bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local circuit neurons of developing and mature macaque prefrontal cortex: Golgi and immunocytochemical characteristics
Authors: Lund Jennifer S. , Lewis David A. 
Published: January 2005

AbstractA study has been made of the nonpyramidal, local circuit neurons in developing and mature macaque monkey prefrontal cortex with Golgi and immunocytochemical techniques. The area chosen for study is located between the cingulate gyrus and the ventral bank of the principal sulcus, and contains areas 9 and 46 as described by Walker (J. Comp. Neurol. 73:59–86, '40). In Golgi studies, the unique axonal features of impregnated neurons made possible the identification of thirteen separate classes of local circuit neurons. Five of these cell types, in their general characteristics, resembled classes identified in human prefrontal cortex, as well as in other cortical areas of macaque monkeys and other species. Measurements of the scale of axon arbors and dendritic fields of the Golgi‐stained local circuit neurons also suggested particular spatial relationships of certain classes to the scale of intrinsic lattice connections made by the axons of pyramidal neurons in the same region. Similarities in morphology between cells described in human prefrontal cortex and neuron varieties described in this study indicate that this region of monkey prefrontal cortex may serve as a useful model for neuron populations in human prefrontal cortex.Sufficient morphological detail was present in immunocytochemical studies to suggest one or more identifying biochemical characteristics for seven of the thirteen classes of local circuit neurons. The calcium binding proteins, parvalbumin, calbindin D‐28K, and calretinin, were found in chandelier and wide arbor neurons, neurogliaform cells, and double bouquet neurons, respectively. In addition, cholecystokinin immunoreactivity was present in medium arbor neurons and in narrow arbor cells connecting layers 2 and 4. Somatostatin 281–12 immunoreactivity was detected in beaded axon neurons in layers 5 and 6. This biochemical characterization of local circuit neurons, although incomplete, confirms the separate identity of at least some of the varieties distinguished by Golgi morphology, and allows a start to be made on studies examining changes in their functional state. The general inhibitory nature of these interneurons suggests that they are likely to play a crucial role in determining patterns of neural activation in the prefrontal cortex. © 1993 Wiley‐Liss, Inc.
A motor neuron‐specific epitope and the low‐affinity nerve growth factor receptor display reciprocal patterns of during development, axotomy, and regeneration
Authors: Chiu Arlene Y. , Chen Edmond W. , Loera Sofia 
Published: January 2005

AbstractSomatic motor neurons begin to express the transmitter synthesizing enzyme, choline acetyltransferase (ChAT) and the low‐affinity nerve growth factor receptor (NGFR) during embryonic development. However, as motor neurons mature in postnatal life, they lose immunoreactivity for NGFR and acquire a motor neuron‐specific epitope that is recognized by the monoclonal antibody, MO‐1. The present study was undertaken to examine the effect of nerve injury in adult rats on these three developmentally regulated markers in two populations of somatic motor neurons.Unilateral transection, ligation, or crushing of the sciatic nerve resulted in a loss of MO‐1 binding and a concomitant rise in immunoreactivity for NGFR within axotomized motor neurons in lumbar levels of the spinal cord. These changes, detectable within 5 days following nerve injury, are reversed with reinnervation, but persist if reinnervation is prevented by chronic axotomy. Thus, regulation of the expression of NGFR and the MO‐1 epitope appears to be critically dependent upon interactions between motor neurons and target muscles. These observations are also consistent with the idea that during regeneration, neurons may revert to a developmentally immature state; in motor neurons, this state is characterized by the presence of NGFRs and the absence of the MO‐1 epitope.Transection of the hypoglossal nerve, a purely motor nerve, resulted in a similar loss of MO‐1 binding and a selective rise in NGFR immunoreactivity in neurons within the ipsilateral hypoglossal motor nucleus. In addition immunoreactivity for ChAT was also lost in axotomized hypoglossal motor neurons. In contrast, injury to the sciatic nerve, which bears both sensory and motor axons, did not result in any detectable change in ChAT immunoreactivity in spinal motor neurons. © 1993 Wiley‐Liss, Inc.
Multimorphic growth cones in the embryonic medicinal leech: Relationship between shape changes and outgrowth transitions
Authors: Kopp Diane M. , Jellies John 
Published: January 2005

