bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axonal pathfinding during the regeneration of the goldfish optic pathway
Authors: Bernhardt Robert 
Published: January 2005

AbstractRetinal ganglion cells in fish and amphibians regenerate their axons after transection of the optic nerve. Fiber tracing studies during the third month of regeneration show that the axons have reestablished a basically normal fiber order in the two brachia of the optic tract; axons originating in the ventral hemiretina are concentrated in the dorsal brachium, axons from the dorsal hemiretina in the ventral brachium. Attardi and Sperry (Exp. Neurol. 7:46–64, 1963) first suggested that the reestablishment of the fiber order reflects path‐finding by the regenerating axons. Recently, however, Becker and Cook (Development 101:323–337, 1987) have claimed that the fiber order observed at later stages of regeneration is due to secondary axonal rearrangements and that the initial brachial choice is random.In order to evaluate whether regenerating axons are capable of navigating in the optic tract and brachia and on the tectum, the present study examined the pathway choices and the morphology of regenerating axons en route to their tectal targets in goldfish. Subsets of axons were labeled at various time intervals (2 to 30 days) following an optic nerve crush, by intraretinal application of the lipophilic fluorescent tracer 1,1‐dioctadecyl‐3‐3‐3′‐3′‐tetra‐methylcarbocyanine (DiI). After a survival time of 18 to 72 hours (to allow for diffusion of DiI along the axons), the experimental animals were perfused with fixative and their right and left optic pathways (nerve, tract, and tectum) were dissected free and separated at the chiasm. Fluorescently labeled axons were traced in whole‐mounted pathways. Pathway choices were examined at the brachial bifurcation where axons from ventral and dorsal hemiretinae normally segregate.DiI was found to label axons reliably up to their growth cones, even at the earliest stages of regrowth. The pathway choices of the axons were nonrandom. The majority of the ventral axons reached the appropriate, dorsal hemitectum through the appropriate dorsal brachium of the tract. Dorsal axons reached the ventral hemitectum mainly through the ventral brachium. This suggests the presence of specific guidance cues, accessible to the regenerating axons. Differences in the complexity of the growth cones of the regenerating axons (simple in the nerve and tectal fiber layer, complex in the tract and the synaptic layer of the tectum) provide further evidence for specific interactions between the regenerating axons and their substrates along the pathway. These result argue that regenerating retinal axons in fish are capable of axonal path‐finding.
Compartmental and topographical distributions of axons in nerves to the amphibian (Bufo marinus) glutaeus muscle
Authors: Brown David R. , Everett Alan W. , Bennett Max R. 
Published: January 2005

AbstractThe present work seeks to determine if axons to an amphibian muscle are segregated in nerve trunks between the spinal cord and muscle according to their primary nerve destination or their topographical projection in the muscle. The distribution of axons to different compartments and subcompartments of the amphibian (Bufo marinus) glutaeus muscle has been determined in transverse sections of spinal and limb nerves after retrogradely labelling the axons with horseradish peroxidase. Glutaeus axons were dispersed widely through spinal nerves 8 and 9 but loosely gathered together in one quadrant of the sciatic nerve after passing through the lumbar plexus. Glutaeus axons became tightly clustered to the exclusion of other axons along the length of the triceps femoris nerve after it divides from the sciatic nerve. Furthermore, axons destined for one of the two glutaeus primary nerve branches segregate from those of the other branch at the level of the triceps femoris nerve before the glutaeus nerve forms. On the other hand, motoneurones that subserve a primary branch are not segregated, but are found throughout the rostrocaudal extent of the glutaeus motoneurone pool.Injection of horseradish peroxidase under the epimysium of either the ventral or the dorsal surfaces of the glutaeus muscle labelled motoneurones preferentially in either the rostral or caudal part of the motoneurone pool, respectively. This confirms studies that have shown a topographical projection from the spinal motoneurone pool onto the glutaeus muscle. However, there was no segregation of dorsally projecting axons in the glutaeus and primary nerve branches. Thus, glutaeus axons segregate according to their muscle compartmental projections well before entering the muscle, but they show no organization in nerves with respect to their topographical projections within a compartment.
Morphology of Golgi‐impregnated neurons in hyperstriatum ventralis, pars caudalis in adult male and female canaries
Authors: Nixdorf Barbara E. , Davis Stephen S. , DeVoogd Timothy J. 
Published: January 2005

