bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secondary vestibulocerebellar projections to flocculonodular lobe in a prosimian primate, Galago senegalensis
Authors: Rubertone J. A. , Haines D. E. 
Published: January 2005

AbstractThe organization of vestibulocerebellar projections to the flocculonodular and adjacent cortices were studied in Galago using horseradish peroxidase (HRP). Implants of HRP pellets or injections (0.14–0.95μI) were placed in floccular, parafloccular, nodular, and uvular cortices. Following survival times of 18–25 hours animals were killed via transcardiac perfusion of heparinized saline followed by a buffered solution of paraformaldehyde and glutaraldehyde. Tissues were processed using DAB as the chromogen.Consequent to floccular implants HRP‐positive cells are found bilaterally in medial (MVN), spinal (SpVN), and superior (SVN) vestibular nuclei. Labeled neurons are present in the ipsilateral subgroup y and interstitial nucleus of the eighth nerve. The prepositus hypoglossal nuclei also contained HRP‐positive somata. A column of labeled cells is present exclusively in dorsomedial MVN subsequent to injection of the paraflocculus. Injections of nodular cortex reveal a distinct bilateral projection to this cortical area. Many labeled cells are located in SpVN, MVN, SVN, subgroups x and y, the interstitial nucleus, and the ganglion of the eighth nerve. Labeled somata are concentrated in dorsal and dorsolateral SpVN and in a bandlike configuration in subgroup x. HRP‐reactive cells appear to have a differential rostrocaudal distribution in MVN, while the majority of positive cells in SVN are found in central portions of the nucleus. After HRP injection into the transition area between nodular and uvular cortices, labeled neurons are present in MVN, SpVN, and the prepositus hypoglossal nucleus. A similar distribution of HRP‐positive cells is seen following injections of ventral uvula; however, cells are markedly fewer in number. In no case, subsequent to injection of the flocculonodular lobe and adjacent cortices, are HRP‐labeled neurons found in the lateral vestibular nucleus.
Regeneration of taste buds after reinnervation of a denervated tongue papilla by a normally nongustatory nerve
Authors: Zalewski Andrew A. 
Published: January 2005

AbstractTaste buds degenerate and disappear after transection of their sensory nerve supply, and they differentiate anew from epithelial cells (e.g., lingual) following regeneration of sensory but not motor or autonomic axons. A controversy exists as to whether only gustatory sensory nerves can cause buds to reform or whether any sensory nerve can perform this function. This issue arose because the results of cross‐innervation studies revealed a specificity whereas grafting data demonstrated a nonspecificity. A retest of specificity in the cross‐reinnervation situation was performed by reinnervating the denervated vallate papilla of adult rat tongue with a sensory branch of the vagus nerve that is not normally gustatory. It was found that taste buds disappeared and remained lost from acutely and chronically denervated papilla. However, some buds were found 90–100 days after reinnervation by the normally nongustatory vagus nerve branch. Transection of the regenerated vagus nerve resulted in the loss of innervation and the degeneration of taste buds from reinnervated papilla indicating that this nerve had supported buds. These results show that a normally nongustatory nerve can induce the formation of taste buds after its axons grow into appropriate tissue. It appears that the ability to support taste buds is a nonspecific, rather than a specific, property of sensory nerve.
Organization of afferent input to subdivisions of area 8 in the rhesus monkey
Authors: Barbas H. , Mesulam M‐M. 
Published: January 2005

