bluuebunny/crossref_metadata_2025_split huggingface dataset:
Receptive field characteristics of superior colliculus neurons and visually guided behavior in dark‐reared hamsters
Authors: Rhoades Robert W. , Chalupa Leo M. 
Published: January 2005

AbstractVisual response properties of single neurons in the superior colliculus of golden hamsters reared from birth to adulthood in total darkness were compared to those of normal hamsters. Directional selectivity, speed preferences, and receptive field organization in dark‐reared hamsters were essentially the same as those found in normally reared animals. Subtle neurophysiological effects of visual deprivation were indicated by the longer latencies of “on” responses to flashed spots of light in the dark‐reared animals. Also, in the visually deprived animals three cells were encountered which changed their responses from phasic to tonic as the size of the visual stimulus was increased. In normally reared animals all cells responding to stationary stimuli showed only phasic responses regardless of spot size. Behaviorally, dark‐reared animals could not be distinguished from normal animals on the basis of visual orienting and following tests. It was concluded that in the golden hamster visual experience during development has a minimal role in the induction or maintenance of the normal functional development of the superior colliculus.
Physiological and morphological changes in cells of the lateral geniculate nucleus in monocularly‐deprived andreverse‐sutured cats
Authors: Hoffman Klaus‐Peter , Holländer Horstmar 
Published: January 2005

AbstractIn the present study the size of large samples of cells and the relative frequency of Y‐cells were measured in the lateral geniculate nucleus of monocularly‐deprived and reverse‐sutured cats. Due to deprivation large cells shrink more than smaller cells. This shrinkage is irreversible even over two years of reverse suture although over the same time the animals showed a remarkable pattern discrimination ability, which, in these animals, depends on the integrity of the geniculo‐cortical system. Physiologically, a significant increase in the probability of recording Y‐cells in the early‐deprived laminae of the LGNd was found after a reverse suture. The relative frequency of Y‐cells in the earlydeprived layers and in the late‐deprived layers was almost equal and not different from normal, although after the early deprivation by itself only 20% Y‐cells were found in the deprived layers. The latter results confirm our previous observation (Sherman et al., '72). The increase in the number of recorded Y‐cells following a reverse suture after monocular deprivation is accompanied by only small changes in the distribution of cell sizes in the LGNd. The number of very large cells in the early‐deprived layers was increased but the mean cell size remained unaltered after long forced usage of the deprived eye.
Interlaminar connections of the visual cortex in the hedgehog (Paraechinus hypomelas)
Authors: Gould Harry J. , Ebner Ford F. 
Published: January 2005

AbstractThe contribution of each cortical lamina to intracortical circuitry was studied in the visual neocortex of the Pakistani hedgehog. Punctate laminar lesions were made electrolytically within the visual cortex, and after five to seven days the brains were processed and stained with the Fink‐Heimer technique. The results of this study suggest that both horizontal and vertical connections are important to the organization of visual cortex in the hedgehog. The horizontal projections originate at three distinct cortical depths. Lesions in layer II reveal projections that traverse the inner one‐half of layer I; lesions in layers III and IV reveal projections that traverse layer IV and that enter the cortical white matter; lesions in layers V and VI reveal projections that traverse the outer one‐half of layer VI and that enter the cortical white matter. The vertical projections are oriented perpendicular to the pial surface. Layers II and III project to underlying layer V. Layers V and VI in turn contribute to a reciprocal projection back to all superficial cortical laminae. This anatomical data about intracortical circuitry is discussed with reference to the functional organization of visual cortex.
The neurons and the synaptic endings in the primate basilar pontine gray
Authors: Cooper Margaret H. , Beal John A. 
Published: January 2005