AbstractGolgi‐impregnated neurons in the song control nucleus hyperstriatum ventralis, pars caudalis (HVc) in male and female canaries (Serinus canarius) have been divided into classes, primarily on the basis of interneuronal variability in spine density and dendritic branching pattern. At least four neuronal classes are found in HVc: aspinous neurons and three classes of spiny neurons. The “furry” dendrite (FD) cell class consists of neurons with long dendrites that are densely packed with spines. Their cell bodies are between 10 and 15 μm in diameter. Neurons of the thick dendrite (TD) cell class also have long dendrites but only about half as many spines along their dendritic branches. Their cell bodies are between 12 and 18 μm in diameter. Neurons of the short dendrite (SD) cell class are characterized by a low spine density, very thin dendrites, and a small dendritic field. Their cell bodies are between 9 and 13 μm in diameter. The TD class can be divided into two subclasses on the basis of the shape of the dendritic field. Principal component factor analysis and cluster analysis provide objective support for this classification scheme.Neurons of subclass TD2 are sexually dimorphic. Neurons from males have dendritic trees that are about 70% larger and have 40% more dendritic endings than do neurons from females. There may also be small sex differences in dendritic morphology in the SD class and in the remainder of the TD class. There are clearly no sex differences in the dendritic morphology of neurons from the FD class. The direct pathway which is believed responsible for dimorphic song production in canaries is from HVc to nucleus robustus archistriatalis (RA) and then to the motor neurons which control the avian vocal organ. It is surprising that the most striking dimorphism in the present data occurs in neurons which, on morphological grounds, are unlikely to project to RA.
Lobule structure and somatotopic organization of the medullary facial lobe in the channel catfish Ictalurus punctatus
Authors: Hayama Tomio , Caprio John 
Published: January 2005

AbstractCorrelation of the somatotopic organization of the facial lobe (FL), a primary medullary gustatory nucleus in the channel catfish Ictalurus punctatus, with its lobular substructure was investigated to examine a possible structural basis for the excellent ability of ictalurid catfishes to localize a food source in the environment. The FL in the channel catfish is composed of six longitudinal columns (ie., lobules) extending rostrocaudally and differing from each other in their length and location within the lobe. Each lobule receives segregated input from discrete portions of the external body surface. The three more medial lobules in the FL receive input (from medial to lateral) from the medial mandibular barbel, the lateral mandibular barbel, and the maxillary barbel, respectively. The proximal‐distal axis of each of the barbels is represented in a posteroanterior lobule axis. The largest lobule, the face‐flank lobule, is located dorsolaterally in the FL, whereas the anteroposterior body axis is represented in the posteroanterior lobule axis. This indicates that the neural representation of the external body surface of the channel catfish faces caudally in the FL. The two shortest lobules, positioned ventral to the face‐flank lobule, receive input from the nasal barbel and the pectoral fin, respectively. The rostrocaudal dimensions of each of the barbel lobules correlate well with the relative lengths of the barbels. Taste‐sensitive portions within the three barbel lobules examined were generally confined to the dorsal regions, whereas tactile responses were observed throughout the lobules. The present findings indicate that the FL of the channel catfish is highly organized to localize tactile and taste stimulation of the external body surface and further suggest that the barbel lobules of the FL are differentiated into two portions: a dorsal taste and tactile region, and a ventral, primarily tactile, zone.
Starburst amacrine cells of the primate retina
Authors: Rodieck R. W. 
Published: January 2005

