bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of GABAergic neurons and axon terminals in the macaque striate cortex
Authors: Fitzpatrick D. , Lund J. S. , Schmechel D. E. , Towles A. C. 
Published: January 2005

AbstractAntisera to glutamic acid decarboxylase (GAD) and γ‐aminobutyric acid (GABA) have been used to characterize the morphology and distribution of presumed GABAergic neurons and axon terminals within the macaque striate cortex. Despite some differences in the relative sensitivity of these antisera for detecting cell bodies and terminals, the overall patterns of labeling appear quite similar. GABAergic axon terminals are particularly prominent in zones known to receive the bulk of the projections from the lateral geniculate nucleus; laminae 4C, 4A, and the cytochrome‐rich patches of lamina 3. In lamina 4A, GABAergic terminals are distributed in a honeycomb pattern which appears to match closely the spatial pattern of geniculate terminations in this region. Quantitative analysis of axon terminals that contain flat vesicles and form symmetric synaptic contacts (FS terminals) in lamina 4Cβ and in lamina 5 suggest that the prominence of GAD and GABA axon terminal labeling in the geniculate recipient zones is due, at least in part, to the presence of larger GABAergic axon terminals in these regions.GABAergic cell bodies and their initial dendritic segments display morphological features characteristic of nonpyramidal neurons and are found in all layers of striate cortex. The density of GAD and GABA immunoreactive neurons is greatest in laminae 2–3A, 4A, and 4Cβ. The distribution of GABAergic neurons within lamina 3 does not appear to be correlated with the patchy distribution of cytochrome oxidase in this region; i.e., there is no significant difference in the density of GAD and GABA immunoreactive neurons in cytochrome‐rich and cytochrome‐poor regions of lamina 3.Counts of labeled and unlabeled neurons indicate that GABA immunoreactive neurons make up at least 15% of the neurons in striate cortex. Layer 1 is distinct from the other cortical layers by virtue of its high percentage (77–81%) of GABAergic neurons. Among the other layers, the proportion of GABAergic neurons varies from roughly 20% in laminae 2–3A to 12% in laminae 5 and 6.Finally, there are conspicuous laminar differences in the size and dendritic arrangement of GAD and GABA immunoreactive neurons. Lamina 4Cα and lamina 6 are distinguished from the other layers by the presence of populations of large GABAergic neurons, some of which have horizontally spreading dendritic processes. GABAergic neurons within the superficial layers are significantly smaller and the majority appear to have vertically oriented dendritic processes. These results provide support for the idea that GABAergic neurons make up a significant proportion of the neurons within the macaque striate cortex and that there are laminar differences in the number and the types of GABAergic neurons—differences that may be relevant for understanding the contributions of GABA‐mediated inhibition to striate cortex function.
Oculomotor system of the weakly electric fish Gnathonemus petersii
Authors: Szabo T. , Lazar G. , Libouban S. , Toth P. , Ravaille M. 
Published: January 2005

AbstractThe peripheral and central aspects of the extraocular system were studied in the weakly electric fish Gnathonemus petersii.All six extraocular muscles show a similar composition of large and small fibers grouped characteristically in the proximal and distal regions respectively.The exit of the three extraocular nerves from the brain is similar to that in other vertebrates. However, the intracephalic and intracranial course of the trochlear nerve is unusual, partly because of the extraordinary hypertrophy of the cerebellum. The three nerves course rostrally on the ventral brain surface; the trochlear nerve penetrates the orbital cavity separately from the two other nerves. The fiber‐diameter spectrum of each extraocular nerve is bimodal; unmyelinated fibers were not observed in any of the nerves.The location of the extraocular motor nuclei was established by retrograde axonal transport of HRP or cobaltic‐lysine complex. The oculomotor nucleus is situated ventral to the posterior pole of the magnocellular mesencephalic nucleus and the trochlear nucleus is found caudal and dorsal to this. The abducens nucleus is situated at the level of the octavolateral efferent nucleus and consists of a single group of cells on each side of the ventral tegmentum.The oculomotor nucleus of G. petersii shows a somatotopic organization. The superior rectus muscle receives a contralateral innervation whereas the inferior rectus and oblique muscles and the internal rectus muscles receive an ipsilateral innervation. The superior oblique muscle is innervated by contralateral trochlear motoneurons and the external rectus by ipsilateral abducens motoneurons.The majority of extraocular motoneurons have piriform perikarya and long beaded dendrites that extend laterally in the oculomotor and abducens nuclei and rostrally in the trochlear nucleus. The terminal dendritic portions of trochlear motoneurons widely overlap with oculomotor dendrites and perikarya. In all three nuclei the axon originates opposite to the main dendrite. Collaterals of the hairpin‐bend abducens axons could be identified in a few cases.The oculomotor system of G. petersii appears basically similar to that of other teleosts; the differences observed concern mainly the structure of the abducens nucleus, the intracranial and intracephalic course of the trochlear nerve, and the relatively small number of axons in each nerve.
Organisation of subcortical pathways for sensory projections to the limbic cortex. II. Afferent projections to the thalamic lateral dorsal nucleus in the rat
Authors: Thompson Scott M. , Robertson Richard T. 
Published: January 2005

