bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organization of anterior dorsal ventricular ridge in snakes
Authors: Ulinski Philip S. 
Published: May 2005

AbstractAnterior dorsal ventricular ridge (ADVR) is a major telencephalic structure in reptiles. The intrinsic, efferent, and afferent connections of ADVR were studied in water snakes (Natrix sipedon) and garter snakes (Thamnophis sirtalis) using orthograde degeneration and Golgi techniques.ADVR in these snakes contains four zones oriented concentric with the ventricular surface and named zones A, B, C, and D, with zone A being the most peripheral. Each zone contains a characteristic population of neurons. Zone A neurons have dendrites which extend obliquely through zone A and into zone B. Zone B neurons have dendrites with a high density of dendritic spines and axons which ramify in zone A concentric with the ventricle, typically bearing large varicosities about 5 μ in length. Zone C neurons have dendrites with a low density of dendritic spines and axons which ramify within about 300 μ of the soma, typically bearing small varicosities about 3 μ in length. Zone D neurons resemble those in zone C, except that their axons may course ventrally out of ADVR into the subjacent striatum.Lesions placed superficially in ADVR produce terminal degeneration which is restricted to ADVR in Fink‐Heimer preparations. Lesions which damage the ventral part of ADVR produce degeneration in striatal nuclei (medial striatal nucleus, intrapeduncular nucleus, and perifascicular complex) as well as in the ventral two‐thirds of the posterior dorsal ventricular ridge. Unilateral transections of the midbrain produce degeneration in a system of thick caliber axons, with thin collaterals, which enters ADVR caudally behind the anterior commissure and rostrally through the lateral forebrain bundle. These fibers are oriented primarily along the radii of ADVR and confined predominantly to zones B, C, and D. Lesions of the dorsal thalamus produce degeneration in a system of thin caliber axons which enters ADVR rostrally through the lateral forebrain bundle. These fibers course radially through zones C and D and then turn to run concentric with the ventricle in zone B.These observations suggest that snake ADVR consists of two fundamentally different parts. Neurons in zones A and B interact strongly with neighboring neurons through somatosomatic and axodendritic contacts and participate in connections which run concentric with the ventricle. Neurons in zones C and D participate in connections which run radially. Some of the neurons in zone D, and possibly some in zone C, project to the striatum. Neurons situated near the ventral border of ADVR are the only source of ADVR efferents. Neurons in each zone interact with those in neighboring zones.
Dark rearing in the cat: Effects on visuomotor behavior and cell growth in the dorsal lateral geniculate nucleus
Authors: Kalil Ronald 
Published: May 2005

AbstractThe morphological and behavioral effects of complete binocular deprivation were studied by rearing cats from birth in total darkness. Nineteen animals were sacrificed immediately upon removal from the dark at intervals that ranged from 3 to 16 weeks. Measurements of cell sizes in the dorsal lateral geniculate nucleus revealed that dark rearing affects cell growth in two stages. During the first three months of dark rearing the growth rate of geniculate cells is reduced, and a maximum size difference between cells from light reared control animals and dark reared cats is seen at 12 weeks. However, during the fourth month of deprivation, geniculate cells recover from the effects of dark rearing, and grow to essentially normal size by 16 weeks.In a separate set of experiments, cats were removed from the dark at 8, 12 and 16 weeks, and given normal visual experience for as long as one and one‐half years. Lateral geniculate neurons in these animals were also normal in size.These results indicate that the effects of dark rearing on cell growth in the lateral geniculate nucleus are significant, but transitory, since they can be reversed either by long term deprivation, alone, or by exposure to normal levels of illumination.Behavioral experiments were performed to study the influence of dark rearing upon visually guided avoidance, jumping, placing, and following. After 8, 12 and 16 weeks of dark rearing, cats appear blind when first examined, and fail each of the behavioral tests. Within four weeks, however, visuomotor behavior recovers almost completely.Visual field perimetry testing was also carried out, and the results indicate that orientation is not reliably affected by periods of dark rearing less than 12 weeks in duration. However, 16 week dark reared animals show visual field defects, which persist for several months, and suggest that only the nasal hemiretina is used for orientation. Since the dark reared cats which showed deficits in orientation also demonstrated a pronounced convergent strabismus, it is proposed that misalignment of the visual axes may be directly responsible for the behavioral impairment.
Cytoplasmic laminated bodies in the lateral geniculate nucleus of normal and dark reared cats
Authors: Kalil Ronald , Worden Ian 
Published: May 2005

