateral lemniscus and central nucleus of the inferior colliculus. In most mammals, neurons in both the medial and lateral superior olives are binaural, but in the mustached bat most neurons in the medial superior olive are monaural. The aims of this study were to determine how the inputs to the medial superior olive contribute to its monaurality and to determine whether the ascending projections from the lateral and medial superior olives overlap or rema in segregated at their targets. Injections of two different tracers were placed in tonotopically matched areas of the lateral and medial superior olives in the same animal. Retrograde transport from injections in the medial superior olive labeled spherical cells in the contralateral anteroventral cochlear nucleus and principal cells in the ipsilateral medial nucleus of the trapezoid body. Few cells were labeled in ipsilateral cochlear nucleus. Anterograde transport resulted in tonotopically specific distributions of label with the same laterality as in nonecholocating mammals. In the dorsal nucleus of the lateral lemniscus, label from the lateral and medial superior olives largely overlapped. In the inferior colliculus, label from the two sources overlapped in the high and low frequency ranges, but in the frequency range around 60 kHz, label from the medial superior olive extended more dorsally than that from the lateral superior olive. These results indicate that projections of the lateral and medial superior olives overlap extensively at their targets. © 1995 Willy‐Liss, Inc.
Expression patterns and deprivation effects on GABAA receptor subunit and GAD mRNAs in monkey lateral geniculate nucleus
Authors: Huntsman M. M. , Leggio M. G. , Jones E. G. 
Published: January 2005

AbstractThe expression and regulation of seven GABAA receptor subunit gene transcripts were examined in the adult monkey lateral geniculate nucleus. In situ hybridization histochemistry was used to localize mRNAs of the genes encoding monkey‐specifical α1, α2, α4, α5, β1, β2, and γ2 subunits. The highest levels of expression in the nucleus were for α1, β2, and γ2 subunit transcripts. The levels were substantially higher in the magnocellular than in the parvocellular layers. Alpha‐2, α4, α5, and β1 subunit mRNAs were expressed at much lower levels, and magno‐ and parvocellular layers had approximately equal levels of expression.Following 4‐ or 21‐day periods of monocular deprivation induced by intravitreal injections of tetrodotoxin, levels of the α1, α2, α4, α5, β1, and β2 mRNAs were decreased in the deprived geniculate laminae. Adjacent sections hybridized with probes specific for 67‐kDa glutamic acid decarboxylase (GAD) mRNA also showed decreased levels of expression in deprived laminae after the 21‐day deprivation period. Levels of γ2 receptor subunit mRNA were unaffected by monocular deprivation. In our previous studies, a clearly significant downregulation is observed for this subunit transcript in the visual cortex of monkeys deprived for equivalent times. The differential expression and responses to deprivation in the lateral geniculate nucleus suggest region‐specific regulation of GABAA receptor subunit genes. © 1995 Wiley‐Liss, Inc.
Expression of four immunoglobulin superfamily adhesion molecules (L1, Nr‐CAM/Bravo, neurofascin/ABGP, and N‐CAM)in the developing mouse spinal cord
Authors: Moscoso Lisa M. , Sanes Joshua R. 
Published: January 2005

AbstractTo identify cell adhesion molecules (CAMs) expressed by mammalian motoneurons, we applied the polymerase chain reaction to a murine motor neuron‐like cell line, NSC‐34. Using primers derived from a group of Ll‐related CAMs, we cloned two alternatively spliced forms of mouse L1, which differ by a 12‐base‐pair insert, plus putative murine orthologs of the chicken cell adhesion molecules Nr‐CAM/Bravo and neurofascin. All four mRNAs are expressed in NSC‐34 cells, but only neurofascin and the insert‐minus form of Ll are expressed in its neuroblastoma parent, N18TG2. Analysis of RNA in neonatal tissues reveals expression largely restricted to the brain and spinal cord. In situ hybridization histochemistry of spinal cord shows that motoneurons express L1, Nr‐CAM, and neurofascin as well as N‐CAM. Ll and N‐CAM RNAs are detected throughout the period studied (from embryonic day,[E]11 to postnatal day [P]28), whereas Nr‐CAM is expressed only at early ages (<E15) and neurofascin is predominantly expressed postnatally. Moreover, each CAM is expressed by distinct subsets of neighboring cells and at distinct times. For example, Nr‐CAM mRNA is present in floor plate cells of embryonic spinal cord, whereas neurofascin is expressed by a subset of glia postnatally. Finally, we show that each CAM has a distinct spatiotemporal pattern of expression in dorsal root ganglia. © 1995 Wiley‐Liss, Inc.
Neurofilament sidearm proteolysis is a prominent early effect of axotomy in lamprey giant central neurons
Authors: Hall Garth F. , Lee Virginia M.‐Y. 
Published: January 2005

