bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visual discrimination following partial telencephalic ablations in nurse sharks (Ginglymostoma cirratum)
Authors: Graeber R. Curtis , Schroeder Dolores M. , Jane John A. , Ebbesson Sven O. E. 
Published: January 2005

AbstractAn instrumental conditioning task was used to examine the role of the nurse shark telencephalon in black‐white (BW) and horizontal‐vertical stripes (HV) discrimination performance. In the first experiment, subjects initially received either bilateral anterior telencephalic control lesions or bilateral posterior telencephalic lesions aimed at destroying the central telencephalic nuclei (CN), which are known to receive direct input from the thalamic visual area. Postoperatively, the sharks were trained first on BW and then on HV. Those with anterior lesions learned both tasks as rapidly as unoperated subjects. Those with posterior lesions exhibited visual discrimination deficits related to the amount of damage to the CN and its connecting pathway. Severe damage resulted in an inability to learn either task but caused no impairments in motivation or general learning ability.In the second experiment, the sharks were first trained on BW and HV and then operated. Suction ablations were used to remove various portions of the CN. Sharks with 10% or less damage to the CN retained the preoperatively acquired discriminations Almost perfectly. Those with 11‐50% damage had to be retrained on both tasks. Almost total removal of the CN produced behavioral indications of blindness along with an inability to perform above the chance level on BW despite excellent retention of both discriminations over a 28‐day period before surgery. It appears, however, that such sharks can still detect light. These results implicate the central telencephalic nuclei in the control of visually guided behavior in sharks.
Golgi studies of the neurons in layer I of the dorsal horn of the medulla (trigeminal nucleus caudalis)
Authors: Gobel Stephen 
Published: January 2005

AbstractTwo kinds of pyramidal neuro	ns and two kinds of multipolar neurons have been identified in layer I in the adult cat on the basis of thier dendritic morphology. The spiny pyramid emits an apical dendrite which beings dividing within 50 μm of the cell body and gives rise to an extensive dendritic arbor in which some second and third order branches extend for over 100 μm. The primary branches of the basal dendrites divide into secondary branches within 20 μm of the cell body. At each of these divisions, one daughter secondary branch will turn 180° and course in the direction of the apical dendrite. It then undergoes further branching and becomes intermingled in the apical dendritic arbor. These recurrent basal dendrites and the apical dendrites are charcterized by numerous long‐necked spines. The other secondary basal branch either courses at right angles to the apical dendrite or droops basally away from it. Many of these basal dendrites are not as robust and extensive as the other dendritic branches. They may end without further branching or when they do branch they tend to be thinner and shorter with some showing signs of stunting. Smooth pyramids differ from the spiny pyramids in several respects. Their dendritic arbors contain fewer, more widely spaced spines and are more expansive than those of the spiny pyramids. While they still send branches into the apical arbors many branches run basally away from the cell body for considerable distances to give the entire dendritic field a more circular appearance. The compact multipolar neuron is found in the inner half of layer I. The long axis of its compact dendritic arbor (∼ 50 μm wide) is oriented in the rostrocaudal axis of the layer. Most of its dendritic branches lie to one side of the cell body squeezed between the axon bundles of the inner half of layer I. The loose multipolar neuron in found throughout the layer. Its loose dendritic arbor is at least 200 μm wide and, like the spiny pyramid, gives rise to several dendrites which terminate abruptly with little branching and without much change in diameter. The dendrites of all four layer I neurons are confined within layer I and its extensions into the spinal V tract. These four layer I neurons are considered to be Golgi type I projection neurons on the basis of the morphology of their initial axonal segment. Golgi type II inteneurons are not found in layer I.
Golgi studies of the neurons in layer II of the dorsal horn of the medulla (trigeminal nucleus caudalis)
Authors: Gobel Stephen 
Published: January 2005

