bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monoclonal antibodies to the turtle cortex reveal neuronal subsets, antigenic cross‐reactivity with the mammalian neocortex, and forebrain structures sharing a pallial derivation
Authors: Kriegstein Arnold R. , Shen Janet M. , Eshhar Nomi 
Published: January 2005

AbstractThe dorsal cortex of the pond turtle (Pseudemys scripta) is a relatively simple structure consisting of two principal classes of neurons that occupy three distinct layers. Morphological, pharmacological, and physiological data suggest many similarities to the mammalian neocortex, rendering it an interesting preparation for comparative studies. We prepared monoclonal antibodies to the turtle dorsal cortex by immunizing mice with cortical tissue from adult turtles. Twelve antibodies were generated that recognize specific components of the turtle cortex. Among these, eight antibodies label only neurons and four label only ependymal glial cells. Differences in tissue staining pattern and immunoglobulin class suggest a heterogeneity of antigenic specificity among the antibodies.The staining patterns of three of our antibodies are described. TC3, like all other neuron‐marking antibodies generated, labels a subset of both pyramidal and stellate cell types. It also cross‐reacts with a subset of mammalian cortical neurons and labels them with a pattern similar to that observed in the turtle cortex. TC5 stains ependymal cells and their glial processes in the turtle cortex, and cross‐reacts with fibrous astrocytelike processes in mammalian neocortical white matter. TC9 appears to recognize antigens of neurons sharing a pallial derivation in turtle.
Glial patterns during early development of antennal lobes of Manduca sexta: A comparison between normal lobes and lobes deprived of antennal axons
Authors: Oland Lynne A. , Tolbert Leslie P. 
Published: January 2005

AbstractThe synaptic neuropil of the olfactory (antennal) lobe of the moth Manduca sexta is subdivided into histologically conspicuous structures called glomeruli that are typical of olfactory systems in vertebrates and invertebrates. Each glomerulus consists of the highly branched neuritic arbors of both primary olfactory axons and antennal‐lobe neurons, bounded by a nearly complete envelope of glial cells. We have studied events occurring during the first half of metamorphic adult development. The first signs of organization of the neuropil into glomeruli are changes in glial cells. Prior to the ingrowth of olfactory axons from the antenna, glial cells form a continuous border around the neuropil. When olfactory axons begin to reach the lobe, glial cells embark on a stereotyped series of changes: the border becomes disrupted, glial cells begin to proliferate and extend processes into the outer regions of the neuropil, and some glial cells migrate toward the center of the neuropil. Shortly thereafter, glomeruli emerge from the neuropil, delineated by glial cells. If, however, afferent axons are prevented from ever reaching the antennal lobe, glomeruli never develop and the glial cells remain almost entirely restricted to a thick layer bordering the neuropil. Thus sensory axons have a direct influence not only on neuronal but also on glial differentiation. Our results lead us to suggest that the glial cells may be in a position to act as intermediaries in developmental interactions between sensory axons and antennal‐lobe neurons.
Topographic organization of the orientation column system in large flat‐mounts of the cat visual cortex: A 2‐deoxyglucose study
Authors: Löwel Siegeid , Freeman Brian , Singer Wolf 
Published: January 2005