AbstractComparative studies of growth cone morphology may provide insight into the mechanisms underlying motility and navigation in vivo. Here we analyzed the morphology of a unique set of growth cones in the embryonic medicinal leech, Hirudo medicinalis. The comb or C‐cell is a transient cell found as a bilateral pair in each midbody segment. Early in development, from embryonic day (E)7 to E11, each C‐cell adds and orients about 70 parallel growth cones that remain relatively nonmotile until E12 when rapid process outgrowth is initiated. Individual C‐cells from E10 to E14 were injected with Lucifer yellow and growth cones were traced with a camera lucida. Growth cone morphology was quantified from the drawings. Lamellar regions increased in area with age and change in extension rate. Young, relatively nonmotile growth cones had numerous short filopodia in many orientations, while at highly motile stages filopodial number decreased, length increased, and orientation became more restricted in the direction of outgrowth. Thus, while filopodia were distributed symmetrically, such that the average filopodial angle was predictive of the direction of outgrowth at all stages, younger (relatively nonmotile) growth cones project more filopodia in many directions than do older more motile growth cones. These results suggest that: (1) alterations in morphology may reflect developmentally regulated changes in extension and the local environment, (2) these growth cones maintain a large area for environmental sampling as they increase extension rate, even as filopodia become more restricted in orientation, and (3) C‐cell growth cones might progressively alter their affinity for local cellular cues as they initiate rapid and directed outgrowth. The C‐cell of embryonic leech may provide a relatively simple system in which to test these ideas experimentally. © 1993 Wiley‐Liss, Inc.
The projections of intracellularly labeled auditory nerve fibers to the dorsal cochlear nucleus of cats
Authors: Ryugo David K. , May Sarah K. 
Published: January 2005

AbstractThe cochlear nucleus receives incoming auditory nerve discharges, preserves or transforms the signals, and distributes outgoing activity to higher centers. The organization of auditory nerve input to the cochlear nucleus will heavily influence the mechanisms by which acoustic information is processed. In order to study structure‐function relationships between auditory nerve and cochlear nucleus, the axonal arborizations of type I spiral ganglion cells were labeled with intracellular injections of horseradish peroxidase after first being electrophysiologically characterized by recording with a micropipette inserted into the axon. For each auditory nerve fiber, spontaneous discharge rate (SR) and a frequency tuning curve were determined. The tuning curve yielded the characteristic frequency (CF, that frequency to which the fiber is most sensitive) and CF threshold in dB SPL. Individual axonal arborizations including all terminal swellings were reconstructed through serial sections with the aid of a light microscope and drawing tube. On average, 13.4 ± 8.1% of the terminal swellings were found in the dorsal cochlear nucleus (DCN) and the remaining terminal swellings were located in the ventral cochlear nucleus. In the DCN, the terminal fields of auditory nerve fibers were restricted to layer III, contributed to cytoarchitectonic striations, and exhibited a systematic relationship between fiber CF and position along the strial (or long) axis of the nucleus. Computer‐aided rotations revealed that the terminal fields were anisotropic, being flattened within the trans‐strial axis. The maximal width of the terminal fields along the strial axis ranged from 31–321 μm and was inversely related to fiber CF and SR. Variation in the number of terminals or depth of the terminal field within layer III was not related to SR grouping or CF of the fiber. © 1993 Wiley‐Liss, Inc.
Neurofilament mRNA is reduced in Parkinson's disease substantia nigra pars compacta neurons
Authors: Hill William D. , Arai Motomi , Cohen Jeffrey A. , Trojanowski John Q. 
Published: January 2005

