bluuebunny/crossref_metadata_2025_split huggingface dataset:
Projections from the posteroventral cochlear nucleus to the superior olivary complex in guinea pig: Light and em observations with the PHA‐L method
Authors: Thompson Ann M. , Thompson Glenn C. 
Published: May 2005

AbstractThe efferent neural projections from posteroventral cochlear nucleus to the superior olivary complex in guinea pig were examined with the Phaseolus vulgaris—leucoagglutinin anterograde tract‐tracing method. Light microscopic analysis demonstrated that the posteroventral cochlear nucleus of guinea pig bilaterally projects to the superior paraolivary nucleus and the rostral, medioventral, and lateroventral periolivary regions. Ipsilaterally, the posteroventral cochlear nucleus projects to the lateral superior olive, the caudal periolivary region, and areas immediately surrounding the capsule of the lateral superior olive. Contralaterally, the posteroventral cochlear nucleus projects to the medial nucleus of the trapezoid body. All of these projection axons travel in the trapezoid body and their terminals make, primarily, en passant endings upon their targets. Exclusively within the contralateral medial nucleus of the trapezoid body, some neurons terminate also in calyceal endings.The assumption that immunolabeled strictures observed with light microscopy made actual synaptic contact in their respective target areas was confirmed with electron microscopy. With postembedding immunocytochemical procedures applied to thin sections, the electron microscope revealed labeled synaptic vesicles and pre‐ and postsynaptic membrane specializations.The projection pattern from posteroventral cochlear nucleus was found to be topographically organized in three distinct regions. The more dorsally located neurons of the posteroventral cochlear nucleus terminated dorsomedially in the ipsilateral lateral superior olive, ventromedially in the contralateral superior paraolivary nucleus, and medially in the contralateral medioventral periolivary region. The more ventrally located neurons of the posteroventral cochlear nucleus terminated dorsolaterally in the ipsilateral lateral superior olive, dorsolaterally in the contralateral superior paraolivary nucleus, and laterally in the contralateral medioventral periolivary region.
Afferent and efferent projections of the glossopharyngeal‐vagal nerve in the hagfish
Authors: Matsuda Hideki , Goris Richard C. , Kishida Reiji 
Published: May 2005

AbstractAnterograde and retrograde transport of horseradish peroxidase was used to examine the afferent and efferent projections of the glossopharyngeal‐vagal nerve in the hagfish Eptatretus burgeri. Anterogradely labeled ganglion cells are scattered in the glossopharyngeal‐vagal nerve trunk, in the saccular ganglion, and in the brainstem. Afferent fibers of the glossopharyngeal‐vagal nerve terminate in both the vagal lobe and the fasciculus communis. Close observation showed no morphological differentiation between these two structures, indicating that they are not separate entities, but a single, continuous structure that is homologous with the nucleus and tractus solitarius of other vertebrates. The median part of this structure (the commissura infima) is displaced more rostrally than the same part of the solitary nucleus in many other vertebrates. Some of the afferent fibers invade the ventral portion of the trigeminal sensory nucleus, which receives the maxillo‐mandibular nerve fibers, and terminate there. Our study showed that the hagfish has only one nucleus in the vagal motor system, i.e., the vagal motor nucleus, which contains both parasympathetic and branchiomotor neurons. The dendrites of the vagal motor neurons in the hagfish are more highly developed than those in other vertebrates. This suggests that the motor reflex are of the glossopharyngeal‐vagal nerve in hagfishes may be simpler than in other vertebrates.
Sources of presumptive glutamatergic/aspartatergic afferents to the mediodorsal nucleus of the thalamus in the rat
Authors: Ray James P. , Russchen Fokje T. , Fuller Terry A. , Price Joseph L. 
Published: May 2005

