bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of individual axons projecting from area V2 to MT in the macaque
Authors: Rockland Kathleen S. 
Published: January 2005

AbstractEfferent axons from area V2 to the middle temporal area (MT) were anterogradely labeled by Phaseolus vulgaris ‐leucoagglutinin (PHA‐L) or biocytin and analyzed in serial reconstructions. Five of seven reconstructed axons had three arbors (each < 200 μm in diameter) in layers 3–4, separated by 200–600 jLm. Two axons terminated in what was apparently a single focus in layers 3–4. Of 15 additional single arbors analyzed, 12 were concentrated in layers 3–4, and measured 200–250 μm across at their widest point. Three of these arbors were more columnar in shape (about 400 μm in diameter), and extended from layer 4 toward layer 1. This system differs in several features from MT‐projecting axons originating from V1. Namely, V2 axons terminating in MT are thinner (∼ 1. 0 μm vs. 3. 0 gm), their terminal specializations are more delicate, and their arbors are concentrated in layer 4 and overlying layer 3, with no collaterals to layer 6. These differences may reflect the distinctive neuronal populations giving rise to these two connectional systems (different sizes of pyramidal neurons in layer 3 of V2, and a mix of pyramidal and spiny stellate cells in area V). Differences may have implications for timing factors; that is, impulses from V1, subserved by large‐caliber axons, may arrive in MT coincidentally with indirect connections via V2 to MT. Another consideration may be the functional architecture of MT. Regularly spaced clusters of neurons have been described in MT which have similar directionality preferences. The interarbor spacing of cortical efferents is consistent with a columnar organization, but the laminar specificity may indicate recruitment of different combinations of postsynaptic populations by V1 or V2 terminations.
Multiple gonadotropin‐releasing hormone (GnRH)‐immunoreactive systems in the brain of the dwarf gourami,Colisa lalia: Immunohistochemistry and radioimmunoassay
Authors: Yamamoto Naoyuki , Oka Yoshitaka , Amano Masafumi , Aida Katsumi , Hasegawa Yoshihisa , Kawashima Seiichiro 
Published: January 2005

AbstractThe present study characterizes gonadotropin‐releasing hormone (GnRH) neuronal groups that are located in several different brain regions by investigating GnRH molecular species and projection patterns in an anabantid fish, Colisa lalia. First, we examined the molecular species of GnRHs in extracts of the brain and the pituitary by reverse‐phase high‐performance liquid chromatography followed by radioimmunoassays. We found salmon GnRH (sGnRH), chicken GnRH‐II (cGnRH‐II), and an unfamiliar GnRH‐like substance.Next, to examine the distribution of each GnRH molecule in different GnRH neuronal groups, we performed immunohistochemistry using four kinds of antisera and an antibody. Furthermore, we performed brain lesioning experiments of terminal nerve (TN) cells, the most conspicuous GnRH‐immunoreactive cells in Colisa lalia. Comparisons of immunoreactive structures between TN‐lesioned fish and untreated fish elucidated the projection area of each neuronal group. Three major neuronal groups were observed. TN‐GnRH cells, which are located in the transitional area between the olfactory bulb and the telencephalon, showed strong sGnRH and weaker cGnRH‐II immunoreactivity. TN‐GnRH cells projected to wide areas of the central nervous system from the olfactory bulb to the spinal cord. The second group, located in the preoptic area, showed only sGnRH immunoreactivity and projected only to the pituitary. The third ond, located in the midbrain tegmentum, exhibited strong cGnRH‐II and weaker sGnRH immunoreactivity. This cell group projected mainly to brain regions posterior to the hypothalamus and the spinal cord. These different projection patterns suggest functional differentiation of each GnRH neuronal group.
Development of branchiomeric and lateral line nerves in the axolotl
Authors: Northcutt R. Glenn , Brändle Kurt 
Published: January 2005

