bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual serotoninergic projections to forebrain in the rat: Morphologically distinct 5‐HT axon terminals exhibit differential vulnerability to neurotoxic amphetamine derivatives
Authors: Mamounas Laura A. , Mullen Crystal A. , O'hearn Elizabeth , Molliver Mark E. 
Published: January 2005

AbstractThe cerebral cortex of the rat and other mammals is innervated by two morphologically distinct classes of serotoninergic (5‐HT) axon terminals: fine axons with minute varicosities and beaded axons characterized by large, spherical varicosities. Fine and beaded 5‐HT axons exhibit different regional and laminar distributions in forebrain and arise from separate brainstem nuclei, the dorsal and median raphe nuclei, respectively. Tha present neuroanatomic study, based on immunocytochemical methods to visualize 5‐HT axons, demonstrates that the two axon types differ markedly in their vulnerability to the neurotoxic amphetamine derivatives, methylenedioxyamphetamine (MDA), and p‐chloroamphetamine (PCA). While both drugs cause extensive degeneration of fine 5‐HT axons throughout forebrain, beaded 5‐HT axons are consistently spared. Fine 5‐HT axons, which richly innervate most regions of dorsal forebrain in control rats, are rarely seen 2 weeks after treatment with MDA or PCA; this loss of fine axons reflects a marked denervation that persists for months after drug administration. The serotoninergic axon terminals remaining after MDA or PCA administration are almost entirely of the beaded type and appear to be unaffected by both drugs. Over a wide range of doses (2.5–40 mg/kg PCA) and survival times (2 weeks to 2 months), these spared 5‐HT axons with large, spherical varicosities cannot be distinguished from the normal, beaded 5‐HT axons in control rats by morphologic criteria. Moreover, beaded 5‐HT axons exhibit a highly characteristic regional distribution which is the same in control as in MDA‐ and PCA‐treated rats: these axons innervate specific zones or layers within parietal and occipital cortex, hippocampus, cingulate cortex, entorhinal cortex, and the olfactory bulb, among other forebrain areas, and they form a dense plexus lining the ventricular system.Taken together, the results of this study demonstrate that fine 5‐HT axons are highly vulnerable to the neurotoxic effects of the amphetamine derivatives MDA and PCA, while beaded 5‐HT axons are markedly resistant. These findings are consistent with the hypothesis that there are two anatomically and functionally distinct sets of serotoninergic neurons projecting to forebrain. While both of these neuronal systems utilize 5‐HT as a neurotransmitter, they differ in several features: (1) origin from separate nuclei in the brainstem (the dorsal and median raphe), (2) two types of morphologically distinct axon terminals, (3) markedly different distribution and innervation patterns in forebrain, and (4) dissimilar pharmacological properties. The results further suggest that psychotropic amphetamine derivatives have a selective action upon fine serotoninergic axons that arise from the dorsal raphe nucleus.
Pattern or retinotectal projection in the megachiropteran bat Rousettus aegyptiacus
Authors: Thiele A. , Vogelsang M. , Hoffmann K.‐P. 
Published: January 2005