AbstractThe distribution of presumptive glutamatergic and/or aspartatergic neurons retrogradely labeled following injections of 3HD‐aspartate into the mediodorsal nucleus of the thalamus (MD) in the rat was compared to the distribution of neurons labeled by comparable injections of the nonspecific retrograde tracer wheat germ agglutinin conjugated horseradish peroxidase (WGA‐HRP). Cells retrogradely labeled by WGA‐HRP were found in the prefrontal and agranular insular cortices; in forebrain structures such as the amygdaloid complex, the piriform cortex, the ventral pallidum and the reticular nucleus of the thalamus; and in several different parts of the brainstem, such as the superior colliculus, central grey, and substantia nigra, pars reticulata.Some, but not all, of these projections are presumably glutamatergic and/or aspartatergic. The projections to MD from the prefrontal and agranular insular cortices are well labeled with 3H‐D‐aspartate, as are projections from the anterior cortical amygdaloid nucleus. Projections from the superior colliculus to the lateral portion of MD also label with this tracer. However, other forebrain and brainstem projections to MD are not labeled with 3H‐D‐aspartate, and apparently do not use glutamate or aspartate as a neurotransmitter. These include the projections from the basal and accessory basal amygdaloid nuclei, as well as possibly GABAergic projections from the ventral pallidum and the substantia nigra, pars reticulata. A small fraction of the cells in the piriform cortex that project to MD label with 3H‐D‐aspartate, suggesting that this projection may be heterogeneous.In other experiments, presumptive GABAergic projections to MD were studied by using 3H‐GABA as a retrograde tracer. Although in these cases the thalamic reticular nucleus is well labeled, the ventral pallidum and the substantia nigra, pars reticulata are only poorly labeled. Pallidal projections to the ventromedial thalamic nucleus (VM), which are likely to be GABAergic, were also studied with this technique. After injections of 3H‐GABA into VM, only a few cells in the substantia nigra, pars reticulata, or entopeduncular nucleus were labeled. This result suggests 3H‐GABA has limited usefulness as a transmitter‐specific retrograde tracer.
The Selective innervation by serotoninergic axons of calbindin‐containing interneurons in the neocortex and hippocampus of the marmoset
Authors: Hornung Jean‐Pierre , Celio M. R. 
Published: May 2005

AbstractThe serotoninergic input to the mammalian cerebral cortex originates in the median and the dorsal raphe nuclei. Median raphe neurons have been previously shown to give rise to beaded varicose axons which form dense pericellular arrays (baskets) surrounding the soma and the proximal dendrites of certain cortical neurons. In the present study, we have searched for specific markers characterizing the neurons of the marmoset neocortex and hippocampus surrounded by these thick varicose serotonin‐containing fibers. The non‐pyramidal nature of these neurons, suggested by their dendritic arborization, was correlated, in immunocytochemical experiments with double‐labelling to demonstrate their surrounding serotonin‐containing basket and their content of glutamic acid decarboxylase (GAD) or of the calcium‐binding protein calbindin. Another calcium‐binding protein common in numerous non‐pyramidal cortical neurons, parvalbumin, was never found in neurons surrounded by serotonin‐containing baskets. This organization was found in all areas of the neocortex and of the hippocampus where serotonin‐containing baskets were present.One of the serotoninergic cortical inputs which originates from the brainstem tegmentum, traditionally described as «diffuse,» proves to be highly selective in that a subset of its axons terminates preferentially on a subpopulation of inhibitory interneurons of the cerebral cortex. It may be emphasized that this subset of cortical interneurons has now been shown to be characterized not only by its axonal and dendritic arborization and its neurotransmitter, but also by a specific type of input which can modulate cortical function in a unique manner.
Rapid changes in protein synthesis and cell size in the cochlear nucleus following eighth nerve activity blockade or cochlea ablation
Authors: Sie Kathleen C. Y. , Rubel Edwin W. 
Published: May 2005