AbstractThe differentiation of neural crest and ectodermal placodes was examined in the axolotl in order to clarify the contribution of these tissues to the formation of the sensory ganglia of the branchiomeric and lateral line cranial nerves in salamanders. The most rostral branchiomeric nerves, the profundal and trigeminal nerves, appear to arise solely from an ectodermal placode and from neural crest, respectively. The sensory ganglia of the more caudal branchiomeric nerves —the facial, glossopharyngeal, and vagal nerves —are formed by a medial component that differentiates from the dorsomedial surface of migrating bands of neural crest associated with each of the developing branchial arches and with one or more lateral components that arise from epibranchial placodes located immediately dorsal and caudal to each pharyngeal pouch. Neuroblasts destined to form these sensory ganglia begin to differentiate from the epibranchial placodes as early as stage 26, whereas neural crest‐derived neuroblasts can be recognized by stage 30. Centrally directed neurites of both groups of neuroblasts enter the medulla by stage 34, and their peripherally directed neurites form recognizable rami by stage 35. Five cranial lateral line nerves, in addition to the octaval nerve, can be recognized in axolotls. Each of these nerves arises from a separate dorsolateral placode that initially gives rise to the neuroblasts of a sensory ganglion whose peripheral neurites innervate sensory receptors subsequently formed from each placode. The time course of the differentiation of these nerves and receptors is comparable to that of the branchiomeric nerves. The possible roles of rhombomeres and their associated regulatory genes and pharyngeal pouches in the induction and specification of neural crest and ectodermal placodes are explored.
Glial cell line‐derived neurotrophic factor supports survival of injured midbrain dopaminergic neurons
Authors: Bowenkamp Kathryn E. , Hoffman Alexander F. , Gerhardt Greg A. , Henry Michael A. , Biddle Paul T. , Hoffer Barry J. , Granholm Ann‐Charlotte E. 
Published: January 2005

AbstractGlial cell‐lined derived neurotrophic factor (GDNF) has been shown to promote survival of developing mesencephalic dopaminergic neurons in vitro. In order to determine if there is a positive effect of GDNF on injured adult midbrain dopaminergic neurons in situ, we have carried out experiments in which a single dose of GDNF was injected into the substantia nigra following a unilateral lesion of the nigrostriatal system. Rats were unilaterally lesioned by a single stereotaxic injection of 6‐hydroxydopamine (6‐OHDA; 9 μg/4 μl normal saline with 0.02% ascorbate) into the medial forebrain bundle and tested weekly for apomorphine‐induced (0.05 mg/kg s. c. ) contralateral rotation behavior, Rats that manifested >300 turns/hour received a nigral injection of 100 μg GDNF, or cytochrome C as a control, 4 weeks following the 6‐OHDA lesion, Rotation behavior was quantified weekly for 5 weeks after GDNF. Rats were subsequently anesthetized, transcardially perfused, and processed for tyrosine hydroxylase immunohistochemistry. It was found that 100 μg GDNF decreased apomorphine‐induced rotational behavior by more than 85%. Immunohistochemical studies revealed that tyrosine hydroxylase immunoreactivity was equally reduced in the striatum ipsilateral to the lesion in both cytochrome C and GDNF‐injected animals. In contrast, large increments in tyrosine hydroxylase immunoreactivity were observed in the substantia nigra of animals treated with 100 μg of GDNF, with a significant increase in numbers of tyrosine hydroxylase‐immunoreactive cell bodies and neurites as well as a small increase in the cell body area of these neurons. The results suggest that GDNF can maintain the dopaminergic neuronal phenotype in a number of nigral neurons following a unilateral nigrostriatal lesion in the rat.
Spatial and temporal pattern of purkinje cell degeneration in shaker mutant rats with hereditary cerebellar ataxia
Authors: Tolbert D. L. , Ewald M. , Gutting J. , La Regina M. C. 
Published: January 2005

