bluuebunny/crossref_metadata_2025_split huggingface dataset:
The avian somatosensory system. I. Primary spinal afferent input to the spinal cord and brainstem in the pigeon (Columba livia)
Authors: Wild J. Martin 
Published: January 2005

AbstractThe process of transganglionic transport was used to determine the pattern of primary afferent projections to the spinal cord and brainstem in the pigeon by (1) applying horseradish peroxidase (HRP) to various peripheral nerves in the leg or wing, (2) by injecting HRP‐lectin into feather follicles of the wing or tail, and (3) by injecting HRP‐lectin into various muscles of the leg or wing.In the spinal cord major peripheral nerves were represented heavily throughout the dorsal horn laminae but sparsely in more ventral laminae. The representations of these different nerves tended to be located in different mediolateral regions of the dorsal horn. Cutaneous nerves and feather follicles were represented predominantly in laminae I and II, and different sets of follicles were represented in different mediolateral regions of these laminae. Afferent labelling from muscles of the leg and wing was located in the lateral portion of the dorsal horn, predominantly in laminae I, II, and IV.In the caudal medulla the representation of the leg within the gracile nucleus was medial to and separate from that of the wing within the cuneate nucleus (Cu). The wing representation, however, extended laterally throughout the external cuneate nucleus (CuE) and lateral regions of the descending trigeminal tract. There was less evidence of separation of the limb representations at more rostral medullary levels where they both occupied predominantly CuE. Afferent labelling from cutaneous nerves and feather follicles was distributed lightly throughout Cu and CuE, and from muscles of both limbs primarily throughout CuE. There was also a small but specific projection from the limbs to the nucleus of the solitary tract, and from the wing to the principal sensory trigeminal nucleus.These results are discussed within a comparative context with a view to highlighting the similarities and differences in the pattern of primary afferent central projections in different vertebrates.
Chemical and electrical synapses between photoreceptors in the retina of the turtle, Chelydra serpentina
Authors: Owen W. Geoffrey 
Published: January 2005

AbstractElectron microscopic observation of the distal retina of the turtle, Chelydra serpentina revealed that photoreceptors contact each other by means of a variety of junctions. The synaptic terminals of the primary and accessory members of a double cone invariably make punctate contact with each other distal to the basal surfaces. This type of contact was only rarely seen between the synaptic terminals of single photoreceptors. Photoreceptor telodendria which emanate from the basal surface of the synaptic terminal and ramify laterally for up to 40 μm in the outer plexiform layer give off branchlets which contact the terminals of both rods and cones. These contacts resemble superficial basal junctions and can be of the “wide‐gap” or “narrow‐gap” type. In cones the branchlets of the telodendria sometimes make a “distal junction” with one of the lateral elements of a synaptic dyad. Gap junctions were not found between the fins radiating from the myoids of adjacent receptors but were seen to occur en passant between photoreceptor telodendria in the outer plexiform layer. These junctions, though small, are probably of sufficient size to account for the rod‐rod coupling observed physiologically in this retina.A prominent organelle resembling a synaptic lamella was occasionally seen in processes making contact with photoreceptors. These processes were identified as bipolar cell dendrites.
Retinal neurochemistry of three elasmobranch species: An immunohistochemical approach
Authors: Brunken William J. , Witkovsky Paul , Karten Harvey J. 
Published: January 2005

