bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the pulvinar of the squirrel monkey
Authors: Mathers Lawrence H. 
Published: December 2004

AbstractThree divisions of the squirrel monkey pulvinar, p. inferior (PI), p. lateralis (PL), and p. medialis (PM), have been studied with light‐ and electron‐microscopic techniques. Two populations of neurons exist. The first neuron is a thalamocortical relay cell (TCR), averaging about 26 μ in diameter, with radial dendritic pattern and thin dendritic appendages. The second is a Golgi type II neuron, about 16 μ average diameter, with more complex dendritic appendages and an axon ramifying in the vicinity of the soma. The TCR: Golgi type II ratio is about 7:3 in PL and PI, and 9:2 in PM.Three types of synaptic terminals are observed: the RS, comprising about 80% of the total population; the RL, comprising about 10%; and the F, comprising about 10%. The first two contain round vesicles and make asymmetrical synaptic contacts, while the third contains both round and flat vesicles and makes symmetrical synaptic contacts. Characteristic groupings of synaptic terminals and dendrites, called “glomeruli”, appear to be organized for structured and efficient interactions. Adhesive contacts are observed between synaptic and non‐synaptic and non‐synaptic structures.Comparisons with other thalamic nuclei are made, and the ultrastructural resemblance among all thalamic nuclei studied thus far is noted. The presence of glomeruli in all is discussed.
The synaptic organization of the cortical projection to the pulvinar of the squirrel monkey
Authors: Mathers Lawrence H. 
Published: December 2004

AbstractThe synaptic morphology of the pulvinar has been examined following cortical lesions in peristriate, posterior temporal and posterior parietal areas. Light‐microscopic stains demonstrate orthograde degeneration in p. lateralis, p. inferior, and the posterior nucleus, with a convergent input to the medial one‐half of p. inferior and the posterior nucleus. Electron microscopic examination shows that parts of two different populations of synaptic terminals degenerate as a result of the cortical lesions: the RS terminal, which rapidly becomes electron‐dense and later is phagocytosed, and the RL terminal, which initially exhibits signs of neurofilamentous hyperplasia and later becomes electron‐dense.Comparisons are made between the pulvinar and other thalamic nuclei with respect to synaptic organization and the origin of extrinsic synaptic terminals. It is pointed out that while the overall arrangements within the pulvinar are equivalent to those in VB, MGB or dLGN, the fact that two different populations of synaptic terminals originate in the cortex suggests functional differences between the pulvinar and other parts of the thalamus examined thus far. The possible phylogenetic origins of different parts of the pulvinar are also discussed.
The dendritic tree of spinal neurons in dogs with experimental hind‐limb rigidity
Authors: Gelfan Samuel , Kao Grace , Ling Hannah 
Published: December 2004

AbstractThe dendritic tree of lumbosacral neurons from dogs with experimental hind‐limb rigidity, produced by temporary lumbosacral ischemia, was reduced to about one‐third of the mean normal size, as previously established in Golgi‐Kopsch preparations. The size reduction was due to the loss only of the more distal segments of the tree by the neurons which survived the ischemic episode, thus decreasing the mean radius of the dendritic projections. The mean number of primary dendrites/neuron remained essentially the same as in the normal but the portions extending beyond about 100 μ from cell body, and all their branches, suffered truncation: the branches originating closer to the cell body suffered the same truncation beyond the 100 μ border. The mean perikaryon size and size range in the sample of 300 neurons from three rigid dogs was not reduced from that of the 360 neuron sample from three normal animals. The loss of nearly two‐thirds of dendrite surface, with consequent loss of all contacts with other neurons normally handled by this major fraction of the dendritic tree, compounded the denervation and isolation sustained by the cell body and surviving proximal part of the tree, due to the marked mortality of interneurons during the ischemic episode. The reduction of the mean of the calculated synaptic endings/neuron for the entire sample to less than one‐fifth of normal and the narrowing of the range of synaptic populations/neuron to one‐seventh of normal are some indications of the magnitude and consequences of this morphological alteration; an alteration concomitant with the demonstrated functional alterations in such neurons. The orderliness of the dendrite organization, as found in the sample of normal neurons, however, did not change to randomness in the altered, „spastic”︁ ones. The peripheral portion of the dendritic arborization failed to survive the denervation and was promptly sloughed, it is postulated, because of its greater vulnerability to denervation, due to a greater dependency upon a continuous transneuronal supply of neurotrophic factors. This dependency may increase exponentially with increasing distance of dendrite segments from cell body. The concept of neuronal interdependence (Gelfan, '64) is extended to include viability of at least part of the dendritic tree.
The projection field of the stria terminalis in the rat brain. An experimental study
Authors: De Olmos Jose S. , Ingram W. R. 
Published: December 2004

