bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topography of projections to the frontal lobe from the macaque frontal eye fields
Authors: Stanton G. B. , Bruce C. J. , Goldberg M. E. 
Published: January 2005

AbstractEfferents from the frontal eye fields (FEF) to the ipsilateral frontal lobe were studied by autoradiography of tritiated tracers (leucine, proline, and fucose) in seven macaque monkeys that were used previously to describe subcortical connections. In four of the cases, tracer injection sites were confirmed by low thresholds for the electrical elicitation of saccadic eye movements. Cases were grouped as lFEF or sFEF cases according to large or small saccades that were characteristic of the injection site.Projections from the FEF terminated in five frontal regions: (1) area FD on the dorsomedial convexity; (2) area FC (containing SEF) medial to the upper limb of the arcuate sulcus; (3) areas FD and FDΔ along the walls of the principal sulcus; (4) area FCBm on the deep, posterior wall of the arcuate sulcus inferior to the sulcal spur; and (5) the inferolateral cortex (area FDi) on the convexity and lateral two thirds of the anterior wall of the arcuate sulcus. Projections in sFEF cases tended to be confined to medial parts of dorsomedial FD and FC and the lateral wall of the principal sulcus and inferolateral convexity. Neither lFEF nor sFEF appeared to project to the SMA or pericingulate cortex. Label in these areas was found only in the cases in which tracer spread into non‐FEF areas.FEF projections terminated in column‐like patches of about 500–600 μm in diameter. Labeled axons and terminals were seen in all cortical layers regardless of location in the frontal lobe.
Changes in synaptic density after developmental compression or expansion of retinal input to the superior colliculus
Authors: Xiong Meijuan , Finlay Barbara L. 
Published: January 2005

AbstractThe retinal projection to the superior colliculus can be made abnormally dense by inducing a “compressed” retinal projection into a subnormal tectal volume, or abnormally spares by monocular enucleation early in development. Any or all of the features of cell number, axonal arbor, dendritic arbor, and synaptic density could potentially be adjusted to compensate for such variations in the convergence of one cell population on another. We have examined the consequences of neonatal partial tectal ablation or monocular enucleation for synaptic length, density, and relative numbers of synapse classes in the superficial gray layer of the hamster superior colliculus.Monocular enucleation resulted in a reduction of synaptic density in the superficial gray layer of the colliculus ipsilateral to the remaining eye. This decrease in density was entirely accounted for by a reduction of the number of synapses with round vesicles, large asymmetric terminal specializations, and pale mitochondria characteristic of retinocollicular terminals (RLP synapses). There was no compensatory increase in any other synaptic class. RLP synapses were larger in monocular enucleates.Partial tectal ablation had no effect on synaptic density, nor on the relative proportions of different synaptic types. Synapses of the RLP class were slightly smaller than normal. These results suggest that synaptic density is normally at a maximum that cannot be altered by increases in potential input. However, density may be reduced by decreasing the number of inputs. Terminal classes do not appear to compete with each other within the collicular volume, suggesting that postsynaptic cells control both the classes and numbers of their potential inputs.
Location of retinal ganglion cells contributing to the early imprecision in the retinotopic order of the developing projection to the superior colliculus of the wallaby (Macropus eugenii)
Authors: Marotte L. R. 
Published: January 2005

