bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cluster organization and response characteristics of the giant fiber pathway of the blowfly Calliphora erythrocephala
Authors: Milde Jülgen J. , Strausfeld Nicholas J. 
Published: January 2005

AbstractIntersegmental descending neurons (DNs) link the insect brain to the thoracic ganglia. Iontophoresis of cobalt or fluorescent dyes reveals DNs as uniquely identifiable elements, the dendrites of which are situated within a characteristic region of the lateral deutocerbrum. Here we demonstrate that DNs occur as discrete groups of elements termed DN clusters (DNCs). A DNC is a characteristic combination of neurons that arises from a multiglomerular complex in which the main components of each glomerulus are a characteristic ensemble of sensory afferents. Other neurons involved in the complex are local interneurons, heterolateral interneurons that connect DNCs on both sides of the brain, and neurons originating in higher centers of the brain. We describe the structure, relationships, and projections of eight DNs that contribute to a descending neuron cluster located ventrally in the lateral deutocerebrum, an area interposed between the ventral antennal lobes and the laterally disposed optic lobes. We have named this cluster the GDNC because its most prominent member is the giant descending neuron (GDN), which plays a cardinal role in the midleg “jump” response and which is implicated in the initiation of flight. The GDN and its companion neurons receive primary mechanosensory afferents from the antennae, terminals of wide‐ and small‐field retinotopic neurons originating in the lobula, and endings derived from sensory interneurons that originate in leg neuropil of the thoracic ganglia.We demonstrate that DNs of this cluster share morphological and functional properties. They have similar axon trajectories into the thoracic ganglia, where they invade functionally related neuropils. Neurons of the GDNC respond to identical stimulus paradigms and share similar electrophysiological characteristics. Neither the GDN nor other members of its cluster show spontaneous activity. These neurons are reluctant to respond to unimodal stimuli, but respond to specific combinations of visual and mechanosensory stimulation. These results suggest that in flies groups of morphologically similar DNs responding to context‐specific environmental cues may cooperate in motor control.
Distribution and synaptic organization of dopaminergic axons in the lateral geniculate nucleus of the rat
Authors: Papadopoulos Georgios C. , Parnavelas John G. 
Published: January 2005

AbstractIn the present study, immunocytochemistry with an antiserum against dopamine (DA) revealed hitherto unknown terminal fields of DA axons in the lateral geniculate nucleus (LGN) of the rat. The innervation of all subdivisions of the LGN is achieved by a common set of afferent fibers that branch to form terminal fields of uneven density. The ventral lateral geniculate nucleus (LGv) receives slightly more DA axons than the dorsal lateral geniculate nucleus (LGd), whereas within the latter, DA afferents innervate the lateral part of the nucleus slightly more densely. Labeled axon terminals and varicosities, examined in single and serial ultrathin sections, were found in the extraglomerular neuropil in the LGd and in the neuropil of the LGv characterized by relatively simple synaptic relationships. They formed predominantly asymmetrical synaptic contacts with dendritic profiles. Occasionally, the postsynaptic elements were found to be presynaptic dendrites of presumptive interneurons. Some of the possible roles of this newly demonstrated DA afferent system in the physiology of the LGN and in the pathophysiology of diseases associated with impairment of dopaminergic activity are discussed.
Fine structure of the magnocellular subdivision of the ventral anterior thalamic nucleus (V Amc) of Macaca mulatta: II. Organization of nigrothalamic afferents as revealed with EM autoradiography
Authors: Kultas‐ilinsky K. , Ilinsky I. A. 
Published: January 2005