AbstractLewy bodies are filamentous neuronal inclusions characteristic of Parkinson's disease, and neurofilament triplet proteins are the major components of the filaments in Lewy bodies. Since the neurofilament proteins found in Lewy bodies are abnormally phosphorylated and partially degraded, the formation of Lewy bodies may be due to the defective metabolism of these proteins, and this could lead to impairments in the structure and function of neurofilament rich neuronal processes (i.e., large caliber axons). To gain further insights into the metabolism of neurofilaments in Parkinson's disease, we evaluated neurofilament mRNA levels by semiquantitative in situ hybridization histochemistry in postmorten tissues from Parkinson's disease and control subjects. Substantia nigra pars compacta neurons were examined with digoxigenin‐UTP labeled cRNA probes to the heavy and light neurofilament mRNAs. The relative abundance of these mRNAs was measured by videodensitometric image analysis of chromogenic reaction product. Using this approach, we demonstrated that the levels of both heavy and light neurofilament mRNAs were reduced in Parkinson's disease substantia nigra pars compacta neurons. Additionally, the levels of heavy neurofilament mRNA were lowest in Lewy body containing neurons in the Parkinson's disease cases. These results suggest that the formation of neurofilament‐rich Lewy bodies in substantia nigra pars compacta neurons is associated with reduced levels of the heavy and light neurofilament mRNAs in Parkinson's disease. Thus, it is possible that the accumulation of abnormal neurofilament proteins in Lewy bodies and diminished neurofilament mRNAs contribute to the degeneration of substantia nigra pars compacta neurons in Parkinson's disease. © 1993 Wiley‐Liss, Inc.
Morphology of the vasopressin‐like immunoreactive (VPLI) Neurons in Many Species of Grasshopper
Authors: Tyrer N. M. , Davis N. T. , Arbas E. A. , Thompson K. S. J. , Bacon J. P. 
Published: January 2005

AbstractIt has previously been shown that the pair of vasopressin‐like immunoreactive (VPLI) neurons of the locust, Locusta migratoria, have cell bodies on the ventral midline of the suboesophageal ganglion and extensive arborisations in all ganglia of the central nervous system. In the present study, we have stained vasopressin‐like immunoreactive neurons in 16 additional species of grasshopper, and consistently find this pair of extensive neurons: we assume these to be interspecies homologues. However, the anatomy of these neurons falls into two morphological types: the first, typified by Schistocerca gregaria, has most of its processes distributed in dorsal and lateral neuropil of all ganglia; the second, typified by Locusta migratoria, is equally extensive in its arborisation, but the distribution of branches is shifted peripherally into the optic lobes and the proximal portions of peripheral nerves. It has been suggested that the peripheral fibres in Locusta migratoria are neurohaemal organs for the release of a vasopressin‐like diuretic peptide. Our sample of 17 Acridoid species has deliberately selected animals from very different habitats, but our extensive survey of VPLI anatomy shows that peripheral fibres are only present in species from the subfamily Oedipodinae (of which Locusta migratoria is a member) and that no peripheral fibres are present in any of the species from the 4 other subfamilies of the Acridoidea that we have examined. The presence of peripheral fibres is therefore determined by phylogeny and not by habitat.The absence of peripheral VPLI fibres in most grasshopper species examined in this study probably means that the release of putative diuretic hormone from VPLI to control water homeostasis cannot be a conserved function of this ubiquitous neuron. In contrast, the extensive central arborisations and rare antigenicity, which are highly conserved features of the VPLI neuron in all those grasshoppers we have examined, suggests that any conserved role is more likely to be central. A central role for the VPLI neuron has yet to be determined. © 1993 Wiley‐Liss, Inc.
Chronic peripheral nerve section results in a rearrangement of the central axonal arborizations of axotomized A beta primary afferent neurons in the rat spinal cord
Authors: Shortland Peter , Woolf Clifford J. 
Published: January 2005

