bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium‐binding proteins as markers for subpopulations of GABAergic neurons in monkey striate cortex
Authors: Van Brederode J. F. M. , Mulligan K. A. , Hendrickson A. E. 
Published: January 2005

AbstractRecent studies have shown that the presence of immunoreactivity for parvalbumin (PV‐IR) and calbindin‐D 28k (Cal‐IR) can be used as markers for certain types of gamma‐aminobutyric acid (GABA) immunoreactive interneurons in monkey cerebral cortex. Little quantitative information is available regarding the features that distinguish these two subpopulations, however. Therefore, in this study we localized PV‐IR and Cal‐IR neurons in Macaca monkey striate cortex and analyzed quantitatively their laminar distribution, cell morphology, and co‐localization with GABA by double‐labeling immunocytochemistry. PV‐IR was found in nonpyramidal cells in all layers of the cortex, although PV‐IR cells in layer 1 were rare. In contrast, Cal‐IR was found mainly in nonpyramidal cells in two bands corresponding to layers 2–3 and 5–6. We found very few double‐labeled PV‐IR/Cal‐IR cells but confirmed that almost all PV‐IR and Cal‐IR cells are GABAergic. Overall, 74% of GABA neurons in striate cortex displayed PV‐IR compared to only 12% that displayed Cal‐IR and 14% that were GABA‐IR only. Quantitative analysis indicated that the relative proportion of GABA cells that displayed PV‐IR or Cal‐IR showed conspicuous laminar differences, which were often complementary. Cell size measurements indicated that PV‐IR/GABA cells in layers 2–3 and 5–6 were significantly larger than Cal‐IR/GABA cells. Analysis of the size, shape, and orientation of stained cell bodies and proximal dendrites further demonstrated that each subpopulation contained several different types of smooth stellate cells, suggesting that Cal‐IR and PV‐IR are found in functionally and morphologically heterogeneous subpopulations of GABA neurons.There was a thick bundle of PV‐IR axons in the white matter underlying the striate but not prestriate cortex. PV‐IR punctate labeling matched the cytochrome oxidase staining pattern in layers 4A and 4C, suggesting that PV‐IR is present in geniculocortical afferents as well as intrinsic neurons. Cal‐IR neuropil staining was high in layers 1, 2, 4B, and 5, where cytochrome oxidase staining is relatively low. We did not find a preferential localization of either PV‐IR or Cal‐IR cell bodies in any cytochrome oxidase compartments in layers 2–3 of the cortex. These findings indicate that PV and Cal are distributed into different neuronal circuits.
Visual projections induced into the auditory pathway of ferrets. I. Novel inputs to primary auditory cortex (AI) from the LP/pulvinar complex and the topography of the MGN‐AI projection
Authors: Pallas Sarah L. , Roe Anna W. , Sur Mriganka 
Published: January 2005

AbstractThe organization of cortical circuitry responsible for processing sensory information is a subject of intense examination. However, it is not known whether cortical cells in different sensory cortices process information in a way that is specific to the modality of their input, or whether there are commonalities in processing circuitry across different cortices. In our laboratory, this question has been investigated at the level of the geniculocortical pathway by routing information of one sensory modality into the processing circuitry of another modality. Appropriate early lesions cause growth of retinal axons into the auditory thalamus (MGN) (Sur et al., Science 242: 1437, '88). Previously, we have established that the MGN carries the resulting visual information on to primary auditory cortex (AI), which thus contains visually responsive neurons and a topographic representation of the retina (Roe et al., Soc. Neurosci. Abstr. 14:460, '88; Sur et al., Science 242:1437, '88), In this paper, we describe anomalous projections from the dorsal part of the thalamus, specifically the lateral posterior/pulvinar complex, into AI. This result demonstrates that thalamic neurons belonging to one modality can be induced to project to cortex that is normally of a different modality. In addition, we have studied in detail the nature of the MGN to AI projection in these animals as compared to the normal projection. The MGN to AI projection appears to be unaltered by the lesions; the location and topography of labelled cells are similar to that in normal animals. Because the MGN to AI projection is still highly divergent along the “isofrequency” dimension when compared to the tonotopic dimension, our data suggest that visual topography in the cortical map is created within the auditory cortex, perhaps by activity‐dependent sharpening of the retinal representation during development.
Growth of injured rabbit optic axons within their degenerating optic nerve
Authors: Lavie V. , Murray M. , Solomon A. , Ben‐Bassat S. , Belkin M. , Rumelt S. , Schwartz M. 
Published: January 2005