AbstractThe sources of ipsilateral afferents to subdivisions of one frontal eye field (Walker, '40a area 8 ) were studied with horseradish peroxidase (HRP) in macaque monkeys. There were major differences in the distribution of cells pro‐ jecting to the caudal and rostral parts of area 8. The majority (53%) of labeled cortical cells projecting to caudal regions were in visual association areas, and an additional 23% were in the ventral bank of the intraparietal sulcus, where neurons may have predominantly visual and visuomotor properties. In contrast, rostral area 8 had a much lower percentage of its cortical input originating in visual association areas (5%) or in the ventral bank ofthe intraparietal sulcus (8%). After HRP injection in this rostral part, 21% of labeled cells were in auditory association areas and 13% in paralimbic regions, whereas labeling in these two types of cortex was negligible after HRP administration to caudal parts of area 8. The percentage of cells in other association regions (portions of the banks of the superior temporal sulcus, dorsolateral parietal, medial parietal, and prefrontal cortices) was higher in the rostral (53%) than in the caudal case (21%). The results suggest that caudal area 8 may be involved in head and eye movements in response to visual stimuli, while its anterior subdivisions may be involved in directing the head and eyes in response to auditory stimuli. Furthermore, limbic input may also be relevant to the neural processing occurring in rostral frontal eye fields, perhaps by directing attention toward motivationally relevant stimuli.
Anatomical demonstration of multiple representation in the forelimb region of the cat motor cortex
Authors: Pappas C. L. , Strick P. L. 
Published: January 2005

AbstractRetrograde transport of HRP was employed to examine the pattern of callosal connections in the forelimb region of area 4$ in the cat. According to the conventional view, areas of the motor cortex which contain the representation of distal body parts neither send nor receive callosal fibers. If this is true, then an absence of callosal connections would define the sites of distal forelimb representation. Following multiple injections of HRP into the contralateral motor cortex, many labeled neurons were found in the forelimb region of area 4$. However, within this region, two spatially separate areas were found where labeled neurons were either absent or present in very low density (“callosal holes”). The anatomically defined callosal holes corresponded in size, shape, and location to the physiologically defined digit zones. To provide direct evidence for this correspondence, retrograde HRP transport was combined with intracortical stimulation in the same animal. Small lesions placed in physiologically identified digit zones were located within the anatomically defined callosal holes. Thus, a double representation of the distal forelimb can be defined in area 4γ of the cat motor cortex using both anatomical and physiological methods.
A collateral pathway to the neostriatum from corticofugal neurons of the rat sensory‐motor cortex: An intracellular HRP study
Authors: Donoghue John P. , Kitai S. T. 
Published: January 2005

AbstractA projection from large pyramidal cells in layer V of the rat somatic sensory‐motor (SSM) cortex both to the neostriatum and the brainstem was demonstrated by intracellular recording and injection of horseradish peroxidase (HRP). Layer V neurons that project to the brainstem were identified either by antidromic activation from the cerebral peduncle or by tracing the HRP‐labeled axon into the internal capsule in histochemically processed sections. Intracellular responses to stimulation of the hindlimb, forelimb or mystacial pad were also examined.Five of 20 HRP‐injected neurons that project to the brainstem had a fine collateral branch within the striatum. These branched corticostriatal cells respond at short latency (7–12 msec) to somatic sensory stimulation. All of the injected corticofugal neurons that had a striatal collateral were large pyramidal neurons located in layer Vb of the forelimb and head areas of SSM cortex.Branched corticofugal neurons have a rich basal dendritic field and a prominent apical dendrite that arborizes in the superficial cortical layers. Intracortical axon collaterals from the branched cells ramify in layers V and VI, and also project to the upper layers of cortex, near the apical dendrite. Beyond the cortex, the main axon has no collateral branches, except for a single laterally directed branch in the neostriatum. The diameter of the striatal collateral is small (about 0.5 μm), compared to that of the main axon (2.0–2.5 μm). It is concluded that these branched cells provide a parallel input to the neostriatum and to brainstem or spinal motor centers.
The organization of somatosensory area II in tree shrews
Authors: Sur Mriganka , Weller Rosalyn E. , Kaas Jon H. 
Published: January 2005