AbstractWe surveyed retinas of Raja erinacea, Mustelus canis, and Squalus acanthias for neurotransmitter substances by using antisera directed against the substances themselves or against their synthesizing enzymes. Both the peroxidase‐antiperoxidase (PAP) and indirect fluorescent techniques were employed to visualize the primary antisera. In all three species positive results were obtained with antisera directed against tyrosine hydroxylase (TOH), glutamic acid decarboxylase (GAD), serotonin (5‐HT), and leucine enkephalin (Lenk). Antisera directed against glucagon, neurotensin, beta‐endorphin, vasoactive intestinal peptide, or bombesin failed to show any specific staining.Immunoreactivity was located in amacrine, interplexiform, and horizontal cells as well as in axons of the optic fiber layer. The four antisera labelled different amacrine cell classes, distinguished on the bases of perikaryal morphology and the distribution of cell processes in the inner plexiform layer (IPL). Amacrine cells that labelled with the same marker were seen to have different morphologies in the species studied. Thus, TOH‐like immunoreactivity was distributed in layers 1, 3, and 5 of the IPL in Mustelus but only in layers 1 and 3 in Raja retina. GAD‐like immunoreactivity was found diffusely over all layers of the IPL in Raja, but in Mustelus it was confined primarily to layers 1, 3, and 5 of the IPL. Lenk‐ and 5‐HT‐like immunoreactivities showed similar species variations.Two neurochemical classes of interplexiform cell were identified in this study. In Mustelus GAD‐like and Lenk‐like immunoreactive interplexiform cells were seen whereas in Raja only GAD‐positive interplexiform cells were detected. In Squalus no unequivocal demonstration of any interplexiform cell was made with these antisera.The GAD antiserum also labelled a subset of the horizontal cells in the dorsal retina of Raja. TOH and 5‐HT‐antisera labelled axons in the optic fiber layer of all three species but reactive ganglion cell perikarya were not identified.
Anatomical studies on the nucleus reticularis tegmenti pontis in the pigmented rat. I. Cytoarchitecture, topography, and cerebral cortical afferents
Authors: Torigoe Yasuhiro , Blanks Robert H. I. , Precht Wolfgang 
Published: January 2005

AbstractThe nucleus reticularis tegmenti pontis (NRTP) is a precerebellar reticular nucleus that has been found to be related to cerebropontocerebellar pathways and, more recently, to eye movements. The present study investigates the cytoarchitecture, the topography, and the cerebral cortical projections to the NRTP in the pigmented rat. The cytoarchitecture and topography of the NRTP was determined by examination of Nissl‐stained material sectioned in the transverse and sagittal planes. Two cytoarchitectonically distinct portions of the NRTP are apparent; a central subdivision (NRTPc) composed of large multipolar, small spherical, and fusiform neurons, and a pericentral subdivision (NRTPp) composed of loosely packed small fusiform and spherical neurons. The NRTPc is located dorsal to the medial lemniscus and pyramidal tracts over the caudal two‐thirds of the pons. It extends caudodorsally to the region just rostral and ventral to the abducens nucleus. The NRTPp is adjacent to the lateral margins of the NRTPc, rostrally, and lies ventral to the caudal portions of the NRTPc. Large injections of horseradish peroxidase (HRP) were made into the cerebellum in order to determine the degree to which each subdivision of the NRTP contributes to the cerebellar projection. A high percentage of NRTPc neurons and a lower percentage of NRTPp neurons were labeled. These differences in labeling density and neuronal morphology noted above confirm the appropriateness of subdividing the NRTP into central and pericentral subdivisions.The cerebral cortical afferents to the NRTP were examined by placing small iontophoretic injections of HRP into the NRTPc and NRTPp. A systematic examination of all cortical areas revealed that the HRP‐labeled neurons are entirely localized within pyramidal layer V of three major cortical areas: (1) the ipsilateral prefrontal cortex (Brodrnann areas 8, 8a, 11, and 32); (2) the ipsilateral motor and somatosensory cortices (Brodmann areas 2, 4, 6, and 10), and (3) the bilateral cingular cortex (Brodmann areas 24a, 24b, 29c, and 29d). By far, the heaviest cortical labeling with HRP injections into the medial NRTPc is within the cingular cortex that may, in the rat, be homologous to the frontal eye field of the cat and monkey. In contrast, injections involving the lateral NRTPc or the NRTPp produced labeling within wide regions of the cortex with the greatest number in the somatomotor cortex. A comparison of these data reveals a topographic organization for the cortical afferents to the NRTP in rat: Namely, the medial areas of the NRTP receive projections from phylogenetically older regions of the cerebral cortex, whereas the lateral areas of the NRTP are more closely related to neocortical regions.
The localization of cytochrome oxidase in the LGN and striate cortex of postnatal kittens
Authors: Kageyama Glenn H. , Wong‐Riley Margaret 
Published: January 2005

