bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lesion‐induced sprouting of hippocampal mossy fiber collaterals to the fascia dentata in developing and adult rats
Authors: Laurberg Søren , Zimmer Jens 
Published: January 2005

AbstractA lesion‐induced formation of an abnormal projection of hippo‐ campal mossy fiber collaterals to the molecular layer of the fascia dentata was studied in rats. Both immature (1–30 days old) and adult rats were subjected to hippocampal and entorhinal lesions which alone or in combination removed one or more of the major afferents to the dentate molecular layer (commissural, associational, and perforant path). Some lesions in addition transected the main part of the mossy fibers en route from the dentate granule cells to the hippocampal pyramidal cells in regio inferior (CA3). The formation of aberrant mossy fiber terminals in fascia dentata (supragranular mossy fibers) was monitored by the histochemical Timm sulphide silver method, but the presence of aberrant terminals was also observed in the electron microscope. Abnormal amounts of supragranular mossy fiber terminals were found following entorhinal lesions of both immature and adult rats, but not following commissural lesions. Even larger amounts of aberrant terminals were, however, found in immature and adult rats subjected to lesions which removed most of the associational hippocampodentate projection by isolating columns of fascia dentata from major parts of the hilus (CA4). Pure transections of the fascia dentata perpendicular to its longitudinal septotemporal axis did not in itself cause aberrant supragranular terminals, although such lesions partially damaged the associational afferents. When the transections were combined with commissural lesions or entorhinal lesions or both, large amounts of supragranular terminals did, however, form at the denervated levels septal to the transection.After comparison of the amounts and distributions of the aberrant terminals found after the different lesions and in transplants of dentate tissue with different amounts of afferent input, we conclude that it is deafferentation of the dentate molecular layer, and not axotomy of the mossy fibers in the hilus or CA3 (pruning), that causes the aberrant growth of mossy fiber collaterals. Moreover, simultaneous removal of more than one afferent system seems to have a potentiating rather than a simple additive effect on the formation of supragranular mossy fibers.
The distal limb motor neurons in the thoracic ganglion of the spiny lobster
Authors: Silvey Gerald E. 
Published: January 2005

AbstractThe 16 motor neurons which innervate the muscles in the limb distal to the autotomy plane have been found in the third thoracic ganglion of the southern rock lobster, Jasus novaehollandiae. They were traced from the autotomy plane to the ganglion by stripping them from the small and large leg nerves to the edge of the ganglion where they were filled with cobalt dye. Cell bodies of 11 of these neurons lie in an anterior cluster of somata, and the remainder lie in a ventral rind of somata. The neurites from these somata expand into enlarged central segments, 400 μm long and 10–30 μm in diameter. These segments run parallel and in apposition to each other as they course through the neuropile a few cell layers beneath the dorsal surface of the ganglion. Near their origin some central segments send branches both medially between fibers of the interganglionic connectives, and anteroventrally into the connective. Distally the segments give rise to side branches which project around the anterior and posterolateral borders of the neuropile. The central segments constrict near the lateral edge of the neuropile, rise to its surface, and form axons. Eight axons, including those which innervate the flexor muscle of the carpus, enter an anterior motor tract which exists the side of the ganglion in a first root, the source of the small leg nerve. The remaining eight axons, which include those that innervate the extensor muscle of the carpus, enter a posterior motor tract which exits the side of the ganglion in a second root, the source of the large leg nerve. All the motor fibers which innervate the muscles of the limb, with the exception of the retractor of the coxa, run in these two tracts within the ganglion. Fibers which innervate the retractor of the coxa and the muscles of the thorax leave the ganglion in a third root at the posterodorsal border of the ganglion. The central segment, as the common structure of confluence of neuropilar branches, is the likely candidate for the integrating region of each neuron.
Differences in binocular interactions between cortical areas 17 and 18 and superior colliculus of siamese cats
Authors: Antonini A. , Berlucchi G. , Di Stefano M. , Marzi C. A. 
Published: January 2005