AbstractThe retinotopic organisation of the superior colliculus (SC) in the megachiropteran bat Rousettus aegyptiacus was examined with single and multi‐unit recordings and by tracing the retrograde and anterograde transport of horseradish peroxidase (HRP) between the retina and the SC.The pattern of projection of the visual field onto the SC in Rousettus resembles the pattern found in most mammals. The whole of the contralateral visual field is represented and, in addition, a region of the ipsilateral visual field extending 25° beyond the vertical 0° meridian. The ipsilateral visual field is represented binocularly in the most anterior 300–500 μm of the rostral pole of the SC. The contralateral visual field up to 25° from the vertical meridian is represented through both eyes for the next 500–800 μm. The peripheral part of the contralateral visual field, 25°–110° from the vertical meridian is seen only by the nasal retina (the monocular crescent) of the contralateral eye and is represented in the caudal part of the SC.Following multiple injections of HRP into one SC, ganglion cells were labeled in both the nasal and temporal‐hemiretina of the contralateral eye. In the retina ipsilateral to the injection site, labeled cells were restricted to the temporal hemiretina.After injections of HRP into one eye, labeled terminals were found all over the contralateral SC, but in the ipsilateral SC they were restricted to a band that begins 300–500 μm caudal from the rostral pole and extends to the middle of the SC.These results suggest that in Rousettus, unlike the megachiropteran bats described by Pettigrew, Jamieson, Robson, Hall, McAnally, and Cooper (Philosophical Transactions of the Royal Society of London Series B 325:489–559,1989), the retinotopic organisation of the SC is not primate‐like, but follows the general mammalian scheme. As the retinotopic organisation of the SC is not consistent among the megachiropteran bats, the pattern of this projection may not be a useful indicator of their phylogenetic origins.
Comparative analysis of the vasotocinergic and mesotocinergic cells and fibers in the brain of two amphibians, the anuran Rana ridibunda and the urodele Pleurodeles waltlii
Authors: González Agustin , Smeets Wilhelmus J. A. J. 
Published: January 2005

AbstractTo obtain more insight into the vasotocinergic and mesotocinergic systems of amphibians and the evolution of these neuropeptidergic systems in vertebrates in general, the distribution of vasotocin (AVT) and mesotocin (MST) was studied immunohistochemically in the brains of the anuran Rana ridibunda and the urodele Pleurodeles waltlii. In Rana, AVT‐immunoreactive cell bodies are located in the nucleus accumbens, the dorsal striatum, the lateral and medial part of the amygdala, an area adjacent to the anterior commissure, the magnocellular preoptic nucleus, the hypothalamus, the mesencephalic tegmentum, and in an area adjacent to the solitary tract. In Pleurodeles, AVT‐immunoreactive somata are confined to the medial amygdala, the preoptic area, and an area lateral to the presumed locus coeruleus. In both species, the distribution of MST‐immunoreactive cell bodies is more restricted: in the frog, MST‐immunoreactive somata are present in the medial amygdala and the preoptic area, whereas, in the urodele, cell bodies are found only in the preoptic area.Both in Rana and Pleurodeles, AVT‐ and MST‐immunoreactive fibers are distributed throughout the brain and spinal cord. A major difference is that in Rana the number of MST‐immunoreactive fibers is evidently higher than that of AVT‐immunoreactive fibers, whereas the opposite is found in Pleurodeles. This holds, in particular, for the forebrain and the brainstem. The presence of several extrahypothalamic AVT‐immunoreactive cell groups and the existence of well‐developed extrahypothalamic networks of AVT‐ and MST‐immunoreactive fibers are features that amphibians share with amniotes. However, this study has revealed that major differences exist not only between species of different classes of vertebrates, but also within a single class. In order to determine whether features of these neuropeptidergic systems are primitive or derived, a broad selection of species of each class of vertebrates is needed.
Interconnections between the primate cerebellum and midbrain near‐response regions
Authors: May Paul J. , Porter John D. , Gamlin Paul D. R. 
Published: January 2005