AbstractA group of readily recognized amacrine cells were observed in Golgi‐impregnated and flat‐mounted macaque, baboon, and human retinas. These cells had roughly circular or oval dendritic fields that were narrowly stratified within the inner plexiform layer (IPL). Most of these cells stratified in the inner half (sublamina b) of the IPL, and they had their somata in the ganglion‐cell layer; a few stratified in the outer half (sublamina a) of the IPL and had their somata in the amacrine‐cell layer.Typically, a single dendrite issued from the soma, and, after passing for 10 μm or so, gave rise to five or more radiate processes. As these processes neared the edge of the dendritic field they branched, turned, and became varicose. Most showed no evidence of an axon, although a few had a short process extending inward, toward the optic‐fiber layer. Dendritic‐field diameters were about 100 μm near the fovea and increased to about 350 μm in the peripheral retina. Mean somal diameter also increased slightly from near the fovea (7.8 μm) to the periphery (8.7 μm).Although the primate cells are smaller, and there are some minor differences in the form of the dendritic fields, these cells appear to be morphologically equivalent to the starburst amacrines of the rabbit retina, whose counterparts have also been observed in the retinas of rats and cats.Presuming that these cells correspond to the choline acetyltransferase immunoreactive primate cells described by Mariani and Hersh (J. Comp. Neurol. 267:269–280, '87), their overlap factor is about ten for the type whose somata lay in the ganglion‐cell layer and about 0.25 for those whose somata lay in the amacrine‐cell layer.
Terminal arbors of individual “Feedback” axons projecting from area V2 to V1 in the macaque monkey: A study using immunohistochemistry of anterogradely transported Phaseolus vulgaris‐leucoagglutinin
Authors: Rockland Kathleen S. , Virga Agnes 
Published: January 2005

AbstractIn the present study, the anterograde tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was injected into area V2 in order to demonstrate the precise morphology of individual axons from area V2 to V1. On the basis of 28 complete axon reconstructions, several characteristic features have been identified. (1) Individual axons arborize in multiple layers: 1, 2, 5, and (inconstantly) 3. A single axon may have numerous terminal clusters in layers 1 and 2, but at most one in layer 3. (2) Axons typically ascend to layer 1, turn asymmetrically in one direction, and travel for long distances in this layer (1.10–4.30 mm; dimensions uncorrected for shrinkage). A few axons (three of 28 reconstructed) were found to have a single terminal cluster (0.3–0.5 mm wide) in layers 1 and 2. (3) Collaterals in layer 5 seem to extend over shorter distances (0.60 mm or less). (4) Delicate sprays of boutons (both beads and spines) are clustered along the main trunk. Spacing is variable but usually ranges from 0.35 mm to 0.65 mm. (5) In addition to clustered boutons, there can be linear collaterals, continuously studded with boutons, parallel to the main axon in layer 1.These results indicate that axons from V2 have complex radial and tangential distributions in V1. Terminations in different layers may be directed to different sets of neurons or to different portions of the dendritic tree (for example, distal portions of pyramidal neuron apical dendrites in layers 1 and 2, but more proximal portions in layer 3). Clustered terminations over wide tangential areas may imply a divergent innervation by a single axon of multiple compartmental structures, such as ocular dominance columns or cytochrome oxidase patches.
Selective destruction of mossy fibers and granule cells with preservation of the GABAergic network in the inferior region of the rat hippocampus after colchicine treatment
Authors: Robain O. , Represa A. , Jardin L. , Ben‐Ari Y. 
Published: January 2005

AbstractLesions induced by colchicine injection into the rat hippocampus were investigated by means of electron microscopy and GABA immunocytochemistry. Granule cells were nearly completely destroyed 3 days after colchicine injection; since the necrosis of their axonal endings was delayed, an anterograde degeneration of the mossy fibers had probably taken place. The selectivity of the lesions was not limited to granule cells, for some pyramidal neurons in CA1 pyramidal layer were damaged. It was, however, striking to observe that throughout the hippocampal structure GABAergic neurons were spared from the effects of colchicine. For instance, GABAergic neurons were found in the vicinity of the completely destroyed granule cell layer. GABAergic neurons and terminals were also present in the CA3 region where the GABA‐containing terminals formed a dense network of synapses with somata and dendrites of pyramidal cells. It was interesting to note that, consistent with previous studies, the GABAergic neurons in CA3 are innervated by mossy fibers.We conclude that after colchicine treatment the destruction of the granule cells was not associated with a lesion of the GABAergic network. This selective lesion provides a useful model with which to study the properties of CA3 neurons deprived of their major excitatory input but with an intact inhibitory network.
Efferent connections of the dorsal cortex of the lizard Gekko gecko studied with Phaseolus vulgaris‐leucoagglutinin
Authors: Hoogland Piet V. , Vermeulen‐Vanderzee Eefke 
Published: January 2005