AbstractTemporal‐spatial patterns of surviving Purkinje cells were studied quantitatively in a rat mutant (shaker) with differential hereditary cerebellar ataxia and Purkinje cell degeneration. Shaker rat mutants are characterized behaviorally as mild if they are ataxic or as strong if they have ataxia and tremor. Purkinje cells degenerate in both mild and strong shaker mutants, but the temporal and spatial patterns of cell death are strikingly different. In mild shaker mutants, Purkinje cell death is temporally restricted, with 31‐46% of the Purkinje cells in lobules I‐IX dying by 3 months of age. Very few Purkinje cells degenerate after this age. Purkinje cell death is spatially random. In lobules I‐IX, every second, third, or fourth Purkinje cell degenerates. Purkinje cells in lobule X do not degenerate. In strong shaker mutants, Purkinje cell degeneration is temporally protracted and spatially restricted. By 3 months of age, most Purkinje cells in lobules I‐VIa, ‐b, and ‐d, and ‐d have degenerated. Numerous Purkinje cells in the paravermis of lobules VIIb‐VIII have also degenerated. Surviving Purkinje cells in the vermis and lateral hemisphere of lobules VIIb‐VIII are aligned in parasagittally oriented stripes or transversely oriented bands. Purkinje cells continue to degenerate in localized areas of the posterior lobe such that, by 18 months of age, surviving Purkinje cells are limited primarily to lobules VIc, VIIa, IXd, and X. Quantitative analysis indicates that none of the Purkinje cells in these lobules degenerate.
Ipsilateral intracortical connections of physiologically defined cutaneous representations in areas 3b and 1 of macaque monkeys: Projections in the vicinity of the central sulcus
Authors: Burton Harold , Fabri Mara 
Published: January 2005

AbstractThis study examined cortical connections of areas 3b and 1 in 17 macaque monkeys in reference to regional somatotopography. The fluorescent retrograde tracers Fast Blue and Diamidino Yellow and the anterograde tracer Rhodamine Dextran were injected into closely related cutaneously responsive sites in primary somatosensory cortex, e. g., adjacent digits.Supra‐ and infragranular layers in nearly all studied areas contained labeled pyramidal cells. Labeled infragranular cells predominated at the fringes of a distribution where cells labeled from different tracer injections in the same brain intermixed more.All topographical regions across area 1 have reciprocal connections with areas 4, 3a, 3b, 1, 2, and 5. Intrinsic connections within area 1 and between it and area 2 are greatest; those with area 3b are less. Intrinsic connections within area 3b exceed all other nearby projections from this area which reciprocally connects with areas 3a, 1 and 2. Connections appear topographically organized, including those with poorly mapped regions, like area 5. These connections link representations of neighboring skin and skip map regions that include disjoint dermatomal areas. Connections from adjacent digit representations overlap; however, double‐labeled cells were not found. Distal and proximal digit zones mostly interconnect within an area. Intrinsic connections spread further in area 1 than in area 3b, thereby joining more disparate topographical zones than interareal connections, which project more homotopically. The domain over which the map in somatosensory cortical area I (SI) dynamically changes following in tracortical microstimulation (Recanzone, Merzenich and Dinse, Cerebral Cortex 2:181‐196, 1992) may depend on the range of intrinsic connections observed in this study. The extent of connections between cortical areas was less than expected and this challenges the hypothesis that these connections directly create receptive field enlargements.
Somal size and location within the ganglia for electrophysiologically identified myenteric neurons of the guinea pig ileum
Authors: Schutte Irma W. M. , Kroese Alfons B. A. , Akkermans Louis M. A. 
Published: January 2005

AbstractThe main goal of the present study was to examine the possibility of electrophysiologically identifying the excitable enteric S and AH neurons by use of one single criterion. Intracellular recordings were made from 189 cells of 64 ganglia in isolated preparations of the myenteric plexus of the guinea pig distal ileum. The recordings were made under visual control of the cells by using Hoffman Modulation Contrast optics at high magnification (600 X). From photomicrographs, the soma size and the location within the ganglion of the individual (unstained) cells were determined.The cells were classified into three types according to their electrical excitability and the shape of the action potential. Excitable cells were classified as AH cells (n = 84) if the action potential showed a shoulder on the falling phase, otherwise as S cells (n = 56). Cells in which no action potential could be evoked by current injection were classified as nonspiking (NS) cells (n = 49). The three classes of cells showed significant differences with respect to membrane potential, input resistance and fast synaptic input. The AH cells had significantly larger somata (P < 0.01) than the S cells. The NS cells were significantly smaller than the AH and S cells (P < 0.01). AH and S cells were found to be randomly located in the ganglia, whereas the NS cells clustered (P < 0.008) in close proximity to the onsets of internodal strands.We conclude that the shoulder of the action potential canbe used as a single criterion to distinguish “on line” S and AH neurons unequivocally.
Prenatal development of rat primary afferent fibers: I. Peripheral projection
Authors: Mirnics Károly , Koerber H. Richard 
Published: January 2005