AbstractThe distribution of cytochrome oxidase (C.O.) was examined in the lateral geniculate nucleus of the kitten during the first postnatal month and compared with the adult pattern. During the first week, most of the C.O. was localized within the perikarya of geniculate neurons. Perigeniculate neurons had darkly reactive dendrites as well as perikaya. A population of relatively large, darkly reactive neurons became distinguishable around the end of the first week, as the level of reactivity diminished to moderate‐to‐light within most medium and small neurons. On the basis of their relative size and pattern of distribution, most of the darkly reactive neurons are likely to represent ones that will later have class 1 morphology and develop Y receptive field properties. These cells normally undergo rapid growth earlier, and their growth is more adversely affected by early short‐term monocular suture than other classes of less reactive geniculate neurons. Thus, in the LGN of developing kitten, C.O. histochemistry may be used as a functional marker for future class 1 Y‐cells. The reactivity of the neuropil gradually increases as synapses with dendrites mature. At the electron‐microscopic level the increased reactivity of the neuropil is due mainly to an increase in the number of reactive mitochondria localized within the growing dendrites.In the developing striate cortex of postnatal kittens dark reactivity is localized in the outer part of layer II for the first 2 weeks and then disappears. Dark reactivity gradually increases in layer IV after the third week. The changes in C.O. reactivity accompany pathway‐specific physiological and anatomical changes that occur during early postnatal development.
Body surface maps in the somatosensory cortex of rabbit
Authors: Gould Harry J. 
Published: January 2005

AbstractThe organization of somatosensory maps was examined in rabbits with the aid of microelectrode multi‐unit recording techniques. Two complete maps of the contralateral body surface are identified in the parietal cortex. The first map, S I, is found entirely on the lateral convexity of the hemisphere and closely resembles S I described in the rat (Welker, '71, '76). It is organized in a complex, though systematic, fashion with the representations of the hindlimb and tail located caudomedially. These representations are followed laterally in sequence by those of the trunk and forelimb and then the representation of the head. Within the head representation the lips are found rostrally, the vibrissae caudomedially, and the displaced representation of the pinna of the ear is located caudolaterally. Unlike the disposition in most other mammals, the dorsal midline of the trunk is represented along the caudal border of S I. Within S I, the representations of the circumoral surfaces, including the lips, philtrum, nose, and vibrissae, are emphasized, occupying approximately 86.4% of the map. It is suggested that S I is contained within a single major koniocortical region, here called the medial parietal area, or Pm. The several previously described parietal regions (Rose, '31; Fleischhauer et al., '80) are interpreted as subregions that are related to particular representations of portions of the body surface.The second map, S II, is located lateral to S I in a region here called the lateral parietal area or Pl. S II shares a common border with S I along the representations of the philtrum, bridge of the nose, and top of the head. The body is oriented in an erect conformation with the head located rostrally and medially and the hindlimb and tail located caudally and laterally.
Morphology and physiology of abducens motoneurons and internuclear neurons intracellularly injected with horseradish peroxidase in alert squirrel monkeys
Authors: McCrea R. A. , Strassman A. , Highstein S. M. 
Published: January 2005

AbstractAxons of abducens motoneurons and internuclear neurons were penetrated with HRP‐filled glass microelectrodes in alert squirrel monkeys. The firing rate of these axons and spontaneous eye movements were recorded and the axons were then injected with HRP for subsequent visualization of the recorded cells. Soma‐dendritic and axon and axonal terminal morphology were studied for possible correlation with firing frequency. The physiology of squirrel monkey abducens neurons is qualitatively similar to their counterparts in the rhesus monkey and the cat, being primarily correlated with the position and velocity of the eyes. The locations of moto‐ and internuclear neurons are similar in the squirrel monkey and cat as are the axonal projections and terminals. However, squirrel monkey abducens cells are smaller than their feline counterparts and have dendrites that are confined to the cellular borders of the abducens nucleus. The size of the soma and proximal dendrites of moto‐ and internuclear neurons are poorly correlated with either their threshold for recruitment or their tonic eye position sensitivity. However, cells with smaller dendritic trees tended to have higher saccadic eye velocity sensitivity than those with larger trees. Three types of internuclear neurons were distinguishable upon the basis of their axon collaterals. All cells terminated within the medial rectus subdivision of the oculomotor nucleus. One class of cells did not give rise to collaterals before projecting to the oculomotor nucleus and the other classes gave rise to collaterals that terminated in the intermediate and/or caudal interstitial nuclei of the median longitudinal fasciculus. Within the IIIrd nucleus internuclear terminations were usually confined to a single subgroup of medial rectus motoneurons.
Are there connections between the thalamic reticular nucleus and the brainstem reticular formation?
Authors: Berry D. J. , Ohara P. T. , Jeffery G. , Lieberman A. R. 
Published: January 2005

