bluuebunny/crossref_metadata_2025_split huggingface dataset:
The representation of the visual field in the lateral geniculate nucleus of Macaca mulatta
Authors: Malpeli Joseph G. , Baker Frank H. 
Published: May 2005

AbstractMicroelectrode recording techniques were used to investigate the projection of the visual field into the lateral geniculate nucleus (LGN) of Macaca mulatta. The data were used to construct charts plotting visual direction, designated in terms of azimuth and elevation, onto sections of the nucleus cut in coronal, sagittal and horizontal Horsley‐Clarke planes. The projection of the horizontal meridian divides the LGN along its plane of symmetry into a medial‐superior half having negative elevations and a lateral‐inferior half having positive elevations. Elevations become more positive or negative with distance from this plane. Azimuths closest to the vertical meridian are located posteriorly, while the most peripheral azimuths are found at the anterior pole. Two families of surfaces representing visual directions of constant azimuth and elevation are described. Visual field zones of increasing eccentricity are represented serially along the posterior‐anterior axis of the LGN, with the foveal area restricted to the posterior pole and the monocular crescent projecting to the anterior pole. The mapping is completely continuous across the horizontal meridian. The edges of the stacked cell laminae exposed around the periphery of the LGN form an oval band which receives the projection of the perimeter of the contralateral hemifield. The vertical meridian is represented by the posterior two‐thirds of this band, while the periphery of the hemifield projects to the anterior third.The central visual field out to the optic disc is represented by six cell layers, while the rest of the binocular field projects to four layers only (2 parvocellular and 2 magnocellular). The monocular crescent is represented by one parvocellular and one magnocellular layer. Features associated with the projection column of the optic disc are integrated into the transition from six to four layers. Details of the receptive field topography in the vicinity of the optic disc discontinuities indicate that these gaps are produced by intralaminar mechanisms.The magnification factor (mm3/steradian) increases monotonically from peripheral visual fields to the foveal center, varying over a range of three decades. This range is intermediate between those derived from data reported in the literature for the retina and the striate cortex. The ratio of LGN magnifications at any two angular eccentricities is a power function, with an exponent of 1.34, of the corresponding ratio of retinal ganglion cell densities. Similarly, the ratio of cortical magnifications (mm2/steradian) at any two eccentricites is a power function, with an exponent of 1.35, of the corresponding ratio of LGN magnifications.
Localization of masticatory motoneurons in the cat and rat by means of retrograde axonal transport of horseradish peroxidase
Authors: Mizuno Noboru , Konishi Akira , Sato Manabu 
Published: May 2005

AbstractTopographical localization of motoneurons supplying the masticatory muscles was investigated in the cat and rat, utilizing retrograde axonal transport of horseradish peroxidase. Following injection of horseradish peroxidase in each masticatory muscle, motoneurons labelled with peroxidase were seen to be aggregated into a cluster within the motor nucleus of the trigeminal nerve. Such clusters of peroxidase‐labelled motoneurons innervating each masticatory muscle were demarcated more sharply in kittens than in adult animals. The pattern of the nuclear representation of the masticatory muscles was found to be essentially the same in the cat and rat; it could be summarized as follows:The motor nucleus of the trigeminal nerve could be divided cytoarchitectonically into the dorsolateral and ventromedial divisions; the former was seen in almost the whole rostrocaudal extent of the nucleus, while the latter was localized at the levels of caudal two thirds of the nucleus. In the dorsolateral division, the temporal muscle was represented dorsally and dorsomedially, the masseter muscle ventrolaterally, and the pterygoid muscles ventromedially. In the ventromedial division, the anterior digastric muscle was represented dorso medially, and the mylohyoid muscle ventrolaterally. It was also confirmed that the motoneurons supplying the posterior digastric muscle were localized in the accessory facial nucleus.
Retinal projections in the ringtailed possum Pseudocheirus peregrinus
Authors: Pearson Lyn J. , Sanderson K. J. , Wells R. T. 
Published: May 2005