AbstractAn EM‐autoradiographic technique was used to identify the ultrastructural features and synaptic sites of nigral afferents to the ventral anterior nucleus pars magnocellularis (V Amc) of the rhesus monkey thalamus. The findings demonstrate that the nigral boutons are of medium‐sized to large, with the majority being of the en passant type. These boutons form symmetric synaptic contacts, and contain pleomorphic or entirely flat vesicles and numerous mitochondria. The nigral input is heavily biased towards thalamocortical projection neurons (PN), whose somata and dendrites represent about 82% of the postsynaptic sites of labeled boutons. The distal dendrites of local circuit neurons (LCN) comprise 13% of the postsynaptic sites. Nigral terminals appear to represent a single extrinsic afferent input to the somata and primary dendrites of thalamocortical projection neurons. A nigral input to LCN somata was not demonstrated but the possibility could not be excluded. Although the basic ultrastructural features of nigral boutons in the monkey are similar to those described earlier in the cat (Kultas‐Ilinsky et al.: J. Comp. Neurol. 216:390‐405,'83), essential species differences exist in the intensity of the nigral input and its distribution on thalamic neurons.
Intermediate and deep layers of the macaque superior colliculus: A golgi study
Authors: Ma Terence P. , Cheng Heng‐Wei , Czech Julie A , Rafols Jose A. 
Published: January 2005

AbstractWe studied the intermediate and deep laayers of the macaque superior colliculus by means of the Golgi technique in an attempt to better understand the structural features of this important oculomotor center. For this study, we examined the optic (stratum opticum, SO), intermediate gray (stratum griseum intermedium, SGI), intermediate white (stratunm album intermedium, SAI), and deep gray (stratum griseum profundum, SGP) layers. These are the four layers in which neurons having saccade‐related activity are localized. We identified eight neuronal types on the basis of differences in somatic and dendritic morphologies: large multipolar neurons (Type I); large pyramidal neurons (Type II); large fusiform neurons (Type III); medium fusiform neurons with spiny, radially. Oriented dendrites (Type IV); dedium round neurons with fan‐shaped dendritic trees (Type V); medium stellate neurons with varicose dendrites (Type VI); medium multipolar neurons with robust, spiny dendrites (Type VII); and local interneurons (Type VIII). Most neuronal, tyupes possessed features thakt are homologous to presynaptic dendritic features in other brain centers. With the exception of the kedium stellate neurons (Type VI), Which are aspinous, and the local interneurons (Type VIII), which are sparsely spinous, all other types had a moderate number of spines on their dendrites. Dendrites, that terminated in the optic layer had specializations not observed elsewhere, suggesting that these tips may sample a tectala afferent that is not present in the more ventral layers. These eight types comprise all the neuronala morphologies observed in a large number of Golgi‐impregnated macaque brains (n = 50). We suggest that they represent the full rage of neuron types in the saccade‐related layers of the macaque tectum.
Serotonin immunoreactive boutons form close appositions with respiratory neurons of the dorsal respiratory group in the cat
Authors: Voss M. D. , De Castro D. , Lipski J. , Pilowsky P. M. , Jiang C. 
Published: January 2005

AbstractThe aim of this study was to examine the location of serotonin immunoreactive boutons on both the soma and dendrites of neurons in the dorsal respiratory group by using a combination of intracellular recording and labelling and immunohistochemistry. Inspiratory neurons in the ventrolateral nucleus of the solitary tract (vl‐NTS) were intracellularly labelled with horseradish peroxidase (HRP) in anaesthetised adult cats. The morphology of 23 neurons, all antidromically activated from the contralateral C3 spinal segment, was examined. Six neurons displayed pronounced dendritic arborizations outside the vl‐NTS, with prominent dorsal and/or medial projections. The dendrites of the remaining neurons were almost entirely confined to the vl‐NTS. Intramedullary axon collaterals were detected in four of nineteen examined axons. Serotoninergic fibres were immunohistochemically demonstrated in the NTS, and the apposition of immunoreactive boutons to the HRP‐filled neurons examined at the light microscopic level. Boutons were identified in close apposition with the somata, proximal and distal dendrites of these neurons. However, the density of contacts was found to be substantially less than in a previous study of phrenic motoneurons (Lipski et al: Soc. Neurosci. Abst. 14:379, '88; Pilowsky et al: J. Neurosci. in press, '90). The relative paucity of contacts of serotonin immunoreactive boutons with premotor inspiratory neurons of the dorsal respiratory group indicates that the serotoninergic system affects respiratory pathways mainly at the level of respiratory motoneurons or at brainstem sites outside the vl‐NTS.
Brainstem afferents to the oculomotor omnipause neurons in monkey
Authors: Langer Thomas P. , Kaneko Chris R. S. 
Published: January 2005