AbstractThe problem of the stria terminalis projection field has been examined by use of two versions of the cupric‐silver technique as well as variations of the Fink‐Heimer and Nauta‐Gygax techniques applied to material fixed under different conditions using brains from very young rats surviving 30 hours to four days after production of lesions at different levels of the course of the stria terminalis and related structures. The findings are as follows:
A dorsal subventricular portion of the stria terminalis divides into retrocommissural and supracommissural contingents which together account for degenerating terminals seen in the ipsilateral bed nuclei of the stria terminalis and of the anterior commissure, and in the medial preoptic‐hypothalamic junction area. The supracommissural bundle also disseminates into the laterobasal septum, nucleus accumbens, olfactory tubercle, the posterior and medial divisions of the anterior olfactory nucleus, and the granular layer of the accessory olfactory bulb. Additional fibers end in the paucicellular capsule of the ventromedial hypothalamic nucleus, also in a small lateral parvocellular tuberal nuclear area, and throughout the premammillary nuclei. A small truly commissural division of the dorsal component was traced to the contralateral cortical amygdaloid nucleus and to small clusters of medial amygdaloid cells.
A ventral juxtacapsular portion of the stria terminalis was traced to the ipsilateral strial bed nucleus, medial preoptic‐hypothalamic junction area, the entire ventromedial hypothalamic nucleus, the lateral tuberal area and the premammillary nuclei. The lateralmost fibers of the dorsal strial component as well as those of the ventral component which lie lateral to the “commissural bundle” appear to terminate exclusively in the lateral portions of the bed nucleus of the stria.
A “commissural bundle” or component, after crossing the midline in the anterior commissure, ends in the bed nucleus of the posterior limb of the latter, in the olfactory tubercle, prepiriform cortex, lateral amygdaloid nucleus and the strial bed nucleus. It is thus a decussation rather than a commissure. No contribution from stria terminalis to stria medullaris could be identified.
Retinofugal pathways in two marsupials
Authors: Royce G. James , Ward Jeanette P. , Harting J. K. 
Published: December 2004

AbstractAutoradiographic and anterograde degeneration tracing methods were used to study and compare the organization of retinofugal pathways in two marsupial opossums, Didelphis virginiana and Marmosa mitis. Seven identical retinal targets were demonstrated for each opossum. These include: (1) the suprachiasmatic nucleus of the hypothalamus, (2) the dorsal and (3) ventral lateral geniculate nuclei, (4) the lateral posterior nucleus, (5) the pretectal complex, (6) the superior colliculus and (7) the accessory optic nuclei.While the pattern of retinal input to six of the seven targets was quite similar in the two species, the organization of the retinogeniculate pathways exhibited striking differences. In particular, our autoradiographs reveal no separation of ocular inputs within the lateral geniculate nucleus of Didelphis, i.e. the ipsilateral input is overlapped completely by the more extensive contralateral projection.In contrast, there is considerable separation, as well as overlap, of the ocular inputs within the lateral geniculate nucleus of Marmosa. Our autoradiographs reveal several distinct bands of label within each geniculate nucleus, and upon superimposing the nuclei, ipsilateral and contralateral to the placement it is apparent that two of the bands overlap, while five do not (three ipsi, two contra).
An anatomical study of some somesthetic afferents to the intercollicular terminal zone of the midbrain of the opossum
Authors: RoBards Martine J. , Watkins David W. , Masterton R. Bruce 
Published: December 2004