AbstractSpontaneous growth of axons after injury is extremely limited in the mammalian central nervous system (CNS). It is now clear, however, that injured CNS axons can be induced to elongate when provided with a suitable environment. Thus injured CNS axons can elongate, but they do not do so unless their environment is altered.We now show apparent regenerative growth of injured optic axons. This growth is achieved in the adult rabbit optic nerve by the use of a combined treatment consisting of: (1) supplying soluble substances originating from growing axons to the injured rabbit optic nerves (Schwartz et al., Science, 228:600–603, 1985), and (2) application of low energy He‐Ne laser irradiation, which appears to delay degenerative changes in the injured axons (Schwartz et al., Lasers Surg. Med., 7:51–55. 1985; Assia et al., Brain Res., 476:205–212, 1988). Two to 8 weeks after this treatment, unmyelinated and thinly myelinated axons are found at the lesion site and distal to it. Morphological and immunocytochemical evidence indicate that these thinly myelinated and unmyelinated axons are growing in close association with glial cells. Only these axons are identified as being growing axons. These newly growing axons traverse the site of injury and extend into the distal stump of the nerve, which contains degenerating axons. Axons of this type could be detected distal to the lesion only in nerves subjected to the combined treatment. No unmyelinated or thinly myelinated axons in association with glial cells were seen at 6 or 8 weeks postoperatively in nerves that were not treated, or in nerves in which the two stumps were completely disconnected. Two millimeters distal to the site of injury, the growing axons are confined to a compartment comprising 5%–30% of the cross section of the nerve. A temporal analysis indicates that axons have grown as far as 6 mm distal to the site of injury, by 8 weeks postoperatively. Anterograde labeling with horseradish peroxidase, injected intraocularly, indicates that some of these newly growing axons arise from retinal ganglion cells.
Cytoarchitecture and fiber connections of the nucleus lateralis valvulae in the carp (Cyprinus carpio)
Authors: Ito Hironobu , Yoshimoto Masami 
Published: January 2005

AbstractThe cytoarchitecture and fiber connections of the nucleus lateralis valvulae of the carp (Cyprinus carpio) were studied by Nissl, Bodian, Golgi, and horseradish peroxidase methods. Chief cells composing the nucleus lateralis valvulae (NLV) are small and granular, and their axons terminate in the cerebellum. These neurons have no dendrite, and the cell body is enveloped in a single terminal of afferent fibers to the NLV. In order to observe local cell clustering, the NLV was three‐dimensionally reconstructed with the aid of a computer image analysis system.Afferent sources to the NLV were the nucleus pretectalis superficialis pars magnocellularis (Northcutt and Braford, '84: Brain Res. 296:181–184), nucleus ventromedialis thalami (Ito et al., '86: J. Comp. Neurol 250:215–227), and the inferior lobe. The NLV projects to the inferior lobe and the cerebellum. In particular, the cerebellar projections were strong and topographically arranged. Some larger neurons lying just beneath the NLV, some of which were intermingled with the NLV neurons, projected to the torus longitudinalis.On the basis of the local cell clustering as well as NLV‐cerebellar connections, three subdivisions of the NLV could be recognized, i.e., anterior, central, and posterior portions. The posterior portion was further subdivided into lateral and medial parts.
Auditory brainstem in the mole (Mogera): Nuclear configurations and the projections to the inferior colliculus
Authors: Kudo Motoi , Nakamura Yasuhisa , Tokuno Hironobu , Kitao Yasuko 
Published: January 2005