AbstractTo determine how saccade‐related areas in the brainstem address the saccade generator, we examined the afferents to the nucleus raphe interpositus. This region contains the omnipause neurons, which are pivotal in the generation of saccades. Horseradish peroxidase injected iontophoretically into the nucleus raphe interpositus retrogradely labeled a variety of brainstem nuclei. The greatest numbers of labeled neurons were in the paramedian pontomedullary reticular formation, in the nuclei reticularis gigantocellularis, and paragigantocellularis lateralis. Labeling was more modest but consistent in the interstitial nucleus of Cajal and the adjacent mesencephalic reticular formation, the middle gray of the superior colliculi, the region dorsolateral to the nucleus reticularis tegmenti pontis, and the medial vestibular nucleus. A few neurons were labeled around the habenulopeduncular tract and in the medial portion of the nucleus of the fields of Forel, in the nucleus reticularis medullaris ventralis, and in the spinal nucleus of the trigeminal nerve, the cochlear nucleus, and the superior olivary complex.The distribution and density of labeling suggest that omnipause neurons in the monkey are more intimately connected with other oculomotor structures than those in the cat. In addition, the rhombencephalic reticular afferents to the monkey omnipause neurons are more concentrated in their immediate vicinity than in the cat. The label consistently found dorsolateral to the nucleus reticularis tegmenti pontis may be a newly discovered link in saccade generation.
Calcium‐binding proteins, parvalbumin‐ and calbindin‐D 28k‐immunoreactive neurons in the rat spinal cord and dorsal root ganglia: A light and electron microscopic study
Authors: Antal Miklós , Freund Tamás F. , Polgár Erika 
Published: January 2005

AbstractThe distribution of two calcium‐binding proteins, parvalbumin (PV) and calbindin‐D 28K (CaBP), was studied by the peroxidase‐anti‐peroxidase immunohistochemical method at the light and electron microscopic level in the rat spinal cord and dorsal root ganglia. The possible coexistence of these two proteins was also investigated.PV‐positive neurons were revealed in all layers of the spinal cord, except lamina I, which was devoid of labelling. Most of the PV‐positive cells were found in the inner layer of lamina II, lamina III, internal basilar nucleus, central gray region, and at the dorsomedial and ventromedial aspects of the lateral motor column in the ventral horn. Neuronal processes intensely stained for PV sharply delineated inner lamina II. With the electron microscope most of them appeared to be dendrites, but vesicle containing profiles were also found in a smaller number. CaBP‐positive neurons appeared to be dispersed all over the spinal gray matter. The great majority of them were found in laminae I, II, IV; the central gray region; the intermediolateral nucleus; and in the ventral horn just medial to the lateral motor column. Laminae I and II were densely packed with CaBP‐positive punctate profiles that proved to be dendrites and axons in the electron microscope. A portion of labelled neurons in lamina IV and on the ventromedial aspect of the lateral motor column in the ventral horn disclosed both PV‐ and CaBP‐immunoreactivity.All of the funiculi of the spinal white matter contained a large number of fibres immunopositive for both PV and CaBP. The highest density of CaBP‐positive fibres was found in the dorsolateral funiculus, which was also densely packed with PV‐positive fibres. PV‐positive fibres were even more numerous in the dorsal part of the dorsal funiculus. The territory of the gracile funiculus in the brachial cord and that of the pyramidal tract in its whole extent were devoid of labelled fibres. In the thoracic cord, the dorsal nucleus of Clarke received a large number of PV‐positive fibres.Dorsal root ganglia displayed both PV‐ and CaBP‐immunopositivity. The cell diameter distribution histogram of PV‐positive neurons disclosed two peaks‐‐one at 35 μm and the other at 50 μm. CaBP‐positive cells in the dorsal root ganglia corresponded to subgroups of small and large neurons with mean diameters of 25 μm and 45 μm, respectively.On the basis of the location of perikarya and dendritic arborization patterns, PV‐ and CaBP‐positive cells are correlated with previously described and neurochemically or physiologically characterized neurons of the spinal cord and dorsal root ganglia.
Unbiased stereological estimation of the number of neurons in the human hippocampus
Authors: West Mark J. , Gundersen H. J. G. 
Published: January 2005