AbstractMicroelectrode multiunit recording methods were used to determine the somatotopic organization of the second somatosensory area, S‐II, in tree shrews. Neurons were activated by light tactile stimuli, and receptive fields were located on the contralateral body surface only. The orientation of S‐II was such that the top of the head adjoined S‐I and the distal limbs pointed away from S‐I so that the representation could be characterized as “erect.” In general, the distortions of the body surface in S‐II were similar to those found in S‐I of the tree shrew (Sur et al., '80), with the exception that proportionately less cortex was devoted to the glabrous nose. The representation in S‐II was more continuous than that in S‐I. Finally, cortex bordering S‐II caudally was found to be responsive to generally more intense somatosensory stimuli such as taps to the body surface.
Lesion‐induced synaptogenesis in the dentate gyrus of aged rats: I. Loss and reacquisition of normal synaptic density
Authors: Hoff Steven F. , Scheff Stephen W. , Benardo Larry S. , Cotman Carl W. 
Published: January 2005

AbstractQuantitative electron microscopy was used to examine the ability of aged (2‐year‐old) and young adult (90‐day‐old) rats to replace those synapses lost (85–90%) in the outer two‐thirds of the molecular layer of the dentate gyrus after a complete unilateral lesion of the entorhinal cortex. In aged rats the synaptic density is significantly lower than that of young adults at 10 days postlesion. Synaptic replacement begins between 2 and 4 days postlesion in young adults, whereas there is a delay until after 10 days postlesion in aged rats. Once synapse replacement begins in aged rats, the rate of synapse reappearance is about equal that of young adults. Thus the initial 10 days postlesion appears critical to growth of responding afferents and reformation of synaptic contacts.Analysis of synapses in terms of noncomplex and complex synaptic types shows that the noncomplex type accounts for the significant synaptic density difference between the two age groups. Replacement of complex synapses is nearly indistinguishable between age groups and is complete by 60 days postlesion. In contrast the initial replacement rate of noncomplex synapses in aged rats is much slower than young adults, though the control synaptic density is achieved by the end of the time course.
Immunohistochemical identification of neurons in the paraventricular nucleus of the hypothalamus that project to the medulla or to the spinal cord in the rat
Authors: Sawchenko P. E. , Swanson L. W. 
Published: January 2005

AbstractA method that allows the concurrent localization of an antigen and a retrogradely transported fluorescent dye (true blue) was used to identify, immunohistochemically, cells in the paraventricular nucleus of the hypothalamus (PVH) that project to autonomic centers in the brainstem or in the spinal cord of the adult albino rat. After placing injections of true blue in the dorsal vagal complex or in upper thoracic segments of the spinal cord, series of evenly spaced sections through the PVH were stained with antisera directed against oxytocin, vasopressin, somatostatin, methionine‐enkephalin, or leucine‐encephalin. The results indicate that both oxytocin‐ and vasopressin‐stained cells in the PVH project to the spinal cord and (or) to the dorsal vagal complex, although about three times as many oxytocinstained cells were doubly labeled after injections centered in either terminal field. The oxytocin‐ and vasopressin‐stained cells that give rise to these long descending projections were found primarily in caudal parts of the parvo cellular division of the PVH, where immunoreactive cells were shown to be significantly smaller than oxytocin‐ and vasopressin‐stained cells in parts of the nucleus that project to the posterior pituitary. Small populations of cells in the PVH that cross‐react with antisera against somatostatin, leucine‐enkephalin, or methionine‐enkephalin were also shown to project directly to the region of the dorsal vagal complex and to the spinal cord, and to have a unique distribution within the PVH. Collectively, the total number of doubly labeled cells that were identified in these experiments accounts for only about one‐fourth of the total number of PVH neurons with long descending projections, thus suggesting that additional neuroactive substances are contained within these pathways.
Retinal ganglion cell projections to individual layers of the lateral geniculate body in Galago crassicaudatus
Authors: Itoh Kazuo , Conley Michael , Diamond Irving T. 
Published: January 2005