AbstractIn Siamese cats most retinal projections are crossed and almost all neurons in cortical areas 17 and 18 respond exclusively to the contralateral eye. However, neurons in visual areas in the suprasylvian sulci (LSA) can be activated from both eyes, since the input from the ipsilateral eye is relayed to them by the corpus callosum (Marzi et al., '80). This study shows that the superior colliculus (SC) is also the site of binocular interactions in Siamese cats with a predominantly monocular organization of areas 17 and 18. In 8 unanesthetized, brainstem‐sectioned Siamese cats, identified as “Boston” on the basis of the pattern of visual field representation in areas 17 and 18 (Hubel and Wiesel, '71; Shatz, '77a), only 25 out of 140 neurons in these areas could be driven from both eyes, whereas as many as 124 out of 143 SC neurons showed a clear binocular input.The input from each eye to the ipsilateral SC and the resulting binocular interactions in our Siamese cats might have depended on corticotectal projections from LSA. If so, since a posterior callosal section abolishes the input from each eye to ipsilateral LSA, the SC should similarly be affected by callosotomy. The posterior half of the corpus callosum was sectioned acutely in three Siamese cats after recording from SC; the input from the ipsilateral eye to SC was suppressed by this operation in one cat (which, however, also had an unintended interruption of the posterior, habenular, and anterior intertectal commissures), and drastically reduced in the other two. In a fourth cat, in which callosotomy was performed three weeks before recording from SC, the number of SC neurons responsive to the ipsilateral eye was significantly inferior to that of Siamese cats with an intact corpus callosum. These findings indicate the importance of the corpus callosum for ipsilateral eye‐SC relations, as well as for SC binocularity, in Siamese cats. At the same time they imply that noncallosal routes can also transmit information from each eye to the ipsilateral SC in callosotomized Siamese cats.
Glial fibrillary acidic protein in the optic nerve of the developing albino rat: An immunoperoxidase study of paraffin‐embedded tissue
Authors: Dixon Richard G. , Eng Lawrence F. 
Published: January 2005

AbstractThe unlabeled peroxidase‐anti‐peroxidase method was used to stain glial fibrillary acidic (GFA) protein in the optic nerve of the developing albino rat. Optic nerves from animals ranging in age from the day of birth to adulthood were embedded in paraffin following fixation with various agents for times ranging from 30 minutes to 48 hours. GFA protein activity was demonstrable at birth in large astrocytic processes following fixation with alcohols or with Perfix for short intervals, but not with 4% or 2% buffered paraformaldehyde solutions. With increasing age, GFA protein could be demonstrated using higher aldehyde concentrations, longer fixation times, and longer paraffin embedding schedules. At all ages GFA protein activity was greater following treatment with nonaldehyde fixatives rather than those containing formaldehyde or glutaraldehyde. At birth the majority of GFA protein‐containing processes were confined to planes which were perpendicular to the axons of the optic nerve. With increasing age, tangential and longitudinal processes became more numerous until, in the mature optic nerve, astrocytic processes were best characterized as being multidirectional.
The connections of the inferior colliculus and the organization of the brainstem auditory system in the greater horseshoe bat (Rhinolophus ferrumequinum)
Authors: Schweizer Hermann 
Published: January 2005

AbstractThe connections of the inferior colliculus, the mammalian midbrain auditory center, were determined in the greater horseshoe bat (Rhinolophus ferrumequinum), using the horseradish peroxidase method. In order to localize the auditory centers of this bat, brains were investigated with the aid of cell and fiber‐stained material.The results show that most auditory centers are highly developed in this echolocating bat. However, the organization of the central auditory system does not generally differ from the mammalian scheme. This holds also for the organization of the superior olivary complex where a well‐developed medial superior olivary nucleus was found. In addition to the ventral and dorsal nuclei of the lateral lemniscus a third well‐developed nucleus has been defined which projects ipsilaterally to the inferior colliculus and which was called the intermediate nucleus of the lateral leminiscus.All nuclei of the central auditory pathway project ipsi‐, contra‐, or bilaterally to the central nucleus of the inferior colliculus with the exception of the medial nucleus of the trapezoid body and the medial geniculate body. The tonotopic organization of these projections and their possible functions are discussed in context with neurophysiological investigations.
Efferent connections of the olfactory bulb in the opossum (Didelphis marsupialis aurita): A Fink‐Heimer study
Authors: Shammah‐Lagnado Sara J. , Negrão Núbio 
Published: January 2005