AbstractThe retinal projections in the ringtailed possum, Pseudocheirus peregrinus were determined using Fink‐Heimer material and autoradiography. At least seven regions in the brain receive retinal projections. These are (1) the suprachiasmatic nucleus of the hypothalamus (2) the dorsal lateral geniculate nucleus (3) the ventral lateral geniculate nucleus (4) the lateral posterior nucleus (5) the pretectum (6) the superior colliculus, and (7) the accessory optic system. The accessory optic system and lateral posterior nucleus receive a contralateral retinal projection only and the other five regions receive a bilateral retinal projection.The dorsal lateral geniculate nucleus consists of two parts: an outer α division of closely packed cells and an inner β division containing loosely scattered cells. There are no cell layers apparent within the α division in Nissl sections. The autoradiographs and Fink‐Heimer material reveal four concealed laminae within the α division. Lamina 1, which is adjacent to the optic tract and lamina 3 receive a predominantly contralateral input. Laminae 2 and 4 receive a predominantly ipsilateral input. The β segment contains a fifth lamina which receives contralateral retinal input.
Morphological and ultrastructural study of the ventral nerve cord in Branchiobdella pentodonta whitman (Annelida, oligochaeta)
Authors: Vagnetti Daniela , Farnesi Rosalba Maria 
Published: May 2005

AbstractThe ventral nerve cord of Branchiobdella pentodonta consists of paired ganglia containing three different types of neurons, a central neuropil showing characteristic synapses and of an intersegmental apparatus made up of two large lateral connectives and a smaller ventral one. Some remarkable differences exist between the ventral nerve cord and that found in other oligochaetes; these include the presence of a large dorsal blood vessel, two dorsal muscular cells per metamere, and supportive glial cells ventral to the neuropil which have long transverse processes coming into contact with the segmental nerves.
Scanning electron microscopic study of the otolithic organs in the bichir (polypterus bichir) and shovel‐nose sturgeon (scaphirhynchus platorynchus)
Authors: Popper Arthur N. 
Published: May 2005

AbstractThe anatomy and ultrastructure of the sacculus, lagena, and utriculus of the ear of Polypterus bichir and Scaphirhynchus platorynchus were studied using the scanning electron microscope. The otolithic organs each contain a single dense calcareous otolith in close contact with a sensory epithelium (macula). The maculae have sensory hair cell typical of those found in other vertebrates, surrounded by microvilli‐covered supporting cells. The hair cells on each macula are divided into several groups, with all of the cells in each group morphologically polarized in the same direction. The cells of the utricular macula in both species are divided into two opposing groups in a pattern similar to that found in other vertebrates. The saccular and lagenar maculae are located in a single large chamber in both species. In Scaphirhynchus the two maculae are on the same plane, while in Polypterus they are at right angles to one another. The hair cells on the saccular maculae of both species are divided into two oppositely oriented groups. In Scaphirhynchus the cells on the posterior half of the macula are oriented dorsally on the dorsal half of the macula and ventrally on the ventral half. The anterior region of the macula is rotated and the cells of the dorsal and ventral groups are shifted so that they are oriented on the animal's horizontal plane. A similar pattern is found in Polypterus, except that this macula is shaped like a “J” with the vertical portion of the J having horizontal cells and the bottom portion vertical cells. The lagenar maculae in both species have dorsally oriented cells on the anterior side of the macula and ventrally oriented cells on the posterior half of the macula. While these data are not sufficient for clarifying the taxonomic relationship between the two species studied, it is clear that the ears in these species have a number of significant differences from the teleost ear that could have functional and/or taxonomic significance.
The ipsilateral optic pathway to the dorsal lateral geniculate nucleus and superior colliculus in mice with prenatal or postnatal loss of one eye
Authors: Godement Pierre , Saillour Paulette , Imbert Michel 
Published: May 2005