AbstractThe translucent band which lies just beneath the spinal V tract at the lower end of the spinal trigeminal nucleus (nucleus caudalis) can be divided into three layers. These three layers are distinguished by textural differences in their neuropil and by the morphology and laminar distribution of the axons and dendrites of their neurons. Layer II contains four different kinds of interneurons.Stalked cells are named after their short, stalk‐like branches. Their cell bodies are found in greatest numbers in the outer half of layer II. Their coneshaped dendritic arbors extend medially across layers II and III and sometimes extend into layer IV. Their axons form extensive, canopy‐like arborizations in layer I. Stalked cells are considered to be excitatory interneurons receiving input on their dendritic spines from primary axonal endings in the layers II and III glamour and transferring it to the dendrites of the layer I projection neurons.Layer II contains three kinds of Golgi type II interneurons, i.e., neurons whose axons branch repeatedly within the confines of their dendrite arbors. Islet cells, similar to those found in layer III (Gobble, 1975a), are found in small clusters in layer II. Their dendrites and axons are largely confined in layer II. The dendrites of the arboreal cell burst, in tree‐like fashion, into highly focal dendrite arbors confined largely in layer II while the extensive rostral and caudal dendrite arbors of the II‐III border cell lie largely in layers II and III with a few branches extending into layer I. The axons of both of these interneurons arborist in layers II and III with a few collaterals extending into layer I. Islet cells, arboreal cells and II‐III border cells are considered to be inhibitory interneurons. They are strategically situated to interrupt transmission between primary axonal endings in layers II and III and the layer I projection neurons by altering the output of the stalked cells.
Catecholamine innervation of the basal forebrain III. Olfactory bulb, anterior olfactory nuclei, olfactory tubercle and piriform cortex
Authors: Fallon James H. , Moore Robert Y. 
Published: January 2005

AbstractThe catecholamine innervation of the olfactory bulb, anterior olfactory nuclei, olfactory tubercle and piriform cortex was studied in the rat using biochemical analysis and fluorescence histochemistry. Biochemical studies demonstrate a moderate norepinephrine (NE) content in all olfactory structures, a high dopamine (DA) content in the olfactory tubercle and a low DA content in the olfactory bulb, anterior olfactory nucleus and piriform cortex. Following locus coeruleus lesions NE content decreases 71% in the olfactory bulb, 82% in the anterior olfactory nucleus, 62% in olfactory tubercle and 77% in piriform cortex. Brainstem transection caudal to locus coeruleus results in a decrease of NE in the olfactory tubercle of 35% without significant changes in other olfactory structures. Following lesions of the medial substantia nigra (SN) extending into the ventral tegmental area (VTA), there is a decrease of DA content (92%) in the olfactory tubercle. VTA lesions produce smaller decreases in olfactory tubercle DA content (79%). The area included in the SN and VTA lesions overlaps, suggesting that both the VTA and SN provide DA in nervation to the olfactory tubercle. VTA lesions also produce decreases in anterior olfactory nucleus DA content (73%) whereas medial SN lesions produce decreases in piriform cortex DA content (44%). Fluorescence histochemical studies using the glyoxylic acid‐Vibratome technique demonstrate the presence of several catecholamine (CA) fiber types in the olfactory system, including large NE fibers in the olfactory tubercle which probably originate in the caudal brainstem, fine NE fibers innervating all four olfactory structures arising from the locus coeruleus, and fine DA fibers from SN‐VTA. These innervate the olfactory tubercle, the anterior olfactory nucleus, piriform cortex and olfactory bulb. The DA innervation is very dense in all layers of the olfactory tubercle, with a variable innervation of the islands of Calleja. The DA fibers enter the olfactory tubercle as fascicles from the medial forebrain bundle. Both NE and DA fibers enter the anterior olfactory nuclei to form a sparse to moderately dense innervation with some continuing in the medial olfactory tract into the olfactory bulb. A moderately dense NE innervation is evident in the inner plexiform and granule cell layer of the accessory olfactory bulb and the granule cell layer of the olfactory bulb. Additional NE fibers are distributed sparsely throughout the remaining components of the olfactory bulb, some entering the glomeruli. There is a very sparse extrinsic DA innervation to the plexiform layer of the olfactory bulb and an intrinsic DA innervation from juxtaglomerular cells.
Catecholamine innervation of the basal forebrain IV. Topography of the dopamine projection to the basal forebrain and neostriatum
Authors: Fallon James H. , Moore Robert Y. 
Published: January 2005