AbstractThe efferent connections from the dorsal cortex of the lizard Gekko gecko have been studied with the anterograde tracer Phaseolus vulgaris‐leucoagglutinin. It appeared that the dorsal cortex is not a homogeneous structure as far as the efferent connections are concerned. All parts of the dorsal cortex project to the septum. All parts except the most medial project to the dorsal ventricular ridge, amygdala, nucleus periventricularis hypothalami, area lateralis hypothalami, and the anterior olfactory nucleus. The most medial part, in addition to the septal projections, is connected with the medial cortex and the contralateral medial and dorsal cortices. From the rostral part additional projections could be traced to the nucleus dorsolateralis hypothalami, nucleus ventromedialis thalami, nucleus dorsolateralis thalami, striatum, pallial thickening, medial cortex, nucleus olfactorius anterior, and the main and accessory olfactory bulbs.From the caudal part additional projections exist to the nucleus dorsomedialis thalami, nucleus accumbens, and the contralateral dorsal cortex. A system of intrinsic connections exists that can be subdivided into four subsystems, each of which subserves the interconnections within four subdivisions of the cortex: (1) the superficial medial part, (2) the deep medial part, (3) the caudal lateral and caudal intermediate parts, and (4) the rostral lateral and rostral intermediate parts. Connections between these four areas are scarce.From the present results the conclusion is drawn that the dorsal cortex of the lizard Gekko gecko has many hodological aspects in common with the ventral subiculum of mammals. The present results do not support the hypothesis that the dorsal cortex is the reptilian equivalent of the mammalian neocortex.
Spatial organization of thalamocortical and corticothalamic projection systems in the rat SmI barrel cortex
Authors: Chmielowska Jolanta , Carvell George E. , Simons Daniel J. 
Published: January 2005

AbstractAxonal tracing techniques were used to examine the distribution of corticothalamic projection neurons in relation to the organization of the thalamocortical recipient zones in the whisker representation of the rat first somatic sensory cortex. Following injection of horseradish peroxidase into the physiologically defined vibrissa area in the ventrobasal complex of the thalamus, labeling in the cortex had a columnar appearance. Dense patches of anterograde labeling were located within the centers of the layer IV barrels and extended superficially through lamina III; the septa between barrels contained considerably less reaction product. Retrogradely labeled neurons were observed in lower layer V and layer VI where they were concentrated preferentially deep to the barrel centers. Regions deep to the septa displayed less over‐all labeling and a lower relative number of thalamic projecting neurons. Zones having the larger numbers of retrogradely labeled cells also contained terminallike labeling of either corticothalamic or thalamocortical origin. Following an injection that included the posterior group medial to the ventrobasal complex, anterograde labeling in layer IV was located largely in the septa. In conjunction with previous findings concerning the origin and termination of other projection systems in the barrel cortex, these results suggest that a vibrissal column contains a central core zone intimately linked with the ventrobasal thalamus that is bounded by narrower regions of more diverse inputs and outputs that form an interface between adjacent cortical columns.
Chemoanatomical organization of the noradrenergic input from locus coeruleus to the olfactory bulb of the adult rat
Authors: McLean John H. , Shipley Michael T. , Nickell William T. , Aston‐Jones Gary , Reyher Christian K. H. 
Published: January 2005