AbstractThe position of ganglion cells contributing to the early imprecision in retinotopic order in the developing retinocollicular projection in the wallaby (Macropus eugenii) has been determined.Deposits of horseradish peroxidase conjugated to wheat germ agglutinin (WGA‐HRP) were made in the caudal pole of the superior colliculus (SC) at ages ranging from 22 days after birth, when sparse retinal axons have only just reached the caudal pole of the SC and are yet to cover its surface completely, to 96 days when the retinotopy of ganglion cell terminals in the SC is precise (Marotte, '90). From 30 days onwards, the deposit of WGA‐HRP resulted in a dense patch of retrogradely labelled retinal ganglion cells that could be seen to be appropriately positioned in nasal retina. However, at all ages prior to 92 days, there were inappropriately positioned labelled cells between the densely labelled patch and the central retina and both dorsal and ventral to the patch. They were not found in far distant regions of retina and composed a relatively small proportion of labelled cells. They reached a peak at 45 days, had decreased to low levels by 63 days, were rare by 81 days, and by 92 days were absent. This latter age fits with the time when retinotopy was judged to be precise in a previous study (Marotte, '90).Inappropriately projecting cells never originate from the entire retina but only from regions adjacent to the appropriate region. Thus, during development there are no gross projection errors. Initially, ganglion cell axons are distributed on the colliculus in a coarse retinotopy. Refinement of the projection then follows, revealed by this technique as a loss of inappropriately projecting ganglion cells. This is complete by 92 days well before eye opening at around 140 days. © 1993 Wiley‐Liss, Inc.
Distribution of parvalbumin‐immunoreactive cells and fibers in the monkey temporal lobe: The amygdaloid complex
Authors: Pitkänen Asla , Amaral David G. 
Published: January 2005

AbstractThe calcium‐binding protein parvalbumin was immunohistochemically localized in the monkey amygdaloid complex. Parvalbumin‐immunoreactive neuronal cell bodies, fibers, and terminals were observed in several amygdaloid nuclei and cortical areas. Three types of aspiny neurons, ranging from small spherical cells (Type 1) to large multipolar cells (Type 2) and fusiform cells (Type 3) were observed in most amygdaloid regions, though the proportions of the cell types were different in each region. The density of parvalbumin‐immunoreactive fibers and terminals tended to parallel the density of labeled cell bodies. The highest densities of parvalbumin profiles were observed in the nucleus of the lateral olfactory tract, the periamygdaloid cortex (PAC2), the magnocellular division of the basal nucleus, the ventrolateral portion of the lateral nucleus, and the accessory basal nucleus. The regions containing the lowest densities of parvalbumin‐positive profiles were the medial nucleus, anterior cortical nucleus, central nucleus, and the paralaminar nucleus. In regions with fiber and terminal labeling, pericellular networks of fibers, reminiscent of basket cell terminations, were commonly observed to surround unstained neuronal cell bodies and proximal dendrites. In the magnocellular division of the basal nucleus, and to a lesser extent in the lateral nucleus, parvalbuminlabeled “cartridges” of axo‐axonic terminals were observed on the initial segments of unlabeled cells. Parvalbumin‐positive varicosities were also commonly observed in close apposition to the soma and dendrites of parvalbumin‐immunoreactive cells. Given the close correspondence between the distribution of parvalbumin‐positive neurons and a subset of GABAergic neurons in many brain regions, these data provide a first indication of the organization of the inhibitory circuitry of the primate amygdaloid complex. © 1993 Wiley‐Liss, Inc.
D2‐like dopamine receptors in amphibian retina: Localization with fluorescent ligands
Authors: Muresan Zoia , Besharse Joseph C. 
Published: January 2005

AbstractDopamine induces several light adaptive changes in amphibian retina via receptors with D2‐like pharmacology, but the identity of the primary target cells has not been determined. Using a fluorescent probe consisting of a selective D2 antagonist, N‐(p‐aminophenethyl)‐ spiperone (NAPS), derivatized with the fluorophore Bodipy (NAPS‐Bodipy), we identified the distribution of dopamine binding sites in the retina of two amphibians, post‐metamorphic Xenopus laevis and larval Ambystoma tigrinum. Specific labeling was defined as staining that was displaced by D2 selective ligands (eticlopride or sulpiride), but insensitve to D1 selective drugs (SCH 23390), adrenergic catecholamines (epinephrine or norepinephrine), or serotoninergic analogues (ketanserin). Both rod and cone cells showed specific dopamine D2‐like binding sites arranged in clustered arrays on discrete membrane domains of the inner segment. Labeling of photoreceptor outer segments was continuous and was not displaced by competition with D2 selective ligands; this labeling was considered nonspecific. In addition, in both species, clustered binding of the D2‐probe was found on Müller cells and on a subset of inner retinal cells with the morphology of amacrine/interplexiform cells. Our data provide direct evidence for D2 receptors on both rods and cones, and suggest that the receptors may be clustered into patches within a discrete cellular domain, the inner segment. © 1993 Wiley‐Liss, Inc.
Direct catecholaminergic innervation of spinal dorsal horn neurons with axons ascending the dorsal columns in cat
Authors: Doyle Christopher A. , Maxwell David J. 
Published: January 2005

