bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anatomy of the gustatory system in the hamster: Synaptology of facial afferent terminals in the solitary nucleus
Authors: Whitehead Mark C. 
Published: January 2005

AbstractThe solitary nucleus is the first level of the central nervous system where processing of taste information can occur. A structural basis for that processing was investigated. Facial taste afferent axons were labelled by application of horseradish peroxidase to either the chorda tympani or the geniculate ganglion. The labelled afferent fibers in the rostral solitary nucleus were studied with light and electron microscopy. Preterminal facial taste afferent axons enter the nucleus from the solitary tract with a pronounced lateral to medial trajectory. The axons bear numerous preterminal and terminal swellings that, with the electron microscope, were identified as synaptic endings located in glomeruli. The endings are ovoid or scalloped, indented by structures that surround them. The primary afferent endings contain large, round vesicles and synapse, by means of slightly asymmetrical junctional complexes, on small dendrites and spines. Two types of unlabelled endings, surrounding the labelled ones, contact the dendrites receiving taste afferent input or contact the endings of taste afferent axons themselves. One type is variable in size and contains scattered large round vesicles. It resembles a presynaptic dendrite. The other is a small axonal ending packed with small, pleomorphic vesicles, that engages in symmetrical junctions. The synaptic milieu of the taste endings allows for the possibility of modulation of taste‐elicited activity in afferent endings or secondorder neurons by other, possibly interneuronal, inputs.
A comparative topographical analysis of dorsal column nuclear and cerebral cortical projections to the basilar pontine gray in rats
Authors: Kosinski Ross J. , Neafsey E. J. , Castro Anthony J. 
Published: January 2005

AbstractThe somatotopic distribution of dorsal column nuclear projections within the basilar pontine gray was examined in relation to the massive corticopontine projection system that emanates most heavily from motor and somatosensory cortex. The distribution patterns of these two systems were compared by combining autoradiographic and degeneration axonal tracing methods within individual animals.Sterentaxic injections of tritiated leucine (50 μCi/μl) and lesions by aspiration were made in animals under ketamine hydrochloride anesthesia. The forelimb cortical injections (0.1–0.3 μl) were centered in either sensory or motor cortical regions as determined by intracortical microstimulation and multiunit recording techniques. Because sensory and motor hindlimb cortical areas overlap extensively in the rat, hindlimb cortical injections (0.1–0.3 μl) were limited to a single hindlimb sensorimotor cortical region. The corresponding contralateral dorsal column nucleus, cuneatus or gracilis, was then aspirated.A somatotopic distribution of fore‐ and hindlimb corticopontine fibers were found in discrete regions of the ipsilateral pontine gray. Hindlimb sensorimotor corticopontine fibers distributed caudal to forelimb projections. Similarly, pontine afferents from the dorsal column nuclei terminated somatotopically in the caudal half of the contralateral pontine gray in that gracilopontine fibers distributed caudal to cuneopontine fibers. Within individual animals, partially overlapping terminations were seen from nucleus cuneatus and the forelimb sensory cortical area as well as from nucleus gracilis and the hindlimb sensorimotor cortical area. No overlap existed in the pontine terminations from nucleus cuneatus and the forelimb motor cortical area.
Somatostatinlike immunoreactive neurons in the hedgehog (Erinaceus europaeus) and the sheep (Ovis aries) central nervous system
Authors: Papadopoulos G. C. , Karamanlidis A. N. , Dinopoulos A. , Antonopoulos J. 
Published: January 2005

AbstractThe morphology and distribution of somatostatinlike immunoreactive perikarya in the central nervous system of the hedgehog and sheep have been studied by means of the peroxidase‐antiperoxidase immunohistochemical method. Intracerebroventricular colchicine infusion not only enhanced the immunostaining but also revealed new immunoreactive cell bodies. In both hedgehog and sheep immunoreactive neurons of various forms, ranging from 12 to 28 μm in diameter, were observed in a number of homologous brain structures. However, some species‐related differences were noticed. Thus, somatostatinlike immunoreactive neurons were found only in the hedgehog anterior olfactory nucleus, olfactory tubercle, nucleus accumbens, medial parabrachial nucleus, raphe nuclei of the medulla, and spinal trigeminal nucleus, whereas some somatostatin‐positive neurons were observed in the locus coeruleus and the pontine reticular formation of the sheep only.Mapping of peptides in species like sheep and hedgehog, with basically different orientations of living behaviour, may contribute in strengthening or extending our views concerning the role of peptides in the central nervous system of mammals.
Electrophysiological and morphological correlates of axotomy‐induced deafferentation of the goldfish mauthner cell
Authors: Wood Malcolm R. , Faber Donald S. 
Published: January 2005