AbstractThe postnatal development of cytoplasmic laminated bodies in lamina A cells of the lateral geniculate nucleus in normal and dark reared cats has been studied quantitatively with light microscopy. In the normal cat laminated bodies develop between the sixth and eighth postnatal week and increase steadily in number thereafter. These inclusion bodies are found chiefly in medium size cells and are distributed more densely in the medial part of lamina A than laterally. Laminated bodies appear not to be a general feature of the visual pathways since they are not found in cells of the visual cortex, superior colliculus, or ventral lateral geniculate. In the dark reared cat laminated bodies develop at about the same time as in the normal animal, but approximately twice as many of them are seen at all ages investigated.Our experiments indicate that dark rearing does not cause a proliferation of multiple laminated bodies within single neurons, but rather induces the formation of a laminated body in cells that normally would not acquire one. This effect appears to be permanent since it is not reversed by long term dark rearing nor by periods of normal visual experience following deprivation.Physiological experiments (Sherman et al., '72) have shown that fewer Y‐cells are recorded in binocularly deprived cats than in normally reared animals. On the basis of the present results, it is suggested that dark rearing influences the functional specificity of developing lateral geniculate neurons. In this view, deprivation prevents normal numbers of Y‐cells from developing. Neurons which would have become Y‐cells develop instead as X‐cells; a change in functional organization which is associated structurally with an increase in the number of cells that contain cytoplasmic laminated bodies.
The cerebellofugal projections in the brachium conjunctivum of the rat. I. The contralateral ascending pathway,
Authors: Faull R. L. M. , Carman J. B. 
Published: May 2005

AbstractThe cerebellofugal projections in the contralateral ascending pathway of the brachium conjunctivum (B.C.) in the rat have been investigated in 23 animals using the Fink‐Heimer technique to demonstrate the axonal degeneration resulting from complete B.C. lesions (7), partial B.C. lesions (14) and control lesions dorsal to the B.C. (2). All of the degeneration resulting from the concomitant involvement of the structures surrounding the B.C. is accounted for in terms of known fiber pathways and from the results in the control experiments.The contralateral ascending pathway ascends rostrally from the decussation of the B.C. through the ventromedial midbrain tegmentum to the diencephalon. In the midbrain, cerebellofugal fibers terminate heavily throughout the red nucleus including the nucleus minimus, while others pass dorsolaterally and dorsomedially from the ascending tract to terminate in adjacent midbrain nuclei. The dorsolaterally directed fibers terminate in the midbrain reticular formation, the stratum griseum profundum of the superior colliculus, the anterior pretectal nucleus and the nucleus of the posterior commissure; the dorsomedially directed fibers terminate in the principal oculomotor nucleus, the nucleus of Dark‐schewitsch, interstitial nucleus of Cajal and the central gray matter. A considerable number of the cerebellofugal fibers proceed more rostrally within the prerubral field and enter the thalamus by two routes. Most follow a direct subthalamic course within field H of Forel and after contributing fibers to the zona incerta, enter the caudal pole of the ventromedial nucleus (Vm) of the thalamus to terminate throughout Vm and the ventrolateral complex (Vl). Others enter via the internal medullary lamina and terminate throughout the parafascicular and central lateral nuclei. A small number of cerebellothalamic fibers form a commissural projection to Vl on the opposite side.The finding that the cerebellothalamic projections to the ventral nucleus are distributed throughout Vm and Vl establishes the Vm‐Vl complex as the homologue in the rat of the ventral anterior and ventral lateral nuclei in the primate thalamus.
Rapid transneuronal degeneration and death of cortical neurons following removal of the olfactory bulb in adult rats
Authors: Heimer Lennart , Kalil Ronald 
Published: May 2005