AbstractThe projections, and more particularly the ipsilateral projections, from the retina to the dorsal lateral geniculate nucleus (dlGn) and the superior colliculus have been investigated in adult mice of the C57BL/6J strain after rearing in one of four different conditions: 1) after normal visual experience; 2) after unilateral enucleation at birth; 3) in mice with congenital unilateral anophthalmia (in which only one eye develops) 4) in mice with congenital unilateral microphthalmia (in which only one eye is of reduced size while the other is normal).In neonatally enucleated and congenitally monocular mice there is an aberrant uncrossed pathway to regions of the dlGn and the superior colliculus which do not normally receive such a projection. This projection is limited in its distribution; in both the neonatally enucaleated and the congenitally monocular animals the uncrossed projection does not reach the lateral and dorsal parts of the dlGn and it only innervates the rostral half of the superior colliculus. The density of the uncrossed pathway in these animals is highest in those regions in which the normal uncrossed pathway terminates. In microphthalmic mice the expansion of the uncrossed pathway is less marked than in monocular mice. In the superior colliculus the aberrant uncrossed projections innervate the stratum griseum superficiale where they are often found distributed in small patches. An intertectal crossing of retinal fibers is described from the contralateral superior colliculus to the deprived ipsilateral superior colliculus.
Lesion‐induced rerouting of hippocampal mossy fibers in developing but not in adult rats
Authors: Laurberg S. , Zimmer J. 
Published: May 2005

AbstractThe organization of the hippocampal mossy fiber system which projects from the granule cells of fascia dentata to the pyramidal cells of the hippocampal regio inferior (CA3) was studied after chronic lesions had been applied to CA3 in neonatal (0–3 day old), 5 and 21 day old, and adult rats. The distribution of terminals was monitored by the histochemical Timm sulphide silver method, and the fibers were demonstrated by the original Nauta silver method.Complete transections of CA3 in neonatal rats induced a layer of aberrant, infrapyramidal mossy fiber terminals in CA3 up to 1,300 μm septal to the transection followed by a corresponding expansion of the suprapyramidal mossy fiber layer for at least 720 μm. At increasing distance above the lesion, the induced changes moved laterally in CA3, affecting more distal parts of the mossy fibers. Corresponding to the layer of aberrant infrapyramidal terminals were aberrant bundles of mossy fibers, with an abnormally ascending septal course. No aberrant mossy fibers or terminals were induced temporal to the complete transections.Partial CA3 lesions in neonates induced changes corresponding to those observed after complete transections septal to the lesions. In addition, a layer of aberrant infrapyramidal mossy fiber terminals was induced in CA3 as far as 900 μm temporal to the partial lesions, accompained by an expansion of the suprapyramidal layer. The infrapyramidal terminals were related to aberrant bundles of fibers which followed an abnormally steep, temporal course, from which they in turn leveled off to join the suprapyramidal bundles.Compared to neonatal lesions, hippocampal transections performed on day 5 induced a slightly less dense layer of aberrant infrapyramidal mossy fiber terminals in CA3, and although a transection on day 21 still induced aberrant infrapyramidal terminals, these were far less abundant than after lesions at day 5. Transections in adult rats induced no such changes at all, and additional denervation of CA3 by simultaneous removal of the commisural projection from the contralateral hippocampus did not have any effect.The lesion‐induced, but age‐dependent redistribution of mossy fibers to CA3 is discussed in terms of reactive reinnervation following partial deafferentation, and compensatory sprouting and rerouting due to pruning‐like effects of the lesions. A rerouting of developing, not fully matured mossy fibers is found to be most likely: Deprived of normal target areas, the fibers have been forced to grow in abnormal directions, ending up hyperinnervating adjacent, accessible levels through the formation of aberrant infrapyramidal terminals and expansion of the suprapyramidal zone.
The pregeniculate nucleus of the monkey (Macaca mulatta). I. A. study at the light microscopy level
Authors: Babb Richard S. 
Published: May 2005