AbstractAxotomy‐induced changes in afferent synapses to the goldfish Mauthner cell have been analyzed with intracellular recordings and with electron microscopy. The studies encompassed 7–208 days after cervical spinal cord transection. The physiological findings suggest a persistent and specific reduction in excitatory chemical inputs to the soma and proximal lateral dendrite, with no changes in somatic inhibition or in the electrotonic and chemical inputs to the more distal regions of the lateral dendrite. Corroborative morphological evidence includes swelling of the M‐cell soma, as indicated by a 35% increase in the length of its minor diameter, an increased spacing and a quantitatively lower density of terminals on the soma, and the appearance of astrocytic processes partially or completely engulfing the terminals in that region. Similar changes were observed on the inferior dendrites projecting from the ventral surface of the soma, although these dendrites do not exhibit the chromatolytic changes observed at the soma. In contrast, there are no noticeable changes in either the synaptic investment of the lateral dendrite or its ultrastructure. Quantitative and qualitative data support the conclusion that there is a restricted and specific reduction in the proximal excitatory inputs to the M‐cell. The evidence also suggests that electrotonic junctions between afferents and the M‐cell remain intact, functionally and structurally.
Origin and identification of fibers in the cranial nerve IX‐X complex of xenopus laevis: Lucifer yellow backfills in vitro
Authors: Simpson H. Blair , Tobias Martha L. , Kelley Darcy B. 
Published: January 2005

AbstractThe central projections of individual components of the IX‐X nerve complex in the South African clawed frog, Xenopus laevis, were mapped by dye diffusion with Lucifer Yellow in an isolated brain preparation. The method reliably revealed fiber tracts, termination zones, and detailed cell morphology. In addition, motor neurons could be doubly labelled by retrograde transport of horseradish peroxidase from muscle targets followed by backfilling the appropriate nerves with Lucifer Yellow. The most anterior root associated with the nerve IX‐X complex, root 1, is composed of lateral line afferents that terminate in the medial medulla. Root 2 contains sensory fibers that terminate in the nucleus tractus solitarii and axons of lateral line efferent neurons. Root 3 is composed of sensory and motor fibers, including a major somatosensory component that terminates in posterior medulla and anterior spinal cord, and axons from cranial nerve nucleus IX‐X. The most posterior root of the IX‐X nerve complex, root 4, contains axons of laryngeal motor neurons and of general visceral efferent neurons.
Immunocytochemical demonstration of topographic ordering of purkinje cell axon terminals in the fastigial nuclei of the rat
Authors: Hawkes Richard , Leclerc Nicole 
Published: January 2005

AbstractWe have used a monoclonal antibody, mabQ113, which selectively stains a subset of cerebellar Purkinje cells, to study the topography of the corticonuclear projection of the median vermis to the fastigial nuclei in the rat. The fastigial projection zone contains both mabQ113+ and mabQ113− Purkinje cells grouped into parasagittal bands. The immunoreactivity extends throughout the Purkinje cell including the axon terminals and thus it is possible to investigate the topographic distribution of mabQ113+ terminals. In the fastigial nuclei the target cells receiving mabQ113+ axon terminals are concentrated in the caudal pole. In the rostral pole, cells receive anti‐GAD+ terminals but not mabQ113+ terminals. There is no gradient in anti‐GAD staining. Double‐labelling experiments with mabQ113, anti‐GAD, and an antisynaptic antibody mabQ155 suggest that there is little or no mixing of mabQ113+ and mabQ113− Purkinje cell terminals on the same target neuron.
The organization of prefrontocaudate projections and their laminar origin in the macaque monkey: A retrograde study using HRP‐gel
Authors: Arikuni Tomio , Kubota Kisou 
Published: January 2005

