bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organization of postcranial kinesthetic projections to the ventrobasal thalamus in raccoons
Authors: Wiener Sidney I. , Johnson John Irwin , Ostapoff E.‐Michael 
Published: January 2005

AbstractTo determine the presence and organization of kinesthetic, as compared with other mechanosensory projection zones in the thalamus of raccoons, unit‐cluster responses to mechanical stimulation of the postcranial body were mapped electrophysiologically in the thalami of 14 raccoons anesthetized with Dial‐urethane. A distinct zone of kinesthetic projections (from receptive fields in muscles, tendons, and joints) was found in the rostral and dorsal aspects of the mechanosensory projection zone. These projections are somatotopically organized: those from axial structures lie dorsalmost and those from successively more distal limb regions are successively more caudoventral. The kinesthetic forelimb representation is large and lies rostrodorsal to a large central core of cutaneous projections from the forepaw digits. A few scattered kinesthetic projections were found at the caudal edge of the sensory thalamic region.The large, spatially and somatotopically distinct kinesthetic projection zone in the thalamus parallels those seen in the cortex and medulla of raccoons. Similar findings in monkeys, and suggestions from data in cats and humans support the hypothesis of a distinct pathway to the cortex for kinesthetic information in all mammals.
A quantitative study of the distribution of neurons projecting to the precentral motor cortex in the monkey (M. fascicularis)
Authors: Ghosh S. , Brinkman C. , Porter R. 
Published: January 2005

AbstractThe relative numbers and locations of neurons projecting to the “fore‐limb” region of the precentral motor cortex were studied in three monkeys by using the retrograde transport of horseradish peroxidase. Within the forelimb area of the motor cortex itself, there are extensive and profuse interconnections. However, regions within this area receive afferents from very few neurons in other parts of the motor cortex representing hindlimb or head movements. Most of the motor cortical representation of the forelimb in the anterior bank of the central sulcus is devoid of callosal connections.In both the ipsilateral and contralateral hemispheres, the premotor (lateral area 6) and supplementary motor (medial area 6) areas dominate quantitatively the inputs to the motor cortical representation of the forelimb. The afferents from the premotor area are restricted and come from a region immediately behind the arcuate spur and adjacent parts of the superior and inferior limbs of the arcuate sulcus in the floor, caudal bank, and caudal lip of that sulcus. From the supplementary motor area (SMA), afferents originate from its whole rostrocaudal extent. Thalamic nuclear regions projecting to a restricted zone in the anterior bank of the central sulcus are recipients of cerebellar and somatosensory outputs. Involvement of more anterior parts of the motor cortex by the tracer labels thalamocortical cells, which are targets of pallidal output also. Within the first somatosensory cortex, cytoarchitectonic areas 1, 2, and 3a project to area 4. The projection from area 3a may provide one pathway by which short‐latency peripheral inputs, especially from muscles, reach the motor cortex.
Quantitative autoradiographic maps of local cerebral glucose metabolism in awake rats: I. Septal region and anterior hypothalamus
Authors: Brainard George C. , Schwartzman Robert J. , Alexander Guillermo M. 
Published: January 2005

AbstractQuantitative 14C‐deoxyglucose autoradiography was used to determine the local cerebral glucose metabolic rate (lCMRG) of nuclei in the septal region and anterior hypothalamus of awake, unanesthetized rats. The lCMRG of the medial and lateral septal areas, preoptic areas, medial preoptic nuclei, suprachiasmatic nuclei, supraoptic nuclei, anterior hypothalamic nuclei, and paraventricular nuclei were measured. The lCMRG of each nucleus was mapped at successive rostral‐caudal levels to determine significant internuclear and intranuclear variations. These data provide a detailed neuroanatomic map of cerebral energy metabolism of the septal and anterior hypothalamic regions in animals under standardized conditions.
Some anatomical observations on the projections from the hypothalamus to brainstem and spinal cord: An HRP and autoradiographic tracing study in the cat
Authors: Holstege Gert 
Published: January 2005