AbstractThe efferent connections of the olfactory bulb (OB) in the opossum (Didelphis marsupialis aurita) were studied by the aid of the Fink‐Heimer technique.Following lesions restricted to the OB, ipsilateral degenerating fibers entered the lateral olfactory tract and were traced to terminal fields essentially limited to the outer portion of the plexiform layer (sublamina IA) of the following structures: all the subdivisions of the anterior olfactory nucleus, the rostroventral tenia tecta, the full extent of the olfactory tubercle, the nucleus of the lateral olfactory tract, the anterior portion of the medial amygdaloid nucleus, the whole cortical amygdaloid nucleus (in the posteromedial subdivision of this structure the degeneration was very scanty), and the sulcal, piriform, and lateral entorhinal cortices. Some degree of topographical organization in the OB projections was noticed in the rostral portion of the lateral olfactory tract and within the external and lateral subdivisions of the anterior olfactory nucleus.In another series of experiments, when the lesion also involved the accessory olfactory bulb, heavy terminal degeneration occurred along the whole extent of the medial amygdaloid nucleus and in the posteromedial subdivision of the cortical amygdaloid nucleus.These findings indicate that, although very similar to those described in other mammals, the OB efferent connections in the opossum present some peculiarities; namely, the existence of dense terminal fields in the sulcal cortex and in the rostral district of the medial amygdaloid nucleus.
Cerebellar corticonuclear fibers of the paramedian lobule of tree shrew (Tupaia glis) with comments on zones
Authors: Haines D. E. , Patrick G. W. 
Published: January 2005

AbstractFollowing a series of lesions in dorsal (DPML) and ventral (VPML) divisions of tree shrew (Tupaia) paramedian lobule (PML), the distribution of degenerated axons within the deep cerebellar nuclei was determined using the Fink and Heimer ('67) method. Damage to PML produced axonal degeneration in lateral (NL), anterior interposed (NIA), and posterior interposed (NIP) cerebellar nuclei. No degenerated fibers could be traced to either the medial cerebellar nucleus or vestibular complex, via juxtarestiform body, from lesions in PML. Corticonuclear fibers to NL, NIA, and NIP from PML cortex are topographically organized. Subsequent to lesions of lateral DPML, axonal debris is found in rostral and medial NL, while the lateral edge of VPML projects primarily into medial NL. According to the terminology of Voogd ('69) these lateral regions of PML represent the D zone. The NIP receives corticonuclear input from a relatively wide middle area of both portions of PML, interpreted as the C2 zone. There is some evidence which suggests that medial portions of the C2 area of DPML project into more lateral areas of NIP, while lateral regions of this zone in DPML are related to more medial NIP. This projection pattern is inverted for the C2 area of VPML; medial C2 to medial NIP, lateral C2 to lateral NIP. Corticonuclear fibers of PML which enter NIA appear to arise from a narrow, irregular, partially discontinuous strip of cortex located at the interface of the D and C2 areas in lateral PML and from a wider, more regular region in the most medial areas of this lobule. These represent, respectively, the C3 and C1 zones.Although an overall pattern of zones is present, there is evidence to suggest that their spatial organization differs from DPML to VPML. The zonal pattern appears to be more obvious in VPML, while this pattern for DPML is less distinct. This is interpreted as indicating that either (1) zones C1−C3 overlap to a greater degree in DPML than in VPML, or (2) zones C1 and C3 may converge in rostral DPML, partially obliterating the intervening zone C2. The different ways in which zonal terminology is applied to both corticonuclear and certain of the afferent cerebellar systems are discussed.
Photoreceptor degeneration preceding clinical scrapie encephalopathy in hamsters
Authors: Buyukmihci Ned , Goehring‐Harmon Faye , Marsh Richard F. 
Published: January 2005