AbstractAfferent projections to the thalamic lateral dorsal nucleus were examined in the rat by the use of retrograde axonal transport techniques. Small iontophoretic injections of horseradish peroxidase were placed at various locations within the lateral dorsal nucleus, and the location and morphology of cells of origin of afferent projections were identified by retrograde labeling.For all cases examined, subcortical retrogradely labeled neurons were most prominant in the pretectal complex, the intermediate layers of the superior colliculus, and the ventral lateral geniculate nucleus. Labeled cells were also seen in the thalamic reticular nucleus and the zona incerta. Within the cerebral cortex, labeled cells were prominent in the retrosplenial areas (areas 29b, 29c, and 29d) and the presubiculum. Labeled cells were also seen in areas 17 and 18 of occipital cortex. Peroxidase injections in the dorsal lateral part of the lateral dorsal nucleus result in labeled neurons in all of the ipsilateral pretectal nuclei, but especially those that receive direct retinal afferents. Labeled cells were also seen in the ventral lateral geniculate nucleus and the rostral tip of laminae IV‐VI of the superior colliculus. In contrast, peroxidase injections in ventral medial portions of the lateral dorsal nucleus result in fewer labeled pretectal cells, and these labeled cells are found exclusively in the pretectal nuclei that do not receive retinal afferents. Other labeled cells following injections in the rostral and medial portions of the lateral dorsal nucleus are seen contralaterally in the medial pretectal region and nucleus of the posterior commissure, and bilaterally in the rostral tips of laminae IV and V of the superior colliculus. Camera lucida drawings of HRP labeled cells reveal that projecting cells in each pretectal nucleus have a characteristic soma size and dendritic branching pattern.These results are discussed with regard to the type of sensory information that may reach the lateral dorsal nucleus and then be relayed on to the medial limbic cortex.
Frontal eye field as defined by intracortical microstimulation in squirrel monkeys, owl monkeys, and macaque monkeys II. cortical connections
Authors: Huerta Michael F. , Krubitzer Leah A. , Kaas Jon H. 
Published: January 2005