AbstractPrevious ultrastructural studies have shown that catecholamine‐containing nerve terminals in the spinal dorsal horn form synaptic junctions with dendrites and somata, but the identity of the neurons giving rise to these structures is largely unknown. In this study we have investigated the possibility that spinomedullary neurons, which project through the dorsal columns to the dorsal column nuclei, are synaptic targets for descending catecholaminergic axons.Neurons with axons ascending the dorsal columns were retrogradely labelled after uptake of horseradish peroxidase by their severed axons in the thoracic (T10–T12) or cervical (C2–C3) dorsal columns. After the retrogradely labelled neurons were visualized, the tissue was immunocytochemically stained with antisera raised against tyrosine hydroxylase or dopamine‐β‐hydroxylase.Three hundred forty‐three retrogradely labelled neurons within laminae III–V of the lumbosacral dorsal horn were examined under high power with the light microscope. In Triton X‐100 treated material, over 60% of cells were found to have dopamine‐β‐hydroxylase‐immunoreactive varicosities closely apposed to their somata and proximal dendrites. The number of contacts per cell varied from 1 to 22, with a mean number of 4.5. Fewer cells (34%) received contacts from axons immunoreactive for tyrosine hydroxylase as a consequence of the weaker immunoreaction produced by this antiserum. Correlated light and electron microscopic analysis confirmed that many of these contacts were regions of synaptic specialization and that immunostained boutons contained pleomorphic (round to oval) agranular vesicles together with several dense core vesicles.These observations suggest that catecholamines regulate sensory transmission through this spinomedullary pathway by a direct postsynaptic action upon its cells of origin. Such an action would be predicted to suppress transmission generally through this pathway. © 1993 Wiley‐Liss, Inc.
Propriospinal input to thoracolumbar sympathetic nuclei from cervical and lumbar lamina I neurons in the cat and the monkey
Authors: Craig A. D. (Bud) 
Published: January 2005

AbstractThe possibility that specific thermoreceptive and nociceptive influences on sympathetic outflow are conveyed directly to spinal sympathetic regions by lamina I neurons was investigated anatomically with the immunofluorescent PHA‐L technique in the cat and the cynomolgus monkey. Iontophoretic injections made with physiological guidance were restricted to lamina I or to laminae I–II in the cervical (C6–8) or lumbar (L6–7) enlargement. Bilateral (symmetric) terminal arborizations were observed (with an ipsilateral predominance) in the intermdiolateral, intermediomedial, and intervening regions of the thoracolumbar intermediate zone. In serial horizontal sections, patches of terminal labeling appeared at regular longitudinal intervals in the intermediolateral region. Longitudinally coursing fibers that had multiple varicosities and gave off small terminal branches were observed in the intermediolateral and the intermediomedial regions. Mediolateral strips of labeling that extended from labeling in the intermediolateral region to labeling in the intermediomedial region occurred at fairly regular longitudinal intervas. Because the longitudinal distribution of these terminations corresponds very well with the characteristic (ladder‐like) longitudinal pattern of organization of the neuropil of the thoracolumbar sympathetic nuclei, i.e., the principal part of the intermediolateral cell column, the central autonomic n., and the intervening n. intercalatus, it is inferred that these lamina I terminations occur within these nuclei. After cervical injections, the labeling was most dense in the upper thoracic T2–4 spinal cord segments in both the cat and the monkey; labeling was also present in the T10–12 segments. After lumbar injections, labeling in the cat was located in the L4 segment; labeling in the monkey was present in the T4–6 and T10–12 segments. The labeling obtained was much more dense in the monkey than in the cat.These observations reveal a spinal lamina I projection that could provide a direct pathway for the somatosympathetic reflex effects of thermal and noxious stimuli. Considered together with reports that lamina I and the sympathetic nuclei both receive descending input from certain key autonomic regions, this result emphasizes the importance of lamina I for homeostasis, in addition to its probable roles in behavioral arousal, affect, and sensation. These observations thus support the proposed concept that lamina I processes and distributes in a functionally specific manner the sensory input relevant to the physiological status of the tissues and organs of the entire organism. © 1993 Wiley‐Liss, Inc.
Crosstalk between the two sides of the thalamus through the reticular nucleus: A retrograde and anterograde tracing study in the rat
Authors: Rao's Vassilis , Bentivoglio Marina 
Published: January 2005