AbstractAnatomical organization of the central auditory system in the mole was studied at the lower brainstem levels. The cyto‐, myelo‐, and chemoarchitectures were examined in Nissl, myelin, and acetylcholinesterase stained materials, and then the origins of the ascending afferents to the inferior colliculus (IC) were identified by injecting wheatgerm agglutinin conjugated to horseradish peroxidase (WGA‐HRP) into the unilateral IC and processing the tissue according to the standard retrograde tracing techniques. The results indicate that the auditory nuclei and pathways in the lower brainstem of the mole conform to the basic plan common to many other mammals. Nevertheless, several characteristic features are evidenced in the present study: (1) in the cochlear nucleus (CochN), granule cell fields are very large in both the ventral (VCN) and dorsal (DCN) nuclei; among several populations of neurons, fusiform cells in the DCN, multipolar cells in the VCN and DCN, and small spherical cells in the VCN project to the IC directly, (2) in the superior olivary complex (SOC), the medial nucleus (MSO) is well developed in comparison with that in the hedgehog, the opossum, the mouse, and the rat, although the general configuration of the SOC is similar to that in those mammals, most strikingly, the MSO projects to the IC bilaterally in the mole, and (3) the nuclei of the lateral lemniscus (NLL) show a great development and consist of three well‐differentiated parts of the dorsal, intermediate, and ventral nuclei. The projections from these subnuclei to the IC conform to the basic mammalian plan.
Direct catecholaminergic innervation of primate spinothalamic tract neurons
Authors: Westlund K. N. , Carlton S. M. , Zhang D. , Willis W. D. 
Published: January 2005

AbstractCatecholaminergic axonal varicosities identified by immunocytochemical staining for dopamine‐beta‐hydroxylase were observed at the light microscopic level apposing the somata of retrogradely labeled spinothalamic tract neurons in the monkey spinal cord, Three retrogradely labeled and two intracellularly labeled spinothalamic neurons were serially sectioned and examined at selected intervals at the electron microscopic level. Electron microscopic study revealed that axonal boutons directly contacted the somata and/or dendrites of lamina I, IV, and V spinothalamic tract neurons. All of the profiles apposing one of the retrogradely labeled lamina I spinothalamic tract neurons were categorized from eight planes of section spaced at 1‐μm intervals. Of the 305 profiles counted that were adjacent to this soma, 17 (5.6%) stained positively for dopamine‐beta‐hydroxylase. Of these 17 appositions, three were followed in serial sections to confirm that they had synaptic thickenings and alignment of vesicles along the membrane contacting the spinothalamic tract soma. Catecholaminergic boutons were observed apposing the somata and dendrites of intracellularly filled STT cells characterized as high threshold and wide dynamic range neurons. These observations clearly indicate a direct innervation of spinothalamic tract neurons by catecholaminergic neurons, providing anatomical data to support previous physiological findings demonstrating that catecholamines modulate nociceptive transmission.
Morphology of a population of mechanosensory ascending interneurones in the metathoracic ganglion of the locust
Authors: Newland Philip L. 
Published: January 2005

AbstractA population of ascending interneurones with cell bodies in the metathoracic ganglion of the locust is described. Interneurones are characterised by their morphology (revealed by intracellular cobalt injection) and by their physiological responses to afferent stimulation. All interneurones have their somata in the ventral cortex of the ganglion, in an area just posterior to the medial tracheae. On the basis of gross morphology the interneurones can be divided into three groups: (1) those that have a main area of fine neurites ipsilateral to the soma and an ipsilateral ascending axon; (2) interneurones that also have their main neurites ipsilateral to the soma but have a contralateral ascending axon, and (3) interneurones that have their main neurites and an ascending axon contralateral to the soma. All interneurones are excited by stimulation of sensory receptors on the hind leg ipsilateral to the main neurites. Interneurones receiving excitatory inputs from tactile hairs on the hind leg have branches in the most ventral neuropil, whereas interneurones receiving input from leg proprioceptors have branches in the more intermediate and dorsolateral neuropil. The branching pattern of an interneurone and the size and position of the receptive field on the leg are correlated. Interneurones with extensive ventral branches have extensive receptive fields; interneurones with restricted branching patterns have restricted receptive fields. The position of the ventral branching reflects the position of the receptive field on the leg. An interneurone with a receptive field restricted to the femur has ventral branches in an anterior position in the ganglion; an interneurone with a receptive field restricted to the tarsus has ventral branches in a more posterior position.
Renewal of electrotonic synapses in teleost retinal horizontal cells
Authors: Vaughan Dana K. , Lasater Eric M. 
Published: January 2005

