bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parasympathetic preganglionic neurons and visceral primary afferents in monkey sacral spinal cord revealed following application of horseradish peroxidase to pelvic nerve
Authors: Nadelhaft I. , Roppolo J. , Morgan C. , de Groat W. C. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) applied to the central stump of the transected pelvic nerve of rhesus monkeys labeled afferent and efferent neurons innervating the pelvic viscera. Preganglionic neurons forming the sacral parasympathetic nucleus (SPN) were located in a narrow band 150–200 μm wide on the border of the ipsilateral intermediate gray matter. The SPN contained an average of 820 neurons and characteristically extended over two or three sacral segments (average length: 14.5 mm) with the majority of cells in S2. It was composed of medium sized, elongated somata (15.7 × 30.7 μm) with their major axes in the transverse plane and oriented parallel to the lateral border of the gray matter. Dendrites extended deep into the lateral funiculus, horizontally into the medial dorsal gray commissure, and dorso‐laterally along the lateral edge of the dorsal horn. Preganglionic axons followed the lateral border of the ventral horn to the ventral rootlets.Pelvic nerve afferent axons carried HRP to neurons in the dorsal root ganglia (DRG) and by transganglionic transport to the spinal cord. The average number of labeled DRG cells was 2, 992 (range: 2, 193–4, 363) with the largest fraction (80%) in S2. The numbers of DRG cells correlated with the numbers of SPN cells in corresponding spinal cord segments. Within the spinal cord labeled primary afferent fibers were prominent in the sacral segments and were also observed in decreasing numbers within two to three segments beyond the rostral and caudal limits of the SPN. In transverse sections, primary afferents were found throughout Lissauer's tract (LT) and in the lateral half of the dorsal columns. A prominent collateral fiber bundle from LT was located in lamina I along the lateral edge of the dorsal horn. This bundle extended into the SPN and a few collaterals continued medially into the dorsal gray commissure and the contralateral side of the cord. A much less prominent collateral fiber group from LT passed medially over the apex of the dorsal horn in lamina 1 and descended into the dorsal gray commissure. Horizontal sections revealed that these two collateral pathways were organized into periodically spaced bundles of fibers about 250 μm apart. HRP reaction product in terminal fields related to these afferent collateral projections were found in the lateral marginal zone and bilaterally in the dorsal gray commissure.
Direct projections from the cerebellar nuclei to the superior colliculus in the rabbit: An HRP study
Authors: Mizuno Noboru , Sugimoto Tetsuo , Itoh Kazuo , Kudo Motoi , Uchida Kuniko 
Published: January 2005

AbstractCerebellar projections to the superior colliculus in the rabbit were studied by the anterograde and retrograde HRP methods. Cerebellotectal fibers arise mainly from the anterior and posterior interpositus nuclei and terminate contralaterally in layer VII, layer VI, layer V, and the deep tier of layer IV of the superior colliculus. Cerebellotectal fibers from the posterior interpositus nucleus originate from the lateral part of the nucleus and end chiefly in the caudal part of the superior colliculus. Cerebellotectal fibers from the anterior interpositus nucleus arise from the ventral part of the nucleus and terminate mainly in the rostromedial part of the superior colliculus. Some neurons in the lateral cerebellar nucleus also send fibers contralaterally to the intermediate and deep layers of the superior colliculus, especially to its rostral and lateral parts. Few, if any, Cerebellotectal fibers arise from the medial cerebellar nucleus.
Pathways of the electric organ discharge command and its corollary discharges in mormyrid fish
Authors: Bell C. C. , Libouban S. , Szabo T. 
Published: January 2005