AbstractIn order to investigate the reorganization of the neuropil of the dorsal horn following peripheral nerve injury, the central terminal arborizations of 35 A beta primary afferent neurons, chronically injured by a cut and ligation of the sural nerve 6–12 weeks previously, were studied by the intra‐axonal injection of horseradish peroxidase. Their morphology was compared to 13 intact sural nerve hair follicle afferents. Following axotomy, three kinds of morphological abnormalities were observed in the collateral arbors of the 26 afferents that were hair follicle‐like. Atrophy with thin stem axons and reduced terminal branch patterns with few boutons was seen in 5 afferents. Sprouting of bouton‐containing terminals into lamina I and IIo was found in 8 afferents. Finally, abnormal arborization patterns in the deeper laminae were observed in 29% of the collateral arbors. Changes included the loss in some arbors of a flame‐shaped appearance, which is characteristic of hair follicle afferents, atypical branching patterns and ventrally directed axons producing wider and deeper arbors, compared to normal.Axotomy also caused a disruption of the normal somatotopic organizaiton of sural nerve A beta afferents. This disruption manifested as a variability in the normally mediolaterally restricted terminal sheet, with a consequent loss of the strict somatotopic register in the rostrocaudal direction. Damage to the peripheral axon of A beta primary afferents induces a structural reorganization of their central terminals in the dorsal horn of the spinal cord, which may modify sensory input to the central nervous system.
Axonal regeneration is associated with glial migration: Comparison between the injured optic nerves of fish and rats
Authors: Blaugrund E. , Lavie V. , Cohen I. , Solomon A. , Schreyer D. J. , Schwartz M. 
Published: January 2005

AbstractThe central nervous systems of mammals and fish differ significantly in their ability to regenerate. Central nervous system axons in the fish readily regenerate after injury, while in mammals they begin to elongate but their growth is aborted a the site of injury, an area previously shown to contain no glial cells. In the present study we compared the ability of glial cells to migrate and thus to repopulate the injured area in fish and rats, and used light and electron microscopy in an attempt to correlate such migration with the ability of axons to traverse this area. One week after the optic nerve was crushed, both axonal and glial responses to injury were similar in fish and rat. In both species glial cells were absent in the injured area (indicated by the disappearance of glial fibrillary acidic protein and vimentin immunoreactive cells from the site of injury in rat and fish, respectively), while at the same time axonal growth, indicated by expression of the growth‐associated protein GAP‐43, was restricted to the proximal part of the nerve. In fish, 2 weeks after the crush, GAP‐43 staining (i.e., growing axons) was seen at the site of injury, in association with migrating vimentin‐positive glial cells. One week later the site of injury in the fish optic nerve was repopulated by vimentin‐positive glial cells, and GAP‐43‐positive axons had already traversed the site of injury and reached the distal part of the nerve. In contrast, the site of injury in the rat remained devoid of glial fibrillary acidic protein immunoreactive cells, and the expression of GAP‐43 by growing axons was still restricted to the proximal part of the nerve. Double‐labeling experiments and transmission electron microscopy performed 2 weeks after crush injury of the fish optic nerve revealed that the frontier of axonal growth (i.e., the leading growth cones) appeared to be 200–300 μm ahead of the nearest vimentin‐positive glial cells. The leading growth cones were associated with other cells, presumably glial precursors, that seemed to have a high migratory potential. We suggest that the ability of fish glial precursor cells to migrate into the injured area may contribute to the potential of growing axons to traverse this area. The failure of glia and glial precursor cells to migrate into the injured area in the rat may partially account for the failure of rat axons to enter and traverse the injured area.
Cerebellar nuclear projections from the basilar pontine nuclei and nucleus reticularis tegmenti pontis as demonstrated with PHA‐L tracing in the rat
Authors: Mihailoff Gregory A. 
Published: January 2005