AbstractIn teleost retinas, the somata of same‐type cone horizontal cells are electrically coupled via extensive gap junctions, as are the axon terminals of same‐type cells. This coupling persists throughout the animal's life and is modulated by dopamine and conditions of light‐ vs. dark‐adaptation. Gap junction particle density in goldfish horizontal cell somata has also been shown to change under these conditions, indicating that these junctions are dynamic. We have used electron microscopy to examine gap junctions in bass horizontal cells with a fixation method that facilitates detection of gap junctions. Annular gap junction profiles were observed in the somatic cytoplasm of all cone horizontal cell types in both light‐ and dark‐adapted animals. Serial sections showed that most profiles represented gap junction vesicles free within the cytoplasm; the remainder represented vesicles still attached to extensive plasma membrane gap junctions by a thin cytoplasmic neck, suggestive of an intermediate stage in endocytosis. Observations of gap junction vesicles containing fragments of gap junctional membrane and/or fused with lysosomal bodies further supported this hypothesis. Because gap junctions persist between the horizontal cells, we propose that gap junction endocytosis and lysosomal degradation are balanced by addition of new junctions. While endocytosis has been widely demonstrated to serve in programmed removal of gap junctions (without subsequent replacement), from both nonneuronal cells and developing neurons, this study indicates that it can also function in the renewal of electrical synapses in the adult teleost retina, where gap junction elimination is not the goa.
Glycinergic contacts in the outer plexiform layer of the Xenopus laevis retina characterized by antibodies to glycine, GABA, and glycine receptors
Authors: Smiley John F. , Yazulla Stephen 
Published: January 2005

AbstractElectrophysiological experiments have predicted a direct synaptic input from glycinergic interplexiform cells (IPCs) to GABAergic horizontal cells in the Xenopus retina. However, previous ultrastructural studies failed to demonstrate this input. Here, we used three immunocytochemical approaches to investigate this issue. First, double‐label postembedding immunocytochemistry with GABA‐ and glycine‐like immunoreactivity (GABA‐LI and glycine‐LI) was used to study possible interactions of the glycinergic IPC with GABAergic horizontal cells. Processes postsynaptic to glycine‐LI IPC terminals in the outer plexiform layer (OPL) fell into two groups, small microtubule‐filled processes and larger electron‐lucent processes with sparse microtubules and occasional mitochondria. In no case did we find glycine‐LI synapses onto GABA‐LI cells or processes. Second, pre‐embedding immunocytochemistry was used to label GABA‐LI cells and processes in the OPL. GABA‐LI was sparse in horizontal cell axons and more intense in horizontal cell somas and in small processes. In agreement with our first set of experiments, GABA‐LI profiles did not receive input from conventional synapses. Third, we localized glycine‐receptor‐like immunoreactivity (GlyR‐LI) to several types of apparent synapses in the OPL. As expected, it was found at IPC synapses. Unexpectedly, GlyR‐LI was also subsynaptic at photoreceptor synapses onto second order neurons, both at ribbon and basal junction type synapses. At least some of the GlyR‐LI photoreceptor synapses were from cones. Also, GlyR‐LI was apposed to photoreceptors and to unidentified small diameter processes, where no other indication of synaptic input was evident. Because glycine‐LI is not found in photoreceptors, we suggest that glycine receptors at photoreceptor synapses are stimulated by glycine that diffuses from other sites, possibly from IPCs. This interpretation is consistent with available physiological studies of glycinergic effects in this retina.
Ultrastructure of cholinergic synaptic terminals in the thalamic anteroventral, ventroposterior, and dorsal lateral geniculate nuclei of the rat
Authors: Hallanger Ann E. , Price Steve D. , Lee Henry J. , Steininger Teresa L. , Wainer Bruce H. 
Published: January 2005

AbstractThe principal relay nuclei of the thalamus receive their cholinergic innervation from two midbrain cholinergic groups: the pedunculopontine tegmental nucleus and the laterodorsal tegmental nucleus. The different thalamic nuclei exhibit populations of cholinergic axons which vary in density and morphology when examined at the light microscopic level. However, the ultrastructure of the cholinergic terminals in different thalamic nuclei has not been described. This study was undertaken to confirm that synaptic contacts are formed by cholinergic axons in several principal thalamic relay nuclei, to describe their ultrastructural morphology, and to identify the types of postsynaptic elements contacted by cholinergic synaptic terminals. The thalamic nuclei examined in this study are the dorsal lateral geniculate nucleus, ventroposteromedial nucleus, ventroposterolateral nucleus, and anteroventral nucleus.Our results confirm that cholinergic axons form synaptic terminals in these thalamic nuclei. Cholinergic synaptic terminals contact structures outside the characteristic synaptic glomeruli, are never postsynaptic, and have morphologies and postsynaptic targets which differ among the thalamic nuclei. In the ventroposterior nuclei, cholinergic terminals form asymmetric synaptic contacts onto larger dendrites in the extraglomerular neuropil. In the anteroventral nucleus, cholinergic terminals form both symmetric and asymmetric synaptic contacts onto dendrites and somata. Cholinergic terminals in the anteroventral nucleus are larger than those in other nuclei. In the dorsal lateral geniculate nucleus, cholinergic terminals contact both somata and dendrites in the extraglomerular neuropil, but the synaptic contacts in this nucleus are symmetric in morphology.
Topography of ganglion cells in human retina
Authors: Curcio Christine A. , Allen Kimberly A. 
Published: January 2005