AbstractThe hypothalamus is closely involved in a wide variety of behavioral, autonomic, visceral, and endocrine functions. To find out which descending pathways are involved in these functions, we investigated them by horseradish peroxidase (HRP) and autoradiographic tracing techniques.HRP injections at various levels of the spinal cord resulted in a nearly uniform distribution of HRP‐labeled neurons in most areas of the hypothalamus except for the anterior part. After HRP injections in the raphe magnus (NRM) and adjoining tegmentum the distribution of labeled neurons was again uniform, but many were found in the anterior hypothalamus as well. Injections of 3H‐leucine in the hypothalamus demonstrated that:

The anterior hypothalamic area sent many fibers through the medial forebrain bundle (MFB) to terminate in the ventral tegmental area of Tsai (VTA), the rostral raphe nuclei, the nucleus Edinger‐Westphal, the dorsal part of the substantia nigra, the periaqueductal gray (PAG), and the interpeduncular nuclei. Further caudally a lateral fiber stream (mainly derived from the lateral parts of the anterior hypothalamic area) distributed fibers to the parabrachial nuclei, nucleus subcoeruleus, locus coeruleus, the micturition‐coordinating region, the caudal brainstem lateral tegmentum, and the solitary and dorsal vagal nucleus. Furthermore., a medial fiber stream (mainly derived from the medial parts of the anterior hypothalamic area) distributed fibers to the superior central and dorsal raphe nucleus and to the NRM, nucleus raphe pallidus (NRP), and adjoining tegmentum.
The medial and posterior hypothalamic area including the paraventricular hypothalamic nucleus (PVN) sent fibers to approximately the same mesencephalic structures as the anterior hypothalamic area. Further caudally two different fiber bundles were observed. A medial stream distributed labeled fibers to the NRM, rostral NRP, the upper thoracic intermediolateral cell group, and spinal lamina X. A second and well‐defined fiber stream, probably derived from the PVN, distributed many fibers to specific parts of the lateral tegmental field, to the solitary and dorsal vagal nuclei, and, in the spinal cord, to lamina I and X, to the thoracolumbar and sacral intermediolateral cell column, and to the nucleus of Onuf.
The lateral hypothalamic area sent many labeled fibers to the lateral part of the brainstem and many terminated in the caudal brainstem lateral tegmentum, including the parabrachial nuclei, locus coeruleus, nucleus subcoeruleus, and the solitary and dorsal vagal nuclei. In the spinal cord labeled fibers were found in the intermediate zone, lamina X, and the thoracolumbar intermediolateral cell column.
A mediolateral organization of the hypothalamic projections to the caudal brainstem is proposed in which the PVN occupies a separate position.
Mode of growth of retinal axons within the tectum of Xenopus tadpoles, and implications in the ordered neuronal connection between the retina and the tectum
Authors: Fujisawa Hajime 
Published: January 2005

AbstractRetinal axons of Xenopus tadpoles at various stages of larval development were filled with horseradish peroxidase (HRP), and their trajectories and the patterns of branching within the tectum were analyzed in whole‐mount preparations. To clarify temporal and spatial modes of growth of retinal axons during larval development, special attention was directed to labeling a restricted regional population of retinal axons with HRP, following reported procedures (H. Fujisawa, K. Watanabe, N. Tani, and Y. Ibata, Brain Res. 206:9–20, 1981; 206:21–26, 1981; H. Fujisawa, Dev. Growth Differ 26:545–553, 1984).In developing tadpoles, individual retinal axons arrived at the tectum, without clear sprouting. Axonal sprouting first began when growing tips of each retinal axon had arrived at the vicinity of its site of normal innervation within the tectum. Thus, the terminals of the newly added retinal axons were retinotopically aligned within the tectum. The retinotopic alignment of the terminals may be due to an active choice of topographically appropriate tectal regions by growth cones of individual retinal axons.The stereotyped alignment of the newly added retinal axons was followed by widespread axonal branching and preferential selection of those branches. Each retinal axon was sequentially bifurcated within the tectum, and old branches that had inevitably been left at ectopic parts of the tectum (owing to tectal growth) were retracted or degenerated in the following larval development. The above mode of axonal growth provides an adequate explanation of cellular mechanisms of terminal shifting of retinal axons within the tectum during development of retinotectal projection. Selection of appropriate branches may also lead to a reduction in the size of terminal arborization of retinal axons, resulting in a refinement in targeting.
Distribution of axons according to diameter in the monkey's optic tract
Authors: Reese B. E. , Guillery R. W. 
Published: January 2005