AbstractSmall iontophoretic placements of the orthogradely transported axonal tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) were made in portions of the basilar pontine nuclei (BPN) or nucleus reticularis tegmenti pontis (NRTP) to determine if these cell groups provide projections to the cerebellar nuclei (CN) in the rat and if so, to visualize the morphology of the axons and teminals and illustrate any topographical organization in this system. Axons that originated from BPN or NRTP neurons and contained PHA‐L were visualized by an immunohistochemical procedure that involved sequential incubation of tissue sections with goat anti‐PHA‐L antibody, biotinylated rabbit anti‐goat immunoglobulin, and a biotin‐avidin‐peroxidase conjugate.Following injections of PHA‐L restricted to ventral and medial portions of the BPN, labeled fibers were observed in the brachium pontis, the white matter dorsal to the CN, and to a lesser extent, in the white matter of the parafloccular stalk. Labeled preterminal axons entered the CN and gave rise to beaded axons that arborized primarily within dorsal portions of the lateral, interposed, and medial cerebellar nuclei. Injections of PHA‐L restricted to either lateral portions of the BPN or ventrolateral regions of NRTP produced labeled fibers in the cerebellum that most frequently involved the parafloccular stalk and ventral portions of the CN. In contrast, dorsomedial NRTP injections resulted in the presence of labeled fibers both in the dorsal cerebellar white matter and the parafloccular stalk as well as dorsal and ventral portions of the CN. With the exception of the rostral and medial territory of interpositus anterior which received very sparse input, all portions of each CN subdivision seemed to exhibit some degree of terminal labeling. The density of labeled axon terminals in the CN appeared to be somewhat greater in the NRTP‐injected cases compared to BPN‐injected animals. These observations indicate that in the rat, both the BPN and NRTP contain neurons whose axons distribute to the CN. It is likely that most of the axons which project to the CN are collaterals of fibers that continue into the cerebellar cortex as mossy fibers but confirmation of this point must await further investigation. In light of the extensive projections from the cerebral cortex to the BPN and NRTP, this axonal system provides the cerebral cortex with a relatively direct route of access to the CN via one synapse in the BPN or NRTP.
Geometry of the projection of the visual field onto the superior colliculus of the wallaby (Macropus eugenii). II. Stability of the projection after prolonged rearing with rotational squint
Authors: James A. C. , Mark R. F. , Sheng X.‐M. 
Published: January 2005

AbstractAt about the time of eye opening, one eye of seven tammar wallaby pouch young was surgically rotated about the optic axis by approximately 90°. In adulthood the projection of the visual field through the rotated eye onto the contralateral superior colliculus was mapped electrophysiologically. Although apparently distorted, the projection could be coherently rerotated mathematically to a reasonable copy of the normal projection from the opposite eye of the same animal, including details such as regional variations of the magnification factor. The same was true of three adult animals in which the eye rotation was done after anaesthesia immediately before the electrophysiological mapping. In animals in which the visual field seen through one eye, the other being normal, was rotated for the entire period of visual experience, there was no sign of compensation or rearrangement of the topographic map. Retinocollicular synaptic connections appear unmoved by such discordant visual experience.
Orderly migration of neurons to the principal sensory nucleus of the trigeminal nerve of the rat
Authors: Al‐Ghoul Walid M. , Miller Michael W. 
Published: January 2005

AbstractAs nuclei in the central nervous system develop, neurons actively migrate from their site of generation to their permanent residence. This study examines the spatiotemporal sequence of the migration of neurons to the principal sensory nucleus of the trigeminal nerve (PSN) of the rat. Tritiated thymidine autoradiography and bromodeoxyuridine immunohistochemistry were used to examine the spatiotemporal patterns of migration of PSN neurons born on gestational day (G) 12 (early‐generated neurons) and of those born on G14 (late‐generated neurons). The final residence of early‐ and late‐generated neurons was determined by injecting a thymidine analog into a pregnant rat on G12 or G14 and sacrificing the pups on postnatal day (P) 30. Early‐ and late‐generated neurons were distributed medially and laterally, respectively. The schedule of the migration of PSN neurons was also determined. A few pioneer neurons born on G12 reached the PSN by G14; however, the last of the neurons born on G12 arrived in the PSN by G18. The migration of neurons born on G14 was completed 2–6 days later than that of the early‐generated neurons. The path followed by migrating neurons was delineated by radial glial fibers. These processes were identified in the developing metencephalon by RAT‐401 immunohistochemistry. Radial glial fibers extended from the lateral part of the ventricular zone through the tegmentum and the PSN to the surface of the metencephalon external to the sensory tract of the trigeminal nerve. RAT‐401‐immunoreactive processes were detected during the period of neuronal migration, but disappeared by P5. Thus, the migration of PSN neurons follows an inside‐to‐outside sequence, which apparently is organized by radial glial fibers. The inside‐to‐outside sequence of neuronal migration directly opposes the outside‐to‐inside gradient of synaptogenesis.