AbstractThe genus Galago provides an unique opportunity to study the relation between layers of the lateral geniculate body and classes of retinal ganglion cells. In the present experiments HRP was restricted to individual layers of the lateral geniculate body with the following results: After injections of the magnocellular layers, layers 1 and 2, labeled retinal ganglion cells ranged in size from 8 to 20 μm. After injections of the parvocellular layers, layers 3 and 6, labeled retinal ganglion cells ranged in size from 6 to 12 μm. After injections involving layers 4 and 5, which layers contain only very small, pale cells, labeled retinal ganglion cells ranged in size from 5 to 14 μm. Thus, the very largest ganglion cells were labeled only after injections of magnocellular layers 1 and 2, while small and medium retinal ganglion cells were labeled after HRP injections in every layer of the lateral geniculate body. Because the magnocellular layers actually contain a mixture of large, medium, and small‐sized cells, we suggest that retinal ganglion cells of different size‐classes project to geniculate relay cells of the corresponding size‐class.
Fiber connections of the corpus glomerulosum in a teleost, Navodon modestus
Authors: Sakamoto Noboru , Ito Hironobu 
Published: January 2005

AbstractFiber connections of the corpus glomerulosum (CG) in a teleost, Navodon modestus, were studied by means of horseradish peroxidase (HRP) and a pars rotunda (GR). Both the GR and the GA have the same cell components and glomeruli. The GR is composed of four layers arranged concentrically around a central fiber net in the following order (Ito and Kishida, 1975): a glomerular layer, a fibrous layer, a small‐cell layer, and a peripheral fibrous capsule including large cells. The GA consists of a central glomerular layer and a peripheral small‐cell which contains some large cells. Following HRP injections into the GR, HRP‐positive cells were found bilaterally in the nucleus corticalis and ipsilaterally in the nucleus intermedius of Brickner (1929). Lesions of the nucleus coryicalis produced degenerating terminals bilaterally in glomeruli in the CG. The course of the fiber connections was coincident with that of the commissura horizontalis. Lesions of the nucleus intermedius resulted in degenerating terminala in the fibrous layer of the GR and the small‐cell layer of the GA. Following the destruction of the GR degenerating terminals occurres in the ipsilateral lobus inferior. Both small and large cells in the ipsilateral CG were labeled after HRP injections into the lobus inferior.
Cytoarchitectonic heterogeneity of the primate neostriatum: Subdivision into island and matrix cellular compartments
Authors: Goldman‐Rakic Patricia S. 
Published: January 2005

AbstractThe cytoarchitecture of the caudate nucleus was examined in Nisslstained sections from rhesus monkeys, in some of which the corticostriatal terminals had also been labeled by anterograde transport of tritiated amino acids injected into prefrontal cortex. The cytoarchitectonic analysis revealed the existence of two cellular compartments that could be distinguished on the basis of cell size, density, orientation, and tinctorial properties: (1) cell islands consisting of approximately 1,500 to 15,000 densely packed neurons that form aggregates of variable shapes and sizes embedded in (2) a matrix compartment of slightly larger and more loosely packed neurons that comprise the remaining and greater part of the caudate nucleus. In coronal sections, cellular islands appear mostly as round or elliptically shaped areas, 300–600 μm in diameter, but can assume more elongated and complex forms particularly in the sagittal and horizontal planes. They are encircled by fibers arranged in a thin, cell‐sparse capsule that sets them apart from the matrix compartment. Analysis of cellular organization and corticostriatal connections in counterstained autoradiograms indicates that the prefrontal cortex projects only to the matrix zone and not to the territory occupied by island cells. Therefore, according to present observations the neostriatum in primates should be viewed as a cytoarchitectonically heterogeneous structure composed of at least two distinct cellular compartments with specific connectivity. These compartments may be related to the histochemical and functional diversity of the neostriatum.
Analysis of temporal and spatial patterns of rat vestibular hair cell differentiation by tritiated thymidine radioautography
Authors: Sans Alain , Chat Mireille 
Published: January 2005