AbstractPhysiological (intracortical microstimulation) and anatomical (transport of horseradish peroxidase conjugated to wheat germ agglutinin as shown by tetramethyl benzidine) approaches were combined in the same animals to reveal the locations, extents, and cortical connections of the frontal eye fields (FEF) in squirrel, owl, and macaque monkeys. In some of the same owl and macaque monkeys, intracortical microstimulation was also used to evoke eye movements from dorsomedial frontal cortex (the supplementary motor area). In addition, in all of the owl and squirrel monkeys, intracortical microstimulation was also used to evoke body movements from the premotor and motor cortex situated between the central dimple and the FEF. These microstimulation data were directly compared to the distribution of anterogradely and retrogradely transported label resulting from injections of tracer into the FEF in each monkey. Since the injection sites were limited to the physiologically defined FEF, the demonstrated connections were solely those of the FEF. To aid in the interpretation of areal patterns of connections, the relatively smooth cortex of owl and squirrel monkeys was unfolded, flattened, and cut parallel to the flattened surface. Cortex of macaque monkeys, which has numerous deep sulci, was cut coronally.Reciprocal connections with the ipsilateral frontal lobe were similar in all three species: dorsomedial cortex (supplementary motor area), cortex just rostral (periprincipal prefrontal cortex) to the FEF, and cortex just caudal (premotor cortex) to the FEF. In squirrel and owl monkeys, extensive reciprocal connections were made with cortex throughout the caudal half of the lateral fissure and, to a much lesser extent, cortex around the superior temporal sulcus. In macaque monkeys, only sparse connections were present with cortex of the lateral fissure, but extensive and dense connections were made with cortex throughout the caudal one‐third to one‐half of the superior temporal sulcus. In addition, very dense reciprocal connections were made with the cortex of the lateral, or inferior, bank of the intraparietal sulcus. Contralateral reciprocal connections in all three species were virtually limited to regions that correspond in location to the FEF and the supplementary motor area.The results of this study reveal connections between the physiologically defined frontal eye field and cortical regions known to participate in higher order visual processing, short‐term memory, multimodal, visuomotor, and skeletomotor functions. Some of the demonstrated pathways may contribute to functional interactions between oculomotor and skeletomotor systems, perhaps facilitating the planning and coordination of related eye, head, and hand movements.
Morphological features of layer V pyramidal neurons in the cat parietal cortex: An intracellular HRP study
Authors: Yamamoto Tetsuro , Samejima Akio , Oka Hiroshi 
Published: January 2005

AbstractLayer V pyramidal neurons in the cat parietal cortex (areas 5 and 7) were investigated with intracellular HRP staining. Antidromic responses were recorded intracellularly as well as extracellularly with pontine stimulation under Nembutal anesthesia. The relationship between the latency of antidromic responses and the morphology of HRP‐stained neurons was analyzed. A total of 65 neurons were stained with HRP, and sixteen of these neurons were activated antidromically with pontine stimulation.Two distinct groups of layer V pyramidal neurons were detected morphologically by intracellular HRP staining; i.e., one (F type) consisted of neurons with relatively large somata (58.4±8.1 μm × 24.5±5.1 μm, N = 11) and aspiny or sparsely spinous apical dendrites, and the other (S type) consisted of neurons with smaller somata (44.6±7.6 μm × 19.3±3.9 μm, N = 22) and richly spinous apical dendrites. These two groups showed different electrophysiological properties; i.e., the former responded antidromically to pontine stimulation at a latency shorter than 1.5 ms (namely, with a conduction velocity faster than 18 m/second) and the latter responded at a latency longer than 1.5 ms.The two neuronal types in the parietal cortex corresponded respectively to fast and slow pyramidal tract neurons (PTNs) investigated in the sensorimotor cortex. Although their morphological features were almost similar to those of PTNs, the branching pattern of apical dendrites of the F‐type pyramidal neuron seemed to be different from that of fast PTNs. In the parietal cortex, apical dendrites of F‐type neurons showed rather frequent branching in layer I. This was simialr to the pattern of branching in slow PTNs. Such a characteristic branching pattern suggested that, in the cat parietal cortex, layer V pyramidal neurons of both types are adapted to receive cerebellar inputs through the ventroanterior (VA) thalamic nucleus to the superficial cortical layers.
Golgi study of the primate substantia nigra. II. Spatial organization of dendritic arborizations in relation to the cytoarchitectonic boundaries and to the striatonigral bundle
Authors: François Chantal , Yelnik Jerome , Percheron Gerard 
Published: January 2005