AbstractIn the accompanying paper, it was shown that axotomy of lamprey spinal axons induces the rapid formation of condensed neurofilamentous masses in the proximal axon stump near the lesion. In this study, we used immunocytochemical and Western blot analysis to characterize these masses further and to determine the time course of their formation and dispersal. We show that monoclonal antibodies specific to the “rod” domain of lamprey neurofilament protein strongly stain such masses in tissue sections without staining other axonal neurofilaments. Antibodies specific for the neurofilament “sidearm” domain fail to recognize neurofilamentous masses but stain other axonal neurofilaments. Western blots of spinal cord segments from the lesion site were compared to unlesioned cord and to samples of cord distant from the lesion. We found that a neurofilament rodrspecific antibody identified breakdown products of the same size as the rod domain in samples from the lesion site, but not elsewhere. Other lesion‐specific neurofilament breakdown products were recognized by a sidearm‐specific antibody. This lesion‐specific pattern of neurofilament proteolysis was visible at 1 day postlesion and was still present 3 weeks later. Immunocytochemistry showed masses of rod‐staining neurofilaments in axon stumps by 12 hours postlesion that remained for 1–2 weeks postaxotomy; these dispersed with the onset of regeneration. Such neurofilament rod staining was also prominent in distal axon stumps undergoing Wallerian degeneration. We conclude that axotomy induces neurofilament sidearm proteolysis near the lesion, permitting antibody access to the rod domain. We suggest that sidearm loss causes the high packing density of neurofilaments within neurofilamentous masses near the lesion site and that neurofilament sidearm proteolysis can be used to distinguish degenerative from regenerative changes in lesioned lamprey axons. © 1995 Wiley‐Liss, Inc.
Neuronal and nonneuronal expression of neurotrophins and their receptors in sensory and sympathetic ganglia suggest new intercellular trophic interactions
Authors: Wetmore Cynthia , Olson Lars 
Published: January 2005

AbstractNerve growth factor promotes the survival of populations of sensory and sympathetic neurons. Although ganglia have been used for classical assays of neurotrophin action, knowledge is incomplete regarding the spatial arrangements through which neurotrophins are delivered to responsive cells within the ganglia and their attached nerve trunks. Whereas populations of ganglionic neurons may be capable of responding to a particular neurotrophin in vitro, the spectrum of receptor components and neurotrophins expressed by the various neuronal and nonneuronal cells comprising the ganglia in adult rats remains to be elucidated in vivo.Brain‐derived neurotrophic factor (BDNF) mRNA was expressed by a population of small to medium sized neurons in all sensory ganglia except in the mesencephalic nucleus of the trigeminal nerve. Interestingly, BDNF immunoreactivity was detected in a more widespread population of neurons of these ganglia, as well as in scattered satellite cells of both sensory and sympathetic ganglia. These nonneuronal cells also expressed mRNA encoding a truncated form of the BDNF receptor, trkB trunc and full‐length transcripts of trkB appeared to be confined to neuronal populations. Several other components of neurotrophin receptors (low‐affinity neurotrophin receptor, trk, and trkC) were prominently expressed by different populations of neuronal cells in sympathetic and sensory ganglia, but they were not detected in nonneuronal cells. Neither nerve growth factor nor neurotrophin‐3 mRNAs were detected in these ganglia.Unexpectedly, BDNF and trkB trunc expression was detected in oligodendrocytes myelinating the central processes of sensory neurons. Schwann cells did not express detectable quantities of either entity, thereby establishing a dramatic boundary delineated by neurotrophin/ neurotrophin receptor expression that coincided with the interface between the oligodendroglia of the central nervous system (CNS) and Schwann cells of the peripheral nervous system (PNS). Localization of BDNF expression to an additional population of nonneuronal cells—satellite cells within sensory and sympathetic ganglia—suggest a more extensive role for neurotrophic factors than originally encompassed by the target‐derived neurotrophic‐factorconcept paradigm. These data support the hypothesis of a possible autocrine or paracrine trophic interaction between populations of neuronal and nonneuronal cells in the peripheral nervous system. BDNF expression in oligodendrocytes but not in Schwann cells at the CNS/PNS junction may provide an additional means of maintaining cell‐appropriate connections in the nervous system. © 1995 Wiley‐Liss, Inc.
Evidence for a high density of secretoneurin‐like immunoreactivit in the extended amygdala of the rat
Authors: Marksteiner Josef , Lassnig Elisabeth , Telser Stefan , Kroesen Stefan , Kirchmair Rudolf , Fischer‐Colbrie Reiner , Miller Carl , Saria Alois 
Published: January 2005