AbstractIn this study the location of dopamine (DA) neuron perikarya in the rostral mesencephalon of the rat was determined using the glyoxylic acid fluorescence histochemical technique. Subsequently the topography of the projection of these mesencephalic neurons on the basal forebrain and striatum was analyzed using the anterograde transport‐autoradiographic tracing method and the retrograde transport‐horseradish peroxidase (HRP) technique. The results of these anatomical studies were correlated with the biochemical and histochemical studies presented in previous reports (Moore, 1978; Fallon and Moore, 1978; Fallon et al., 1978) to provide the following conclusions. The topography of the DA neuron projection on the basal forebrain and neostriatum is organized in three planes, dorsal‐ventral, medial‐lateral and anterior‐posterior. DA cells are found almost exclusively in the substantia nigra (SN) and ventral tegmental area (VTA). Ventral cells of the SN and VTA project to the dorsal structures of the basal forebrain such as the septum, nucleus accumbens and neostriatum. The latter includes some DA cells located ventrally in the pars reticulata of the SN. Dorsal cells project to ventral structures. The medial‐lateral topography is organized such that the medial sectors of the SN‐VTA area project to the medial parts of nuclei in the basal forebrain and neostriatum whereas lateral sectors of the SN‐VTA area project to the lateral parts of nuclei in the basal forebrain and neostriatum. An anterior‐posterior topography also is evident such that anterior parts of the SN‐VTA project anteriorly whereas the posterior SN‐VTA projects more posteriorly in these areas. These observations are consistent with the view that the DA neurons of the SN‐VTA complex form a single nuclear group with a highly topographically organized projection innervating not only deep nuclei of the telencephalon but allocortical structures as well.
An autoradiographic study of the organization of intrahippocampal association pathways in the rat
Authors: Swanson L. W. , Wyss J. M. , Cowan W. M. 
Published: January 2005

AbstractThe longer associational connections of the hippocampal formation have been studied autoradiographically in a series of adult rats after small injections of 3H‐amino acids into each of its various cytoarchitectonic fields. The major findings can be summarized as follows. The dentate gyrus projects in a topographically ordered manner upon the pyramidal cells of the regio inferior by way of the supra‐ and infrapyramidal bundles of mossy fibers. Certain cells in the hilar region of the dentate gyrus (which operationally may be defined as constituting field CA4 of Ammon's horn) give rise to a hippocampodentate projection to the inner one‐quarter of the molecular layer of the dentate gyrus. Either the same or closely related cells give rise to fibers which join the Schaffer collateral system from field CA3 to the stratum radiatum and stratum oriens of the regio superior. The regio inferior is also characterized by a longitudinally directed associational bundle which runs throughout the septo‐temporal extent of the hippocampus and is centered in the region of subfield CA3a. The regio superior has no reciprocal projection to the regio inferior but sends a substantial projection back to the subiculum and to the entorhinal area. There is also a projection to the subiculum from the regio inferior, and the subiculum itself probably contributes significantly to the projection to the entorhinal and perirhinal cortices.There is a striking parallelism between certain of these associational connections and the commissural projections to the hippocampus and dentate gyrus. Each cytoarchitectonic field that contributes a commissural projection also gives rise to an ipsilateral associational pathway which in its intrahippocampal course and its mode of termination exactly matches that of the commissural projection, although in general, the associational connections are more extensive in their distribution along the septo‐temporal extent of the hippocampus than the corresponding commissural connections. The reverse is not true; there are a number of associational projections which are not paralleled by commissural projection. All of the associational projections are topographically arranged, but those which extend across the transverse axis of the hippocampus usually show considerable divergence so that afferents from different levels overlap fairly considerably within their respective projection fields.
Spinal and medullary input to the lateral cervical nucleus
Authors: Craig A. D. 
Published: January 2005