AbstractFollowing lesions of the dorsal column nuclei, spinal cord and sensorimotor cortex, anterograde degeneration was traced to a common target in the central midbrain: the intercollicular terminal zone. Although not all the midbrain projections of the three pathways are contained within this zone, it receives overlapping projections from each of the three body‐related somesthetic pathways studied. The intercollicular terminal zone covers the entirety of the external nucleus of the inferior colliculus and the intercollicular nucleus of Mehler, spilling over into adjacent parts of the central gray and deep layers of the superior colliculus. Little evidence of somatotopy in the somesthetic projections was disclosed, and bilateral input was found in each experimental case, regardless of the type of lesion. Golgi‐stained material was examined to explore the basis of the extensiveness of the terminal zone. These materials showed that the dendritic spread of neurons in the external nucleus of the inferior colliculus and the intercollicular nucleus, taken together, covers the entirety of the intercollicular terminal zone. That is, the dendrites invade the same portions of the central gray and deep layers of the superior colliculus which are covered by the terminal field. We conclude that a tripartite division of the sensory midbrain may be justified: with the somesthetic modality being represented anatomically in a fashion at least roughly analogous to that of vision and audition.
Postnatal development of the cerebellar cortex in the rat: V. Spatial organization of Purkinje cell perikarya
Authors: Altman Joseph , Winfree Arthur T. 
Published: December 2004

AbstractThe development of the spatial organization of Purkinje cell perikarya was examined in the rat cerebellum from birth to adulthood. Dispersion of the perikarya following birth is made possible by the rapid expansion of the cortical surface. Their subsequent regular monocellular alignment is ensured by mechanical factors, the pressure exerted from below by the expanding granular layer and the barrier formed above by the pile of parallel fibers which prevent the penetration of the bulky perikarya into the molecular layer. The perikarya remain in this position even after the slender stem dendrite pierces the molecular layer along the descending axons of basket cells.The increase in interperikaryal distance between Purkinje cells is rapid up to day 12, then declines. This is temporally associated with the growth of the basket cell plexus and glial envelope around the perikaryon. The increase in perikaryal size continues up to day 30. This may be temporally associated with the growth of the Purkinje cell dendritic arbor as reflected by the expansion of the molecular layer up to day 30.The spatial arrangement of Purkinje cells within the monocellular sheet was graphically displayed with computer aid. In the adult cerebellum a hexagonal arrangement could be recognized in a proportion of “near‐neighborhoods,” consisting of about six Purkinje cells and their neighbors. When the neighborhoods were extended with fixed orientation with respect to the axis of the folium, the hexagonal arrangement disappeared. When orientation was ignored, the superimposed nearneighborhoods could be rotated to produce a hexagonal pattern. In the infant cerebellum the hexagonal arrangement could not be demonstrated before the alignment of Purkinje cells in a monolayer. Thereafter there appeared to be an increase with age in the proportion of hexagonally arranged near‐neighborhoods.It was concluded that in the monocellular ganglionic layer Purkinje cells are not aligned in regular rows with respect to the geometrically arranged elements of the supraganglionic layer. The formation of an imprecise hexagonal pattern, like the alignment of Purkinje cells in a monolayer, was attributed to mechanical factors.
Effects of low‐level X‐irradiation on cat cerebella at different postnatal intervals: II changes in purkinje cell morphology
Authors: Anderson William J. , Stromberg Melvin W. 
Published: December 2004