AbstractIncreasing awareness that the thalamic reticular nucleus (TRN) plays an important role in controlling the output of cortically projecting cells in nuclei of the dorsal thalamus has focused attention on the question of whether there exist ascending projections to the TRN from the mesencephalic or other parts of the brainstem reticular formation (BRF). We have examined this and the related question of whether the neurons of TRN project to the BRF, by anterograde and retrograde tracing experiments with horseradish peroxidase (HRP) and HRP conjugated to wheat germ agglutinin. Injections of tracer were placed stereotaxically in the BRF at various depths and rostrocaudal and mediolateral coordinates, and the TRN and adjacent nuclei were examined in serial coronal sections, using tetramethylbenzidine as the principal chromogen.Retrogradely labelled cell bodies were consistently seen in hypothalamus and zona incerta but never in TRN, suggesting that, in the rat, TRN neurons do not project caudal to the thalamus.After 54 out of 60 injections, no terminal label was detected in any part of the TRN although such label was present in other parts of the thalamus, including the intralaminar nuclei, in the same sections. We therefore conclude that direct projections from the BRF to the TRN must be extremely sparse, and that those effects of BRF stimulation upon thalamocortical transmission that are mediated by the TRN (rather than by direct projections to dorsal thalamic nuclei) probably depend chiefly on indirect polysynaptic pathways.
Regional specialization of the rat retina: Catecholamine‐containing amacrine cell characterization and distribution
Authors: Versaux‐Botteri C. , Martin‐Martinelli E. , Nguyen‐Legros J. , Geffard M. , Vigny A. , Denoroy L. 
Published: January 2005

AbstractThe distribution of catecholaminergic amacrine cells has been investigated in rats by means of immunohistochemical labelling of wholemounted retinas. Two groups of catecholamine‐containing cells could be distinguished on the basis of their catecholamine and biosynthetic enzyme content. Both groups could be stained with an anti–tyrosine hydroxylase (TH) antiserum. The first group was composed of large, strongly TH‐immunoreactive stellate amacrine cells, located principally in the innermost row of the inner nuclear layer (INL) and sending processes to the outermost sublamina of the inner plexiform layer (IPL). Some were displaced in the IPL or in the ganglion cell layer (GCL). This first group of cells can be regarded as dopaminergic since they were also stained by an anti‐dopamine (DA) antiserum. The second group was composed of small, weakly TH‐positive cell bodies, located slightly more sclerad within the INL. Their processes were usually not labelled with anti‐TH. Identical cells could be better visualized with an anti‐phenylethanolamine‐N‐methyltransferase (PNMT) antiserum. Their processes were observed in the middle sublamina of the IPL. A great number of these cells were displaced in the GCL. They could be regarded as epinephrine cells.Concerning the density and distribution throughout the retina a striking difference was observed between the superior and inferior halves of the retina, whereas a lower difference was observed between the nasal and temporal regions. Almost all the PNMT‐immunoreactive cells were located throughout the upper retina, whereas the DA‐cells were especially concentrated in the upper temporal quadrant. The distribution of the DA cells parallels that of the ganglion cells whose density is also maximal in the upper temporal retina.
Cortical projections originating from the cat's insular area and remarks on claustrocortical connections
Authors: Guldin Wolfgang O. , Markowitsch Hans J. , Lampe Regina , Irle Eva 
Published: January 2005

