bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thalamic projections to motor, prefrontal, and somatosensory cortex in the sheep studied by means of the horseradish peroxidase retrograde transport method
Authors: Dinopoulos A. , Karamanlidis A. N. , Papadopoulos G. , Antonopoulos J. , Michaloudi H. 
Published: May 2005

AbstractIn this study the motor, prefrontal, and somatosensory areas of the sheep cerebral cortex were defined on the basis of their thalamic afferents traced with the horseradish peroxidase method.The motor area (areas 4 and 6) occupies the cruciate gyrus. It receives a substantial projection from the thalamic nuclei ventralis anterior, ventralis lateralis, medialis dorsalis, and centralis lateralis and a smaller one from the nuclei ventralis medialis, centralis medialis, paracentralis, lateralis dorsalis, lateralis posterior, centromedianus, parafascicularis, suprageniculatus, ventralis posterolateralis, and the midline nuclei. Area 4 receives afferents mainly from the nuclei ventralis anterior, ventralis lateralis, medialis dorsalis, and lateralis posterior, whereas area 6 receives afferents mainly from the nuclei ventralis anterior, medialis dorsalis, and lateralis posterior and fewer afferents from the nucleus ventralis medialis.The prefrontal area occupies the gyrus proreus and receives numerous afferents from the nucleus medialis dorsalis and fewer from the nuclei lateralis posterior and ventralis medialis.The area extending between the lateral fissure, the coronal sulcus, the presylvian sulcus, and the rostral branch of the lateral fissure is connected mainly with sensory thalamic nuclei. Thalamic afferents were found to emanate from the nuclei ventralis posteromedialis (its parvicellular part included), ventralis posterolateralis, ventralis medialis, paracentralis, lateralis posterior, medialis dorsalis, centromedianus, suprageniculatus, paraventricularis, the substantia nigra, and the ventral part of the lateral geniculate nucleus. The first somatosensory area (Johnson et al., '74, J. Comp. Neurol. 158:81–108) was found to extend between the coronal, the diagonal, and the anterior suprasylvian sulci and to receive afferents almost exclusively from the nucleus ventralis posteromedialis.
Localization of enkephalin‐like immunoreactive amacrine cells in the larval tiger salamander retina: A light and electron microscopic study
Authors: Watt Carl B. , Li Hai‐Biao , Fry Keith R. , Lam Dominic Man‐Kit 
Published: May 2005

AbstractImmunohistochemistry was utilized to examine the light and electron microscopic localization of enkephalin‐like (enk) immunoreactive amacrine cells in the larval tiger salamander retina. The vast majority of enk‐immunoreactive cells were typical amacrine cells whose round or oval cell bodies (14–16 μm) were situated in the innermost cell row of the inner nuclear layer. A relatively small number of enk‐stained oval cell bodies (14–22 μm) were located in the ganglion cell layer and were designated as those of displaced amacrine cells. Enkephalin immunostaining was observed in the inner plexiform layer as a fine plexus in sublamina 1 and as a dense network of fibers in sublamina 5. In both the center and periphery of the retina the density of typical enk‐amacrine cells was determined to be 250 ± 16.36 cells per mm2 surface area of the retina.At the ultrastructural level typical enk‐stained amacrine cells possessed a round, indented nuclear membrane. Enk‐immunoreactive processes sometimes contained dense‐core vesicles (60–115 nm) in addition to a rather homogeneous population of small, round, agranular synaptic vesicles (25–35 nm). In sublamina 1 the processes of enk‐amacrine cells were presynaptic to amacrine and bipolar cells. They also contacted processes devoid of synaptic vesicles which possibly arise from ganglion cells. As the postsynaptic element in sublamina 1, they received synaptic input from amacrine cells. In sublamina 5 the processes of enk‐amacrine cells were presynaptic to amacrine cells, bipolar cells, and the somas of cells situated in the ganglion cell layer. They also formed synaptic contacts onto processes devoid of synaptic vesicles, which may originate from ganglion cells. As the postsynaptic member in sublamina 5, the processes of enk‐amacrine cells received synapses from amacrine cells and bipolar cells.
Early vascularization of the embryonic cerebral cortex: Golgi and electron microscopic studies
Authors: Marin‐Padilla Miguel 
Published: May 2005