AbstractSecretoneurin is a novel 33‐amino‐acid neuropeptide produced by endoproteolytic processing from secretogranin II, which is a member of the chromogranin/secretogranin family. In this mmunocytochemical study, we compared the distribution pattern of secretoneurin immunoreactivity with that of tyrosine hydroxylase, calbindin, substance P, and Leu‐enkephalin in adjacent sections of rat forebrain. Secretoneurin appeared mainly in varicosities and fibers. Only a few cell bodies were stained. In the nucleus accumbens, a partial overlap of secretoneurin‐immunoreactive patches with enkephalin‐immunopositive areas was found. Secretoneurin displayed low to moderate levels of immunoreaction in calbindin‐rich as well as in calbindin‐immunonegative areas of the caudate‐putamen. In the globus pallidus, entopeduncular nucleus, and substantia nigra, secretoneurin immunoreactivity was oriented ventromedially preferentially in woolly fibers. The dense immunostaining in the medial nucleus accumbens was directly continuous with dense secretoneurin immunoreactivity in the bed nucleus of the stria terminalis. Two strongly secretoneurin‐immunopositive bands, one in the sublenticular portion and a smaller one along the posterior limb of the anterior commissure, interconnected the highly secretoneurin‐immunopositive centromedial amygdala with the bed nucleus of the stria terminalis. Thus, the distribution pattern of secretoneurin immunoreactivity provides a marker of the extended amygdala that forms a continuum between the centromedial amygdala and the bed nucleus of the stria terminalis. © 1995 Wiley‐Liss, Inc.
Distribution of gonadotropin‐releasinghormone immunoreactivity in the brain of the pacific hagfish, Eptatretus stouti (craniata: Myxinoidea)
Authors: Braun Christopher B. , Wicht Helmut , Northcutt R. Glenn 
Published: January 2005

AbstractThe distribution of gonadotropin‐releasing hormone (GnRH)‐like immunoreactivity in the brain of a myxinoid, the Pacific hagfish (Eptatretus stouti), was investigated via immunohistochemistry, including the use of six different antisera. In the diencephalon, immunoreactive cell bodies were found in two systems: the infundibular hypothalamus, a neuromodulatory nucleus with diffuse projections of varicose fibers to most areas of the brain, and a primarily preoptic system of putatively hypophysiotropic neurons that projects to the neurohypophysis. Some potential neurovascular and CSF contacts were also identified. These findings are consistent with those of similar studies in other craniates and suggest that a preoptic hypophysiotropic system may be present in all craniates. We therefore tentatively accept the homology of this system in hagfish and vertebrates. The homology of the distributed hypothalamic system is more dubious. It may be homologous to a caudal GnRH system of modulatory neurons found in many vertebrates. Antiserum PBL‐49 displays a differential affinity for the two systems, indicating that the two systems differ in the amount or identity of the immunoreactive substance. We suggest that the two systems have distinct functions in hagfish. The primitive function of GnRH‐like molecules in craniates may have thus been both neuromodulatory and hypophysiotropic. These findings also indicate that the brain‐pituitary axis of hagfish is more similar to that of vertebrates than has been previously suggested. © 1995 Wiley‐Liss, Inc.
Cervical primary afferent input to vestibulospinal neurons projecting to the cervical dorsal horn: An anterograde and retrograde tracing study in the cat
Authors: Bankoul S. , Goto T. , Yates B. , Wilson V. J. 
Published: January 2005

AbstractVestibulospinal neurons in the caudal half of the medial and descending vestibular nuclei terminate in the cervical spinal cord, not only in the ventral horn and intermediate zone but also in the dorsal horn. The purpose of the present study was to examine whether the areas containing these vestibulospinal neurons are reached by cervical primary afferents. In one group of experiments, wheat germ agglutinin‐horseradish peroxidase conjugate and horseradish peroxidase were pressure injected into spinal ganglia C2‐C8 and revealed anterogradely labeled fibers and boutons in the caudal part (caudal to the dorsal cochlear nucleus) of the ipsilateral medial and descending vestibular nuclei. This projection was verified in experiments in which wheat germ agglutinin‐horseradish peroxidase conjugate was microiontophoretically injected into the caudal half of either the medial or the descending vestibular nuclei and revealed retrogradely labeled cells only in ipsilateral spina ganglia C2‐C7, with a maximum of cells in C3. In another group of experiments, after microiontophoretic injections of Phaseolus vulgaris leucoagglutinin or Biocytin into either the medial or the descending vestibular nuclei, anterogradely labeled fibers and boutons were present in the cervical spinal cord, mainly bilaterally in the dorsal horn (laminae I–VI) but also, to a lesser extent, in the ventral horn and intermediate zone. The existence of a loop that relays cervical primary afferent information to vestibulospinal neurons projecting to the cervical spinal cord, in particular the dorsal horn, may have implications for vestibular control over local information processing in the cervical dorsal horn. © 1995 Wiley‐Liss, Inc.