AbstractDevelopment of the peripheral innervation patterns of the L1‐S1 lumbosacral ganglia and motor segments in embryonic day 12‐17 (E12‐17) rat embryos was examined using carbocyanine dyes. Individual dorsal root ganglia (DRGs) and/or isolated ventral horn (VH) segments, or individual peripheral nerves, were isolated in rat embryos fixed at different stages and filled with one of three carbocyanine dyes; DiI, DiA, and DiO. Individual experimental preparations included labeling of (1) single DRGs; (2) multiple DRGs with alternating dyes, DiO, DiI, and DiA; (3) single isolated VH segments; (4) multiple VH segments with alternating dyes; (5) single VH segments and the corresponding segmental DRGs with different dyes; and (6) two or more individual peripheral nerves labeled with different dyes.Results from these preparations have shown that the first fibers exited the lumbar ventral horn and DRGs at E12. At E13 major nerve trunks (e. g., femoral and sciatic) were visible as they exited the plexus region. By E14 afferent fibers were present in the epidermis of the proximal hindlimb, and the major nerve trunks extended into the leg. Fibers originating from L3 to L5 (DRG and VH) reached the paw by E14. 5‐E15, and the epidermis of the most distal toes was innervated by E16‐E16. 5. While afferent fibers and motor axons of the same segmental origin mixed extensively in the spinal nerve, fibers of different segmental origin combined in the plexus and major nerve trunks with little or no interfascicular mixing.Dermatomes observed at E 14 were in general spotty and non‐contiguous. However, by E 16 the dermatomes resembled mature forms with substantial overlap only between adjacent ones. Thus the adult pattern of spatial relationships between cutaneous afferent fibers in the periphery is established early in development.
Zonal organization of the flocculovestibular nucleus projection in the rabbit: A combined axonal tracing and acetylcholinesterase histochemical study
Authors: Tan J. , Epema A. H. , Voogd J. 
Published: January 2005

AbstractWith the use of retrograde transport of horseradish peroxidase we confirmed the observation of Yamamoto and Shimoyama ([1977] Neurosci Lett. 5:279‐283) that Purkinje cells of the rabbit flocculus projecting to the medial vestibular nucleus are located in two discrete zones, FZII and FZIV, that alternate with two other Purkinje cell zones, FZI and FZIII, projecting to the superior vestibular nucleus. The retrogradely labeled axons of these Purkinje cells collect in four bundles that occupy the corresponding floccular white matter compartments, FC1 –4, that can be delineated with acetylcholinesterase histochemistry (Tan et al. [1995a] J. Comp. Neurol., this issue). Anterograde tracing from small injections of wheat germ agglutin‐hoseradish peroxidase in single Purkinje cell zones of the flocculus showed that Purkinje cell axons of FZII travel in FC2 to terminate in the medial vestibular nucleus. Purkinje cell axons from FZI and FZIII occupy the FC2 and FC3 compartments, respectively, and terminate in the superior vestibular nucleus. Purkinje cell axons from all three compartments pass through the floccular peduncle and dorsal group y. In addition, some fibers from FZI and FZII, but not from FZIII, arch through the cerebellar nuclei to join the floccular peduncle more medially. No anterograde tracing experiments were available to determine the projections of the FZIV and C2 zones. The functional implications of these results are discussed. © 1995 Wiley‐Liss, Inc.
Double labeling of GABA and cytochrome oxidase in the macaque visual cortex: Quantitative EM analysis
Authors: Nie Feng , Wong‐Riley Margaret T. T. 
Published: January 2005