AbstractDestruction of the cochlea causes secondary changes in the central auditory pathway through transynaptic regulation. These changes appear to be mediated by an activity‐dependent process and can be detected in the avian auditory system as early as 30 minutes after deafferentation. We compared the early changes in cochlear nucleus neurons following deafferentation by cochlea ablation with those seen following activity deprivation by perilymphatic tetrodotoxin (TTX) exposure. Protein synthesis and size of large spherical cells in the anteroventral cochlear nucleus (AVCN) of 14‐day‐old gerbils were measured during the first 48 hours after the manipulations.Both cochlea ablation and TTX produced a reliable decrease in protein synthesis by AVCN neurons (30–‐40%) by 1 hour. The magnitude of change in tritiated leucine incorporation was similar at all survival times, in both experimental groups. In contrast to the rapid changes in protein synthesis, the decrease in cell size was first evident 18 hours after TTX exposure and 48 hours after cochlea ablation. There was no significant change in protein synthesis or cell size in control groups at any of the survival times. These findings are consistent with changes in the avian auditory system in response to deafferentation and TTX exposure.Cochlea ablation and TTX exposure induced similar transneuronal changes, supporting the hypotheses that activity of auditory afferents in young mammals plays a regulatory role in the metabolism and morphology of their target neurons in the central auditory pathway, and that early changes following destruction of the peripheral receptor are due to reduction of activity‐dependent interactions of presynaptic and postsynaptic cells.
Isthmotectal axons make ectopic synapses in monocular regions of the tectum in developing Xenopus laevis frogs
Authors: Udin Susan B. , Fisher Mark D. , Norden Jeanette J. 
Published: May 2005

AbstractDuring the development of binocular maps in the tectum of Xenopus laevis, axons that relay input from the ipsilateral eye via the nucleus isthmi undergo a prolonged period of shifting connections. This shifting accompanies the dramatic change in eye position that takes place as the laterally placed eyes of the tadpole move dorsofrontally. There is a concomitant expansion of the proportion of tectum that receives contralateral retinotectal input corresponding to the binocular portion of the visual field. Electrophysiological recording demonstrates that ipsilateral units are present in those rostral tectal zones, and anatomical methods show that the isthmotectal axons arborize densely in the rostral region but also extend sparser branches into the caudal zone, which is occupied by contralateral inputs with receptive fields in the monocular zone of the visual field.A mechanism that aligns the ipsilateral and contralateral maps is activity‐dependent stabilization of isthmotectal axons that exhibit firing patterns correlated with those of nearby retinotectal axons. In order for activity patterns to function in stabilizing correct connections and promoting the withdrawal of incorrect connections, synaptic communication of some sort is hypothesized to be essential. We have investigated whether isthmotectal axons make morphologically identifiable synapses during development and where such synapses are located.We find evidence for morphologically identifiable synapses in all regions of the tectum, along with many growth cones and structures that are probably immature synapses. As in the adult, the synapses contain round, clear vesicles, have asymmetric specializations, and terminate on structures that appear to be dendrites. In both adult and tadpole, the rarity of serial synapses involving isthmotectal terminals suggests. That the interactions between retinotectal and isthmotectal inputs are mediated by postsynaptic dendrites. © 1992 Wiley‐Liss, Inc.
Selective innervation of foreign muscles following damage or removal of normal muscle targets
Authors: Boss Valerie , Wigston Donald J. 
Published: May 2005

AbstractThe restoration of a normal pattern of neural connectivity following nerve injury depends upon the selective reinnervation of appropriate postsynaptic targets. Previous studies suggest that, in the neuromuscular system, recognition between regenerating motoneurons and target muscles depends upon the positions of origin of the motoneurons and muscles. In axolotls, portions of the motor pools of adjacent muscles overlap. We found that, following removal of a pair of adjacent hindlimb muscles, anterior and posterior iliotibialis, many regenerating iliotibialis motor axons invaded foreign muscles. A more anterior foreign muscle, puboischiofemoralis internus, received greater innervation from anterior iliotibialis motoneurons, whereas a more posterior muscle, iliofibularis, received greater innervation from posterior iliotibialis motoneurons. Furthermore, anterior iliotibialis motoneurons that reinnervated puboischiofemoralis internus occupied the rostral portion of anterior iliotibialis motor pool, which overlaps that of puboischiofemoralis internus. Anterior iliotibialis motoneurons that reinnervated iliofibularis occupied the caudal portion of the anterior iliotibialis motor pool, which overlaps that of iliofibularis.When both anterior and posterior iliotibialis were damaged so that their myofibers were permanently destroyed, the rostrocaudal origins of the motoneurons that reinnervated them were virtually the same, suggesting that the motoneurons had difficulty distinguishing between the myofiberless iliotibialis muscles. However, some iliotibialis motoneurons invaded puboischiofemoralis internus instead of their myofiberless targets. Puboischiofemoralis internus received more innervation from the anterior iliotibialis motoneurons than the positionally less appropriate posterior iliotibialis motoneurons. These data are consistent with the hypothesis that selective reinnervation of muscle depends upon a system of recognition cues based on position. © 1992 Wiley‐Liss, Inc.
GABA‐immunoreactive terminals synapse on primate spinothalamic tract cells
Authors: Carlton Susan M. , Westlund Karin N. , Zhang Dongxian , Willis William D. 
Published: May 2005