AbstractTwo developmental aspects in the establishment of the vasculature of the embryonic cerebral cortex have been analyzed: the vascular perforation of the external basal lamina and marginal glia by leptomeningeal capillaries and their early intracortical angiogenesis. Electron microscopic and rapid Golgi preparations have been used in this study. Four phases have been identified in the vascular perforation of the cortex. First, the leptomeningeal capillary approaches and establishes direct contact with the external basal lamina and marginal glia of the cerebral cortex. Second, the leading endothelium of the glia‐touching capillary undergoes considerable membrane activity forming many filopodia and pseudopodia. Some filopodia of this activated endothelium perforate the vascular and cortical basal laminae and penetrate into the neural tissue. This filopodial perforation is accompanied by swelling and disintegration of the subadjacent marginal glial endfeet. Third, the original perforation enlarges progressively and allows an entire endothelial cell (or cells) to penetrate into the neural tissue. Fourth, proliferation and progressive canalization of penetrated endothelial cells result in the formation of a new cortical capillary in situ. Its proximal wall becomes surrounded by perivascular glial processes which appear to replace the degenerated ones. Thus a vasculoglial barrier is formed around the growing capillary, isolating it from the neural tissue, while the filopodia at its leading edge are still growing among the neural elements without recognizable basal lamina. The formation of a shallow pial‐funnel at the capillary entrance can also be recognized at this time. This funnel contains the fine processes of leptomeningeal cells, a few collagen fibers, and the basal laminae of the penetrating vessel and of the perivascular glia. It represents an early stage in the formation of the Virchow‐Robin space. The intracortical embryonic vasculature is characterized by both capillary angiogenesis and regression and by the formation of anastomotic plexuses. While capillary angiogenesis and reabsorption are found everywhere and appear as random phenomena, the location of the anastomotic plexuses is specific and always associated with actively growing cortical regions.
Postnatal volumetric development of the prefrontal cortex in the rat
Authors: van Eden C. G. , Uylings H. B. M. 
Published: May 2005

AbstractThe medial and orbital parts of the prefrontal cortex (PFC) increase in volume during the first weeks of postnatal life. At the end of this period, however, the volumes of both parts of the PFC reach a significantly higher value than in adulthood. Subsequently the volumes decrease until the adult volume is attained. The three subareas of the medial PFC (i.e., the medial precentral area, the dorsal anterior cingulate, and the prelimbic area) reach a maximum volume around day 24, while the two orbital PFC subareas (i.e., the dorsal and ventral agranular insular areas) attain their maximum value around day 30. The differences found in the growth pattern of the five PFC subareas, which are innervated by specific subnuclei of the mediodorsal nucleus of the thalamus, suggest a role of these subnuclei in the PFC development.
Evidence for corticotropin‐releasing factor, neurotensin, and somatostatin in the neural pathway from the central nucleus of the amygdala to the parabrachial nucleus
Authors: Moga Margaret M. , Gray Thackery S. 
Published: May 2005

AbstractThe central nucleus of the amygdala (CNA) and the parabrachial nucleus of the pons (PBN) are included within a group of brain nuclei involved in autonomic responses. Previous studies have shown that the CNA sends a considerable projection to the PBN and that both nuclei contain neurons immunoreactive to many different peptides. In the present study, we used the combined retrograde fluorescence‐immunofluorescence method to determine whether the CNA projection to the PBN contains any of the following neuropeptides: corticotropin–releasing factor (CRF), neurotensin (NT), somatostatin (SS), and enkephalin (ENK). Following injections of fluorescent dye into the PBN, neurons within both lateral and medial subdivisions of the CNA were retrogradely labeled. A significant percentage of CRF (54–66%)–, NT (40–53%)–, and SS (31–50%)‐immunoreactive neurons were retrogradely labeled, predominantly within the lateral CNA. Enkephalin‐immunoreactive neurons were never retrogradely labeled, although they were often found adjacent to retrogradely labeled neurons. Our results show that the lateral CNA is a major source of CRF, NT, and SS terminals within the PBN. Neurons in the medial CNA also provide a significant contribution to the CNA‐PBN pathway, but their chemical nature remains to be determined. We conclude that CRF, NT, and SS are important putative neurotransmitters in the CNA's regulation of PBN function. This CNA‐PBN peptidergic pathway may participate in stress‐related cardiovascular and respiratory responses.
Corticocortical efferent systems in the monkey: A quantitative spatial analysis of the tangential distribution of cells of origin
Authors: Caminiti Roberto , Zeger Scott , Johnson Paul B. , Urbano Antonio , Georgopoulos Apostolos P. 
Published: May 2005