AbstractIn order to investigate the possible routes linking the thalamus in the two sides of the brain, the connections of the reticular nucleus (RT), the major component of the ventral thalamus, with contralateral dorsal thalamic nuclei were systematically investigated in the adult rat. This study was performed with several tract‐tracing techniques: single and double retrograde labeling with fluorescent tracers, and anterograde tracing with biocytin. Retrograde tracing was also combined with immunocytochemistry to provide additional criteria for the identification of labeled RT neurons.The data obtained with the retrograde transport of one fluorescent tracer showed that RT neurons project to contralateral dorsal thalamic domains. In particular, retrograde labeling findings indicated that the anterior intralaminar nuclei, as well as the ventromedial (VM) nucleus, are preferential targets of the contralateral RT projections. Commissural neurons were concentrated in two portions of RT: its rostral part, including the rostral pole, which projects to the contralateral central lateral (CL) and paracentral (Pc) nuclei, and the ventromedial sector of the middle third of RT, which projects to the contralateral VM and posterior part of CL and Pc. The double retrograde labeling study of the bilateral RT–intralaminar connection indicated that at least part of the commissural RT cells bifurcate bilaterally to symmetrical portions of the anterior intralaminar nuclei.The targets of the RT commissural system inferred from the retrograde labeling data were largely confirmed by anterograde tracing. Moreover, it was shown that RT fibers cross the midline in the intrathalamic commissure.The present data demonstrate that bilateral RT connections with the dorsal thalamus provide a channel for interthalamic crosstalk. Through these bilateral connections with thalamic VM and intralaminar neurons, RT could influence the activity of wide territories of the cerebral cortex and basal ganglia of both hemispheres. © 1993 Wiley‐Liss, Inc.
NILE/L1 and NCAM‐polysialic acid expression on growing axons of isolated neurons
Authors: van den Pol Anthony N. , Kim Warren T. 
Published: January 2005