AbstractThe total numbers of neurons in five subdivisions of human hippocampi were estimated using unbiased Stereological principles and systematic sampling techniques. The method addresses the problems associated with the results and conclusions of previous quantitative studies, virtually all of which have been based on biased estimates of neuron densities. For each subdivision, the total number of neurons was calculated as the product of the estimate of the volume of the neuron‐containing layers and the estimate of the numerical density of neurons in the layers.Each hippocampus was cut into 3‐mm‐thick slabs, transverse to the rostrocaudal axis. One 70‐μUm‐thick section from each slab was used in the analysis. The volumes of the layers containing neurons in five major subdivisions of the hippocampus (granule cell layer, hilus, CA3–2, CA1, and subiculum) were estimated with point‐counting techniques after delineation of the layers on each section. The numerical densities of neurons in each subdivision were estimated on the same sections with optical directors. The sampling used in both estimates was performed systematically in all three dimensions.In an example of five hippocampi, the mean numbers of neurons (CV = SD/mean) in the different subdivisions were as follows: granule cells 15 × 106 (0.28), hilus 2.0 × 106 (0.16), CA3‐2 2.7 × 106 (0.22), CA1 16 × 106 (0.32), subiculum 4.5 × 106 (0.19). The stereological measurements contributed approximately 25% of the observed variance. Among the five subjects there was a significant inverse relationship between age (which ranged from 47 to 85 years) and the total number of neurons in CA1 (which ranged from 24 to 11 × 106).An optimized sampling scheme for studies of the number of neurons in the human hippocampus has been designed on the basis of an analysis of variance of the estimates at different levels of the sampling scheme. Counting neurons in the five subdivisions of the human hippocampus with the optimized sampling scheme takes less than 4 hours.
Fluorescent histochemical localization of neutral endopeptidase‐24.11 (enkephalinase) in the rat brainstem
Authors: Back Stephen A. , Gorenstein Charles 
Published: January 2005

AbstractCharacterization of the distribution of the peptide‐degrading enzyme neutral endopeptidase‐24.11 (E.G. 3.4.24.11; NEP; enkephalinase) in the rat brainstem was examined by means of a unique fluorescent histochemical method. Enzyme staining was completely blocked by three potent NEP inhibitors (thiorphan, phosphoramidon, and JHF‐26) at a concentration of 50 nM, supporting the specificity of this method to visualize sites of NEP activity selectively.At all levels of the brainstem, NEP was localized to cell bodies, cell processes, or terminal‐like fields and was localized to more than 90 distinct nuclei or subnuclei. In the mesencephalon these included the central gray, cuneiform n., dorsal and lateral tegmental n., inferior colliculus, interpeduncular n., lateral and medial geniculate n., central linear raphe n., mesencephalic n. of the trigeminal nerve, mammillary nuclei, Occulomotor n., red n., superior colliculus, ventral n. of the lateral lemniscus, substantia nigra‐ventral tegmental area, and the zona incerta.In the pons, NEP staining was restricted to fewer regions or nuclei, including the dorsal and ventral cochlear n., facial n., motor trigeminal n., principal sensory trigeminal n., parabrachial nuclei, pontine n., the oral and caudal pontine reticular n., pontine olivary nuclei, several pontine tegmental nuclei, pontine raphe nuclei, and the trapezoid n. In the cerebellum, staining was localized largely to the granule cell layer of the cerebellar cortex. Scattered staining was observed in the molecular cell layer.The medulla contained extensive NEP staining localized to nuclei that included the ambiguus n., dorsal motor n. of the vagus, hypoglossal n., inferior olivary n., prepositus hypoglossus n., solitary tract n., nuclei of the spinal tract of the trigeminal n., and the lateral, medial, and superior vestibular nuclei. Nuclei of the medullary reticular formation that were also richly stained for NEP included the raphe magnus n., raphe obscurus n., raphe pallidus n., dorsal, lateral, and ventral reticular nuclei of the medulla, and the gigantocellular, lateral paragigantocellular, linear, paramedian and parvicellular reticular nuclei.The widespread distribution of NEP in the brainstem suggests the existence of a number of functional systems, including the pathways involved in the mechanisms of pain and analgesia, which are potential targets of NEP inhibitors. In most regions, the distribution of NEP closely overlapped with that reported for the enkephalins, and showed a more restricted overlap with the reported distribution of substance P.
Denervation‐induced intraspinal synaptogenesis of calcitonin gene‐related peptide containing primary afferent terminals
Authors: McNeill D. L. , Carlton S. M. , Coggeshall R. E. , Hulsebosch C. E. 
Published: January 2005

