bluuebunny/crossref_metadata_2025_split huggingface dataset:
The anatomical organization of the cerebello‐olivary projection in the cat
Authors: Tolbert D. L. , Massopust L. C. , Murphy M. G. , Young P. A. 
Published: December 2004

AbstractThe cerebello‐olivary pathway in the cat has been examined using orthograde and retrograde neuroanatomical tracing techniques.The orthograde transport of 3H‐leucine from injection sites in the deep cerebellar nuclei labeled dentate and interpositus projections to the rostral two‐thirds of the contralateral inferior olivary complex. These projections are topographically organized, with the dentate nucleus projecting to the principal olivary nucleus and the posterior and anterior interpositus nuclei projecting to the medial and dorsal accessory olives respectively. Fibers from the ventral half of the dentate nucleus terminate in the lateral bend and ventral lamina of the principal olive, whereas the medial and lateral parts of the dorsal half of the nucleus project to the medial and lateral regions of the dorsal lamina respectively. It is apparent that the more caudal parts of the interpositus nuclei project to areas of the medial and dorsal accessory olives near the caudal end of the principal olivary nucleus, whereas neurons in the more rostral parts of the interpositus nuclei project to the more rostral areas of the accessory olivary nuclei. A connection between the fastigial nucleus and the inferior olive could not be demonstrated.The retrograde transport of horseradish peroxidase (HRP) from injections sites in the inferior olive labeled cells throughout the contralateral dentate and interpositus nuclei. The labeled cells were especially numerous in the ventral parts of the dentate and posterior interpositus nuclei. These HRP‐positive neurons were consistently small (10–15 μ) ovoid or spindle‐shaped cells, with relatively large nuclei and light‐staining Nissl substance.This evidence strongly suggests that the cerebello‐olivary pathway originates from a population of small neurons in the dentate and interpositus nuclei and projects to specific, topographically defined areas in the contralateral inferior olive.
Ultrastructure of the feline area postrema
Authors: Klara P. M. , Brizzee K. R. 
Published: December 2004

AbstractThe morphology of the feline area postrema (AP), a circumventricular organ, has been studied by scanning (SEM) and transmission electron microscopy (TEM). In SEM preparations the boundary of the AP was sharply delineated by the absence of kinocilia. Microvilli were numerous and seemed to be concentrated at the junction between ependymal cells, imparting a polygonal surface pattern superimposed on cell boundaries. Some cell processes were present on the AP surface, but no supra‐ependymal cell bodies could be seen over the AP proper. In TEM preparations the AP was characterized by blood vessels with distinct perivascular spaces. These spaces contained fibroblasts and collagen, and were limited by basal laminae. Capillary endothelial cells were typically fenestrated and contained numerous pinocytotic vesicles. Bulbous endings of attenuated cellular processes terminated on the external basal laminae of AP vasculature. Some of these endings could be traced to the cells covering the ventricular surface of the AP. These cells demonstrated several features common to ependymal cells which have been identified as tanycytes. The presence of small neurons frequently seen in groups of three or four confirm previous light microscopic studies. Synapses predominantly of the axodendritic variety were observed, and both dense cored and clear cored vesicles were present on the same ending. Myelinated and unmyelinated axons were a consistent finding in the AP with the former being more abundant in the lateral margins of the AP and in the region of the area subpostrema. The chemoreceptive function of the AP has been widely accepted; however, studies indicate that it is not possible to distinguish species possessing an emetic reflex on the basis of ultrastructural morphology. The possibility that the AP serves functions in addition to emetic chemoreception is considered.
Age‐related deterioration of pyramidal cell basal dendrites in rat auditory cortex
Authors: Vaughan Deborah W. 
Published: December 2004