AbstractThe distribution of axonal diameters in the optic tract of Old World monkeys was examined by light and electron microscopy. Axon diameters were measured in samples of 100 axons taken from several locations in a cross section of the tract about 5 mm behind the optic chiasm. Fine‐caliber axons (<1.75 μm in diameter) were found in all parts of the tract. Dorsally no coarse axons were present. Further ventrally, coarse axons gradually appeared and increased steadily in proportion. The largest optic axons (>2.5 μm) were found in the most ventral parts of the tract, near the pial surface.This pattern of segregation of axons of differing diameters in the optic tract is a rearrangement of the distribution of axon diameters seen in the nerve rather than a continuation of the same pattern. Examination of axon diameters in the optic nerve has shown that there is a preponderance of fine axons centrally, while coarser axons are found in the periphery, near the pial surface; however, histograms from central parts of the nerve contain a greater proportion of coarse axons than the dorsal parts of the optic tract, while histograms from the periphery of the optic nerve contain a conspicuously greater proportion of fine axons than do histograms from the most ventral parts of the tract. This relatively greater segregation of axons according to diameter in the optic tract demonstrates that the distribution of axons in the tract cannot be formed by the simple combination of two hemiretinal maps contained in each optic nerve, as suggested in classic descriptions.The optic axons of different diameters are likely to arise from morphologically distinct retinal ganglion cell types. Previous studies in the cat have demonstrated that axons of differing diameter classes, which arise from the distinct retinal ganglion cell types, are distributed in a uniform fashion in the optic nerve but are partially segregated according to their diameter in the tract. This rearrangement of axons between the nerve and tract in carnivores has been related to the temporal gradient of neurogenesis of the different retinal ganglion cell classes, axonal order in the optic tract being an index of axonal arrival during development. We suggest that the same occurs in the development of the monkey's retinofugal system.
Primary afferent projections to the central octavus nuclei in the elasmobranch, Rhinobatos sp., as demonstrated by nerve degeneration
Authors: Dunn Robert F. , Koester David M. 
Published: January 2005

AbstractNerve degeneration studies were performed to determine the central projections of the octavus nerve in the guitarfish, Rhinobatos sp. Most first‐order octavus nerve afferents are confined to the ventral longitudinal column of the medulla, which consists of four octavus nuclei: the nucleus octavus anterior (NOA), nucleus octavus magnocellularis (NOM), nucleus octavus descendens (NOD); and nucleus octavus posterior (NOP). Central projections of the octavus nerve outside of the ventral octavus nuclear column are to the vestibulolateral lobe of the cerebellum, the large multipolar cells that lie deep to the cerebellar crest of nucleus intermedius, the reticular formation, and the nucleus octavolateralis efferens. In addition, the cytoarchitectural features of the four octavus nuclei have been analyzed: the NOA consists of large spindle‐shaped neurons and medium‐sized multipolar neurons; the NOM is a small nucleus consisting of very large multipolar neurons; the NOD contains several types of neurons including large spindle‐shaped neurons, large multipolar neurons, and polymorphic small and medium‐sized neurons; and the NOP contains small spherical and small multipolar neurons evenly distributed throughout the nucleus. On the basis of the morphology of the neurons, the NOA and NOD appear to have subdivisions suggesting a more complex organization of the octavus nuclear column than previously recognized.
Morphometric analysis of serotoninergic bipolar cells in the retina and its implications for retinal image processing
Authors: Schäutte Michael , Weiler Reto 
Published: January 2005