AbstractTwo types of neurons, projection and intrinsic, previously identified in Golgi preparations of the adult monkey (Macaca mulatta) basilar pontine gray (Cooper and Fox, 1976) were observed electronmicroscopically in Macaca mulatta and the squirrel monkey Saimiri sciureus. The cell body of the projection neuron measures up to 37 μ and its cytoplasm is rich in organelles. The Golgi apparatus, ribosomes, and mitochondria are disposed around the nucleus, while rough endoplasmic reticulum though abundant is usually confined to one half of the cell body. The cell body of the intrinsic neuron measures less than 20 μ and its cytoplasm displays prominent ribosomes, but a paucity of other organelles.Five types of synaptic profiles have been identified in the neuropil of the basilar pons; one measures up to 5 μ and the rest 2 μ or less. They are: (1) a large profile (MSV) containing medium size vesicles (500 Å) and a central core of mitochondria and neurofilaments; (2) a profile (SSV) containing small round vesicles (250‐500 Å) which is the most abundant and ubiquitous; (3) a profile (F) containing flattened or pleomorphic vesicles; (4) a profile (LSV) containing large oval egg shaped vesicles (750 Å); and (5) a pale profile (PP) that contains oval and occasionally pleomorphic vesicles. MSV, SSV, and LSV terminals form asymmetrical contacts and F terminals form symmetrical contacts with both dendritic and vesicle‐containing, pale profiles. The vesicle‐containing, pale profile is both pre‐ and post‐synaptic and participates in serial synapses. Following unilateral cortical ablations both dark and filamentous degeneration were observed in the ipsilateral basilar pontine gray.
Converging projections from the mediodorsal thalamic nucleus and mesencephalic dopaminergic neurons to the neocortex in three species
Authors: Divac I. , Björklund A. , Lindvall O. , Passingham R. E. 
Published: January 2005

AbstractPrevious studies in the rat have shown that the neocortical dopaminergic afferents, originating in the mesencephalon, terminate in those areas of the forntal lobe which receive projections from the mediodorsal thalamic nucleus i.e., the prefrontal cortex. In order to clarify whether this overlap is accidental for the rat or a consistent feature of several species we have compared the projection areas of the ventral tegmental area and the mediodorsal thalamic nucleus in three species, rat, opossum and tree shrew, using HRP injections in combination with glyoxylic acid histofluorescence method. The results have shown, first, that the area innervated by the mediodorsal nucleus of the thalamus is localized in a different part of the frontal lobe in each species: dorsolateral in the opossum, anteromedial, polar and suprarhinal in the rat and frontopolar in the tree shrew. Secondly, this area alone in each species receives dense innervation in the deep cortical layers by fluorescent fibres probably containing dopamine. The neighbouring neocortical areas receive afferents neither from the mediodorsal nucleus of the thalamus nor from the ventral mesencephalic tegmentum; their catecholamine innervation is mainly confined to the superficial layers and appears to be of noradrenergic nature. Although the techniques used did not allow a precise determination of the borders of the two projection areas and, therefore, the exact degree of overlap, it appears that mesencephalic dopaminergic innervation is a characteristic feature of the prefrontal cortex in the mammalian brain.
Structure of the leech nerve cord: Distribution of neurons and organization of fiber pathways
Authors: Fernandez Juan 
Published: January 2005

AbstractThe abdominal nerve cord of the leech Macrobdella decora was studied under the light and electron microscopes. The ganglionic cortex consists of six hemicone‐shaped packets of neuronal perikarya and apical processes regularly assembled in bilaterally symmetric rows. The orderly projection of the apical processes into the hilum of the packets is also followed by an orderly distribution of their branches across the neuropile. This part of the ganglion is made of two symmetrical halves or hemineuropiles enclosing two types of nerve tissue: coarse and fine neuropiles. The coarse neuropile has seven longitudinal and four commissural tracts of fibers and a distinctively segregated synaptic zone. Nerve processes in this neuropile mostly proceed from neurons in the ganglia and some are the branches of giant afferent axons. The fine neuropile includes several longitudinal tracts of fibers and a non‐segregated synaptic zone. Most nerve processes in this neuropile are small afferent axons and some come from neurons in the ganglia. Bundles of axons in the connectives result by the orderly projection of the neuropile longitudinal tracts and together form fiber pathways connecting the synaptic zones of successive ganglia. Pathways of through‐ganglia giant axons, linking the coarse neuropile synaptic zones, and of small axons, linking the fine neuropile synaptic zones, are described.
Characterization of various nervous tissues of the chick embryos through responses to chronic application and immunocytochemistry of β‐bungarotoxin
Authors: Hirokawa Nobutaka 
Published: January 2005