AbstractGamma‐aminobutyric acid (GABA) is a putative inhibitory neurotransmitter in the vertebrate nervous system. Several lines of evidence suggest that GABA plays an important role in the processing and modulation of sensory input in the spinal cord dorsal horn. In the present study, the relationship between GABA‐immunoreactive (GABA‐IR) terminals and spinothalamic tract (STT) cells in the monkey lumbar cord was investigated. Physiologically characterized STT cells, one located in lamina V and two located in lateral lamina IV, were intracellularly injected with horseradish peroxidase (HRP). A fourth STT cell, located in lamina I, was retrogradely labeled following injection of HRP into the contralateral thalamus. Immunogold labeling of ultrathin sections through the cell bodies and proximal dendrites of the STT neurons demonstrated that the percentage of the GABA‐IR terminals in contact with these profiles was 24.7% and 36%, respectively. The average STT surface length contacted by GABA‐IR terminals for cell bodies and proximal dendrites was 18.2% and 26.7%, respectively. For the lamina I cell, 7 out of 35 (20%) of the terminals were GABA‐IR and they covered 9.6% of the surface analyzed. These data demonstrate that GABA‐IR terminals synapse directly on STT cells, constituting a substantial proportion of the terminal population on these cells. Furthermore, compared to the cell bodies, a greater percentage of the input on the proximal dendrites is GABAergic. These anatomical data are consistent with the findings of a previously published iontophoretic study that demonstrated that GABA can exert a strong inhibitory influence on STT cells. These findings are discussed in relation to GABAergic involvement in tonic and phasic inhibition of STT neurons.
5′‐Nucleotidase: A new marker for striosomal organization in the rat caudoputamen
Authors: Schoen Siegfried W. , Graybiel Ann M. 
Published: May 2005

AbstractThe distribution of the adenosine‐producing ectoenzyme 5′‐nucleotidase was studied by means of a histochemical lead technique in the caudoputamen of normal adult rats and of rats in which injections either of 6‐hydroxydopamine in the medial forebrain bundle or of ibotenic acid in the caudoputamen had been made 1–3 weeks previously. The patterns of striatal 5′‐nucleotidase activity in these animals were compared in serial sections to the patterns of calbindin‐D28k immunoreactivity and of 3H‐naloxone ligand binding, which respectively mark the known matrix and striosome (patch) compartments of the caudoputamen. In the normal rats, 5′‐nucleotidase activity was differentially concentrated in striosomes, where it produced a dense staining of the neuropil. The enzymatic staining followed a striosomal distribution in all but the caudal caudoputamen. Within the striatal matrix, 5′‐nucleotidase staining also observed a lateromedial density gradient. Depletion of the dopamine‐containing nigrostriatal innervation of the caudoputamen with 6‐hydroxydopamine did not alter the striosomal selectivity of 5′‐nucleotidase activity. Destruction of intrastriatal neurons by ibotenic acid led to a strongly 5′‐nucleotidase‐positive gliosis within the resulting necrotic region. Elsewhere in the caudoputamen, the enzyme's striosomal distribution was not detectably altered. We conclude that 5′‐nucleotidase histochemistry provides an advantageous tool for detecting the striosomal architecture of the rat's caudoputamen. Moreover, 5′‐nucleotidase is prominently associated with glial membranes in the central nervous system, so that the concentration of this enzyme in striosomes could mark these as sites of selective glial populations within striatum. These properties and actions of 5′‐nucleotidase in purinergic neurotransmission and in neuroadhesion may contribute to the specialized functions of striosomes and matrix. © 1992 Wiley‐Liss, Inc.
Genesis of neurons in the retinal ganglion cell layer of the monkey
Authors: Rapaport David H. , Fletcher Jeffery T. , LaVail Matthew M. , Rakic Pasko 
Published: May 2005