AbstractThe motoneurons which innervate the mormyrid electric organ are driven by a descending volley from the medullary relay nucleus. This nucleus does not initiate the electric organ discharge (EOD) but is driven in an obligatory manner by another center, a command nucleus. One goal of the present study was to identify this command nucleus anatomically. A second goal was to determine the pathways by which corollary discharges of the EOD motor command exert their effects on sensory input to the electrore‐ceptive lateral line lobe.Horseradish peroxidase (HRP) was injected into the medullary relay nucleus and other EOD command‐related centers. Placement was guided by recording the electrical activity preceding the EOD.A nucleus of smaller cells is found immediately beneath the large cells of the medullary relay nucleus. This nucleus, nucleus C, projects densely to the medullary relay nucleus and is hypothesized here to be the command nucleus. Nucleus C appears to receive input from the mesencephalon and from unspecified sources of input to the nearby reticular formation.Nucleus C projects to the medullary relay nucleus and to a lateral nucleus, the bulbar command‐associated nucleus. This nucleus is probably the source of the corollary discharge signals. It projects to the medullary relay nucleus and to the paratrigeminal and mesencephalic command‐associated nuclei. The latter two nuclei project to separate regions which in turn project to the electroreceptive lateral line lobe. There are thus at least two different paths by which the presumed EOD command nucleus, nucleus C, can affect the electroreceptive lateral line lobe.
Opiate receptor localization in rat cerebral cortex
Authors: Lewis Michael E. , Pert Agu , Pert Candace B. , Herkenham Miles 
Published: January 2005

AbstractThe differential distributions of [3H]naloxone‐labeled and [3H]D‐Ala‐D‐Leu‐enkephalin‐labeled opiate receptors in rat cerebral cortex were localized autoradiographically and quantified by grain counting and computerized densitometry. In addition, receptor distributions were compared to terminal patterns of thalamocortical projections labeled by axoplasmion transport of [3H]amino acids. Opiate receptors labeled with [3H]naloxone ligand selectivity pattern show striking laminar heterogeneity and are densest in limbic cortical areas, intermediate in the motor cortex, and fewest in the primary sensory areas. By contrast, opiate receptors labeled with [3H]D‐Ala2‐D‐Leu5‐enkephalin in a delta ligand selectivity pattern are much more homogeneously distributed across both regions and laminae within regions.Mu receptors in most cortical areas have density peaks in layers I and VI and each peak shows a density gradient that is sloped within the layer so that the highest densities are at the most superficial and the deepest portions of cortex. In addition, there is an intermediate peak whose laminar position varies depending on the area in which it is found. In rostral agranular cortex, including limbic and motor areas, the [3H]naloxone binding peaks are in layers I, III, and VI. In primary somatosensory cortex, the intermediate peak is in layer Va and in most of remaining homotypical cortex it is in layer IV. Some areas have only bilaminar labeling, in superficial and deep layers; these include portions of the sulcal and retrosplenial cortices. Piriform and entorhinal cortices have dense [3 H]naloxone binding only in the deepest layer and show a descending gradient of density toward the superficial layer.The positions of the mu receptor peaks were compared with termination patterns of projections originating in the thalamus. Close correspondence was found between receptor binding in the prelimbic, primary somatosensory, and entorhinal areas and projection terminations arising from the thalamic mediodorsal, posterior, and central medial nuclei, respectively.Although regional variations in [3H]D‐Ala2‐D‐Leu5‐enkephalin‐labeled receptor density are uncommon, a gradual decrease in the number of sites along the dorsomedial wall of the cortex from anterior cingulate to caudal retrosplenial limbic cortex can be observed. Laminar variations in binding density are small as well; higher concentrations of the peptide binding sites are usually found in the deep cortical layers. These findings emphasize aspects of opiate receptor architecture which may be relevant to identifying cortical “opiatergic” neurocircuitry and raise the possibility of opiate modulation of thalamocortical transmission.
Programmed cell death in the nervous system of an adult insect
Authors: Truman James W. 
Published: January 2005

AbstractThe tobacco hornworm moth, Munducasexta, shows extensive degeneration of abdominal neurons after the adult moth emerges (ecloses) from the old pupal skin. Death of interneurons begins about 2 hours before eclosion and continues through the next 30 hours. Motorneuron degeneration starts slightly later, commencing at about 8 hours after eclosion. Analysis of the death of identified motorneurons showed that there was a precise spatial and temporal program of neuronal death. Particular cells invariably either continued to live or died and, among the latter, the time of death varied from cell to cell but for a given cell was constant. This program of cell death was somewhat flexible in that the fates of certain cells could be adaptively modified by behaviors that might naturally occur in the life of the insect.
Propriospinal fibers in the rat
Authors: Chung Kyungsoon , Coggeshall Richard E. 
Published: January 2005