AbstractThe laminar and tangential distributions of association neurons projecting from areas 4 and 6 of the frontal lobe to area 5 of the superior parietal lobule were studied in macaque monkeys by using horseradish peroxidase histochemistry. In both areas 4 and 6 association neurons were medium‐large pyramidal cells of layers II and III, and pyramidal and fusiform cells of layers V‐VI. Tangentially, they were distributed unevenly over the cortical surface occupying only certain parts of areas 4 and 6, including the dorsomedial part of area 6, the proximal arm region of Woolsey's M1 map, parts of the postarcuate cortex, and the supplementary motor area. Within these projection zones, the number of projection cells waxed and waned in a periodic fashion.Quantitative methods, including spectral analysis techniques, were used to characterize precisely spatial periodicities along the rostrocaudal dimension. The same quantitative analyses were used to determine the nature of the tangential distribution of corticocallosal cells of area 5 projecting to contralateral area 5. Both association and callosal spectra contained a strong component in the range of low spatial frequencies, corresponding to periods greater than 2 mm. Moreover, a consistent peak was observed in both spectra at spatial frequencies corresponding to periods ranging from 0.85 to 1.28 mm. This peak is in accord with the hypothesis of a modular organization of the cells of origin of these projection systems.
The origins of descending spinal projections in lepidosirenid lungfishes
Authors: Ronan Mark C. , Northcutt R. Glenn 
Published: May 2005

AbstractThe origins of descending spinal projections in the lepidosirenid lungfishes were identified by retrograde transport of horseradish peroxidase (HRP) introduced into the rostral spinal cords of juvenile African (Protopterus annectans and Protopterus amphibians) and South American (Lepidosiren paradoxa) lungfishes. Standard HRP histochemistry revealed retrogradely labeled neurons in the nucleus of the medial longitudinal fasciculus, midbrain tegmentum, red nucleus, optic tectum, mesencephalic trigeminal nucleus, granule cell layer of the cerebellum, superior, middle, and inferior medullary reticular nuclei, magnocellular and descending octaval nuclei, region of the descending trigeminal tract, solitary complex, and the margins of the spinal gray matter anterior to the spinal HRP implant. A small number of retrogradely labeled neurons were also present in the ventral thalamus of Protopterus. A descending spinal projection from the forebrain was not evident in either genus of lepidosirenid lungfishes. The presence of projections to the spinal cord from the diencephalon, medial reticular formation of the midbrain and medulla, octaval (vestibular) nuclei, solitary complex, and probable nucleus of the descendin trigeminal tract in lungfishes and their overall similarity to comparable projections in other vertebrates suggest that these pathways are among those representative of the primitive pattern of descending spinal projections in vertebrates.
Afferents to the zona incerta in the rat: A combined retrograde and anterograde study
Authors: Roger Michel , Cadusseau Josette 
Published: May 2005

AbstractIn a first set of experiments, the retrograde transport of horseradish peroxidase (HRP) was utilized to investigate the afferent projections to the zona incerta (ZI) in the hooded rat. HRP was introduced in its crystalline form into various sectors of the ZI of seven subjects. The largest contingent of afferents arises from the following centers: the cingulate and somatosensory cortices, central amygdaloid nucleus, ventromedial hypothalamic nucleus, posterior thalamic nucleus, anterior pretectal nucleus, peripeduncular area, deep and intermediate layers of the superior colliculus, dorsal and ventral parabrachial nuclei, principal and interpolar trigeminal subnuclei, and cuneate nucleus. Other centers less systematically or more sparsely labeled were the lateral hypothalamic area, ventrobasal complex, lateral geniculate nucleus pars ventralis, medial geniculate nucleus, interstitial nucleus of Cajal, Darkschewitsch nucleus, perirubral fields, cuneiform, tegmental pedunculopontine, and deep mesencephalic reticular nuclei, pontine reticular nucleus pars oralis, lateral and interpositus cerebellar nuclei, and gracile nucleus.In a second set of experiments, an anterograde tracer (WGA‐HRP) was injected in several centers projecting to the ZI in order to localize their terminal fields within this structure. It has been thus possible to distinguish a ventral zone (ventral sector of pars caudalis and pars ventralis) in which the somesthetic somatosensory cortex, trigeminal complex, and dorsal column nuclei (DCN), collicular, and cerebellar projections terminate, from a dorsal zone (pars dorsalis) to which a limbic input (cingulate cortex and ventromedial hypothalamic nucleus) is directed. In most cases, the labeled terminal fields consisted of well‐delimited, narrow bands disposed obliquely, parallel to the cerebral peduncle or the internal capsule.The contingent of somatosensory afferents is relatively large and there is a high degree of overlapping between the different somatosensory terminal fields within the ventral ZI. This suggests a participation of this structure in the treatment of somesthetic information and/or in the transmission of noxious stimuli.
The afferent connections of the substantia innominata in the monkey,Macaca fascicularis
Authors: Russchen F. T. , Amaral D. G. , Price J. L. 
Published: May 2005