AbstractThe goal of this study was to determine the pattern of the connections between the midbrain and cerebellum that may play a role in the modulation of the near‐response in the macaque. Injection of the retrograde tracer wheat germ agglutinin conjugated horseradish peroxidase (WGA‐HRP) into the physiologically identified midbrain near‐response region, which includes the supraoculomotor area, labelled cells throughout the deep cerebellar nuclei. However, labelled cells were particularly concentrated in the ventrolateral corner of the contralateral posterior interposed nucleus and in the contralateral and, to a lesser extent, the ipsilateral fastigial nuclei. Subsequently, injections of WGA‐HRP were used to define the midbrain terminations of the deep cerebellar nuclei. Fastigial nucleus injections labelled terminals in a band along the border between the oculomotor nucleus and the supraoculomotor area that included the Edinger‐Westphal nucleus. Injections of the posterior interposed nucleus labelled terminals in the portion of the supraoculomotor area dorsal to the fastigial projection and did not involve the Edinger‐Westphal nucleus. In both cases, the terminal label was primarily found contralaterally. In contrast, retrogradely labelled cells were primarily found ipsilaterally within the supraoculomotor area following cerebellar injections. Retrogradely labelled cells projecting to the deep nuclei were also found bilaterally in the anteromedian nucleus, along with sparse terminal label.Taken as a whole, these results demonstrate the presence of a highly specific pattern of labelling in the supraoculomotor area, which may indicate that the posterior interposed nucleus and the fastigial nucleus play different roles in the control of the near‐response. Alternatively, these projections may subserve other functions, such as modulating the pupillary light reflex. The fact that the projection from the deep nuclei is primarily contralateral, while the supraoculomotor projection to the deep nuclei is primarily ipsilateral, suggests that this may not be a simple feedback system, but may instead be involved in balancing the gains in the two eyes. In sum, physiological experiments have indicated the presence of near‐response neurons in the midbrain supraoculomotor area and have indicated that the cerebellum may play a role in modulating the components of the near‐response, as well as activity in the intrinsic eye muscles. The present experiments suggest a pattern of connections that might subserve this cerebellar modulation.
Response of retinal terminals to loss of postsynaptic target neurons in the dorsal lateral geniculate nucleus of the adult cat
Authors: Pearson Helen E. , Stoffler Deborah J. , Sonstein William J. 
Published: January 2005

AbstractWe have used the neurotoxin kainic acid to produce rapid degeneration of neurons in the dorsal lateral geniculate nucleus (dLGN) of the adult cat. This degeneration mimics the rapid loss of geniculate neurons seen after visual cortex ablation in the neonate. Subsequent anterograde transport of horseradish peroxidase injected into the eye was used to reveal the projection patterns of retinal ganglion cell axons at different survival periods after the kainic acid injection. The density of retinal projections to the degenerated regions of the geniculate was reduced considerably at 4 and 6 months survival, but at 2 months was not significantly different from normal. The laminar pattern of projections to degenerated regions of the geniculate did not change in any animals studied, even when an adjacent lamina contained surviving cells. Electron microscopic examination of degenerated dLGN revealed intact retinal (RLP) and RSD terminals at all survival times, although the density of terminals appeared much reduced when compared to controls. Some RLP terminals exhibited the “dark reaction” of degeneration and these degenerating terminals were most numerous at 2 months survival. These findings demonstrate that, in response to degeneration of their usual target cells, mature retinal ganglion cells will withdraw their axon terminals from these regions of degeneration. We conclude that mature retinal ganglion cells continue to be dependent on target integrity for the maintenance of a normal axonal arborization.
Immunocytochemical localization of luteinizing hormone‐releasing hormone (LHRH) in the nervus terminalis and brain of the big brown bat, Eptesicus fuscus
Authors: Oelschläger Helmut A. , Northcutt R. Glenn 
Published: January 2005