AbstractFollowing olfactory bulb removal in young and adult rats, many neurons in the primary olfactory cortex become markedly argyrophilic in silver impregnated preparations. Although argyrophilic neurons are found scattered throughout the pyramidal and multiform cell layers, the heaviest concentration is seen in the superficial part of the pyramidal layer.Electron microscopic analysis reveals that argyrophilic neurons are undergoing rapid degeneration. The degenerative changes are similar in all affected cells, although some cells begin to disintegrate within 24 hours following bulbectomy, whereas others are just beginning to show pathological changes at three or four days. The first clear signs of cellular degeneration occur in the cytoplasm of the perikaryon and involve swelling of mitochondria and polysome disaggregation. An increase in the electron density of the cytoplasm follows and this is accompanied by the appearance of enlarged cisternae and disruption of the nuclear membrane. Degenerative changes in the nucleus usually are detected at a slightly later stage than in the cytoplasm. Nuclear changes are characterized by the proliferation of local aggregations of condensed chromatin, and the replacement of the nucleolus with large homogenous islands of electron dense material. In advanced stages of degeneration ribosomes are increased in density and become uniformly dispersed throughout the cytoplasm. Remnants of necrotic organelles are visible only at the cellular periphery, and phagocytosis of dying neurons by astrocytes and microglia follows quickly.Evidence from HRP‐studies indicates that cells in the olfactory cortex, which project directly to the bulb do not correspond to those which show fulminant necrosis following olfactory bulb removal. The majority of those which degenerate are located superficially, whereas the cells of origin of the centrifugal projection lie more deeply. Based on this dissociation, it is proposed that rapid cell death in the olfactory cortex is not caused by retrograde factors involving axotomy, but is due instead to transneuronal deafferentation that results from a sudden massive loss of input from the olfactory bulb.
Autoradiographic evidence for pathways from the medial preoptic area to the midbrain involved in the drinking response to angiotensin II
Authors: Swanson L. W. , Kucharczyk J. , Mogenson G. J. 
Published: May 2005

AbstractThe 3H‐amino acid autoradiographic method was used to localize intracerebral sites from which angiotensin II (AII) elicits drinking and to identify their efferent neural pathways. Small injections (0.02‐0.1 μl) of AII and 3H‐amino acid mixtures were injected together or separately into widespread regions of the forebrain of adult rats in normal food and water balance. From an analysis of 39 positive and negative injection sites it was concluded that the caudal half of the medial preoptic area and the adjacent rostral part of the anterior hypothalamic area are sensitive to AII. Two anatomically defined pathways arising from neurons within this region were identified. One descends through the medial forebrain bundle and appears to terminate in the lateral hypothalamic area, the ventromedial nucleus, the mammillary body, and the ventral tegmental area. The other descends through the periventricular region and posterior hypothalamic area to end in the midbrain central gray. Additional widespread connections with the amygdala, septum, habenula, and pons appear to arise in the lateral preoptic area (Swanson, '76). Combined AII‐3H‐amino acid injections centered in the subfornical organ only elicited drinking in those cases in which injected label diffused through the third ventricle to the medial preoptic area. No efferent pathways were identified in experiments in which a small injection (0.02 μl) heavily labeled cells strictly confined to the subfornical organ and there was no ventricular spread of label.
Comparison of mauthner cell size in teleosts
Authors: Zottoli Steven J. 
Published: May 2005