AbstractThe afferent connections of the substantia innominata and the magnocellular nuclei within it (the nucleus of the horizontal limb of the diagonal band, NHDB, and the nucleus basalis of Meynert, NBM) have been studied with anterograde and retrograde axonal tracing techniques. Prominent inputs arise in the amygdaloid complex, restricted areas of the cerebral cortex, parts of the thalamus and hypothalamus, and nuclei of the lower brainstem.Autoradiographic tracing experiments indicate that the amygdaloid fibers are distributed throughout the NHDB and the NBM, and to a lesser extent to the ventral pallidum. Relatively few fibers innervate the more medially located nucleus of the vertical limb of the diagonal band (NVDB) and the medial septal nucleus. Visualization of the amygdalofugal fibers with the tracer PHA‐L (Phaseolus vulgarisleuco‐agglutinin) shows that they have varicosities resemblingboutons en passantalong their length in the substantia innominata. Retrograde tracing experiments using WGA‐HRP indicate that the cells of origin of the projection from the amygdala are concentrated in the parvicellular basal nucleus, the caudal part of the magnocellular basal nucleus, the magnocellular accessory basal nucleus, and the central nucleus. Relatively few fibers to the substantia innominata arise in the rostrodorsal part of the magnocellular basal nucleus, or in the lateral or parvicellular accessory basal nuclei.Cortical cells projecting to the substantia innominata were retrogradely labeled in the orbitofrontal cortex (including areas 11–14 and 25), the rostral insula (especially the agranular area), the rostroventral temporal cortex (including areas 35, 36, and parts of TG and TE), and the piriform and entorhinal cortices. The projections from the orbital and rostral temporal cortex were confirmed with anterograde tracers. Projections to the substantia innominata were not found from the more lateral, dorsal or caudal parts of the cerebral cortex, although fibers from temporal area TA may pass through the dendritic field of the most caudal cells of the NBM.Diencephalic cells projecting to the substantia innominata are distributed diffusely throughout the preoptic area and hypothalamus, with higher concentration in the lateral preoptic area and in the pre‐, supra‐, and tuberomammillary nuclei. Cells are also found in the midline thalamic nuclei and in the region between the peripeduncular and subparafascicular nuclei.In the brainstem, high concentrations of cells projecting to the substantia innominata are located in the dorsal and median raphe nuclei, the parabrachial nuclei, and the ventral tegmental area and pars compacta of the substantia nigra. There are also cells in the central gray and pedunculopontine region, the reticular formation, the locus coeruleus, and the nucleus of the solitary tract.
The somatotopic organization of forelimb cutaneous nerves in the brachial dorsal horn: An anatomical study in the cat
Authors: Nyberg Gunnar , Blomqvist Anders 
Published: May 2005

AbstractThe projection of forelimb cutaneous nerves to the brachial dorsal horn was studied in the cat by the transganglionic transport method. The results demonstrate a precise somatotopic termination pattern. Afferent nerves from the paw occupy the largest area, with the palm represented most medially in the dorsal horn, followed progressively more laterally by the representations for the palmar and dorsal surfaces of the digits and the dorsum of the paw. The digits are represented in a longitudinal sequence, with the first digit in the caudal part of C6 and the fifth in the caudal part of C8. The projections of the wrist and arm are split, with the line of discontinuity located along the ventral surface of the limb, so that the radial side is represented rostral to the paw and the ulnar side caudal to the paw, with the dorsal surface of the arm represented lateral to the paw. Nerves innervating the skin of the back project to the lateralmost part of the dorsal horn. The degree of overlap or separation of the terminal fields of the nerves along the mediolateral axis of the dorsal horn seems to correspond to the degree of overlap or separation of the peripheral innervation fields. However, along the rostrocaudal axis there appears to be an overlap for which there is no counterpart peripherally.
Ultrastructure of the olfactory neuron of the bullfrog: The dendrite and its microtubules
Authors: Burton Paul R. 
Published: May 2005