AbstractThe basal dendritic trees of layer V pyramidal cells in the rat auditory cortex were examined quantitatively in a group of 3‐month‐old and a group of 34‐ and 36‐month‐old rats. Two forms of analysis were used on the Golgi preparations: (1) the number of intersections between the basal dendrites and a series of concentric circles whose common center lies over the perikaryon center, and (2) the number of dendritic branches, by order, per neuron. The data indicate that in the old animals the density of the dendritic tree has decreased significantly within a radius of about 150 μ of the perikaryon, yet the extent of the dendritic domain has not changed appreciably. Analysis of the dendritic branching suggests that there has been a deterioration not only in the peripheral branches of the dendritic tree, but also that entire dendrites have been lost. This loss of primary branches was confirmed through the reconstruction of layer V neuronal perikarya and their proximal dendrites from 1‐μ plastic serial sections of auditory cortex. Concomitant with the loss of dendrites which accompanies advancing age is a tendency for the perikaryon to be smaller, but not distorted, in the old animals.
The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. IV. The projection to the anterior lobe
Authors: Brodal Alf , Walberg Fred 
Published: December 2004

AbstractFollowing injections of horseradish peroxidase (HRP) in the cerebellar cortex of the anterior lobe of the cat, the distribution of labeled cells in the inferior olive was mapped. The findings largely confirm those made previously in studies of olivary retrograde cell loss following cerebellar ablations (Brodal, 1940b). In addition, they reveal further olivary areas projecting onto the anterior lobe, and permit a more detailed analysis of the pattern in this projection. Concerning major points the results are in agreement with physiological studies by Armstrong et al. (1974). They bring supporting evidence for a longitudinal zonal pattern in the anterior lobe (fig. 6C).The middle zone of the vermis receives its fibers from a large central area in the caudal half of the medial accessory olive, a lateral zone of the vermis from the lateral half of the dorsal accessory olive. Both olivary areas project to the corresponding cerebellar zone throughout lobules V‐I.The lateralmost part of the anterior lobe (lobules IV‐V) receives afferents from an area in the dorsal lamella of the principal olive. The intermediate part of lobules IV‐V receives afferents from the medial half of the dorsal accessory olive and from an area in the rostral half of the medial accessory olive. There is suggestive evidence that the latter projects lo a middle zone, the former to a medial and a lateral zone within the intermediate part as found physiologically. Conclusions concerning projections to the intermediate part of lobules III‐II could not be made.The findings in this and preceding studies with the HRP‐method show that the concept of a longitudinal pattern in the cerebellum is scarcely generally valid of the entire olivocerebellar projection.Within the projections of the lateral half of the dorsal accessory olive and the area in the rostral part of the medial accessory olive there appears to be a topical relation with the folial pattern in the anterior lobe.An analysis of the findings with reference to the afferents traced anatomically to the various olivary areas permits some conclusions as to the functional role of the olivary areas. Comparison with Oscarsson's (1973) diagram of the sites of termination of two of the spinal‐olivary pathways (his DF‐SOCP and VF‐SOCP) permits an anatomical explanation as concerns the projections to the vermis, while correlations as concerns the intermediate part are less satisfactory.
The effect of cortical and tectal lesions on the visual fields of binocularly deprived cats
Authors: Sherman S. Murray 
Published: December 2004

AbstractThe visual fields of seven cats raised with binocular lid suture were measured before and after various neural lesions. Each of the cats preoperatively responded with each eye to stimuli from 90° ipsilateral through to the midline. A transection of the optic chiasm rendered one cat bline on the visual field tests. Large bilateral occipito‐temporal cortical ablations (4 cats) did not measurably affect orienting responses or the extent of visual field. Unilateral occipito‐temporal cortical ablations (2 cats) also had no affect on the visual fields, but subsequent ablations of the contralateral superior colliculus produced permanent blindness in the hemifield contralateral to the ablated tectum. These two cats also were apparently blind with the eye contralateral to the ablated tectum; but with the other eye, the cats retained their preoperative orienting responses. These data are consistent with the hypothesis that, with early binocular deprivation, cats develop dependence upon retinotectal and not thalamocortical pathways for visually guided orienting behavior.
An autoradiographic investigation of the subcortical visual system in chimpanzee
Authors: Tigges Johannes , Bos Jane , Tigges Margarete 
Published: December 2004