Abstractβ‐Bungarotoxin (β‐BT) was applied to chick embryos at 3‐day intervals beginning on the fourth day of incubation to investigate ultrastructurally the effects of chronically and massively applied β‐BT on various nervous tissues and muscles. On the twenty‐first day of incubation, spinal cords of β‐BT treated embryos were conspicuously decreased in size. Ventral root fibers, dorsal root fibers, white matter, and motor neurons disappeared. Although spinal ganglia and sympathetic trunk ganglia were completely absent, Auerbach's and Meissner's ganglia nerve cells in the small intestine and adrenal medullary cells were not affected. In retinas of β‐BT treated animals ganglion cells and optic nerve fibers disappeared, but photoreceptor cells, bipolar cells and horizontal cells remained intact. Furthermore, olfactory nerve cells and their unmyelinated nerve fibers ensheathed by Schwann cells were quite undamaged. Skeletal muscles degenerated, whereas cardiac muscles were unaffected. In the present study various nervous tissues of the twenty‐first day normal chick embryos were incubated with β‐BT and target cells of β‐BT were detected directly by the reaction with horseradish peroxidase labelled anti β‐BT guinea pig IgG. Motor nerve cells in the spinal cords, spinal and sympathetic ganglia nerve cells, ganglion cells and some nerve cells at the inner part of the inner nuclear layer in the retinas were positively stained, whereas Auerbach's and Meissner's ganglia nerve cells in the small intestine, adrenal medullary cells, photoreceptor cells, bipolar cells and horizontal cells in the retina and olfactory nerve cells were negative. Thus the present study shows that β‐BT has extensive destructive effects on various nerve cells which were revealed to be target neurons of β‐BT by immunocytochemistry. Those nerve cells, affected by β‐BT and positively stained with immunocytochemical reaction were supposed to have different characteristics from unaffected cells. One of the differences between these affected cells and unaffected cells may be whether there exist binding sites for β‐BT on the plasma membrane or not. The possibility of the use of β‐BT to characterize various nervous tissues is presented in the present study.
The organization of the hippocampus of the fence lizard: A light microscopic study
Authors: J. Lacey Daniel 
Published: January 2005

AbstractThe hippocampus of the fence lizard (Sceloporus undulatus) is composed of two laminated regions that are readily distinguishable on the basis of position and perikaryal size in Nissl preparations: the small‐celled (Hsc) and the large‐celled (Hlc) hippocampal divisions. Based upon cellular and fibrillar characteristics, the layers of the Hsc are: (1) the superficial plexiform layer; (2) the cellular layer; (3) the deep plexiform layer; (4) the layer of deep fibers, or alveus; and, (5) the ventricular ependyma. The layers of the Hlc are: (1) the tangential layer; (2) the molecular layer; (3) the pyramidal layer; (4) the deep plexiform layer; (5) the alveus; and, (6) the ventricular ependyma. The neurons of each hippocampal layer were grouped into classes based upon somal position and appearance, and dendritic and axonal arborization patterns in Golgi sections. Neurons of the Hsc are more numerous and pleomorphic than those of the Hlc. Data do not suggest an intrinsic organization that closely parallels that found in the mammalian hippocampus.
The organization of monoamine‐containing neurons in the brain of the sunfish (Lepomis gibbosus) as revealed by fluorescence microscopy
Authors: Parent A. , Dube L. , Braford M. R. , Northcutt R. G. 
Published: January 2005