AbstractA study of the pregeniculate nucleus of the monkey (Macaca mulatta), in Klüver‐Barrera‐stained, and Golgi‐impregnated material confirmed, with reservations, that the nucleus is bilaminar. The inner lamina extends anterior to posterior as a compact band of neuropil within the optic tract, passing from a dorsomedial position to occupy a more dorsolateral position with respect to the lateral geniculate nucleus. The neuropil of this lamina is formed from a plexus of very fine fibers, many having varicosities, which appear to make contact with dendrites. The outer lamina appears to be formed that part of the thalamic reticular nucleus that is apposed to the lateral geniculate nucleus.Three types of neurons were observed in the nucleus: Type I are found only in the inner lamina; they have small (12–14 μm) spheroid somata with thin dendrites having terminal arborizations formed by long protrusions and axons exhibiting varicosities. Type II neurons in contrast are found only in the outer lamina; their cell bodies are large (21 by 33 μm to 26 by 37 μm) and polygonal, contain much Nissl substance, and exhibit thick, relatively spine‐free dendrites. Type III neurons, which are the most common, are found in both laminae; they have medium‐sized 13 by 27 μm to 19 by 40 μm ellipsoid somata containing moderate amounts of Nissl substance and exhibiting well‐developed spine‐bearing dendrites. Since the axon of the type I neuron impregnates and is found only within the nucleus, this cell is considered to be an intrinsic neuron; on the other hand, types II and III are judged to be principal neurons, as their axons do not impregnate.
Topographical organization of ascending cerebellar projections from the dentate and interposed nuclei in Macaca mulatta: An anterograde degeneration study
Authors: Stanton Gregory B. 
Published: May 2005

AbstractDiscrete electrolytic lesions were placed in the dentate and interpositus cerebellar nuclei in the monkey Macaca mulatta and anterograde degeneration was traced in the ascending limb of the brachium conjunctivum using the Wiitanen technique. The dentate and interpositus anterior (IA) nuclei project topographically onto the two somatotopically organized divisions of the red nucleus and the ventrolateral‐ventral intermediate nuclei of the thalamus (VL‐Vim). Caudal parts of the dentate project to face areas in medial parts of the parvocellular red nucleus (RNpc) and VL‐Vim, rostrolateral parts to central arm areas in these nuclei. There is a small projection from the rostroventral dentate to lateral hindlimb areas in RNpc and VL. Dorsal parts of the dentate project to ventral parts of RNpc and VLc‐Vim (distal limb musculature area) exclusively, whereas ventral parts of the dentate project to dorsal parts of RNpc with some overlap ventrally dorsomedial VLc (proximal limb musculature and premotor areas). Caudal parts of IA project to medial forelimb and rostral parts to lateral hindlimb areas in the magnocellular red nucleus (RNmc) and VL‐Vim. Projections from IA are greatest to distal musculature areas in VL‐Vim. No projections from the interpositus posterior nucleus (IP) to the red nucleus could be identified positively, but projections to VL‐Vim are to proximal hindlimb musculature and premotor areas.
Denervation of non‐optic brain areas along the course of the optic tract does not affect the success of optic nerve regeneration in frogs
Authors: Bohn Ronald C. , Stelzner Dennis J. 
Published: May 2005

AbstractUnsuccessful axonal regeneration in frog or goldfish spinal cord is thought to be due in part to inappropriate denervated synaptic sites attracting regenerating axons as they pass by the lesion zone (Bernstein and Bernstein, '69; Bernstein and Gelderd, '73). The reported success of optic nerve regeneration in these same animals may result because there are no inappropriate synaptic sites available to the regenerating axons. To test for this we denervated areas within thalamus and mesencephalon which lie along the path of regenerating optic axons to determine whether or not abnormal connections would form in these areas and affect the success of optic nerve regeneration. After transection of the brainstem through the isthmal region, terminal degeneration was found in several zones adjacent to optic nerve targets or the optic tract (i.e., nucleus rotundus, corpus geniculatum laterale, and torus semicircularis). In adult frogs receiving left isthmal transection, we also crushed the right optic nerve and then examined the regenerated optic projection at intervals up to six months after nerve crush using anterograde transport of 3H‐proline. In no instance did the regenerating optic axons alter their distribution within visual neuropil zones or invade those areas deafferented by the isthmal lesion. Histological study showed that the axons cut by the isthmal lesion did not regenerate back to their sites to prevent the invasion of optic axons into these zones. We then attempted to force optic axons into foreign territory by removing a major projection zone, the optic tectum. With tectal ablation and isthmal transection, regenerating optic axons were offered synaptic space made available by both lesions. However, we found abnormal optic projections only in the middle and posterior thalamic neuropil and in the remaining tectal hemisphere. Optic axons did not expand into any of the areas deafferented by the isthmal transection, even though some of them were further denervated by the tectal ablation. We conclude that optic axons will not invade non‐optic areas deafferented by an isthmal lesion even if a large number of optic axons have no normal target to innervate.
Differentiation of an identified sensory neuron (SR) and associated structures (CTO) in grasshopper embryos
Authors: Heathcote R. David 
Published: May 2005