AbstractBased on one adult chimpanze monocularly injected with radioactive proline, retinofugal fibers were found to terminate bilaterally in the suprachiasmatic, prgeniculate, lateral geniculate, olivary, pretectal and lateral terminal nuclei, and the superior colliculi; the existence of a dorsal terminal nucleus of the accessory optic system is in doubt. In the ipsilateral geniculat nucleus, the fibers terminat in layers 2, 3 and 5; in the contralateral nucleus, they end in layers 1, 4, and 6. Miday throuh the geniculate nucleus, 3 and 4 split medially into two daughter layers 3 and 4 split medially into two daughter layers each. In the superior colliculi, most of the retinal terminals are aggregated superficially in a band located in the stratum griseum superficiale. The contralateral band is interrupted by gaps; the ipsilateral band has fewer gaps, is slightly thicker and located more deeply. There is a limited second tier of terminals in the contralateral superficial gray.
The commissural projection of the superior colliculus in the cat
Authors: Edwards Stephen B. 
Published: December 2004

AbstractThe origin, course, and termination of the commissural projection of the superior colliculus were studied using the orthograde autoradiographic tracing method and the retrograde method utilizing horseradish peroxidase.The complementary and mutually confirming sets of data showed that the commissural fibers interconnect a restricted region of the colliculi. This region includes the strata grisea intermedium and profundum and to a lesser degree the stratum opticum. It extends throughout only the rostral part of the colliculus where it ends abruptly at a level slightly less than half the distance from the anterior border of the deep gray layers. By using the needle used for isotope injection to record multiunit reponses to somatic and visual stimuli, direct evidence was obtained that this region falls within that functional area of the colliculus devoted to face representation and central vision. The results also suggested that more commissural fibers arise from lateral than medial parts of this region and that many fibers interconnect corresponding points in the colliculi. In addition to intertectal connections, the commissural projection contains decussating axons which terminate in tegmental structures and within a restricted zone of the central gray matter directly overlying the oculomotor complex.The results are discussed in relation to the possible role the commissural projection plays in the regulation of eye and head movements.
Normal nerve fibers in the barrel region of developing and adult mouse cortex
Authors: Waite Phil M. E. 
Published: December 2004

AbstractThe pattern of normal nerve fibers associated with barrel‐shaped structures in the somatosensory cortex of both young and adult mice, has been studied using a reduced silver method. In adult animals, the [barrel] sides and septa can be seen to contain densely packed bundles of nerve fibers running vertically between layers III and V. In parasagittal sections, these fibers appear as very dark bands between adjacent barrels, while in tangential sections the fibers, cut in crosssection, appear as rings of dark spots concentrated around the barrel edges. In contrast to this, barrels in immature animals have dark, evenly stained centers and pale, cell dense sides. This immature pattern can first be distinguished in 2‐day‐old animals and persists until 18 to 19 days. Between 18 and 24 days a change from the immature to the adult pattern occurs with the appearance of darkly stained, fine fibers within layer IV, particularly within the barrel sides. It is suggested that the immature pattern is due, primarily, to the staining of thalamic afferents while the adult pattern appears with the development of intracortical and association fibers. Electron microscopy, on tissue previously treated by the silver method, shows that the silver deposits are mainly attached to longitudinal elements of the axoplasm and not associated with myelin. This may explain the success of this method in showing fibers in young, unmyelinated brains.
The prenatal development of some of the visual pathways in the cat
Authors: Anker Robyn L. 
Published: December 2004