AbstractThe morphological organization of the monoamine‐containing neurons in the brain of the sunfish (Lepomis gibbosus) was studied by means of the Falck‐Hillarp histofluorescence method. No attempt was made to distinguish between norepinephrine and dopamine, both primary catecholamines (CA) yielding a similar yellow‐green fluorescence after paraformaldehyde treatment. In the brain stem of this teleost fish, three groups of CA‐containing neuronal somata have been found. First, there is a small collection of CA perikarya located just caudal to the obex of the fourth ventricle. The neurons of this medullo‐spinal group give rise to numerous CA fibers many of which ascend within the central portion of the medulla. Intermingled with these CA fibers are some CA cells that constitute the central medullary group. The CA perikarya of this group are scattered between the levels of cranial nerves X and VIII. The tegmentum of the isthmus also contains a small group of very closely packed CA neurons. The large‐sized CA cells of the isthmal group are located dorsolateral to the medial longitudinal fasciculus, partly within the periventricular gray. High densities of CA varicosities were also disclosed in various brain stem structures such as the optic tectum, the torus semicircularis and the cerebellar valvula. In addition, numerous serotonin (5‐HT)‐type neuronal somata were found in the raphe region of the brain stem, particularly at caudal mesencephalic, isthmal and rostral medullar levels.A large number of CA cell bodies were visualized in the sunfish hypothalamus. Most of them form two populations of small, round cells that are located along and partly within the ependymal walls of the posterior and lateral recesses of the third ventricle. These bipolar cells possess one short club‐like process protruding into the ventricle and their thin ependymofugal processes contribute to the CA innervation of numerous hypothalamic regions. Large CA neurons apparently without direct CSF contact also occur in the area of nucleus posterior tuberis, at the level of the mesodiencephalic junction. Although the hypothalamic inferior lobes are devoid of CA cell bodies they are heavily innervated by CA axons.The sunfish telencephalon also receives a strikingly massive and complex monoaminergic innervation. Numerous CA fibers which are first observed at the level of the preoptic area, ascend through the central zone of the telencephalon and arborize profusely particularly within the medial zone of area dorsalis telencephali. Other CA fibers, as well as abundant fine 5‐HT varicosities were found in the lateral zone of area dorsalis. Although the exact origin of the telencephalic CA afferents in Lepomis is not known, part of it may arise from the isthmal CA cell group which appears similar to the locus coeruleus of reptiles, birds and mammals.
Topography of estrogen target cell in the forebrain of goldfish, Carassius auratus
Authors: Kim Ye Soon , Stumpf Walter E. , Sar Madhbananda 
Published: January 2005

AbstractThe topographical distribution of estradiol‐concentrating cells in the brain of male and female teleost, Carassis auratus, was determined by autoradiography, after injection of 3H estradiol‐17β. Radioactively labeled neurons and found in specific regions of the forebrain, with a similar topographical distribution both in males and females. Regions of accumulation of estrogen target cells include the supracommissural area of the telencephalon, the preoptic area, the central hypothalamic area and the thalamic area. Unlabeld estradiol injected prior to the administration of 3H estradiol reduces or eliminates nuclear uptake of radioactivity.The autoradiographic results demonstrate the existence of estrogen target neurons in the teleost forebrain at sites similar to those described in mammalian brains. However, under the conditions of the experiment, there exists no pallial representation of estrogen target cells.
A raphe dendrite bundle in the rabbit medulla
Authors: Cummings John P. , Felten David L. 
Published: January 2005

AbstractA Golgi‐Cox, histofluorescence, and electron microscopic examination of the serotonergic raphe nuclei of the rabbit medulla has revealed a large, vertically‐oriented midline dendrite bundle extending from the floor of the fourth ventricle to the ventral boundary of nucleus raphe pallidus. The bundle was confined to the medulla, and averaged 150–200 μm in width in the adult. This dendrite bundle received contributions from four major sources: (1) Dendrites of midline and paramedian neurons of nucleus raphe obscurus; (2) Dendrites of midline and paramedian neurons of nucleus raphe pallidus; (3) Shafts from tanycytes located on the midline floor of the fourth ventricle; and (4) Dendrites from neurons of the medullary reticular formation. Perikarya and dendrites of serotonergic raphe neurons frequently abutted tanycyte shafts, midline blood vessels, and perikarya and dendrites of other raphe neurons. The tanycyte shafts extended from the floor of the fourth ventricle into the bundle, and often ran the entire length of the bundle, where they intertwined themselves among neurons and dendrites of the medullary raphe nuclei. This study suggests that neurons of the medullary raphe may be influenced by communication channels including dendro‐dendritic contacts within the midline bundle, fourth ventricular cerebrospinal fluid‐borne influences through tanycyte shafts, blood‐borne influences through the direct neuronal‐vascular relationship in the raphe, and traditionally described axonal contacts impinging upon raphe neurons. We suggest that the raphe neurons might act as both neurons and endocrine‐neural transducer cells.
The development of the septal region in the rat. II. Morphogenesis in normal and X‐irradiated embryos
Authors: Bayer Shirley A. 
Published: January 2005