AbstractSegments of rat spinal cord were isolated by transecting in two places and sectioning all dorsal roots between the transections. Following this procedure, the areas of the gray and white matter are decreased by approximately 50% compared to normal. We feel, for reasons elaborated in the discussion, that the white matter of the isolated segments contains almost exclusively propriospinal axons. If this is accepted, then the axonal counts in this paper provide estimates of the numbers of propriospinal axons in rat spinal cord. In the isolated segments, the lateral funiculi contain 21,000 myelinated and 31,000 unmyelinated axons and the ventral funiculi 10,500 myelinated and 1,500 unmyelinated axons. The number of these fibers is approximately 33% of the number in unoperated spinal cords. Thus approximately one‐third of the axons in rat sacral lateral and ventral funiculi are propriospinal, a lower figure than would have been predicted from classical work. The ratio of myelinated to unmyelinated fibers is higher for proprio‐spinal fibers than for the other axons in these funiculi. Thus the propriospi‐nal axons, as a group, are slightly larger than the other axons in these funic‐uli. This is against currently accepted thinking which generally regards the propriospinal fibers as the finest in the white matter of the cord. Finally, the quantification of propriospinal systems in these funiculi allows more precision in our thinking about the organization of the spinal cord.
Topographic analysis of the innervation of the rat neocortex and hippocampus by the basal forebrain cholinergic system
Authors: McKinney Michael , Coyle Joseph T. , Hedreen John C. 
Published: January 2005

AbstractThe basal forebrain‐cortex connections of the rat were topographically mapped by retrograde tracer methods; and their contribution to the cholin‐ergic innervation of the cortex was assessed by excitotoxin lesions placed in the rostral and caudal aspects of the complex. Discrete injections of tracer into frontal cortex labeled the prominent multipolar acetylcholinesterase (AchE)‐positive cells of the ventromedial globus pallidus. Injections of tracer into the parietal cortex labeled cells in the ventral globus pallidus, the underlying substantia innominata, and the lateral hypothalamus. Separate injections of Fast Blue and Nuclear Yellow in the frontal and in the parietal cortex resulted in double‐labeled cells in the ventral globus pallidus, which indicates that at least some of these cells may possess collateralizing axons. The cingulate cortex is innervated predominantly by neurons in the nucleus of the horizontal limb of the diagonal band. The occipital cortex was also shown to receive a projection primarily from the nucleus of the horizontal limb of the diagonal band. The hippocampal formation is innervated primarily by cells located in the vertical limb of the diagonal band and in the medial septum. Consistent with the results of the retrograde tracing studies, excito‐toxin lesions affecting the diagonal band and medial septum decreased cho‐line acetyltransferase (CAT) activity up to 40% in the occipital cortex and by 64% in the hippocampus, but did not affect CAT activity in the rostral neo‐cortex. In contrast, ibotenate lesions of the caudal ventral globus pallidus and substantia innominata caused decreases in CAT activity in the frontal cortex of up to 65% without affecting enzyme activity in the hippocampal formation. The results of the present study provide details on the topographic organization of the cortical projections originating in the basal fore‐brain complex and indicate that these neurons are the predominant source of cortical cholinergic innervation.
The afferent and efferent connections of the feline nucleus tegmenti pedunculopontinus, pars compacta
Authors: Edley Sandra Moon , Graybiel Ann M. 
Published: January 2005