AbstractThe spatial organization of Golgi‐stained dendritic arborizations of the substantia nigra was studied in three dimensions by using a video computer system. Dendritic orientation was analyzed in relation to the cytoarchitectonic boundaries and to the direction of the axons of the striato‐pallidonigral bundle. All the brains, humans and macaques, were sectioned according to the same ventricular planes. The striatal bundle is made up of dense fascicles of very thin parallel axons. Sixty neurons located in the pars reticulata, lateralis, and compacta were reconstructed from serial sections. In the anterior pars reticulata and lateralis, the dendritic arborizations spread in all directions inside the striatal bundle. Below the pars compacta fringes, the dendrites of pars reticulata neurons extend ventrolaterally in the bundle. Because one nigral arborization can cover the whole thickness of the striatal bundle, we are led to believe that nigral neurons exert a role of convergence of the corticostriatal information similar to that of pallidal neurons (Percheron et al., '84a,b). The pars reticulata neurons appear to receive information mainly from the associative striatal territory. The pars lateralis neurons, conversely, appear to receive information from the sensorimotor territory. The anterior pars compacta neurons are organized in such a way that their ventral dendrites, located inside the pars reticulata, are ventrolaterally oriented, perpendicular to the striatal bundle. Their dorsal dendrites remaining in the pars compacta can receive other input. At more caudal levels, the posterior pars compacta neurons have dendrites radiating outside the striatal bundle.
Distribution of afferent fibers in the brainstem from end organs in the ear and lateral line in the european eel
Authors: Meredith G. E. , Roberts B. L. , Maslam Suharti 
Published: January 2005

AbstractSensory nerve fibers from the lateral line system and labyrinth of Anguilla anguilla were labeled with horseradish peroxidase and traced to various targets in the ipsilateral brainstem.The three rami of the anterior lateral line nerve and the supratemporal ramus of the posterior lateral line nerve form overlapping terminal zones in the ventral portion of nucleus medialis. The posterior lateral line nerve on the body is represented exclusively in the dorsal half of the nucleus medialis. Eighth nerve fibers from the otolithic end organs in the inner ear send fibers into dorsal portions of three octavus nuclei: anterior, magnocellular, and descending, and saccular fibers lie most medial and utricular fibers most lateral. Fibers from vestibular organs, especially the semicircular canals and utricle, end densely in ventral portions of these nuclei and in the tangential nucleus. All labyrinthine sense organs send fibers into the region of a Mauthner‐like neuron, and all except the saccule terminate in the reticular formation, tangential nucleus, and eminentia granularis of the cerebellum. Primary sensory input to the octavolateralis efferent nucleus comes only from the labyrinth, and fibers from the saccule alone penetrate the region of efferent neuronal somata. Fibers from labyrinthine end organs except the saccule project to the reticular formation where they may contact the dendrites of efferent somata. Fibers from the lateral line and the eighth nerve overlap most extensively at the rostral pole of the nucleus medialis and in the eminentia granularis of the cerebellum.
Immunocytochemical analysis of the dopamine system in the forebrain and midbrain of Raja radiata: Evidence for a substantia nigra and ventral tegmental area in cartilaginous fish
Authors: Meredith Gloria E. , Smeets Wilhelmus J. A. J. 
Published: January 2005

AbstractThe distribution of dopamine‐containing cell somata and fibers in the forebrain and midbrain of a cartilaginous fish, Raja radiata, was investigated by means of antibodies directed against dopamine. Many small dopamine immunoreactive neurons are distributed throughout the telencephalon, including the olfactory bulbs. Within the diencephalon and particularly in the hypothalamus, i.e., in the nucleus preopticus, nucleus suprachiasmaticus, the paraventricular organ, lateral hypothalamic area, recessus mamillaris, and nucleus tuberculi posterioris, numerous cell somata stain for dopamine. In the mesencephalon, two distinct cell masses are found, which on the basis of their immunoreactivity for dopamine and their location, may be homologous to the substantia nigra and ventral tegmental area of other vertebrates, Dopamine immunoreactive fibers are found in the glomeruli of the olfactory bulbs, in ventral portions of the telencephalon, where a dense dopaminergic plexus innervates the area superficialis basalis and striatum, and in the diencephalon, where the inferior lobe is the most densely innervated structure. In the mesencephalon, the dopamine immunoreactive fibers are confined predominantly to the periventricular zone and lateral portions of the tectum.We conclude that much of the dopaminergic system in Raja radiata is strikingly similar to that seen in amniotes.
Effect of different optic nerve lesions on retinal ganglion cell death in the frog Rana pipiens
Authors: Humphrey Martin F. 
Published: January 2005