AbstractLesions were made in the visual system in a series of cat fetuses of known gestational age, and fiber and terminal degeneration were stained by the Eager method.The times of development of the retinal projection, of the thalamocortical and corticothalamic projections of area 17 of the visual cortex, and of the intrinsic fibers in the visual cortex were examined.Enucleation of one eye resulted in degeneration being detected bilaterally in the lateral geniculate nuclei (LGN), superior colliculi (SC) and optic tracts. The optic nerves reached the optic chiasm by the thirtieth embryonic day (E30) and the optic tract connections with the LGN and SC were made by E37. The projection always appeared stronger in the contralateral LGN and SC, and the amount of degeneration increased in both sides with increasing age.A parasagittal knife cut was made in the dorsomedial crest of the visual cortex. Where the lesion passed through the cellular layers of the cortex, intrinsic fibers were cut when these were present. The deeper part of the incision through the white matter undercut the medial wall of the visual cortex, interrupting thalamocortical and corticothalamic fibers when these were present.The longer horizontal fibers that were intrinsic to the visual cortex began to develop during the last two weeks of gestation but were not fully developed at birth. In the undercut visual cortex distant from the place of entry of the lesion, and before the intrinsic fibers of the cortex had developed, degeneration was found in layers 1 and 4, demonstrating the presence of a thalamocortical pathway. The youngest fetus to show this degeneration was operated at E48. This degeneration was not present three days earlier at E45. Fiber plexuses that have been described earlier in development (Marin‐Padilla, '71; Cragg, 75) do not appear to degenerate after undercutting the cortex.The corticothalamic pathway to the lateral posterior nucleus medial to the LGN was developed at E45. The descending pathways to the ipsilateral LGN and SC were developed by E48, but it is not known whether they are present before this.Thus degeneration has been used to detect the development of axonal pathways in the fetus for the first time; the major afferent and efferent pathways are developed at an earlier stage than has previously been described.
A study of aging in the Human abducens nucleus
Authors: Vijayashankar Narayanakurup , Brody Harold 
Published: December 2004

AbstractAs part of a continuing study of the relationship between age and neuronal number within the human brainstem, the abducens nucleus was examined in a total of 20 brains. While the nucleus almost doubles in length between birth and adulthood, there is no significant change in cell number after birth. With the exception of some specimens which may indicate an individual variation, the average number of cells in this nucleus for all specimens examined was found to be 6,454. Approximately the same number is found in the nucleus of the newborn (6,500), confined within a length of 1.5 mm. With maturity, the nucleus enlarges to 3.0 mm but since the cell number does not significantly change, the cell density in any one section of the nucleus is considerably decreased, thus emphasizing the importance of absolute counts in such studies. At least among the brainstem nuclei already examined by various investigators it appears that neuronal loss is not a concomitant of aging as has been described for the cerebral and cerebellar cortices.
Projections from cortical visual areas 17, 18, and MT onto the dorsal lateral geniculate nucleus in owl monkeys
Authors: Lin C. S. , Kaas J. H. 
Published: December 2004

AbstractProjections from cortical visual Areas 17, 18, and MT to the dorsal lateral geniculate nucleus of owl monkeys were revealed by the use of the autoradi‐ographic tracing method. Restricted injections of H‐proline into Area 17 resulted in dense columns of labeled tissue extending through all layers of the nucleus and roughly perpendicular to the layers. There was some lateral spread of the label in the interlaminar zones. Projections from Areas 18 and MT were distributed over the ventral layers of the nucleus including the magnocellular layers, layer S, and the adjoining interlaminar zones. The input from Area 18 was relatively sparse. The projections from all three cortical visual areas appear to connect hornotopic locations in the geniculate and cortical representations of the visual field.
The projection from the lateral geniculate nucleus onto the visual cortex in the cat. A quantitative study with horseradish‐peroxidase
Authors: Hollaänder Horstmar , Vanegas Horacio 
Published: December 2004