AbstractThe fiber connections of the nucleus tegmenti pedunculopontinus, pars compacta (TPc) were studied by means of the anterograde autoradiographic and retrograde horseradish peroxidase tracer methods. The limits of TPc, which is not a cytoarchitecturally distinct cell group in the cat, were estimated on the basis of autoradiographic experiments in which we plotted the distribution of afferent connections from the entopeduncular nucleus, motor cortex, substantia nigra, and subthalamic nucleus. We concluded that in the cat, TPc can most readily be identified by the terminal distribution of fibers originating in the substantia nigra. Deposits of radiolabel in the motor‐pre‐motor cortex, the entopeduncular nucleus, and subthalamic nucleus weakly labeled the same tegmental region. Parallel horseradish peroxidase experiments suggested that neurons near the entopeduncular nucleus, especially in the lateral hypothalamus and subthalamus, contribute to the pallido‐TPc pathway; that entopeduncular neurons projecting to TPc are most numerous in the ventral part of the nucleus; and that of the neocortical motor fields, both areas 4 and 6 project to TPc.An autoradiographic study of the efferent connections of TPc showed that the major connections were directed toward more rostral structures. Small deposits of labeled amino acids centered in TPc invariably elicited bilateral labeling of the pars compacta of the substantia nigra and the subthalamic nucleus, the densest label being on the ipsilateral side. Other structures variably or more sparsely labeled were: the posterior and lateral hypothalamus; centre median complex; an intermediate part of the lateral thalamic nucleus; central gray substance; nucleus parabrachialis pigmentosus (retro‐rubral nucleus); the raphe nuclei linearis intermedius, dorsalis, and magnus; nucleus reticularis tegmenti pontis; the pontine and medullary reticular for‐mation including the nuclei pontis oralis and caudalis; and the nucleus reticularis gigantocellularis, especially its ventral supraolivary part. These observations demonstrate that TPc shares some connections with a wider tegmental region, but that, in addition, TPc is characterized by a set of afferent and efferent connections that differentiate it from the surrounding teg‐mentum and affiliate it with the basal ganglia. By comparison with findings in the monkey and rat, these experiments further suggest that the connections of TPc may vary across mammalian species. The location and fiber connections of TPc indicate that it is probably distinct from the physiologically defined mesencephalic locomotor region, but suggest the hypothesis that TPc, as a part of an extrapyramidal tegmental loop‐circuit, may be involved in the production of simple resting tremors.
Efferent projections of the cat oculomotor reticular omnipause neuron region: An autoradiographic study
Authors: Langer Thomas P. , Kaneko Chris R.S. 
Published: January 2005

AbstractOmnipause neurons (OPNs) are midline pontine neurons that are thought to be instrumental in the generation of saccadic eye movements. Inhibition of the tonically active OPNs is postulated to disinhibit the burst neurons that cause the saccadic discharge in motoneurons, leading to a sac‐cade. To test whether the anatomical connections of OPNs are consistent with this scheme, we studied the efferent projections of the OPN region by using the technique of anterograde transport of tritiated amino acids.Injections into the OPN region yield a distinct pattern of labeled tracts and terminal fields that is different from the patterns following control injections in the surrounding reticular formation. Caudally, there are terminal fields over the paramedian reticular formation, the caudal part of the medial accessory nucleus of the inferior olivary complex, the nucleus prepositus hypoglossi, and the nucleus reticularis paragigantocellularis dorsalis caudal and ventromedial to the abducens nuclei. Rostrally, terminal label is distributed over parts of the nuclei reticularis pontis caudalis and oralis, the nucleus raphe pontis, the nucleus reticularis tegmenti pontis, the mesencephalic reticular nucleus, the central gray, and the nucleus of the H‐field.Thus, there are direct projections from the OPN region to all areas known to contain burst neurons. In addition, OPNs also apparently have in‐direct access to the spinal cord and cerebellum. Many of the latter connec‐tions parallel the efferent projections of the superior colliculus.
The nucleus tractus solitarii of the cat: A comparison of Golgi impregnated neurons with methionine‐enkephalin‐ and substance P‐immunoreactive neurons
Authors: Maley Bruce , Mullett Terrence , Elde Robert 
Published: January 2005

AbstractGolgi‐impregnated and methionine‐enkephalin (ME)‐ and substance P (SP)‐immunoreactive neurons were studied throughout the feline nucleus tractus solitarii. The majority of Golgi‐impregnated neurons in the NTS range in size from 5 to 18 μm. A noticeable exception is the large (15–30 μm) neurons of the ventrolateral subdivision. The Golgi‐impregnated neurons possess dendritic trees which remain within the nucleus and even at times within the particular subdivisions. Golgi‐impregnated neurons had a variety of spine forms: pedunculated, sessile, filiform, and complex. A number of neurons exhibited axons originating from the cell and they could be followed for distances up to 100 μm.ME‐ and SP‐immunoreactive neurons were found in commissural, medial, lateral, and parvocellular subdivisions while ME‐immunoreactive neurons were situated additionally in the intermediate and ventrolateral subdivisions. Both types of immunostained neurons were similar in size (6–20 μm) and shape of dendritic arbor. One population of ME‐immunoreactive neurons resembled the large ventrolateral neurons of the Golgi impregnations. Neither type of immunostained neuron possessed the extensive dendritic arbor, numbers of spines, or axons of the Golgi–impregnated neurons. The presence of ME‐ and SP‐immunoreactive neurons in regions which are associated with autonornic regulation suggests that these two peptides are involved in this process.
Afferent and efferent components of the hypoglossal nerve in the grass frog, Rana pipiens
Authors: Stuesse Sherry L. , Cruce William L.R. , Powell Katina S. 
Published: January 2005