AbstractHamsters experimentally inoculated with scrapie had histologic and ultrastructural changes in their retinas before clinical signs of central nervous system disease became evident at 50 days postinoculation. The retinal changes were limited to the photoreceptors and began with degenerative changes in the inner segments as early as 8 days postinoculation. As the inner segment lesions became more prominent, associated degenerative changes within outer segments were seen (38 days postinoculation). An influx of macrophages was associated with increasing degenerative changes; these cells engulfed cellular debris but did not appear to contribute directly to the degenerative process. Retinas having the greatest damage to the inner segment area also had moderate reduction in outer nuclear layer density and outer segment length, and in numbers of outer segments. All of the retinal changes described occurred almost exclusively in the central to mid‐region of retina with relative sparing of peripheral retina.
Ultrastructural evidence for compensatory sprouting of climbing and mossy afferents to the cerebellar hemisphere after ipsilateral pedunculotomy in the newborn rat
Authors: Angaut P. , Alvarado‐Mallart R. M. , Sotelo C. 
Published: January 2005

AbstractUnilateral section of the inferior and middle cerebellar peduncles was performed in rats at postnatal days 1 or 2. The ultrastructure of the cerebellar hemispheric cortex ipsilateral to the lesion was examined 3 months later. The absence of contralateral inferior olive and of ipsilateral middle peduncle, together with a marked regression of the contralateral pontine gray, were indicative of successful pedunculotomy.In spite of a relative atrophy of the hemisphere, its cytological structure was qualitatively normal. Mossy and climbing fibers were present and their terminal varicosities disclosed normal features. The density of climbing fiber terminals was reduced compared to control cerebellum, whereas the density of mossy terminals seemed unchanged. Subsequent to the reduction of climbing afferents two subclasses, or types, of Purkinje cells were present: A “normal” type characterized by its climbing fiber innervation and a “hyperspiny” type devoid of climbing fiber.In some of the adult rats pedunculotomized at birth, section of the contralateral peduncles was performed 24 hours before fixation. Terminal degeneration of climbing and mossy fibers was observed in the neonatally deprived hemisphere, providing the proof that these fibers result from a compensatory transcommissural sprouting of afferents destined to the contralateral hemicerebellum.These results demonstrate that the cerebellar cortex neonatally deprived of its main afferents can be innervated by climbing and mossy fibers through a process of transcommissural sprouting. Although the newly formed synapses maintain their target specificity, a functional reorganization must occur because of the altered distribution of both systems of afferents.
Ganglion cells of the cat accessory optic system: Morphology and retinal topography
Authors: Farmer Samuel G. , Rodieck R. W. 
Published: January 2005

AbstractThe ganglion cells of the cat's retina form classes that are distinct in their cell morphology, retinal distribution, central projections, and functional properties. By means of the retrograde transport of horseradish peroxidase injected into the accessory optic nuclei of the cat midbrain, we have characterized the retinal ganglion cells projecting to these nuclei.The retinal projection is virtually completely crossed to the medial terminal nucleus and to the lateral terminal nucleus. This appears to be true for the dorsal terminal nucleus as well, although difficulties of the technique limit our findings for this region. No differences were found in either the spatial distribution, or the somal size distribution, or the morphological characteristics of the ganglion cells projecting to these three nuclei. In spatial distribution, these cells are concentrated in the area centralis and visual streak and show no evidence of a nasotemporal divison. Morphologically, they have small to medium‐sized somas and delicate, sparsely branching dendrites. They do not appear to belong to any of the morphological cell types thus far identified.
Cytoarchitecture, fiber connections, and ultrastructure of nucleus isthmi in a teleost (Navodon modestus) with a special reference to degenerating isthmic afferents from optic tectum and nucleus pretectalis
Authors: Ito Hironobu , Sakamoto Noboru , Takatsuji Koichi 
Published: January 2005