AbstractThe organization of the prefrontocaudate connection in the macaque monkey was studied with a polyacrylamide gel of horseradish peroxidase that was injected, after callosotomy, into the head of the caudate nucleus. Tissues were processed for peroxidase activity with tetramethylbenzidine. Retrogradely labeled cells appeared bilaterally in the prefrontal cortex, and ipsilaterally in the premotor area, frontal operculum, insula, and rostral region of the temporal cortex. In the prefrontal cortex, labeled cells were located in cortical layers 2–6. In layer 2, labeled cells were occasionally seen. In layer 3, a considerable number of labeled cells were seen and were mainly distributed in its lower part. They were pyramidal cells. Layer 4 contained a considerable number of labeled cells that were pyramidal or round. Somal sizes of these labeled cells were from 5 to 15 μm, but none of the cells less than 5 μm were labeled. Layer 5 was densely packed with labeled cells, though at a higher density in its upper part (5a). They were pyramidal cells. In layer 6, pyramidal or fusiform cells were labeled at a lower density than in layer 5. The laminar pattern and density of labeled cells were different among various regions of the prefrontal cortex, but, in general, the supragranular labeling tended to frequently occur in the regions containing the numerous labeled cells. There was a topographical relationship between the prefrontal regions containing the majority of labeled cells and the injection sites in the head of the caudate nucleus: the medial orbitofrontal cortex and the medial surface extending downward from the rostral sulcus project ipsilaterally to the medialmost portion of the ventromedial part of the head of the nucleus, the lateral orbitofrontal cortex projects to the ventromedial part of the head of the nucleus, and the dorsolateral prefrontal cortex ventral to the principal sulcus projects to the central part of the head of the nucleus. Our findings in the macaque monkey indicate that the corticocaudate connection is similar in laminar organization of efferent neurons to the corticocortical connections.
Afferent and efferent connections of cerebellar lobe C1 of the mormyrid fish Gnathonemus petersi: An HRP study
Authors: Meek J. , Nieuwenhuys R. , Elsevier D. 
Published: January 2005

AbstractThe corpus of the highly developed cerebellum of the weakly electric fish Gnathonemus petersi is differentiated into four lobes, numbered C1 to C4. The present paper deals with the extrinsic connections of the rostralmost lobe C1. Relevant nuclei were studied in normal histological material and HRP injections were placed in lobe C1, the neighbouring pedunculus valvulae, and the brainstem.The largest number of afferents to lobe C1 originates from the nucleus lateralis valvulae, a large nucleus of tightly packed small cells in the dorsal midbrain tegmentum. In Gnathonemus this nucleus encompasses nine subdivisions, of which the rostral, caudal, and exterolateral parts project in particular to lobe C1. Larger neurons in the dorsal midbrain tegmentum and presumed mesencephalic trigeminal neurons project to C1 as well. In the rhombencephalon, afferents to lobe C1 arise from the first funicular nucleus, the lateral reticular nucleus, and the inferior olive.Efferents of lobe C1 have been found to arise from a peculiar cell type in the Purkinje cell layer (so‐called eurydendroid neurons) and to project predominantly to the nucleus of the fasciculus longitudinalis medialis, the nucleus reticularis superius and medius, and the trigeminal motor nucleus. Additional small projections terminate in the tectum mesencephali and in the nucleus reticularis inferior.Compared with other parts of the mormyrid cerebellum as well as with the cerebellum of other teleosts, the connections of lobe C1 appear to be quite restricted and specialized. In this respect the connections with the trigeminal nerve via the first funicular nucleus, the mesencephalic trigeminal nucleus, and the trigeminal motor nucleus are of particular interest. The absence of central cerebellar nuclei intercalated in the efferent cerebellar connections, in combination with the presence of a precerebellar nucleus (lateralis valvulae) involved in the afferent cerebellar connections, represents a remarkable difference between teleosts and other vertebrate classes.
Biochemical and morphological correlates of transmitter type in C2, an identified histaminergic neuron in Aplysia
Authors: Schwartz James H. , Elste Alice , Shapiro Eli , Gotoh Hideki 
Published: January 2005