AbstractIn amphibians, the spinomedullary region of the central nervous system is compressed rostrocaudally because of the absence of a neck. In Ranid frogs, the hypoglossal nerve emerges as the ventral ramus of the second spinal nerve. The first spinal nerve, though present in tadpoles, is absent as a separate nerve in adults. To investigate the central nervous system components of the hypoglossal nerve in Rana pipiens, we soaked identified, transected branches of this nerve in horseradish peroxidase, a retrograde and antercgrade tracer. We found that the hypoglossal nerve in these frogs originates from two efferent nuclei located in the caudal medulla, a medial and a lateral one. Afferent fibers, primarily from the tongue, are also found in the hypoglossal nerve and travel in the dorsolateral funiculus of the spinal cord, descending to thoracic levels of the cord. Efferents to intrinsic tongue muscles and the genioglossus muscle originate in the medial medullary nucleus. Efferents to the sternohyoid muscle, which travel through the hypoglossal nerve, originate in the lateral medullary nucleus. Since in mammals the sternohyoid muscle is innervated by the first spinal nerve, we have obtained experimental evidence that the hypoglossal nerve in Rana pipiens contains components of this spinal nerve.
Postnatal maturation of neurons in the cat's lateral geniculate nucleus
Authors: Mason Carol Ann 
Published: January 2005

AbstractThe maturation of dendrites in the cat's dorsal lateral geniculate nucleus was studied in Golgi Kopsch preparations of kittens from 3 days to 8 weeks postnatal. During the first postnatal week, more than a month after their birthdate, cells are immature and lack dendrites, bearing only multiple somatic processes or a few short thick extensions. Cells enter an active phase of dendritic extension during the second postnatal week. Growth cone‐like structures and filopodia occur at the ends of dendrites and also at dendritic branch points. Assignment to general cell classes based on dendritic disposition is possible only after this period, and characteristic grapelike appendages are obvious after the third week. Mature cells in the lateral geniculate nucleus are not considered spiny, yet spines and hairs are ubiquitous on most cells once dendrites elongate and remain numerous on peripheral dendrites even after the soma and proximal dendrites become smooth, by 4–6 weeks. The decline of spine levels continues after this period.All cells go through a similar but nonsynchronous sequence of maturation. Large cells may mature first, but no correlation was noted between rate of maturation and laminar location or retinal representation. In the second and thirdpostnatal weeks, although the terminal arbors of retinal axonspre‐synaptic to geniculate cells have already attained their final topography and laminar placement, the shape and synaptic relations of axon terminal swellings remain immature (Mason, 1982a,b) through the most active phase of dendritic outgrowth. After 3 weeks, both retinal axons and target geniculate cell dendrites finalize the shapes of characteristic appendages and synaptic relations in tandem. Potential interactions between immature axon terminal arbors and dendrite‐bare geniculate cells during dendrite outgrowth and subsequent remodeling of structural details are discussed.
Space‐Mapped auditory projections from the inferior colliculus to the optic tectum in the barn owl (Tyto alba)
Authors: Knudsen Eric I. , Knudsen Phyllis F. 
Published: January 2005

AbstractThe optic tectum of the owl contains a topographic representation of auditory space. We have investigated the source of this space‐mapped auditory activity by using retrograde tracing with horseradish peroxidase. The major source of auditory input to the optic tectum is the ipsilateral external nucleus of the inferior colliculus (ICX), which is known to contain a map of auditory space also. Additional minor projections originate in the superficial nucleus of the inferior colliculus and the nucleus isthmi parvocellularis. There is no apparent projection to the optic tectum from the contralateral ICX or any other brainstem auditory nucleus. The projection from the ICX to the optic tectum is point‐to‐point: rostral ICX projects to rostral tectum, caudal ICX to caudal tectum, dorsal ICX to dorsomedial tectum, and ventral ICX to ventral tectum. Thus, the space‐mapped organization that exists in the ICX is passed on by topographic projections to the optic tectum.