AbstractCytoarchitecture and fiber connections of the nucleus isthmi in a teleost (Navodon modestus) were studied by means of Nissl, Bodian, toluidine blue, Golgi, and Fink‐Heimer methods. Synaptic terminals were classified by the ultrastructural characteristics, and their origins were determined by electron microscopic degeneration experiments.The nucleus isthmi is composed of an outer cellular area or shell and an inner noncellular area or core. The shell covers anterior, dorsal, and ventral aspects of the core. The cell bodies in the shell are oval (15 × 20 μm) with an anteroposterior long axis, and have many somatic spines. Spines are also seen on the initial segment of the axon. Primary dendrites extend postermedially and branch out in the core. The core contains thin and thick myelinated fibers, which originate in the optic tectun and in the nucleus pretectalis, respectively.At least two types of axons terminal were distinguished in the nucleus isthmi: S type, containing spherical vesciles, and F type, containing flattened vesicles. S terminals are derived from thin myelinated fibers and are only seen in the core where they form asymmetric synapses with dendrites. Frequently a portion of the S terminal membrane near the usual synaptic cleft is in close apposition with the membrane of an adjacent small dendrite or spine. F terminals, which derived from thick myelinated fibers, make symmetric synaptic contacts with both cell bodies in the shell and dendrites in the core. S terminals degenerate after ipsilateral ablation of the optic tectum, whereas F terminals degenerate after destruction of the nucleus pretectalis.
Reorganization of raccoon somatosensory cortex following removal of the fifth digit
Authors: Rasmusson Douglas D. 
Published: January 2005

AbstractThe organization of part of the primary somatosensory cortex was examined in anesthetized raccoons at 2, 8, or 16 weeks after the normal peripheral input to this region of cortex had been removed by amputation of the fifth digit. Electrophysiological recordings were made in and around the cortical area representing the fifth digit. Eight intact animals were used to verify that this specific area could be accurately localized on the basis of the sulci and to determine the normal response characteristics of this area. The results from nine animals with the fifth digit removed provided evidence for a gradual reorganization of the cortical area which had been functionally denervated. At 2 weeks postamputation the field was almost totally unresponsive to sensory input. At 8 weeks many sites were responsive to high intensity stimulation of rather extensive regions of the hand. At 16 weeks the cells fired more readily to peripheral stimulation than at 8 weeks and tended to have smaller, more restricted receptive fields. The location of receptive fields in this latter group suggested that the fifth digit area was taken over primarily by input from the fourth digit. The time course of this reorganization is suggestive of extensive anatomical changes either within the cortex itself or at subcortical levels.
The medial forebrain bundle of the rat. I. General introduction
Authors: Nieuwenhuys Rudolf , Geeraedts Leo M. G. , Veening Jan G. 
Published: January 2005

AbstractThis paper is the first of a projected series of studies on the strcture and composition of the medial forebrain bundle (MFB) of the rat and the relations of this fiber system to its bed nucleus, the lateral hypothalamic area. The first part of the paper comprises an extensive review of literature on the MFB from its discovery by Ganser in 1882 to the present. This review serves as the basis for an evalution of our present‐day knowledge of the organization of the MFB, which is presented in the second part of this paper. Despite the wealth of information available on the origins and sites of termination of the axons that constitute the MFB, surprisingly little attention has been given to the bundle itself, to its topographic boundaries, its fiber composition, or to the spatial arrangement of its constituent components. These features of the MFB as it extends through the lateral preoptic and lateral hypothalamic areas have been analyzed in normal Klüver‐Barrera‐ and Bodian‐stained material. From this analysis, a detailed atlas of the MFB and some of the surrounding structures has been prepared. This atlas, which forms the third section of this paper, illustrates the appearance and organization of the MFB at ten equidistant levels through the lateral preoptic and lateral hypothalamic continuum.