AbstractWe developed a flat‐mount technique in order to visualize, without additional reconstruction, the system of orientation columns in the cat visual cortex by using 2‐deoxyglucose‐autoradiography.Experimental animals were injected with 2‐deoxyglucose and then stimulated for 45–60 minutes either with vertical or horizontal or oblique gratings alone or with vertical and horizontal gratings presented in alternation.In both areas 17 and 18 stimulation with either vertical or horizontal or oblique stripes produced similar and highly ordered patterns of parallel bands of increased 2‐deoxyglucose uptake that were perpendicular to the boundaries of the areas. In area 17 they occasionally extended without interruption from the 17/18 border on the top of the lateral gyrus to the monocular segment in the splenial sulcus. Superposition of serial sections revealed that these bands were present in all cortical layers and in precise register along lines orthogonal to the lamination. The center‐to‐center spacing of the bands was 1.0–1.1 mm in area 17 and 1.2–1.4 mm in area 18. Stimulation with alternating vertical and horizontal contours led to a pattern the general organization of which resembled that induced by a single orientation but the spacing of which was reduced by a factor of 0.5. This strongly supports the concept that orientation is mapped in a system of parallel bands and argues against a recently formulated hypothesis that iso‐orientation bands extend like spokes from centers that lack orientation selectivity (Braitenberg and Braitenberg, Biol. Cybern, 33:179–186, '79).Another characteristic feature, revealed by the flat‐mount technique, was a periodic variation of 2‐deoxyglucose uptake along the bands that gave them a beaded appearance. The mean center‐to‐center distance between adjacent beads on the same band was in the range of 0.9–1.2 mm and remained unchanged when horizontal and vertical gratings were presented in alternation. We propose that these beads reflect another columnar system whose features have yet to be determined.
Time course of the reaction of glial fibers in the somatosensory thalamus after lesions in the dorsal column nuclei
Authors: Wells Joseph , Tripp Leslie N. 
Published: January 2005

AbstractThese experiments were designed to examine the relationship of glial hypertrophy to the time course of reactive synaptogenesis in the ventral posterolateral nucleus of the rat thalamus after lesions in the dorsal column nuclei. Because synaptogenesis is delayed for 30 days following lesions of the dorsal column nuclei, the initial hypertrophy of the glial processes in response to degeneration can be separated temporally from synaptogenesis. Glial hypertrophy was determined by measuring the relative area of neuropil occupied by profiles of glial processes on electron micrographs. The initial glial hypertrophy reached its peak 2 days after the lesion. However, at the time when synaptogenesis began, the area of neuropil occupied by glial processes was less than normal. When synaptogenesis was complete, the area of glial profiles also returned to normal. The role of glia in synaptogenesis was clearly different from its role in response to degeneration. In those systems such as the hippocampus, in which reactive synaptogenesis starts early in the recovery sequence, the relationship of glia to synaptogenesis may be masked by the glial response to degeneration.Hypertrophy of glial processes after lesions of other afferent pathways to the ventral posterolateral nucleus was compared to the hypertrophy following lesions of the dorsal column nuclei in order to see if there was a special relationship between glia and the lemniscal afferents to the ventral posterolateral nucleus. Lesions were placed in the medial lemniscus, somatosensory cortex, and the mesencephalon in addition to the dorsal column nuclei. The area of neuropil occupied by the glial processes expanded markedly after each of the lesions. The initial glial hypertrophy was relatively independent of the size of the lesion in the dorsal column nuclei, the degree of degeneration in the ventral posterolateral nucleus, the proximity of the lesion to the ventral posterolateral nucleus, and the site of the lesion.
Postembryonic neurogenesis in the CNS of the tobacco hornworm, Manduca sexta. I. Neuroblast arrays and the fate of their progeny during metamorphosis
Authors: Booker Ronald , Truman James W. 
Published: January 2005