AbstractMorphogenesis of the septal region was examined in normal rat embryos from embryonic day (E) 10 to E22. The greater part of the septal region is postulated to form from two separate anlagen which can be clearly distinguished in the telencephalon by E13 and E14. One lies in the anterior ventromedial wall and presumably forms the nucleus of the diagonal band, medial, lateral, and triangular septal nuclei. The other lies in the posterior ventrolateral ridge and presumably forms the bed nuclei of the stria terminalis and the anterior commissure. On E15, the early differentiating cells in these anlagen fuse in the same region where the anterior commissure will cross on E17. With later embryonic development, differentiating cells of the strial bed nucleus accumulate rostral and caudal to the fused area. The same pattern is found in the medial and triangular septal nuclei and in the nucleus of the diagonal band. The differentiating cells of the lateral septal nucleus accumulate dorsal and lateral to the medial and triangular septal nuclei. On E16 and E17, a prominent subependymal zone develops in the anterior septal region and presumably gives rise to the nucleus accumbens.A quantitative analysis was made of three cell zones (neuroepithelium, subependymal zone, differentiating cell zone) at coronal levels through the developing nucleus accumbens and the nucleus of the diagonal band (anterior level) and the medial and lateral septal nuclei (middle and posterior levels). At all levels, the area of the neuroepithelium continually declines, that of the differentiating cell zone continually increases, and that of the subependymal zone shows a rise and decline. On a proportional basis, both the neuroepithelium and subependymal zone occupy significantly more area anteriorly than posteriorly, while the differentiating cell zone shows the reverse gradient. To accurately locate regions of primitive mitotic and migratory cells within the zones at each level, the number of cells surviving a single exposure to 200 R X‐rays in embryonic brains (E15‐E22) were compared with controls. Each zone responded differently to X‐ray insult. The radiosensitivity of the neuroepithelium decreases significantly after E19; the subependymal zone is highly radiosensitive throughout; the differentiating cell zone is radioresistant throughout. The significance of these findings is discussed in the light of the autoradiographic determination of the time of formation of septal neurons (Bayer, '79).
The morphology of local non‐spiking interneurones in the metathoracic ganglion of the locust
Authors: Siegler M. V. S. , Burrows M. 
Published: January 2005

AbstractThe morphology is described of a number of non‐spiking interneurones in the metathoracic ganglion of the locust that control motor neurones innervating muscles in the coxa and femur of a hind leg. The nonspiking interneurones are penetrated with microelectrodes, physiologically characterized, injected with cobalt, and the stain subsequently intensified with silver. The interneurones have diverse shapes but all are local, intraganglionic interneurones. Their cell bodies are 10–20 μm in diameter and lie in either the ventral or dorsal layers of cell bodies that form a cortex around the ganglion. The branches of the interneurones are profuse and overlap those of the motor neurones that they affect. One interneurone may have branches in both the most ventral and the most dorsal areas of the neuropile. Most interneurones have branches only in one half of the ganglion, but one interneurone has extensive and asymmetrical regions of branches in both halves of the ganglion (fig. 4). Similar physiological effects can be mediated by interneurones with distinct morphologies. For example, the single slow extensor motor neurone is excited by six distinct morphological types of interneurones (figs. 10–13). It is suggested that as many as 65% of the neurones within a ganglion may be local interneurones, many of which in turn may be non‐spiking.