AbstractIn the primate striate cortex, cytochrome oxidase (CO)‐rich puffs differ from CO‐poor interpuffs in their metabolic levels and physiological properties. The neurochemical basis for their metabolic and physiological differences is not well understood. The goal of the present study was to examine the relationship between the distribution of gamma aminobutyric acid (GABA)/non‐GABA synapses and CO levels in postsynaptic neuronal profiles and to determine whether or not a difference existed between puffs and interpuffs. By combining CO histochemistry and postembedding GABA immunocytochemistry on the same ultrathin sections, the simultaneous distribution of the two markers in individual neuronal profiles was quantitatively analyzed. In both puffs and interpuffs, GABA‐immunoreactive (GABA‐IR) neurons were the only cell type that received both non‐GABA‐IR (presumed excitatory) and GABA‐IR (presumed inhibitory) axosomatic synapses, and they had three times as many mitochondria darkly reactive for CO than non‐GABA‐IR neurons, which received only GABA‐IR axosomatic synapses. GABA‐IR neurons and terminals in puffs had a larger mean size, about twice as many darkly reactive mitochondria, and a higher ratio of non‐GABA‐IR to GABA‐IR axosomatic synapses than those in interpuffs (2.3:1 vs. 1.6:1; P < 0.01). There were significantly more synapses of both non‐GABA‐IR and GABA‐IR types in the neuropil of puffs than of interpuffs; however, the ratio of non‐GABA‐IR to GABA‐IR synapses was significantly higher in puffs (2.86:1) than in interpuffs (2.08:1; P < 0.01). Our results are consistent with the hypothesis that the level of oxidative metabolism in postsynaptic neurons and neuronal processes is tightly governed by the strength and proportion of excitatory over inhibitory synapses. Thus, the present results suggest that (1) GABA‐IR neurons in the macaque striate cortex have a higher level of oxidative metabolism than non‐GABA ones because their somata receive direct excitatory synapses and their terminals are more tonically active; (2) the higher proportion of presumed excitatory synapses in puffs imposes a greater energy demand there than in interpuffs; and (3) excitatory synaptic activity may be more prominent in puffs than in interpuffs because puffs receive a greater proportion of excitatory synapses from multiple sources including the lateral geniculate nucleus, which is not known to project to the interpuffs. © 1995 Wiley‐Liss, Inc.
Ultrastructural localization of SNAP‐25 within the rat spinal cord and peripheral nervous system
Authors: Duc Christophe , Catsicas Stefan 
Published: January 2005

AbstractSynaptosomal associated protein of 25 kDa (SNAP‐25) has been implicated in the membrane fusion machinery of neurotransmitter release and axonal growth. Using immunocytochemistry, we have analyzed the distribution and ultrastructural localization of SNAP‐25 in selected areas of the central and peripheral nervous systems of adult rats. We show that the protein is specifically expressed in the trans face of the Golgi apparatus and in the axonal compartment. In axons and nerve endings, SNAP‐25 is localized to discrete areas of the membranes of most organelles such as the axoplasmic reticulum, the axolemma, the outer membrane of mitochondria and synaptic vesicles. This wide distribution of SNAP‐25 suggests that the protein is involved in the fusion of membranes in the whole axonal compartment of neurons. © 1995 Wiley‐Liss, Inc.
Distribution of fine neurites of stomatogastric neurons of the crab Cancer borealis: Evidence for a structured neuropil
Authors: Baldwin David H. , Graubard Katherine 
Published: January 2005

AbstractThe neuropil of the stomatogastric ganglion of the crab Cancer borealis contains many neuronal processes that may be arranged either at random or in some form of orderly structure. In this study, we provide evidence for two types of order in the neuropil, a segregation of the processes based on their size and a cell‐specific distribution to the fine neurites. Identified neurons were injected with Lucifer yellow, fixed, and imaged as whole mounts with a confocal microscope. Four cell types were analyzed using the serial images, two pyloric neurons, one mixed pyloric/gastric neuron, and one gastric neuron. All of the neurons consisted of a ∼ 60‐μm‐diameter soma, a ∼ 20‐μm‐diameter primary neurite projecting into the center of the neuropil, a number of < 10‐μm‐diameter medium‐sized neurites radiating away from the center, and many < 3‐μm‐diameter fine neurites around the periphery of the neuropil. The neuropil can, therefore, be divided into three layers, a central core containing the largest neurites, an intermediate region containing both medium‐sized and fine neurites, and a peripheral neuropil containing mostly fine neurites. The distribution of the fine neurites was mapped using a three‐dimensional grid. We found that the fine neurites were distributed not at random within the neuropil but in consistent, cell‐specific patterns. © 1995 Wiley‐Liss, Inc.