AbstractThe location in time and space of the terminal mitoses of type I and type II sensory hair cells (HCI and HCII) of the developing crista ampullaris in rat lateral semicircular canal and macula utriculi was determined by radioautographs of specimens exposed to tritiated thymidine from the 13th to the 20th day of gestation. Qualitative analysis and statistical treatment of the percentages of labeled HCI and HCII show that the terminal mitoses occur first in the macula utriculi with a maximum percentage of the 14th day of gestation, for the HCI, and on the 15th day of gestation, for the HCII. In the lateral crista, the maximum percentage of labeled HCI occurs on the 17th and 18th day of gestation and on the 19th day of gestation for the HCII. A spatial distribution of this labeling activity is also described: the older cells are located at the top of the crista and at the level of the striola of the macula utriculi while the younger cells are found at the bottom of the crista and on the sides of the utricle. A study of the vestibular receptors in the fetuses shows that synaptic contacts already exist on the 18th day of gestation in the macula utriculi at the level of the striola and on the 19th day at the top of the crista; the cells situated on the periphery are still immature. The first hair cells to undergo their terminal mitoses are, therefore, connected first. These results also suggest that the two types of cells are genetically programmed and that the HCI start functioning first during the development of the labyrinth.
The thalamo‐cortical projection of the nucleus submedius in the cat
Authors: Craig A. D. , Wiegand S. J. , Price J. L. 
Published: January 2005

AbstractThe cortical projection of the nucleus submedius (Sm) was studied in the cat with the autoradiographic and horseradish peroxidase (HRP) methods. The results indicate that Sm projects topographically on to layer 3 of a distinct agranular cortical field that occupies the posterolateral gyrus proreus, the adjacent fundus of the rhinal sulcus, and the postero‐ventral portion of the medial wall of the presylvian sulcus. This cortical field is denoted the ventrolateral orbital cortex (VLO), consonant with previous nomenclature in the rat (Krettek and Price, '77a). The more ventral part (VLOβ) is cytoarchitectonically distinct from the dorsal part (VLOα); the former receives input from the anterior part of Sm (Sma), while the latter receives superficial layer 1 of VLO probably also arises from Sm, and there may be an input to layers 5 and 6. The corticothalamic projection from VLO to Sm reciprocates the ipsilateral thalamocortical projection and also has a moderate contralateral component. A dense, subpial layer 1 input to VLO arises from cells of the ventromedial nucleus (VM) subjacent to Sm. The present experiments also indicate that clusters of cells in VM probably provide input to layer 3 of the cortex in the fundus of the presylvian sulcus, as well as area 6aβ in the lateral wall of the presylvian sulcus and the ventral bank of the cruciate sulcus. Results from the HRP experiments additionally indicate that VLOβ and the anteroventral (Smv) portion of VLOα are reciprocally connected with the ventral agranular insular cortex and the cingulate cortex, ipsilaterally, while the posterodorsal (Smd) portion of VLOα is instead connected with specific portions of the somatosensory cortical areas bilaterally. All portions of VLOα appear to project to the ventrolateral periaqueductal gray.In light of the recent suggestion that (Smd) is involved with nociception (Craig and Burton, '81), the present results suggest that the related portion of VLOα may serve as a cortical representation for noxious stimuli.
Origin and organization of pigment epithelial apical projections to cones in cat retina
Authors: Fisher Steven K. , Steinberg Roy H. 
Published: January 2005

AbstractThe apical surface of the retinal pigment epithelial cells (RPE) in the cat extend long sheetlike membranes that wrap concentrically above and around cone outer segments forming the cone sheath. The origin and organization of these sheetlike projections were studied in serial sections by electron microscopy. The apical surface of the RPE cells was found to consist of a thin zone of anastomosing ridges, or microplicae, from which longer projections extend. The lamellar projections forming the cone sheath originate from the microplicae as small cytoplasmic tabs that rapidly expand into broader sheets. Growth of individual sheets to their final size and shape continues by lateral and longitudinal expansion, fusion, and subdivision of the membrane. The small area of connection to the cell body allows the lamellae to overlap and interdigitate in forming the complex organization of the sheath. Microfilaments but not microtubules extend into the apical processes. RPE cilia (9 + 0 microtubules) with associated basal bodies, striated rootlets, and microtubules mark the location of retinal cones. These structures may be part of a microtubule organizing center that participates in morphogenesis of the cone sheath. They also may be involved in anchoring the apical projections forming the sheath, or in the movement of apical projections during the phagocytosis of outer segment discs shed from cone tips.