AbstractThe Mauthner cells (M‐cells) are a pair of neurons found in the medulla oblongata of most fish and amphibians. This neuron is not the same size in all teleosts. Based on the hypothesis that differences in M‐cell size might be related to fish family and possibly fish habitat, M‐cell and nuclear size were compared between fish families. In order to minimize effects of fish length on cell or nuclear size, statistical treatment of the data was made for four separate length classes. The results indicate at least three groupings by cell or nuclear size. The cell is large in fish from the Salmonidae, Catostomidae and Cyprinidae, small in the Stichaeidae, Cottidae and Pleuronectidae and absent in Batrachoididae, Lophiidae, Ogcocephalidae and Cyclopteridae. In general a correlation exists between fish that lack or have small M‐cells and a demersal habitat. Since these fish may rely on camouflage for protection against predation, the M‐cells may have altered excitability or function as compared to more active fish in which the M‐cell is known to function in initiating the startle response (larval zebrafish and goldfish). Differences in input to M‐cells of different sizes in conjunction with known electrophysiological properties of the goldfish M‐cell are discussed in relation to the function of this neuron.
A documentation of an age related increase in neuronal and axonal numbers in the stingray, Dasyatis sabina, leseuer
Authors: Leonard Robert B. , Coggeshall Richard E. , Willis William D. 
Published: May 2005

AbstractThe present study documents that in the stingray Dasyatis sabina the numbers of (1) dorsal root ganglion cells, (2) dorsal root axons, (3) ventral root axons and (4) “motor” cells in the ventral horn increase steadily as the animals increase in size. This increase in axonal and neuronal numbers persists much further into adult life than is the case for other vertebrates that have been studied from this point of view. We hypothesize this steady increase in axonal numbers may be related to the ability of fish to regenerate parts of their central and/or peripheral nervous systems.
The organization of monoamine neurons within the brainstem of the north american opossum (didelphis virginiana)
Authors: Crutcher Keith A. , Humbertson Albert O. 
Published: May 2005

AbstractThe distribution of monoamine‐containing neurons within the brain of the opossum is described using the Falck‐Hillarp histofluorescence technique. Catecholamine‐containing neurons are organized into four groups. The medulla contains one group which is located dorsolateral to the lateral reticular nucleus and ventrolateral to the dorsal vagal nucleus. The second collection is found within the pons and includes both the locus coeruleus and a region continuous with it referred to as the nucleus coeruleus, pars α. The third aggregate includes the substantia nigra, the ventral tegmental area, and the mesencephalic reticular formation and a fourth group is located within the periventricular and dorsal paraventricular nuclei of the hypothalamus. The indoleamine‐containing cell bodies are distributed within the nuclei raphe obscurus, pallidus, magnus, dorsalis, and the nuclei linearis and superior centralis except at certain pontine levels where they appear laterally within the reticular formation. A number of small intensely fluorescent (SIF) cells are present within the connective tissue surrounding the brain and its blood vessels as well. Although certain differences are present, the didtribution of monoamine neurons in the American opossum conforms generally to that described for the placental mammals studied to date.
Ocular dominance columns and their development in layer IV of the cat's visual cortex: A quantitative study
Authors: Levay Simon , Stryker Michael P. , Shatz Carla J. 
Published: May 2005