AbstractThe distributions of spinal and medullary cells projecting to the lateral cervical nucleus (LCN) have been investigated in young cats and dogs using the retrograde horseradish peroxidase (HRP) technique. Labeled spinal cells, whose axons contribute to the spinocervical tract (SCT), were found at all levels of the spinal cord ipsilateral to the injection sites. No significant differences were found between cat and dog, nor between cases with single injections at different levels of the LCN. SCT cells were found predominantly, in not exclusively, within lamina IV, with some extension into medial lamina V. No apparent mediolateral or dorsoventral density gradient was observed within lamina IV; cells of all sizes were labeled. Cells in cervical laminae I and V‐VII were occasionally labeled; these, however, were considered to be propriospinal, supplying afferent fibers to the C1–2 dorsal horn. Cells of origin of spinocerebellar fibers consistently remained unlabeled in cases with restricted HRP injections and minimal fiber damage in the dorsolateral funiculus (DLF) around the injection sites. These results, therefore, corroborate and refine the findings of electrophysiological studies of the SCT and the LCN.Labeled medullary cells were located in the caudoventral and rostral portions of the dorsal column nuclei (DCN; stellate and fusiform cells), the underlying n. medullae oblongatae centralis, subnucleus dorsalis (parvicellular medullary reticular formation), the marginal and magnocellular layers (both large and small cells) of the n. trigeminalis spinalis pars caudalis and also in pars interpolaris; a cluster of cells was also consistently labeled in the lateral reticular formation just ventral to pars caudalis. The projection from the DCN to the LCN was confirmed with the anterograde Nauta technique. Fiber degeneration was observed in the entire ipsilateral LCN, although it was less abundant than that observed in the adjacent C1–2 dorsal horn. These results indicate that neurons in the rostral portions of the DCN not only may affect the input to the LCN (at the level of the dorsal horn), but also the output of the LCN itself. These data also suggest the possibility of both noxious and non‐noxious facial input to the LCN.
Distribution of the crossed olivocochlear bundle in the chinchilla's cochlea
Authors: Iurato Salvatore , Smith Catherine A. , Eldredge Donald H. , Henderson Donald , Carr Charles , Ueno Younosuke , Cameron Susan , Richter Robert 
Published: January 2005

AbstractThe efferent crossed olivocochlear bundle (COCB) was transected in the brain stem of the chinchilla, and the animals sacrificed 7 to 96 days later. Electron microscopy revealed that all the large efferent nerve endings on outer hair cells in the basalmost 2 mm (round window region) of the cochlea had degenerated, 87.5% in the remainder of the first turn, 70% in the second turn and 43% in the third turn. Only a few degenerating nerve fibres were seen in the medial spiral tract (inner spiral and tunnel bundles) of the experimental animals. Nerve fibers were counted in the medial spiral tracts of the cochleas of control animals as well as in those animals whose COCB had been transected. There were considerable individual variations in the fiber numbers, and statistical analysis showed no significant difference between the numbers of nerve fibers in normal and experimental animals.The cochlear microphonics (CM) and nerve action potentials (AP) of acute animals were assessed before and after COCB section. The CM and AP of the chronic experimental animals were compared with responses from normals. Overall, no changes in a physiological response of the anesthetized chinchilla could be attributed to complete section of the COCB.
A golgi study of goldfish optic tectum
Authors: Meek J. , Schellart N. A. M. 
Published: January 2005