AbstractThe tobacco hornworm Manduca sexta exhibits dramatic changes in its body morphology and behavior as it is transformed from a larva into an adult during metamorphosis. Accompanying these changes is an extensive reorganization of this moth's central nervous system (CNS), which involves both the death and remodeling of subsets of larval neurons. We report here that the segmental ganglia of the larvae also contain a stereotyped array of identifiable neuronal stem cells (neuroblasts) that contribute over 2,000 cells to each thoracic ganglion and about 40–80 cells to each abdominal ganglion. The distribution of these neuroblasts varies in a segment specific manner. Dormant neuroblasts are found adjacent to the neuropil in late embryos and early first instar larvae. After the molt to the second instar, these cells enlarge and begin to divide. Through a series of asymmetrical divisions, each neuroblast generates a discrete nest of 10–90 progeny by the end of larval life. These progeny (the imaginal nest cells) are developmentally arrested at an early stage of differentiation and remain so until metamorphosis. At the onset of metamorphosis, a wave of cell death sweeps through the nests, the extent of the death being much greater within the abdominal nests than in the thoracic nests. The surviving imaginal nest cells then differentiate to become functional neurons that are incorporated into the adult CNS.
Hair cell innervation by spiral ganglion neurons in the mouse
Authors: Berglund A. M. , Ryugo D. K. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) was injected extracellularly into the auditory nerve of adult mice so that the enzyme could infuse individual spiral ganglion neurons. Forty‐two well‐stained neurons were reconstructed through serial sections from their cell bodies to peripheral terminations in the organ of Corti with the aid of a light microscope and drawing tube. No neuron was observed to innervate both inner and outer hair cells (IHCs and OHCs). Previous observations from neonatal mammals that reported that IHCs and OHCs were innervated by the same neuron are thus presumed to describe a transient developmental phenomenon.Two populations of spiral ganglion neurons were determined on the basis of the differences in receptor innervation. The type I neurons innervated exclusively IHCs by way of thick (1–2 μm) radial fibers, whereas the type II neurons innervated only OHCs by way of thin (∼0.5 μm) outer spiral fibers. Certain features of the peripheral process in the vicinity of the cell body were highly correlated with fiber type. This pattern of separate innervation of IHCs and OHCs by type I and type II neurons, respectively, may represent the general plan of afferent organization for the adult mammalian cochlea.
Topography of the corticofugal projection to the lateral reticular nucleus in the monkey
Authors: Wiesendanger R. , Wiesendanger M. 
Published: January 2005

AbstractThe cortical projection to the lateral reticular nucleus (LRN) was explored in monkeys prepared for autoradiography and horseradish peroxidase (HRP) histochemistry. An unambiguous projection was revealed only in cases with injections of the precentral forelimb and hindlimb areas. The forelimb area projection occupied centromedial segments, the hindlimb area projection occupied ventrolateral segments of the LRN with very little overlap. Some sparse labeling was also seen with injections of the supplementary motor area (SMA), but only when the lectin‐bound tracer HRP was injected and not when autoradiography was used. Retrogradely labeled cortical cells occupied a larger cortical area in one case with injection of free HRP into the LRN. Since the additional expanse of cortex, however, was not examined in anterograde cases, and since the injected marker substance had diffused to neighboring structures, the significance of the labeled cells outside the precentral motor cortex is questionable. There was no evidence for a projection from the precentral face area with either anterograde tracing method. The corticoreticular projection was bilateral and only slightly more marked contralateral to the injection. The labeling was largely confined to the magnocellular division with minor amounts in the parvicellular division (especially in the hindlimb cases). The subtrigeminal portion was spared in all cases. It is concluded that the LRN constitutes another somatotopically organized precerebellar nucleus relaying signals from the motor cortex to the cerebellum. Compared with the corticopontocerebellar parthway in monkeys, however, the LRN is only a minor component of the corticocerebellar transmission system.
Structural features of the terminal loop region of frog retinal rod outer segment disk membranes: I. Organization of lipid components
Authors: Corless Joseph M. , Fetter Richard D. , Costello M. Joseph 
Published: January 2005

AbstractWe have applied thin sectioning and freeze‐fracture techniques to investigate the terminal loop structure of photoreceptive disks in frog retinal rod outer segments. Our studies of this region demonstrate a highly curved terminal loop bilayer that is continuous with both lamellar bilayers of the disk, and equivalent to them in dimensions and staining properties. Rhodopsin, however, appears to be excluded from this region of high curvature.
Distribution of carbonic anhydrase activity in neurons of the rat
Authors: Wong Vivien , Barrett Charles P. , Donati Edward J. , Guth Lloyd 
Published: January 2005