AbstractLittle is known about the immunohistochemistry of the nervous system in bats. This is particularly true of the nervus terminalis, which exerts strong influence on the reproductive system during ontogeny and in the adult.Luteinizing hormone‐releasing hormone (LHRH) was visualized immunocytochemically in the nervus terminalis and brain of juvenile and adult big brown bats (Eptesicus fuscus). The peripheral LHRH‐immunoreactive (ir) cells and fibers (nervus terminalis) are dispersed along the basal surface of the forebrain from the olfactory bulbs to the prepiriform cortex and the interpeduncular fossa. A concentration of peripheral LHRH‐ir perikarya and fibers was found at the caudalmost part of the olfactory bulbs, near the medioventral forebrain sulcus; obviously these cells mediate between the bulbs and the remaining forebrain. Within the central nervous system (CNS), LHRH‐ir perikarya and fibers were distributed throughout the olfactory tubercle, diagonal band, preoptic area, suprachiasmatic and supraoptic nuclei, the bed nuclei of stria terminalis and stria medullaris, the anterior lateral and posterior hypothalamus, and the tuber cinereum. The highest concentration of cells was found within the arcuate nucleus. Fibers were most concentrated within the median eminence, infundibular stalk, and the medial habenula.The data obtained suggest that this distribution of LHRH immunoreactivity may be characteristic for microchiropteran (insectivorous) bats. The strong projections of LHRH‐containing nuclei in the basal forebrain (including the arcuate nucleus) to the habenula, may indicate close functional contact between these brain areas via feedback loops, which could be important for the processing of thermal and other environmental stimuli correlated with hibernation.
Organization of association projections from area 17 to areas 18 and 19 and to suprasylvian areas in the cat's visual cortex
Authors: Ferrer José Manuel R. , Kato Nobuo , Price David J. 
Published: January 2005

AbstractCells in area 17 that are labelled by single, discrete injections of retrogradely transported tracers into extrastriate visual areas are discontinuously distributed in dense patches. In this study we made multiple, closely spaced injections of fluorescent dyes into extrastriate areas, to generate large deposits that would reveal whether the distributions of corticocortical cell bodies in area 17 are truly patchy or appear clustered only after small injections. By injecting a different tracer into each extrastriate area, or group of areas, we examined the spatial relationships between the populations of association cells.All deposits of tracers in areas 18, 19, or suprasylvian cortex, irrespective of size, label cells in a series of clusters in topographically related parts of area 17. We conclude that the complete populations of cells in area 17 that project to areas 18, 19, and the lateral suprasylvian cortex are all genuinely distributed in a patchy fashion. There appears to be a complex relationship between the sets of association cells projecting to different extrastriate regions: they do not completely overlap, only partially, and share some cortical zones but not others.In these experiments, only tiny percentages (2–5%) of labelled cells in the overlapping regions were filled with both tracers, suggesting that very few association cells in area 17 project to more than one of the extrastriate areas we studied.By comparing the dimensions of each injection site and of the labelled region in area 17, we estimated the extent of the convergence from area 17 to areas 18, 19, and posteromedial suprasylvian areas in retinotopic terms. The functional convergence was very similar in these pathways.
Five topographically organized fields in the somatosensory cortex of the flying fox: Microelectrode maps, myeloarchitecture, and cortical modules
Authors: Krubitzer Leah A. , Calford Mike B. 
Published: January 2005

AbstractFive somatosensory fields were defined in the grey‐headed flying fox by using microelectrode mapping procedures. These fields are: the primary somatosensory area, SI or area 3b; a field caudal to area 3b, area 1/2; the second somatosensory area, SII; the parietal ventral area, PV; and the ventral somatosensory area, VS. A large number of closely spaced electrode penetrations recording multiunit activity revealed that each of these fields had a complete somatotopic representation. Microelectrode maps of somatosensory fields were related to architecture in cortex that had been flattened, cut parallel to the cortical surface, and stained for myelin. Receptive field size and some neural properties of individual fields were directly compared. Area 3b was the largest field identified and its topography was similar to that described in many other mammals. Neurons in 3b were highly responsive to cutaneous stimulation of peripheral body parts and had relatively small receptive fields. The myeloarchitecture revealed patches of dense myelination surrounded by thin zones of lightly myelinated cortex. Microelectrode recordings showed that myelin‐dense and sparse zones in 3b were related to neurons that responded consistently or habituated to repetitive stimulation respectively. In cortex caudal to 3b, and protruding into 3b, a complete representation of the body surface adjacent to much of the caudal boundary of 3b was defined. Neurons in this area habituated rapidly to repetitive stimulation. We termed this caudal field area 1/2 because it had properties of both area 1 and area 2 of primates.In cortex caudolateral to 3b and lateral to area 1/2 (cortex traditionally defined as SII) we describe three separate representations of the body surface coextensive with distinct myeloarchitectonic appearances. The second somatosensory area, SII, shared a congruent border with 3b at the representation of the nose. In SII, the overall orientation of the body representation was erect. The lips were represented rostrolaterally, the digits were represented laterally, and the toes were caudolateral to the digits. The trunk was represented caudally and the head was represented medially. A second complete representation, PV, had an inverted body representation with respect to SII and bordered SII at the representation of the distal limbs. The proximal body parts were represented rostrolaterally in PV. Finally, caudal to both SII and PV, an additional representation, VS, shared a congruent border with the distal hindlimb representation of both SII and PV. VS had a crude topography, and receptive fields of neurons in VS were relatively large. Many neurons in VS responded to both somatosensory and auditory stimulation.
Structure of neurons and ganglia of the guinea pig gallbladder: Light and electron microscopic studies
Authors: Cornbrooks Ellen B. , Pouliot Wendy A. , Mawe Gary M. 
Published: January 2005