AbstractFollowing optic nerve crush in various species of frog, a proportion of the retinal ganglion cells re‐establishes functional contact with the optic tectum. However, as much as 50% of the retinal ganglion cells die during this process. The determinants of an individual ganglion cell's fate have not been established. In this study of Rana pipiens, cell survival after optic nerve crush was compared with that after nerve cut followed by stump separation, a procedure that considerably delayed entry of optic axons to the brain. It was also ascertained, in the case of delayed ingrowth, whether application of nerve growth factor immediately after lesion influenced the cell death process.This study confirmed that retinal ganglion cell death is a relatively late event in regeneration, because in several animals‐where anterograde HRP labeling demonstrated regenerating axons within the tectum, no cell death had occurred. There was no statistically significant difference in cell death at 75 days after lesion between animals receiving nerve crush and those receiving nerve cut with stump separation, even though most crush animals had regenerated a complete visual projection, whereas most nerve cut animals had not. The application of NGF did not influence the level of cell death at 75 days after lesion.These results suggest that contact of optic axons with the optic tract or tectum is not necessary for retinal ganglion cell death to occur. However, this does not necessarily mean that contact with the brain is not involved with cell death during regeneration following nerve crush because it is possible that the mechanisms of cell death are different when axons are prevented from regenerating. Further investigations are therefore required to establish the reasons for this cell death.
Spinocerebellar projections from the central cervical nucleus in the cat, as studied by anterograde transport of wheat germ agglutinin‐horseradish peroxidase
Authors: Matsushita Matsuo , Tanami Toshio 
Published: January 2005

AbstractThe projection of the Spinocerebellar, tract arising from the central cervical nucleus with crossed ascending axons was studied by the anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) in the cat.Following injections of WGA‐HRP into the C1 to the C4 or C5 segments, labeled terminals were seen in lobules I–VI, sublobule VIIb, lobules VIII and IX, the paramedian lobule, crus I and crus II, and the simple lobule. About 67–80% of the total number of labeled terminals were in the anterior lobe and 20–33% in the posterior lobe; the labeled terminals were abundant in lobules I (11–20%), II (11–28%), III (5.7–9.6%), IV (8.6–15.4%), and VIH (9–12%). The labeled terminals were densely distributed in the basal half or basal two‐thirds of sublobules IIa‐Va and VIf–VIb in their apicobasal extent and the transitional areas between neighboring sublobules. In sublobules Ia, Ib, and Vg they were distributed over the entire sublobule. The labeled terminals were most abundant within 0.5 mm of the midline (30–55% of the total number in each sublobule). Results in cases with injections into the C2–C4 segments, preceded by hemisection between the C1 and C2 segments, revealed that the projections were bilateral but predominantly contralateral to the cells of origin; the proportion of the quantity of the contralateral projection to that of the ipsilateral was about 60:40% in sublobules Ia–Vb and sublobules Ve–Vg.The projection field in the horizontal plane of the lobule was reconstructed from a series of cross sections through each sublobule. The labeled terminals were distributed in three major longitudinal areas named areas 1, 2, and 3, respectively. These areas were confined in the basal half to two‐thirds of lobules III–V: area 1 located in zone A1 of Voogd (within 0.25 mm of the midline); area 2 located in zones A1 to A2 (at around 0.5 mm lateral to the midline); and area 3 located in the lateral part of zone A2 to zone B (between 0.75 mm and 1.5 mm lateral to the midline in lobule III, and between 1.0 mm and 2.0 mm lateral to the midline in lobules IV–VI). An indefinite area 4 appeared in zones B and C of some lobules. In sublobules Ia, Ib, Vf, and Vg the three areas extended throughout the apicobasal length.The present study demonstrates that the central cervical nucleus projects bilaterally to the anterior lobe, sublobules VIf‐VIc, lobule VIIb, lobules VIII and IX, the paramedian lobule, crus I and crus II, and the simple lobule. The projections were localized to three major longitudinal areas in the vermis of the anterior lobe and lobule VI of the posterior lobe.