AbstractThe whole‐head of infant kittens was irradiated with fractionated doses of 150 R and 200 R at different postnatal intervals. Experimental age conditions consisted of an irradiated newborn, 1‐week, 2‐week, 3‐week, and a 4‐week age condition while the age of sacrifice remained constant at 70 days. The molecular layer thickness was reduced by 47% in the newborn, 40% in the 1‐week group, 17% in the 2‐week group, 19% in the 3‐week group and by 9% in the 4‐week group. An evaluation of Golgi impregnated material revealed that the dendritic arborizations of Purkinje cells were consistently reduced the earlier the age at which radiation was begun. A reduction in spiny branchlets was seen in all of the experimental conditions. All experimental age conditions displayed the phenomenon of dendritic “damming” at the pial surface, which consisted of an excessive crowding of spiny branches at this level. An increased growth of the primary dendrite before branching tood place was seen in the newborn and 1‐week group. This became less but was still significant in the 2‐week group. A correlation of this phenomenon with the presence or lack of stellate cells is discussed. Purkinje cells with two or more dendrites emerging from their soma were classified and analyzed separately. It was found that the primary dendritic branching in these cells often followed separate morphological patterns and appeared to be independent of each other. Climbing fibers were found to conform to the abnormal dendritic arborizations of the Purkinje cells, and were reduced in complexity in the early radiation treatment groups. This suggested that climbing fibers had no influence upon the dendritic growth pattern, but instead were under the influence of the Purkinje cell dendritic growth.
Abnormal interhemispheric connections in the visual system of boston siamese cats: A physiological study
Authors: Shatz Carla 
Published: December 2004

AbstractIn the normal cat most visual fibers in the splenium of the corpus callosum are concerned with a representation of the vertical meridian of the visual field. These fibers for the most part originate from cortical regions forming the border between adjacent architectonic areas, such as the anatomical 17‐18 border. Due to a genetic mutation in Boston Siamese cats, the anatomical 17‐18 border now represents a region in the ipsilateral visual field roughly 20 degrees away from the vertical meridian, and the representation of the vertical midline is displaced from the border to regions within areas 17 and 18 proper. Do visual fibers in the Boston Siamese cat corpus callosum originate, as in normal cats, from the 17‐18 border even though the vertical meridian is no longer represented there? The present paper deals with this question from a physiological standpoint.Single visual fibers in the corpus callosum of 11 Boston Siamese and two normal cats were recorded using extracellular microelectrodes. Receptive fields were mapped and their positions used to infer the likely cortical site of origin for each fiber. In confirmation of earlier findings, most callosal receptive fields in the normal cat were closely apposed to the vertical meridian, as would be expected if only those visual cortical regions which represent the vertical meridian, such as the border between areas 17 and 18, contribute to the corpus callosum. In Boston Siamese cats, however, an abnormally large amount of visual field was represented in the corpus callosum, with some receptive fields located as far as 25 degrees away from the vertical meridian. The representation of the vertical meridian was nevertheless substantial.The present findings suggest, therefore, that in Boston Siamese cats callosal fibers do not originate solely from the boundary regions between adjacent cortical areas, such as the anatomical 17‐18 border, but originate also from other cortical regions, especially the vertical meridian representation, regardless of their location with respect to such boundaries.
An intricately patterned prefronto‐caudate projection in the rhesus monkey
Authors: Goldman Patricia S. , Nauta Walle J. H. 
Published: December 2004

AbstractThe distribution of prefronto‐caudate fibers in the caudate nucleus was studied autoradiographically in monkeys of various ages in which tritiated amino acids had been injected into the middle one‐third of the length of the dorsal bank of the principal sulcus. The results indicate that, contrary to previous reports which had suggested a projection to only the head of the caudate nucleus, area 9 of Brodmann projects to the entire length of the nucleus.In the head of the caudate nucleus the cortico‐caudate fibers are distributed in a pattern which is remarkable in two respects. First, the grains are not uniformly distributed but rather are segregated into clusters separated from one another by territories in which grain density does not exceed background. Second, individual clusters of grains, circular or elliptical in shape, surround grain free cores. These patterns of fiber distribution within the head of the nucleus are more sharply defined in newborn than in older monkeys. Our findings suggest that the caudate nucleus is organized more as an anatomic and functional mosaic than as the homogeneously organized structure that it is commonly considered to be.
Retinal projections in larval, transforming and adult sea lamprey, Petromyzon marinus
Authors: Kennedy Michael C. , Rubinson Kalman 
Published: December 2004