AbstractThere is compelling evidence that histamine serves as a neurotransmitter in C2, a pair of symmetrical neurons in the cerebral ganglion of Aplysia californica. These cells had previously been shown to contain high concentrations both of histamine and of its biosynthetic enzyme, histidine decarboxylase; in addition, 3H‐histamine injected intrasomatically was found to move along C2's axons by fast transport. Furthermore, several actions of C2 on identified follower cells were simulated by the application of histamine. We have now characterized this identified neuron further. C2 converts 3H‐histidine to histamine: 16% of the labeled precursor was converted to histamine 1 hour after intrasomatic injection. Synthesis of 3H‐histamine is specific, since no conversion occurred after injection of other identified Aplysia neurons that are known to use other neurotransmitter substances.We also examined the fine structure of C2's cell body, axons, and axon terminals within the cerebral ganglion and in the nerves that carry its three peripheral branches, identified after injection of Lucifer Yellow, 3H‐histamine, or horseradish peroxidase. Characteristic dense‐core vesicles are present in all regions of the neuron, and are labeled after intrasomatic injection of 3H‐histamine. These 100‐nm vesicles together with 60‐rim electron‐lucent vesicles fill the varicose extensions of C2's neurites that are widely distributed within the ganglion, but only the smaller vesicles cluster at the membrane specializations presumed to be active zones that make contact with many neurons. The widespread distribution of axon terminals and varicosities is consistent with the idea that C2 is modulatory in function; 3H‐histamine is taken up selectively by the cell body and axons of C2 and of several other putative histaminergic neurons in a Na+‐dependent manner. Characterization of these biochemical and morphological features of C2 adds to the large amount of information already available to make this identified cell a standard for identifying other neurons that use histamine as a transmitter.
Optic tectum of the eastern garter snake, Thamnophis sirtalis. V. Morphology of brainstem afferents and general discussion
Authors: Dacey Dennis M. , Ulinski Philip S. 
Published: January 2005

AbstractBrainstem neurons that project to the optic tectum of the eastern garter snake were identified by retrograde transport of horseradish peroxidase. The distribution and morphology of tectal afferent axons from the thalamus, pretectum, nucleus isthmi, and midbrain reticular formation were then studied by anterograde transport of horseradish peroxidase.Diencephalic projections to the tectum arise from the ventral lateral geniculate complex ipsilaterally and the ventrolateral nucleus, suprapeduncular nucleus, and nucleus of the ventral supraoptic decussation bilaterally. Three pretectal groups (the lentiform thalamic nucleus, the lentiform mesencephalic‐pretectal complex and the geniculate pretectal nucleus) give rise to heavy, bilateral tectal projections. Small neurons in nucleus isthmi and large reticular neurons in nucleus lateralis profundus mesencephali also give rise to bilateral projections. Caudal to the tectum, projections arise bilaterally from the pontine and medullary tegmentum, nuclei of the lateral lemniscus, the posterior colliculus, and the sensory trigeminal nucleus. A small contralateral projection arises from the medial vestibular complex.Tectal afferents from the thalamus, pretectum, nucleus isthmi, and midbrain reticular formation had characteristic morphologies and laminar distributions within the tectum. However, these afferents fall into two groups based on their spatial organization. Afferents from the thalamus and nucleus isthmi arise from small neurons with spatially restricted, highly branched dendritic trees. Their axons terminate in single, highly branched and bouton‐rich arbors about 100 μm in diameter. By contrast, afferents from the midbrain reticular formation and the pretectum arise from large neurons with long, radiate, and sparsely branched dendritic trees. Their axons course parallel to the tectal surface and emit numerous collateral branches that are distributed widely through the mediolateral and rostrocaudal extent of either the central or superficial gray layers. Each collateral bears several small, spatially disjunct clusters of boutons.
Stimulation‐induced [14C]2‐deoxyglucose labeling of synaptic activity in the central auditory system
Authors: Nudo R. J. , Masterton R. B. 
Published: January 2005