AbstractCertain neurons of dorsal root ganglia (DRG) and some fibers of the sciatic nerve contain histochemically demonstrable carbonic anhydrase activity. Since the distribution of this enzyme throughout the nervous system has not yet been evaluated systematically, we conducted a comprehensive histochemical survey focusing particularly on structures derived from the neural crest and nonneural crest ectoderm. In the peripheral nervous system, we observed carbonic anhydrase activity in some, but not all, neurons of dorsal root, trigeminal, celiac, and myenteric ganglia as well as in glial cells throughout the CNS. Some neurons of the nodose ganglion also showed carbonic anhydrase activity. In all first order sensory ganglia that were studied, the enzyme was found only in large (50 μm or above) and medium (20–50 μm) size neurons; in the case of spinal ganglia, the reactive neurons constituted approximately 30% of the total neuronal population. Of these reactive neurons, 56% were heavily stained and 44% were moderately stained. Several possible roles for neuronal carbonic anhydrase are considered.
Serotonin and dopamine in the retina of a lizard
Authors: Engbretson Gustav A. , Battelle Barbara‐Anne 
Published: January 2005

AbstractThe objective of this paper is to report the presence and localization of serotonin and dopamine in the retina of the lizard Uta stansburiana. High performance liquid chromatography and electrochemical detection were used to identify and quantitate the two amines. Both compounds are present as endogenous molecules in this retina and are found in concentrations similar to those reported in other non‐mammalian retinas. The same methods were employed to confirm, in the isolated retina, the synthesis of serotonin from precursor, tryptophan.Immunocytochemical methods were used to localize, in the neural retina, serotonin and the rate‐limiting enzyme of dopamine synthesis, tyrosine hydroxylase. Serotonin immunoreactivity was observed in bistratified amacrine cells (ca.7 μU dia.) with processes ramifying in sublayers 1,4, and 5 of the inner plexiform layer. Immunoreactivity to tyrosine hydroxylase was observed in a different population of bistratified amacrine cells (ca. 11 μ dia.) that had processes ramifying in sublayers 1 and 5 (and perhaps 3) of the inner plexiform layer. The enzymes for further metabolism of dopamine were not found in the retina of this lizard by immunocytochemical methods.The results of this research suggest that only single classes of serotoninergic and dopaminergic neurons are present in the retina of U. stansburiana. This retina might, therefore be an appropriate place in which to investigate the functioning of these amines in visual information processing.
Action and location of neuropeptide tyrosine (Y) on hippocampal neurons of the rat in slice preparations
Authors: Haas H. L. , Hermann A. , Greene R. W. , Chan‐Palay V. 
Published: January 2005

AbstractThe action of bath applied NPY (1–1,000 nM) was investigated on hippocampal slices of the rat with extra‐and intracellular recording. Neuropeptide Y (NPY) at 10–1,000 nM caused a concentration‐dependent, long–lasting reduction of excitatory postsynaptic potentials (EPSPs) in the hippocampal subfield CA1 and the area dentata, and an even stronger reduction of population spikes. Paired pulse experiments with low intensity, stimulation‐evoked PSPs showed a marked increase in facilitation in the presence of NPY, indicating a presynaptic action. Spontaneous burst firing of CA1 pyramidal cells in low calcium, high magnesium medium was reduced, indicating a partially postsynaptic inhibitory action of NPY on their dendrites. Intracellular recording from CA1 somata during NPY administration revealed a reduction of the amplitudes of excitatory–inhibitory postsynaptic potential (EPSP–IPSP) sequences in the absence of changes in membrane potential and conductance. Accommodation of firing during long depolarizing pulses and afterhyperpolarizations were unchanged. The innervation pattern of NPY immunoreactive fibers in the same regions was studied in slices adjacent to the ones used for electrophysiology by using antisera against NPY and light and electron microscopy. There is a dense innervation of CA1 by NPY‐immunoreactive axons and terminals, particularly in the stratum moleculare. NPY‐immunoreactive neurons are present in the stratum oriens and pyramidale. The NPY labeled axons of the stratum moleculare participate in numerous synaptic contacts with the smaller dendritic elements in this layer, many of which belong to pyramidal neurons. These observations provide evidence for a dendritic NPY‐immunoreactive innervation of CA1 neurons, which is in keeping with the electrophysiological effects of NPY on pyramidal neurons. We conclude that NPY has inhibitory actions, presynaptically to reduce excitatory transmitter release and at a distal dendritic site to reduce postsynaptic excitability. The physiological significance of the NPY effects appears to be a long‐lasting depression of excitatory input to pyramidal cell dendrites controlled through local interneurons and through other extrinsic projections of NPY neurons from elsewhere in the brain.
Organization of intracortical and commissural connections in somatosensory cortical areas I and II in the raccoon
Authors: Herron Paul , Johnson John Irwin 
Published: January 2005