AbstractUnilateral enucleations were performed on larval, transforming and adult sea lampreys. Following 5 to 11 days survival, the animals were sacrificed and the brains were processed using a modified Fink‐Heimer technique. In larvae, contralateral optic projections were found to the posterior one‐third of the dorsal thalamus, the pretectum, and the optic tectum. No ipsilateral projections were present in the larvae. In enucleated transforming and adult lampreys, degenerating axons were observed in the optic chiasm and bilaterally in the optic tracts. Retinal efferents projected bilaterally to a lateral neuropil region (“tractus opticus”) in the posterior one‐half of the dorsal thalamus. Contralaterally, a conspicuous dorsomedial cell group (lateral geniculate nucleus) also received a projection. Contralateral projections to the superficial layers of the pretectum and optic tectum were observed. Ipsilateral retinal projections to the pretectum and optic tectum in transforming and adult lampreys were restricted to a small zone at the ventrolateral margins of the pretectum and tectum. The changes in distribution of retinofugal projections during transformation appear to be occurring at the same time that the eye differentiates into its adult form.
Central connections of ventral root afferents as demonstrated by the HRP method
Authors: Maynard Christine W. , Leonard Robert B. , dan Coulter Joe , Coggeshall Richard E. 
Published: December 2004

AbstractTo study the central connections of ventral root afferents, horseradish peroxidase was injected into the lumbosacral spinal cord of the cat and the appropriate dorsal ganglia were examined from segments with (1) both dorsal and ventral roots intact, (2) both roots sectioned, and (3) only the dorsal root sectioned. The key finding was that a number of labeled cells (up to 133) were observed in the ganglion after dorsal rhizotomy. We interpret these findings to mean that the central processes of the labeled cells projected to the spinal cord through the ventral root. As expected, when both roots wer cut, almost no cells were labeled and when both roots were intact, there were large numbers of labeled cells.Of the labeled cells observed in ganglia after dorsal rhizotomy, all were found to be within the ganglion itself. No labeled aberrant dorsal root ganglion cells could be found.
Neurogenesis in the epithalamus, dorsal thalamus and ventral thalamus of the rat: An autoradiographic and cytological study
Authors: McAllister James P. , Das Gopal D. 
Published: December 2004

AbstractTimes of final mitotic division for neurons of the epithalamic, dorsasl thalamic and subthalamic nuclei of the rat were determined with the aid of thymidine‐H3 autoradiography. Intensely labelled neurons were observed in the brains of animals injected with radiochemical from days 13 to 19 of gestation. The pattern of distribution of the labelled neurons indicated that neurogenesis in these regions followed caudorostral, lateromedial and ventrodorsal neurogenetic gradients, all of which were found to operate simultaneously. Since neurogenesis in the epithalamus, subthalamus and caudolateral thalamic regions began on days 13 and 14 of gestation, the ventrodorsal and lateromedial proliferative gradients were clearly discerned only within the ventral and dorsal thalamus exclusive of the epithalamus. These directional neurogenetic gradients were apparent throughout the entire thalamus and within individual thalamic nuclei. No neurogenetic pattern based upon neuronal size was observed, i.e., large neurons were not preferentially formed earlier than smaller ones. Detailed information has also been provided on the cytological character of each thalamic nucleus.
Genetically‐associated variations in the development of hippocampal pyramidal neurons may produce differences in mossy fiber connectivity
Authors: Vaughn James E. , Matthews Dee Ann , Barber Robert P. , Wimer Cynthia C. , Wimer Richard E. 
Published: December 2004

AbstractThe neuronal generation patterns of hippocampal pyramids were analyzed in two inbred strains of house mice (SM/J and BALB/cJ) using tritiated thymidine radioautography. These two strains of mice possess markedly different patterns of mossy fiber synapses upon pyramidal neurons within a specific segment of regio inferior. The results of this study show that this same segment of regio inferior also displays markedly different patterns of pyramidal neuron generation in the two strains. Specifically, the pyramids of this segment of regio inferior are generated according to the typical [inside‐out] sequence in SM/J mice, but this pattern is reversed into an [outside‐in] sequence in BALB/cJ mice. The remaining segment of regio inferior, and all of regio superior, is formed in an inside‐out sequence in both strains. These results strongly suggest that altered temporal patterns of pyramidal neuron generation may play a major role in determining mossy fiber connectivity patterns.