AbstractWe have analyzed the genesis of various neuronal classes and subclasses in the ganglion cell layer of the primate retina. Neurons were classified according to their size and the time of their origin was determined by pulse labeling with 3H‐thymidine administered to female monkeys 38 to 70 days pregnant. All offspring were sacrificed postnatally, and their retinas processed for auto radiography.The somata of cells in the retinal ganglion cell layer generated on embryonic day (E) 38 ranged from 9 to 14 μm in diameter. Between E40 and E56, the minimum soma diameter remained around 8–9 μm, while the maximum gradually increased to 22 μm. As a consequence, the means of the distributions of labeled cells also increased with age, from 11.8 μm diameter for cells generated on ESS to 14.6 μm diameter at E56. Over this period the percentage of labeled cells in the 10.5–16.5 μm and > 16.5 μm diameter range gradually increased. The proportion of the labeled cells in the < 10.5 μm diameter range decreased from ESS to E45, but subsequently increased rapidly. At the end of neurogenesis in the retinal ganglion cell layer, around E70, most labeled cells were considerably smaller (7–9 μm) than those generated earlier.Our results indicate that within the ganglion cell layer of the macaque, neurons of small caliber are generated first, followed successively by medium sized cells. Large, putative Pα cells are generated late. The production between E56 and E70 of cells with the smallest somata suggests that the last‐generated neurons in the ganglion cell layer are predominantly displaced amacrine cells. Within the same sector of retina, different classes of neurons in the ganglion cell layer of the rhesus monkey appear to have a sequential schedule of production. © 1992 Wiley‐Liss, Inc.
Multiple neurotransmitters in the tuberomammillary nucleus: Comparison of rat, mouse, and guinea pig
Authors: Airaksinen Matti S. , Alanen Sari , Szabat Ewa , Visser Theo J. , Panula Pertti 
Published: May 2005

AbstractTuberomammillary neurons in the posterior hypothalamus are the sole source of neuronal histamine in adult mammalian brain. In the rat, these cells are reported to contain immunoreactivity for γM‐aminobutyric acid (GABA) and several neuropeptides. We compared the presence of these substances in the tuberomammillary cells of the rat, mouse, and guinea pig.In all three species, all histamine‐immunoreactive neuronal cell bodies were positive for GABA. This suggests that GABAergic transmission may be important in tuberomammillary function. No cell bodies immunoreactive for thyrotropin releasing hormone (TRH) were found in the guinea pig or mouse tuberomammillary area. In contrast, about 14% of the histamine‐immunoreactive tuberomammillary cells in the rat were TRH‐positive. These cells were small or medium‐sized and were located only in the medial part of the tuberomammillary complex. An antibody against porcine galanin stained about 45% of the tuberomammillary cell bodies in the rat and about 28% in the mouse, but none in the guinea pig. A large proportion of the cells in the rat and mouse, but none in the guinea pig, were positive for met‐enkephalin‐arg‐phe. In contrast, all histamine‐containing tuberomammillary cells in the guinea pig, but none in the rat or mouse, were immunoreactive for met‐enkephalin. This may indicate a different expression of proenkephalin‐derived peptides in the tuberomammillary neurons in these species. Some substance P‐immunoreactive cell bodies were located in the tuberomammillary area in all three species. However, only 3% of the histamine‐immunoreactive cell bodies in the rat and mouse but none in the guinea pig were substance P‐positive.The neurochemical properties of the tuberomammillary nucleus that exhibited species commonality deserve to be studied neurochemically and electrophysiologically in order to determine the functional relevance of coexisting transmitters in this nucleus. © 1992 Wiley‐Liss, Inc.