AbstractThe distribution of geniculocortical afferents serving the left and right eyes was studied in abult cats and in kittens of various ages. Methods used were autoradiography of transneuronally transported 3H‐proline injected into one eye, and physiological recordings.In the adult cat, patches of label in layer IV corresponding to ocular dominance columns were seen both ipsilateral and contralateral to the injected eye. Between the patches, however, grain density was substantially above background, especially on the contralateral side. Similarly, in the contralateral lateral geniculate nucleus (LGN) there was substantial labelling of neuronal cell bodies in lamina A1, which receives no innervation from the injected eye. Such spillover of radioactivity into the inappropriate laminae of the LGN was measured in autoradiographs of semithin sections, and its effect on the cortical labelling pattern calculated. Spillover appeared to account quantitatively for the labelling seen between patches in the cortex. It was concluded that the geniculocortical afferents for the ipsilateral and contralateral eyes are equally and almost completely segregated from each other at the centers of columns, although there is extensive overlap at the borders. This pattern is consistent with the physiological pattern of ocular dominance in layer IV.In kittens studied at one to two weeks of age, radioactive label formed a continuous band in layer IV on both sides of the brain. On the ipsilateral side, this appearance could not be accounted for by spillover in the LGN, but reflected a continuous, non‐columnar distribution of afferents. Physiological recordings at this age showed most cells in layer IV to be nearly equally responsive to stimulation of either eye, in contrast to the adult pattern. Periodic variations in grain density were first noted at three weeks, and a pattern similar to that of the adult was reached by about six weeks of age. On the contralateral side the uniform labelling pattern seen in the 1‐ to 2‐week‐old kittens was uninterpretable, owing to the very great spillover of radioactivity in the contralateral LGN, but the physiology suggested that the contralateral afferents, too, were uniformly distributed in layer IV.The results suggest that the earliest functional connections formed by geniculocortical afferents have a uniform, non‐columnar arrangement in layer IV, and that the formation of the adult pattern is likely to involve the breakage and reformation of synaptic connections. This process appears to be similar to that described for the monkey (Hubel et al., '77; Rakic, '76), except that the beginning of segregation is postponed until postnatal life.
The trigeminal system in the pigeon (Columba livia) I. Projections of the Gasserian ganglion
Authors: Dubbeldam Jacob L. , Karten Harvey J. 
Published: May 2005

AbstractThe central projection of the Gasserian ganglion were investigated in the pigeon, Columba livia. Lesions were placed in the ganglion either by direct surgical exposure or stereotaxically, and following survival times of one to four days, the brains stained with the Fink‐Heimer method. The main group of central axons bifurcate to from distinct ascending and descending branches, the tractus trigemini ascendens (TTA) and the tractus trigemini descendens (TTD). A smaller lateral tract also courses caudally (lTTD) separate of TTD proper to terminate in the nucleus cuneatus externus.The TTA projects topographically upon the principal sensory nucleus of the trigeminus, ending in both the pars dorsalis and a smaller pars ventralis. The neurons at the point of bifurcation of the entering radix have been designated as the pars oralis of nTTD. The TTD distributes caudally to several distinct subnuclei at each level, and extends into the cervical spinal cord. Relatively discrete regions corresponding to the pars interpolaris and caudalis were recognized.The projections to the cervical cord terminate in laminae I‐IV.There was no evidence of projections to the cerebellum, or contralateral PrV or TTD. There was a small projection to the contralateral cervical spinal cord. No clear evidence of a projection to the nucleus solitarius was found.The distribution of primary trigeminal axons is compared to that described in other vertebrates.
An autoradiographic study of the projection of visual cortical area 1 to the thalamus, pretectum and superior colliculus of the rabbit
Authors: Giolli R. A. , Towns L. C. , Takahashi T. T. , Karamanlidis A. N. , Williams D. D. 
Published: May 2005

AbstractThe projections of visual cortical area 1 (vl) to the thalamus, pretectum and superior colliculus of the rabbit have been studied by Giolli and Guthrie (1967, 1971) using the Nauta and Fink‐Heimer methods to determine the course and distribution of degenerating nerve fibers. The present study represents a reinvestigation of these same projections utilizing the tracing method of autoradiography.An injection of 3H leucine was produced within a small region of vl in each of 18 adult albino rabbits, and the brains were subsequently processed for autoradiography by the method of Cowan et al. (1972). The results have confirmed the observations of Giolli and Guthrie (1967, 71) (1) By showing that vl of the rabbit projects to the thalamic reticular nucleus, the ventral lateral geniculate nucleus, the dorsal lateral geniculate nucleus; the pulvinar, the anterior and posterior pretectal nuclei and the superior colliculus and (2) by showing that a particular retinotopic organization is present in each of these projections. However, unlike Giolli and Guthrie (1967, 1971), the present autoradiographic study has further revealed (1) that both the ventrolateral and the posterior thalamic nuclei receive inputs from vl and (2) that the nucleus of the optic tract is not innervated by axons originating from vl.