AbstractThe organization of intracortical and callosal projecting cell bodies was examined in somatosensory representation areas I (SI) and II (SII) of the raccoon by use of horseradish peroxidase (HRP) or horseradish peroxidase‐wheat germ agglutin (HRP‐WHA) HRP and HRP‐WHA were injected into commissurally and noncommissurally connected subdivisions of SI and SII. Injection sites in SII were identified electrophysiologically. Results were obtained from transverse sections in which the HRP was visualized with the aid of the substrates dihydrochlorobenzidine or tetramethyl benzidine in the presence of hydrogen peroxidase.The principal findings were the following: (1) there are reciprocal connections between SI and SII; (2) in SI the intracortically projecting cell bodies and terminals are located primarily in sulcal cortex; (3) intracortically projecting neurons in SI are located primarily in layers III whereas in SII they are located principally in layers III and V; (4) there are connections between disparate areas within SI; and (5) there are intracortical connections between callosum‐connected and acallosal regions in SII. These results are discussed with regard to the results of mapping studies of the SI, the significance of intracortical connections to the formation of sulci in SI, and the possible roles of nonhomotopic connections in the intermanual transfer of learning.
Development of the precerebellar nuclei in the rat: III. The posterior precerebellar extramural migratory stream and the lateral reticular and external cuneate nuclei
Authors: Altman Joseph , Bayer Shirley A. 
Published: January 2005

AbstractSequential thymidine radiograms from rats injected on day E15 and killed thereafter at daily intervals up to day E22 were analyzed to trace the migratory routes and settling patterns of neurons of the lateral reticular nucleus and the external cuneate nucleus. The neurons of the lateral reticular and external cuneate nuclei originate in the primary precerebellar neuroepithelium at the same site as the inferior olivary neurons but follow a different migratory route. The labeled young neurons that are produced on day E15 (the last one‐third of the total) join the posterior precerebellar extramural migratory stream. The cells move circumferentially over the wall of the medulla in a ventral direction and by day E17 reach the midline and cross it beneath the inferior olive. The crossing cells apparently continue to migrate circumferentially on the opposite side. One complement of these cells begins to form a ventrolateral extramural condensation on day E19. By day E20 some cells begin to penetrate the parenchyma and settle as neurons of the lateral reticular nucleus. The settling of the lateral reticular neurons continues on the following day, and by day E22 all the cells destined for the lateral reticular nucleus have penetrated the parenchyma. A dorsomedial‐to‐ventrolateral neurogenetic gradient is indicated for the settling lateral reticular neurons.Another complement of migrating cells continues dorsally and forms a condensation on day E19 that we interpret as the external cuneate component of the crossed stream. These cells begin to penetrate the parenchyma on day E20, and by days E21 and E22 two components of the external cuneate nucleus are identifiable–the dorsal and ventral external cuneate nuclei. The neurons of the lateral reticular and external cuneate nuclei differ from neurons of all the other precerebellar nuclei in that their cerebellar projection is predominantly ipsilateral. We speculate that the axons of all precerebellar neurons are genetically specified to cross the midline ventrally to provide a contralateral efferent projection, but this is modified in the case of the ipsilaterally projecting lateral reticular and external cuneate neurons by the cell bodies following their neurites to the opposite side.
Anesthetic state does not affect the map of the hand representation within area 3b somatosensory cortex in owl monkey
Authors: Stryker Michael P. , Jenkins William M. , Merzenich Michael M. 
Published: January 2005

AbstractReceptive fields defined for small clusters of neurons within the middle cortical layers of area 3b differed little in size or in the skin locations represented among: (a) alert, (b) nitrous oxide‐anesthetized, (c) deep sodium pentobarbital‐anesthetized, and (d) ketamine‐anesthetized owl monkeys. Repeated recordings from nearly identical cortical loci yielded nearly identical multiunit receptive fields under different conditions of anesthesia.