AbstractThe entire population of retinal serotoninergic bipolar cells in the turtle Pseudemys scripta elegans was labeled by immunocytochemical methods. This allowed a systematic analysis to be made of the morphological variabilities among a functionally homogeneous neuronal population. The analyzed morphological characteristics included: (1) size of the Landolt club, (2) size of the soma, (3) lateral extension of the ramification within the outer plexiform layer, (4) course of the axon across the inner nuclear layer, (5) pattern of the axonal ramification within the inner plexiform layer, (6) lateral extension of these ramifications, and (7) density of the cells.Whereas characteristics 1–4 and 7 show a morphological variability strictly related to the location of the bipolar cell with respect to the visual streak, a fovealike structure, characteristics 5 and 6 show no such correlation. The size of the soma increases by a factor of 4 from the visual streak toward the periphery. The area covered by the ramification in the OPL increases from 330 μm2 at the visual streak to 50,000 μm2 at the dorsal and ventral edges of the retina. The coverage factor remains the same throughout the retina, as well as the area covered by the ramifications in the IPL, which is about 2,000 μm2. At the visual streak and at 110μ ventral and 68μ dorsal of the visual streak, the bipolar axons cross the INL perpendicularly. In between the axons take an oblique course leading to an axon‐induced shift between input and output of up to 250 μm. The density of cells has its maximum of about 8,000 cells/mm2 at the visual streak and its minimum of about 500 cells/mm2 at the dorsal and ventral periphery.These morphometric data reveal a distorted projection from the outer plexiform layer onto the inner plexiform layer with an overrepresentation of the visual streak area. This helps to increase the visual acuity of this area and possibly supports motion detection.
Ectosylvian visual area of the cat: Location, retinotopic organization, and connections
Authors: Olson Carl R. , Graybiel Ann M. 
Published: January 2005

AbstractWe have mapped out the ectosylvian visual area (EVA) of the cat in a series of single‐ and multiunit recording studies. EVA occupies 10–20 mm2 of cortex at the posterior end of the horizontal limb of the anterior ectosylvian sulcus. EVA borders on somatosensory cortex anteriorly, auditory cortex posteriorly, and nonresponsive cortex laterally. EVA exhibits limited retinotopic organization, as indicated by the fact that receptive fields shift gradually with tangential travel of the microelectrode through cortex. However, a point‐to‐point representation of the complete visual hemifield is not present.We have characterized the afferent and efferent connections of EVA by placing retrograde and anterograde tracer deposits in EVA and in other cortical visual areas. The strongest transcortical fiber projection to EVA arises in the lateral suprasylvian visual areas. Area 20, the granular insula, and perirhinal cortex provide additional sparse afferents. The projection from lateral suprasylvian cortex to EVA arises predominantly in layer 3 and terminates in layer 4. EVA projects reciprocally to all cortical areas from which it receives input. The projection from EVA to the lateral suprasylvian areas arises predominantly in layers 5 and 6 and terminates in layer 1. EVA is linked reciprocally to a thalamic zone encompassing the lateromedial‐suprageniculate complex and the adjacent medial subdivision of the latero‐posterior nucleus.We conclude that EVA is an exclusively visual area confined to the anterior ectosylvian sulcus and bounded by nonvisual cortex. EVA is distinguished from other visual areas by its physical isolation from those areas, by its lack of consistent global retinotopic organization, and by its placement at the end of a chain of areas through which information flows outward from the primary visual cortex.
Afferent and efferent connections of the A5 noradrenergic cell group in the rat
Authors: Byrum Christopher E. , Guyenet Patrice G. 
Published: January 2005

AbstractThe supraspinal afferent and efferent connections of the A5 noradrenergic cell group were examined in rats. Very small deposits of HRP‐WGA were made in the rostral A5 area. Catecholamine histofluorescence techniques were used to confirm that the deposits overlapped the A5 column. Retrogradely labeled cells were present in the perifornical area and paraventricular nucleus of the hypothalamus, the Kölliker‐Fuse nucleus, dorsal parabrachial area, intermediate and caudal portions of the nucleus of the solitary tract, and the ventral medullary reticular formation in the areas of the A1 and B1 cell groups.Anterograde HRP‐WGA labeling was found in several areas of the subcortical CNS. The contribution of A5 neurons to this labeling was confirmed with retrogradely transported fluorescent latex microspheres combined with catecholamine histofluorescence techniques. The A5 cell group was found to have significant projections to the central nucleus of the amygdala, perifornical area of the hypothalamus, midbrain periaqueductal gray, parabrachial area, and the nucleus of the solitary tract. Other A5 projections include the paraventricular nucleus of the thalamus, the bed nucleus of the stria terminalis, and possibly the zona incerta and lateral and dorsal hypothalamic areas. In addition, A5 neurons may innervate the ventrolateral reticular formation of the medulla.Virtually all of the areas innervated by A5 noradrenergic neurons are involved in cardiovascular regulation. In addition, the A5 area receives afferent input from major cardiovascular regulatory centers of the supraspinal CNS. Thus the A5 cell group has the potential to exert a significant influence on the cardiovascular regulatory system.
Evidence for a viscerotopic sensory representation in the cortex and thalamus in the rat
Authors: Cechetto David F. , Saper Clifford B. 
Published: January 2005