AbstractThe ciliated dendritic bulb of the olfactory neuron of the bullfrog was studied with the electron microscope, with emphasis on microtubular elements. Methods used included various fixation procedures with and without detergent extraction, serial sectioning, microtubule polarity assays, and an assay to demonstrate F‐actin. Structural continuity exists, via microtubules, between the ciliary membrane and the perikaryon of the neuron. One type of structural link connects the distal end of the basal body to the plasma membrane and, in slightly oblique cross sections of the basal body, the link shows a highly characteristic tripartite profile resembling a claw hammer. The six to ten basal bodies of a dendritic bulb have a lateral foot that serves as an organizing center for microtubules, and these microtubules (totaling about 150) extend toward the perikaryon in the basal half of the epithelium. Polarity assays indicate that the attached or minus ends of dendritic microtubules are in the dendritic bulb, with their plus or fast‐growing ends near or within the perikaryon of the neuron. It is shown that dendritic microtubules are depolymerized by direct osmium tetroxide fixation, in contrast to olfactory axonal microtubules, which persist after such fixation. F‐actin appears to be abundantly present in the dendritic bulb of the neuron, and it is possible that this actin could play a role in shape changes of the dendrite. The various findings provide new information about the olfactory dendrite, its microtubule organizing centers, and the nature and relationships of its microtubules.
Projections to the subcortical forebrain from anatomically defined regions of the medial geniculate body in the rat
Authors: LeDoux Joseph E. , Ruggiero David A. , Reis Donald. J. 
Published: May 2005

AbstractAlthough the auditory cortex is believed to be the principal efferent target of the medial geniculate body (MG), our recent behavioral studies indicate that in rats the conditioned coupling of emotional responses to an acoustic stimulus is mediated by subcortical projections of the MG. In the present study we have therefore used WGA‐HRP as an anterograde and retrograde axonal marker to (1) define the full range of subcortical efferent projections of the MG; (2) identify the cells of origin within the MG of each projection; and (3) determine whether the subregions of the MG that project to subcortical areas receive inputs from acoustic relay nuclei of the midbrain, particularly the inferior colliculus.The rat MG was first parcelled into three major cytoarchitectural areas: the ventral, medial, and dorsal divisions. The suprageniculate nucleus, located within the body of the MG just dorsal to the medial division, was also identified.Efferent projections of the MG were determined by combined anterograde and retrograde tracing methods. Injections of WGA‐HRP in the MG produced anterograde transport to cortex and several subcortical areas, including the posterior caudate‐putamen and amygdala, the ventromedial nucleus of the hypothalamus, and the subparafascicular thalamic nucleus. The cells of origin of the subcortical projections were then mapped retrogradely after injections in the anterogradely labeled areas. Injections in the caudate‐putamen or amygdala retrogradely labeled the medial division of the MG and the suprageniculate nucelus, as well as several adjacent areas of the posterior thalamus surrounding the MG. In contrast, injections in the ventromedial nucleus of the hypothalamus or the subparafascicular thalamic nucleus only produced labeling in the areas surrounding MG.Afferents to MG from the inferior colliculus were then identified. The central nucleus of the inferior colliculus, the main lemniscal acoustic relay nucleus in the midbrain, was found to project to the ventral and medial divisions of the MG. In contrast, the dorsal cortex and external nucleus of the inferior colliculus project to each division of the MG and to several additional nuclei in adjacent areas of the posterior thalamus.These data demonstrate that the medial division of MG, the suprageniculate nucleus, and immediately adjacent areas of the posterior thalamus provide a direct linkage between auditory neurons in the inferior colliculus and subcortical areas of the forebrain and thereby support the view that thalamic sensory nuclei relay afferent signals to subcortical as well as cortical areas.