AbstractA study of goldfish optic tectum was performed with rapid‐Golgi, Golgi‐Kopsch and a modified Golgi‐Cox impregnation which proved quite suitable to impregnate cells in the middle tectal layers and to study more closely axonal properties. Fifteen cell types are distinguished, based upon the position of dendritic trees and axonal properties. Two cell types are found with dendrites in the marginal layer: type I with an axon terminating in the central gray layer and type II without an impregnated axon. Three cell types (III, IV, and V) have dendrites in a single, specific tectal layer and an axon terminating within the tectum. Five cell types (VI–X) have dendrites in two horizontal planes. Two of them have myelinated axons leaving the tectum, whereas the axons of the remaining three types project to different tectal layers. While these first ten cell types have dendrites almost exclusively in the superficial half of the tectum, the remaining five types have dendrites in deeper layers too. This specially holds for the most conspicuous tectal cells (types XII and XIII), which have dendritic trees branching at three or more horizontal levels and a myelinated axon leaving the tectum, with sometimes a very peculiar course (XIII1). Also type XI has three or more dendritic trees, but its axon was not found. The numerous cells with cell bodies in the deepest tectal layer (type XIV) have dendrites and axonal terminations anywhere in the tectum, except in the most superficial and the deepest layer. However, most dendrites occur in the optic layers, whereas the axons, always originating from the dendritic shaft in the superficial tectal half, generally terminate in the middle tectal layers. Type XV cells have their soma in the deepest tectal layer as well, but their dendrites do not reach the optic layers. Per tectal lobe the following numbers are estimated: type I: 5,000–20,000 neurons. Type III: 2,500–10,000; types IV – XIII: each 500–2,000 and type XIV: 1,000,000–2,000,000. The total number of myelinated tectal efferents is estimated at 2,000–8,000. Comparison with other Golgi studies in teleosts leads to the conclusion that the tecta of these species of fish are basically similar.
Laminar origins of spinothalamic projections in the cat as determined by the retrograde transport of horseradish peroxidase
Authors: Carstens Earl , Trevino Daniel L. 
Published: January 2005

AbstractThe method of retrograde axonal transport of horseradish peroxidase (HRP) was used to identify the locations of cells of origin of the spinothalamic tract in the cat. Injections of from 0.2–3.0 μl of 30% HRP were made unilaterally in various regions of the somatosensory thalamus. Massive injections of the caudal thalamus in several cats showed the spinothalamic cells of origin to be located mainly in laminae I, VII and VIII in the lumbar enlargement, and in laminae I, V and VII–VIII in the cervical enlargement.Small injections of HRP were made into the three major spinothalamic terminal zones in the thalamus, to determine the laminar origin(s) of the spinal projections to each zone. Neurons in lamina I in both cervical and lumbar enlargements were found to project almost exclusively to the rostral VB‐caudal VL border zone. A small number of neurons in laminae VII and VIII also project there but a larger number project to the intralaminar region. Neurons projecting to the PO regions were located mainly in laminae IV and V. This anatomical segregation of thalamic afferents probably reflects a functional segregation of input, since the functional properties of spinal neurons vary according to their laminar location.Comparison of these data with the differential projection spinothalamic neurons in the rat and monkey indicate that it is unlikely that the proposed “paleo‐” and “neospinothalamic” systems would arise from anatomically separate groups of spinal neurons.
The olivocerebellar projection in the cat studied with the method of retrograde axonal transport of horseradish peroxidase. VII. The projection to lobulus simplex, crus I and II
Authors: Kotchabhakdi N. , Walberg F. , Brodal A. 
Published: January 2005

AbstractThe olivocerebellar projection to lobulus simplex, crus I and II in the cat was investigated by means of retrograde axonal transport of horseradish peroxidase (HRP). The distribution of labeled cells in the inferior olive following HRP injections in lobulus simplex, crus I and II confirmed the findings by Brodal ('40b) that the rostral half of the principal olive projects to these areas of the cerebellar hemisphere. However, concerning details there are some differences in so far as the heaviest contribution to crus I comes from the medial parts of the ventral and dorsal lamella, that to crus II from its lateral part, especially the ventral bend. The present findings show that in addition the rostral part of the medial and the rostramedial part of the dorsal accessory olive project to these areas of the cerebellar corotex. Further details in the projection are shown in figure 8B. The findings agree fairly well with the electrophysiological results of Armstrong et al. ('74) and the experimental anatomical data of Groenewegen and Voogd ('77a, b). An attempt is made to correlate the findings with the pattern of longitudinal zonal subdivision of the cerebellum. There is evidence for a topical organization within the projection to crus I and II and parts of their projection areas in the principal olive.The distribution of the labeled cells which project to lobulus simplex, crus I and II is discussed in relation to afferent pathways to the inferior olive.