AbstractThe neuron adhesion molecules NILE/L1 and NCAM may be involved in axonal guidance and cell recognition. To investigate all exposed membrane domains of single neurons, something which has not previously been done for any adhesion molecule, we used digitally processed scanning electron microscopy with a high‐energy backscatter electron detector. This allowed a quantitative analysis of immunogold staining densities on all surfaces of isolated rat hippocampal neurons in culture to study NILE/L1 and NCAM expression independent of potentially inductive innervation.During early stages of neuritic extension, all growth cones showed similar NILE/L1 expression, but as soon as a single process extended farther than the others (by 20 hours), this putative axon and its growth cone generally showed a stronger level of NILE/L1 immunogold labeling than the other neurites. This is the earliest evidence of plasma membrane differentiation between axons and dendrites. With further neuritic growth, the relative NILE/L1 expression on axons and their growth cones continued to increase. In contrast to some earlier reports, NILE/L1 was expressed on axonal growth cones growing on both polylysine‐coated glass and astrocyte substrates.Strong immunostaining for NCAM‐related polysialic acid (PSA) was found on axonal growth cones and filopodia, suggesting that the homophilic adhesive action of NCAM may be reduced during axonal growth. PSA showed greater labeling on distal axons than on other areas of the neuron, indicating a variable NCAM‐mediated adhesion on different regions of the same cell. Neither NILE/L1, NCAM, nor PSA appeared to show regional differences in axons fasciculating or defasciculating on themselves. A strong intercellular heterogeneity of NILE/L1, NCAM, and PSA expression levels on neurons in the same culture dish was found, suggesting that subsets of cells from the hippocampus may express biologically relevant differences in adhesion molecules compared to neighboring neurons.In light of the growing body of evidence pointing to the multifaceted array of homophilic and heterophilic binding interactions that NILE/L1 and NCAM may exhibit, and the functional importance of molecular densities, the quantitative data here support the hypothesis that sufficient cellular and subcellular heterogeneity exists for these molecules to be involved in some aspects of axonal guidance. © 1993 Wiley‐Liss, Inc.
Pre‐ and postnatal development of the primary visual cortex of the common marmoset. I. A changing space for synaptogenesis
Authors: Missler Markus , Eins Siegfried , Merker Hans‐Joachim , Rothe Hartmut , Wolff Joachim R. 
Published: January 2005

AbstractThe primary visual cortex of Callithrix jacchus occupies a large portion of the occipital neocortex and can be safely delineated from fetal stages onwards. In 20 animals ranging in age from fetal to adult age the morphological development of area 17 was evaluated and compared with the growth of whole brain, skull, and head size. Cortical thickness, surface area, and volume of the area were determined in addition to predominant growth directions. The volume of area 17 approximately doubles between birth (241 mm3) and three months of age (506 mm3). This maximum value marks an overshoot in growth (volume: 180%, surface area: 150%, thickness: 122%), which is followed by a considerable reduction before adult values (100%) are reached. Although these values seem to indicate that the overall reduction in size is fairly isometric, growth and regression are locally anisometric. For example, layers II–IVc contribute disproportionately to the overshoot; thickening is less pronounced than tangential growth and follows a slightly different time course. These data suggest that the developing visual cortex represents a highly dynamic distribution space for the developing synaptic junctions which should be taken into account in studies on synaptogenesis. By comparison it is suggested that this growth dynamic is not restricted to area 17 but also occurs in some other parts of the cerebral cortex. In contrast, most subcortical brain regions apparently do not undergo overshoot growth. Structural changes of the skull compensate the overshoot in cortex growth, so that head size increases steadily. © 1993 Wiley‐Liss, Inc.
Glia cells of the monkey retina. I. Astrocytes
Authors: Distler C. , Weigel H. , Hoffmann K.‐P. 
Published: January 2005

AbstractMorphology and distribution of retinal astrocytes have been studied in macaque monkeys by immunocytochemical localization of glial fibrillary acidic protein (GFAP). With the exception of the fovea and the far periphery, astrocytes are ubiquitous in the nerve fiber layer (NFL) and the ganglion cell layer (GCL) of the monkey retina. The morphology of NFL astrocytes changes gradually, from star‐shaped in the periphery to bipolar close to the optic disc. By contrast, GCL astrocytes maintain their star‐shaped appearance throughout the retina. Astrocytes are unevenly distributed in the monkey retina, showing the highest concentration around the optic disc, and particularly low densities in the perifoveal region and the far periphery. The fovea proper is devoid of astrocytes. Employing high‐resolution confocal microscopy, we could demonstrate that astrocytes from manifold contacts to blood vessels. In addition, bundles of NFL astrocyte processes are co‐localized with axon bundles, individual astrocytes forming contacts to several axon bundles. In contrast, a similar affinity of astrocytes to ganglion cell somata was never observed. Thus, our data confirm and extend the current knowledge of morphology and putative function of astrocytes in mammalian and especially the primate retina. © 1993 Wiley‐Liss, Inc.