AbstractThe functional organization of the insular cortex was studied by recording neuronal responses to visceral sensory stimuli. Horseradish peroxidase (HRP) was then iontophoresed at the recording sites to identify afferents from the ventrobasal thalamus to specific visceroceptive sites in the insular cortex. The relationship of the ventrobasal thalamus to the insular cortex and to brainstem relay nuclei for the ascending visceral projections was then examined by using the axonal transport of HRP, wheat germ agglutinin conjugated to HRP (WGA‐HRP), and fluorescent dyes. Of a total of 55 neurons that were tested for responses to visceral sensory stimuli, 33 units responded to atleast one visceral sensory modality: 6 received gastric mechanoreceptor input, 8 responded to taste inputs, 13 were activated by arterial chemoreceptors and/or showed respiratory related activity, and 6 responded to cardiovascular baroreceptor stimulation. On the basis of its cytoarchitecture and connections with the thalamus, the insular cortex was divided into a dorsal granular area, an intermediate dysgranular region, and a ventral agranular strip. Taste‐responsive neurons were located anteriorly, primarily in the dysgranular region, whereas unit responses to general visceral modalities were distributed dorsally and posteriorly in the granular insular cortex. Gastric mechanoreceptor‐responsive units were situated more dorsally and anteriorly in the granular insular cortex, while cardiopulmonary inputs were located more ventrally and posteriorly. Injections of HRP into the gustatory insular cortex resulted in retrograde labeling of neurons in the parvicellular part of the ventroposterior medial thalamic nucleus (VPMpc). Injections into the general visceral insular cortex retrogradely labeled neurons lateral to VPMpc in the ventroposterior lateral parvicellular thalamic nucleus (VPLpc). Injections of HRP, WGA‐HRP, and fluorescent dyes into VPMpc and VPLpc verified that their projection to the insular cortex is topographically organized. In the same experiments, retrogradely labeled neurons in the parabrachial nucleus identified the likely subnuclei within this nucleus for relay of visceral sensory information to the thalamus. Injections of WGA‐HRP into the parabrachial nucleus demonstrated that its projection to the ventrobasal thalamus is also topographically organized. These results demonstrate the relationship of general visceral and special visceral (taste) representations in the insular cortex. The ascending pathway for visceral sensory information appears to be viscerotopically organized at all levels of the neuraxis, including the insular cortex.
Forms and spatial arrangement of neurons in the primary motor cortex of man
Authors: Meyer Gundela 
Published: January 2005

AbstractThe morphology and the spatial arrangement of neurons in the primary motor cortex (area 4) of the adult human brain have been investigated by the Golgi method. The human motor cortex displays a great variety of pyramidal and nonpyramidal cells, expressed as important differences in soma shape and size, and in the dimensions and the distribution of dendritic trees, which are described in detail. The neuronal composition of each layer and the white matter is analyzed. In sublayers III b and c, the somata and dendritic trees of pyramidal and nonpyramidal cells are grouped into columnar aggregations, 100–300 μm wide and separated by cell‐sparse spaces of 50–100 μm width. Within the aggregations, the apical dendrites of pyramidal cells form several bundles. The dendrites of most nonpyramidal cells do not surpass the columnar width. Sections in different planes reveal that the columnar aggregations observed in sections perpendicular to the long axis of the precentral gyrus are actually the cross‐sectioned representatives of elongate strips running parallel to the long axis of the gyrus. The dendrites and somata of pyramidal cells in layers III and V show a preferential orientation in the same direction, parallel to the main axis of the gyrus. In layers II, IV, and V, aggregations like those in layer III are not recognizable; however, in layer V, loose assemblages of neurons of all sizes group around the giant Betz cells. Layer VI has a radial appearance due to the radii of myelinated fibers entering and leaving the white matter. The vertical, columnar organization of layer III and the asymmetry of somata and dendritic trees are not observed consistently throughout area 4, but are more pronounced at the boundary of the precentral gyrus and the central sulcus.