AbstractThis study was undertaken to examine the morphological features of cells within ganglia of the guinea pig gallbladder, and to examine the ultrastructure of the ganglionated plexus. Gallbladder neurons are large, with a relatively simple form, having only one or two major processes. Neurobiotin often filled axons to their varicose arbors on smooth muscle in close proximity to the interganglionic connectives. With the exception of connective tissue clefts that sometimes penetrated into them, ganglia were devoid of intercellular spaces, capillaries, or connective tissue elements such as collagen and basal laminae. However, ganglia were surrounded by a single, continuous basal lamina that was enclosed within a fibroblast and collagen capsule. Within ganglia, neurons were insulated by the processes of cells that resembled the astrocyte‐like glia of enteric ganglia. Although few classical synapses were observed, numerous sites of direct apposition were identified between vesicle‐rich profiles and processes of gallbladder neurons. Direct appositions between vesicle‐rich profiles and the ganglion‐limiting basal laminae were also observed. Vesiculated profiles contained small clear vesicles and large dense‐core vesicles. Within interganglionic connectives, axons were unmyelinated and were isolated from one another by processes of glia that resembled Schwann cells. As was seen in the ganglia, direct appositions between vesicle‐rich profiles and the connective‐limiting basal laminae were observed.The results of this study demonstrate that gallbladder ganglia are similar, ultrastructurally, to enteric ganglia in the CNS‐like composition of the neuropil. However, the greater degree of glial investment, lesser degree of innervation, and simpler neurons indicated differences from the enteric nervous system that may be functionally significant.
Neurotrophic activity of interphotoreceptor matrix on human Y79 retinoblastoma cells
Authors: Tombran‐Tink Joyce , Li Anren , Johnson Michael A. , Johnson Lincoln V. , Chader Gerald J. 
Published: January 2005

AbstractA neurotrophic activity of adult monkey and bovine interphotoreceptor matrix (IPM) was examined by using cultured human Y79 retinoblastoma cells as a model system. The cells were stimulated for 7 days in suspension culture with soluble IPM components and then attached to poly‐D‐lysine substratum. IPMs from both species induced greater than 80% neuronal differentiation of Y79 cell aggregates after 11 days of attachment as adjudged morphologically by the extension of lengthy, neurite‐like processes. Immunocytochemical studies indicate that differentiated Y79 cells had an increased level of expression of neuron‐specific enolase and a concomitant decreased expression of glial fibrillary acidic protein. This neurotrophic activity cannot be ascribed to nerve growth factor, platelet‐derived growth factor, fibroblast growth factor, epidermal growth factor, or transforming growth factor beta. Although the nature of the factor and its cellular source have yet to be characterized, it may be related to a recently described neurotrophic protein secreted by human fetal retinal pigment epithelial cells in culture. Our findings provide evidence supporting the neuroblastic potential of the Y79 cell line and indicate that the IPM contains a potent neurotrophic activity. Such factors may be important to normal differentiation and maintenance of function of the neural retina.