AbstractHorseradish‐peroxidase (HRP) was injected (9‐18 μg in 0.03‐0.06 μl) into cortical areas 17, 18 or 19 of 11 adult cats. After survival times of 17 hours to 7 days, the thalamus was examined for retrogradely HRP labelled nerve cells in serial transverse sections. From these sections, the percentage of labelled cells occurring in each subdivision of the dorsal lateral geniculate nucleus (LGNd) was calculated for each animal. One case each for injections in areas 17, 18 and 19 was then chosen for nerve cell size measurements in each LGNd subdivision. The peri‐karyal area of each labelled cell (N=689), and of representative samples of unlabelled cells (N=1137), was measured by planimetry. Size distribution histograms, mean values, standard deviations, and statistical significance levels were obtained by computer.It was found that area 17 receives a projection almost exclusively from laminae A and Al, and that the projecting cells belong to all cell size classes. Area 18 receives a projection mainly from laminae C and Al, and from the medial interlaminar nucleus (MIN). The projecting cells belong mainly to the large cell size classes. Area 19 receives a projection largely from MIN, and also from the C‐laminae and extrageniculate cell groups. The projecting cells belong to all cell size classes, with some emphasis on the large cells of lamina C. A significant projection was found to exist from the parvocellular laminae of LGNd onto area 19 and, to a lesser degree, area 18. In conclusion, as one goes from area 17 to 18 and to 19 the projection source shifts from the A‐laminae through the C‐laminae on to MIN and extrageniculate cell groups. The cells which project to area 18 are on the whole larger, than those which project to areas 17 and 19. A significant proportion of the contralateral visual input to area 18 is relayed via lamina G.These results provide a quantitative confirmation and extension of previous anatomical findings, and are in close relationship with physiological results regarding parallel channel processing in the visual system.
The origin of spinocerebellar pathways. II. The nucleus centrobasalis of the cervical enlargement and the nucleus dorsalis of the thoracolumbar spinal cord
Authors: Petras J. M. , Cummings J. F. 
Published: December 2004

AbstractThe origin of spinocerebellar projections from the caudal cervical, the thoracic, and the cranial lumbar regions of the spinal cord was studied in neonatal dogs.The present cytoarchitectonic and experimental studies of the cervical intumescence of the spinal cord led to the description of a cell group prominent in the dorsal horn, the nucleus centrobasalis. This nucleus, comprised of neurons of varying size and shape, extended over the length of the cervical intumescence. The largest neurons of then. centrobasahexhibited retrograde reaction following cerebellar injury or they accumulated horseradish peroxidase (HRP) after injection of the enzyme into the cerebellum. Unilateral cerebellar ablation or cordotomy evoked retrograde changes in the ipsilateral nucleus. The cerebellar‐projecting neurons were large, multipolar and chromatophilic. They occured singly, in small clusters, or in columns. The columnar arrangement was common at caudal levels of the cervical intumescence where these large cells were most abundant.The results of earlier experiments with cats and rhesus monkeys have demonstrated massive fiber degeneration in then. centrobasahfollowing dorsal rhizotomy (Petras, '65, '66; Petras and Cummings, '72). The presence of spinal afferents in this nucleus suggests that its largest neurons may serve as a link for the passage of forelimb afferent information to the cerebellum by way of an uncrossed brachiospinocerebellar projection. The present anatomical data suggest too that these large neurons are the cells of origin for the rostral spinocerebellar tract (Oscarsson and Uddenberg, '64; Oscarsson, '65).The cellular composition of the nucleus dorsalis was studied also, and the results compared with Loewy's ('70) findings in the cat. Three types of neurons were present in then. dorsalis. These have been classified as giant, medium, and small‐sized neurons. The giant and medium‐sized neurons responded to cerebellectomy, and accumulated enzyme following HRP injections into the cerebellum. The retrograde responses, generally, were most pronounced in cranial thoracic segments and diminished progressively in more caudal segments. Unilateral cerebellar ablations, cerebellar pedunculotomy, and cordotomy almost exclusively affected ipsilateral neurons. The present study provides the first demonstration of discrete retrograde changes in the giant cells of Clarke's column following cerebellectomy. The contribution of the medium‐sized neurons of then. dorsalisto spinocerebellar projections is established for the first time.