AbstractThe relative contribution of active synapses and discharging neurons to [14C]2‐DG labeling in film autoradiographss of the auditory system was studied in a series of three experiments, two in cat, one in chick. In the first, the lateral superior olive in cats was specially prepared so that its inhibitory afferents could be stimulated without concurrent stimulation of its excitatory afferents. The film autoradiographs showed clear 2‐DG labeling in the vicinity of the activated inhibitory synapses.In the second experiment, the medial superior olive in cat was specially prepared so that it could be stimulated antidromically without concurrent orthodromic stimulation. The film autoradiographs showed little or no elevations in 2‐DG labeling of the antidromically stimulated nucleus over its unstimulated contralateral control despite heavy labeling of nearby orthodromically stimulated nuclei.In the third experiment, the highly polarized nucleus laminaris of a chick was specially prepared so that one set of its excitatory afferents could be stimulated without concurrent stimulation of the other set. The film autoradiographs showed that the distribution of heavy 2‐DG labeling matched the distribution of the activated synapses and not the distribution of discharging postsynaptic membrane.The outcomes of the three experiments taken together suggest that it is active synapses and not actively discharging neurons that dominate typical [14C]2‐DG film autoradiographs, at least of the vertebrate central auditory system. It follows that [14C]2‐DG labeling of central auditory system tissue is not necessarily evidence of local cell discharge but instead evidence of synaptic activity whether excitatory or inhibitory, and whether or not it is accompanied by significant levels of postsynaptic cell discharge.
Functional morphology of insect neuronal cell‐surface/glial contacts: The trophospongium
Authors: Hoyle Graham , Williams Melissa , Phillips Christine 
Published: January 2005

AbstractUltrastructural studies were carried out on the surfaces of insect nerve cell bodies. Some of the neurons were identified, by using physiological criteria, before filling with dye. Their surface patterns were compared, to provide data needed for understanding dynamic relationships with glial cells, in the trophospongium. The data are also needed in connection with interpretation of electrical signals recorded from the somata and of their roles in integration and in learning and memory. The surfaces were found to be extremely complex and also varied, even for neurons of comparable size and function, as well as for different regions of the same neuron, suggesting that the surface is constantly changing as the neuron receives food and loses waste. There is a variety of cytoplasmic types of invagination of neuron somata by glial processes. The invaginations were classified into four easily recognized types: regular, chunky, filigree, and ridge (present only in axon hillock regions). Motor neurons also make reciprocal invaginations into the glial cells that surround them. Some of these extend for distances up to 40 μxsm from the surface. The effective surface area is increased, compared with that calculated for a smooth surface, as a result of the invaginations, by from as little as 5% for a small interneuron to as much as 12‐fold for a large motor neuron. The axon hillock region of all types of neurons is heavily invaginated.
Quantitative autoradiographic analysis of Mu and delta opioid binding sites in the rat hippocampal formation
Authors: Crain Barbara J. , Chang Kwen‐Jen , McNamara James O. 
Published: January 2005

AbstractThe distributions of mu and delta opioid binding sites were studied in rat hippocampal formation by using quantitative in vitro autoradiography. Mu binding sites, labeled with 125I‐FK‐33824, showed a highly organized laminar distribution. Binding was greatest at the foot of the obliterated hippocampal fissure in stratum lacunosum‐moleculare of CA3. Stratum pyramidale and stratum lacunosum‐moleculare of CA2 and stratum pyramidale of CA3 were next highest in mu binding, followed by stratum oriens and stratum radiatum of CA2, stratum oriens of CA3, and stratum pyramidale of CA1. The distribution of delta binding sites, labeled with 125.I‐D‐ala2 ‐Dleu5‐enkephalin in the presence of the unlabeled mu receptor ligand PL‐032, was similar to the distribution of mu binding in that binding within each region was greatest in a band centered over stratum pyramidale and in stratum lacunosum‐moleculare. Over all, delta binding was greatest in CA2 followed by CA3 and then CA1. Compared to mu binding, delta binding was relatively enriched in stratum moleculare of the dentate gyrus. These laminar distributions correlate reasonably well with the distribution of enkephalin immuno‐reactivity in hippocampal formation, although binding was surprisingly low in stratum lucidum, an area rich in dynorphin and enkephalin immunoreactivity.