AbstractThe cortical projections originating in the cat's insular cortex and claustrum were investigated with the aid of the horseradish peroxidase retrograde tracing technique. Twenty small injections of horseradish peroxidase were distributed along lateral and medial regions of the hemisphere. Labeling in the insular cortex occurred following all injections except those six situated along the lateral gyrus–that is, within the visual cortex.In the claustrum labeled neurons were found following all injections, except following the injection situated in the posterior temporal area. Claustral labeling was frequently more intense than insular labeling. The injections into the occipital cortex that revealed no insular innervation nevertheless received a considerable number of claustral projections. As the insular cortex itself receives at most a minor projection from the claustrum the differing cortical projection patterns of insula and claustrum have to be considered unrelated.Our findings confirm the view that the claustrum projects to most regions of the cerebral cortex; these projections are at least in part topographically organized. A topographical pattern can also be constructed for the insular cortex, though it is less stringent than for the claustrocortical connections.Both the afferent and efferent connections of the insula show similarities to those of the prefrontal cortex. Nevertheless, the insula differs in that it receives strong input from the sensory associative nuclei of the thalamus. Consequently, and in line with behavioral observations following its ablation, we consider the insula as involved in the temporal structuring of perceived patterns.
Mechanosensory appendages and giant interneurons in the firebrat (Thermobia domestica, thysanura): A prototype system for terrestrial predator evasion
Authors: Edwards John S. , Rajarami Reddy G. 
Published: January 2005

AbstractAspects of the structure and function of the abdominal cerci and caudal filament sensory systems, and associated giant interneurons of the thysanuran insect Thermobia domestica, the firebrat, extend comparative studies of a widespread predator evasion system. All elements of the cercal system, which is well known from diverse orthopteroid insects, are present in the primitively wingless thysanuran. In addition, a median terminal sensory appendage, the caudal filament, projects to the same general regions of the terminal ganglion but shows limited overlap of synaptic regions with cercal input. A segmental series of giant interneurons appears to be homologous with those of the orthopteroid insects. The cercal system, which may have evolved with the first terrestrial hexapods, reaches its zenith in the orthopteroid insects, but was replaced in holometabolan insects by visual startle mechanisms with descending giant interneurons.
The early development of the optic nerve and chiasm in embryonic rat
Authors: Horsburgh Gwynn M. , Sefton Ann Jervie 
Published: January 2005

AbstractTo establish the time course and major features of the development of the optic nerve and chiasm in the embryonic rat, the growth of axons from the retina to the brain has been studied by light and electron microscopy. On embryonic dy 14 (E14), the first axons are generated by retinal ganglion cells. Fascicles of axons can be detected in the‐optic stalk at E14.5 and in the diencephalon by E15.0. In the vitreal retina and optic fissure, large extracellular spaces resemble the oriented channels previously described in the mouse. They form approximately 12 hours before the invasion of optic axons and contain hyaluronic acid. In the optic stalk and diencephalon of the rat, similar spaces are not present, but the timed autolysis of neuroepithelial cells could provide a pathway of minimal resistance for the earliest axons. Degenerating cells are prominent in the ventral stalk and rostral diencephalon prior to the arrival of the first optic axons that preferentially invade these regions. The role of pigment in the development of visual pathways is controversial. In one strain of rat, Manchester Hooded, the retinae are heavily pigmented, but little pigment is seen at any stage in the stalk; in albinos, pigment is absent from both retina and stalk. However, the distribution of axons within the developing optic stalk is very similar in both strains, suggesting that the reduction in size of the ipsilateral pathway observed in the albino rat compared with the Manchester Hooded is not due to a lack of pigment in the optic stalk early in development. Several factors previously reported to contribute to the development of retinotopic order in other species are also present in the rat. These include the sequence in which axons grow into the stalk, and fasciculation. Intermembranous contacts observed between growth cones and adjacent tissues suggest one mechanism by which fasciculation occurs. A small group of fascicles, which may represent the ipsilateral projection, diverges from the crossing fibers on E15.5, without evidence of being deflected by any glial or other structures.