AbstractThe locus coeruleus contains noradrenergic neurons which project widely throughout the CNS. A major target of locus coeruleus projections in the rat is the olfactory bulb (Shipley et al.: Brain Res. 329:294–299, '85) but the organization of the projections within the bulb has not been systematically examined. In this study, the laminar distribution and densities of locus coeruleus‐noradrenergic fibers in the main and accessory olfactory bulbs were determined with anterograde tracing and immunocytochemical techniques.Following iontophoretic injections of 1% wheat germ agglutinin‐horseradish peroxidase into the locus coeruleus, the densest anterograde label in the accessory olfactory bulb was observed in the external plexiform layer, granule cell layer, and especially in the internal part of the mitral cell layer. Virtually no label was observed in the glomerular layer. In the main olfactory bulb, labelled axons were observed in the granule cell layer, in the internal and external plexiform layers, occasionally in the mitral cell layer, and least often in the glomerular layer.Noradrenergic fibers in the olfactory bulb were identified by using immunocytochemistry with an antibody to dopamine‐β‐hydroxylase. Laminar patterns and densities of noradrenergic innervation were determined with quantitative image analysis. In the accessory olfactory bulb, the densest innervation was in the innermost portion of the mitral cell layer followed by the granule cell layer, the superficial part of the mitral cell layer, and the external plexiform layer. The density of fibers in the glomerular layer was least. The laminar pattern of noradrenergic fiber distribution in the main olfactory bulb was similar to that in accessory olfactory bulb.The present studies demonstrate that locus coeruleus‐noradrenergic fibers terminate preferentially in the internal plexiform, granule cell, and external plexiform layers. This suggests that the major influence of the locus coeruleus input to both the main and accessory the olfactory bulbs is on the predominant neuronal element in those layers, the granule cells. Additional studies are needed to resolve how this input influences specific olfactory bulb circuits.
Retinotopic organization within the lateral posterior complex of the cat
Authors: Hutchins Bob , Updyke B. V. 
Published: January 2005

AbstractElectrophysiological mapping methods were employed to systematically study the retinotopic organization within the cat's lateral posterior complex (LP). Visual responses were recorded in all the major subdivisions of the LP as well as in several adjoining cell groups. Specifically, separate representations of the visual field were identified for pulvinar, zones LPl‐c, LPl‐r, LPi, and LPm. Partial representations of the visual field were also evident in the geniculate wing, subdivisions of the lateral posterior shell, the inferior division of the posterior nuclear group, the suprageniculate nucleus, and the central lateral nucleus. Sufficient mapping observations were made to define the internal organization of major visual representations. Additionally, there was a very close correspondence between the mapping observations when they were compared with the cytoarchitectural criteria for recognizing functional cell groups (Updyke: J. Comp. Neurol. 219:143–181, '83).
Distribution of noradrenaline immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko
Authors: Smeets Wilhelmus J. A. J. , Steinbusch Harry W. M. 
Published: January 2005

AbstractThe distribution of noradrenaline (NA) immunoreactivity in the forebrain and midbrain of the lizard Gekko gecko was studied by means of recently developed antibodies against NA. Noradrenaline‐containing cell bodies are found in the hypothalamic periventricular organ and ependymal wall of the infundibular recess of the diencephalon. They are also present in the locus coeruleus and the nucleus of the solitary tract of the brainstem. Noradrenaline‐immunoreactive (NAi) fibers and varicosities are widely, but not uniformly, distributed throughout the forebrain and midbrain. In the telencephalon, dense plexuses of NAi fibers are found in the bed nucleus of the medial forebrain bundle, the vertical limb of the nucleus of the diagonal band of Broca, and the caudoventral part of the septal region. The diencephalon, the periventricular preoptic area, the supraoptic nucleus, and, in particular, the medial habenular nucleus are densely innervated by NAi fibers, whereas in the midbrain NAi plexuses are found in the ventral tegmental area, the substantia nigra and its dorsolateral extension (RA8), and in an area ventral to the nucleus interpeduncularis, pars ventralis. Moderately dense plexuses of NAi fibers are found in the small‐celled medial cortex, the dorsal cortex, and the midbrain tectum. The remaining forebrain and midbrain areas are generally not or only sparsely innervated by NAi fibers.The distribution of NAi cell bodies and fibers resembles the pattern revealed with antibodies against dopamine‐β‐hydroxylase (DBH). A remarkable exception is that the cells in the hypothalamic periventricular organ and ependymal wall of the infundibular recess are immunonegative for DBH. Possible explanations for this discrepancy are discussed. The present study on the distribution of NA immunoreactivity in the brain of Gekko gecko combined with the results of a previous report on the distribution of dopamine in the same species (Smeets et al., '86b) offer the opportunity to differentiate between the two catecholamines in the brain of this vertebrate.