AbstractThe differentiation of an identified sensory neuron, the grasshopper wing hinge Stretch Receptor (SR), is examined throughout embryogenesis. The morphological features of the SR axon, as it finds its path from the peripheral cell body to the CNS, and the timing of this peripheral growth were determined by intracellular injection of Lucifer yellow. The course of growth of the SR axon within the CNS and the sequence of formation of the identified branches in its characteristic central arborization were investigated by silver intensification of cobalt‐stained axons. In addition, intracellular recording from the cell body of SR was used to determine the onset of electrical excitability and the characteristics of the somal action potential. A brief account of the differentiation of the closely associated wing hinge Chordotonal Organ is also given.During differentiation, the cell bodies of SR and the first wing hinge Chordotonal Organ neuron (CTN1) extend processes and migrate posteriorly along a peripheral epithelial ridge. The cell bodies migrate up to 150 m̈m with a group of undifferentiated cells to a specific site at the posterior edge of the segment.As the SR and CTN1 cell bodies migrate, their trailing axons stretch across the epithelial ridge. These axons form the medial body wall nerve (1D2) that the axons of subsequent sensory neurons follow.
Identification of and interactions between noradrenergic and serotonergic neurites in the myenteric plexus
Authors: Gershon Michael D. , Sherman Diane L. 
Published: May 2005

AbstractInteractions between enteric noradrenergic and serotonergic neurites in the myenteric plexus were examined. The influence of exogenous norepinephrine (NE) and endogenously released NE on the release of 3H‐serotonin (3H‐5‐HT) from electrically stimulated, everted segments of guinea pig small intestine were analyzed. In addition, methods were employed to permit the ultrastructural identification of enteric serotonergic and noradrenergic neurites. These included electron microscopic radioautographic localization of 3H‐5‐HT in gut from animals treated with 6‐hydroxydopamine (6‐HD; 100 mg/kg) and examination of NaMnO4‐fixed tissue from animals given desmethylimipramine and the indolic neurotoxin, 5, 7‐dihydroxytryptamine (5,7‐DHT). Exogenous NE antagonized the stimulated release of 3H‐5‐HT; this action was mediated through alpha adrenoceptors. Evidence was obtained, however, that endogenous NE liberated from sympathetic postganglionic nerve terminals had a different action on the stimulated release of 3H‐5‐HT from that of exogenous NE. Endogenous NE appeared to facilitate 3H‐5‐HT release through an action on beta adrenoceptors. Terminals identified as probably serotonergic by radioautographic labeling with 3H‐5‐HT or by loading with 5,7‐DHT were most often found to end on neuronal somata or proximal dendrites. Synaptic specializations were found by radioautography in these locations. Terminals, dendrites, and cell bodies that took up 5,7‐DHT could be identified in NaMnO4‐fixed material that also permitted the simultaneous recognition of noradrenergic varicosities. Apparent noradrenergic‐serotonergic axoaxonic contacts were found by means of this double‐labeling technique. Together with the results of the experiments on the release of 3H‐5‐HT, these anatomical observations suggest that noradrenergic axons form facilitatory axoaxonic synapses with enteric serotonergic neurons.