AbstractWe quantified the spatial distribution of presumed ganglion cells and displaced amacrine cells in unstained whole mounts of six young normal human retinas whose photoreceptor distributions had previously been characterized. Cells with large somata compared to their nuclei were considered ganglion cells; cells with small somata relative to their nuclei were considered displaced amacrine cells. Within the central area, ganglion cell densities reach 32,000‐‐38,000 cells/mm2 in a horizontally oriented elliptical ring 0.4‐‐2.0 mm from the foveal center. In peripheral retina, densities in nasal retina exceed those at corresponding eccentricities in temporal retina by more than 300%; superior exceeds inferior by 60%. Displaced amacrine cells represented 3% of the total cells in central retina and nearly 80% in the far periphery. A twofold range in the total number of ganglion cells (0.7 to 1.5 million) was largely explained by a similar range in ganglion cell density in different eyes. Cone and ganglion cell number were not correlated, and the overall cone: ganglion cell ratio ranged from 2.9 to 7.5 in different eyes. Peripheral cones and ganglion cells have different topographies, thus suggesting meridianal differences in convergence onto individual ganglion cells.Low convergence of foveal cones onto individual ganglion cells is an important mechanism for preserving high resolution at later stages of neural processing. Our improved estimates for the density of central ganglion cells allowed us to ask whether there are enough ganglion cells for each cone at the foveal center to have a direct line to the brain. Our calculations indicate that (1) there are so many ganglion cells relative to cones that a ratio of only one ganglion cell per foveal cone would require fibers of Henle radiating toward rather than away from the foveal center; and (2) like the macaque, the human retina may have enough ganglion cells to transmit the information afforded by closely spaced foveal cones to both ON‐ and OFF‐channels. Comparison of ganglion cell topography with the visual field representation in V1 reveals similarities consistent with the idea that cortical magnification is proportional to ganglion cell density throughout the visual field.
Cortical neurons expressing the cholecystokinin gene in the rat: Distribution in the adult brain, ontogeny, and some of their projections
Authors: Burgunder J.‐M. , Young W. S. 
Published: January 2005

AbstractRecent studies of neuronal cholecystokinin (CCK) expression performed with more sensitive techniques have demonstrated that the distribution of the expression of this peptide is more widespread than previously thought. In the present study, hybridization histochemistry was used to map cortical neurons expressing the CCK gene in adult and developing rats. Retrograde tracing with Fluorogold in combination with hybridization histochemistry was used to demonstrate some of the projections of these neurons.Neurons expressing the CCK gene were found in all areas of the neo‐ and allocortices. They were of several morphological types, including pyramidal neurons, and were found in almost all layers, albeit at different relative numbers and with different levels of expression. Generally, layers II and III, deep layer V, and layer VI had many neurons expressing CCK mRNA.Cortical CCK expression was first detected on the 15th day of gestation in the primordial plexiform layer. Expression developed thereafter in a regular and continuous fashion until an adult‐like pattern was present on the 21st day after birth.Cortical neurons containing CCK mRNA were found in almost all the projections studied. Many neurons in both neo‐ and allocortical areas with cortico‐cortical, associational, and commissural pathways contained CCK mRNA. Similarly, numerous corticostriatal neurons contained CCK mRNA; however, only a few corticothalamic neurons expressed CCK mRNA. These results demonstrate that in the rat cortex the distribution of projection neurons expressing CCK is much more widespread than had been previously shown and will stimulate further investigations into the role of CCK in these neurons.