AbstractThe purpose of the present study is to provide evidence that chronic spinal denervation leads to an increase in numbers of synaptic terminals from a specific population of primary afferent fibers. Rats were unilaterally deafferented for 35 days (chronic denervation) by dorsal rhizotomies performed from T2 to T8 and T10 to L5, which isolates or spares the T9 root. The contralateral T9 root was spared by similar surgery 5 days (acute denervation) prior to sacrifice. The survival time on the chronic side presumably allows sprouting of T9 primary afferents to occur, whereas the time on the acute side does not. The terminals were labeled with calcitonin gene‐related peptide (CGRP), which is a compound that labels a specific population of primary afferent fibers and terminals, and stereological methods were used to determine the numbers of immunolabeled terminals in laminae I and IIo on the chronic and acute sides of the T9 spinal cord. The findings are that the chronic side had approximately twice as many terminals as the acute side. This difference is statistically significant. These findings are compatible with the hypothesis that chronic denervation leads to synaptogenesis from surviving primary afferent fibers.
Early climbing fiber interactions with Purkinje cells in the postnatal mouse cerebellum
Authors: Mason Carol A. , Christakos Sylvia , Catalano Susan M. 
Published: January 2005

AbstractThe time and place of initial contacts between afferent axons and their target cells are not known for most regions of the mammalian CNS. To address this issue, we have selectively visualized afferent climbing fiber axons together with their synaptic targets, Purkinje cells, in postnatal mouse cerebellum. Climbing fibers were orthogradely labeled by injection of rhodamine isothiocyanate into their brainstem source, the inferior olivary nucleus. Purkinje cells were localized with an antibody to a calcium‐binding protein, calbindin D‐28k(CaBP), in the same section or in adjacent sections.A novel view of the olivocerebellar projection and the morphology of climbing fiber arbors prior to the well‐known “nest” stage has emerged from this analysis. At birth, climbing fibers project into the zone of Purkinje cells, before these cells have aligned into a monolayer. During this phase, climbing fibers have simple morphologies consisting of relatively unbranched terminal arbors and small tapered growing tips. Purkinje cells are arranged 3–6 cells deep and have tufted dendrites and relatively smooth somata.By postnatal days 3–4, climbing fibers branch over several adjacent Purkinje cell perikarya, which are still organized in a band several cells thick. From postnatal days 5–7, when climbing fibers subsequently make focused nests on individual cells, Purkinje somata are smoother and form a more distinct monolayer. Up to this time, however, climbing fibers continue to associate with Purkinje perikarya, even though Purkinje cell dendrites have emerged and branched extensively. By postnatal days 8–10, climbing fiber terminals climb onto the trunk of the relatively mature Purkinje dendritic tree.At birth, mossy fibers originating from the pontine nuclei resemble immature climbing fibers in that they also have a simple unbranched morphology and growing tips, but project only so far as the internal granule cell layer. Occasional individual fibers reach into the Purkinje zone both at postnatal day 0 and postnatal day 4, confirming that the fibers formerly described as “combination fibers” (Mason and Gregory, '84, J. Neurosci. 4:1715–1735) can be mossy in origin.These data demonstrate that climbing fibers project among Purkinje cells earlier than suspected, before these afferents begin to arborize and form pericellular nests. Our observations are not in accord with the view derived from autoradiographic tracing studies that, as in other cortical areas, climbing afferents wait in the vicinity of Purkinje cells in the early neonatal period, then advance onto these cells in synchrony with Purkinje cell alignment into a monolayer and dendritic maturation. Instead, climbing afferents associate with Purkinje perikarya for an extended period during target cell positioning and initial dendritic growth, lagging behind in their translocation up relatively mature Purkinje dendrites.