bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topological analysis of the brain stem of the axolotl Ambystoma mexicanum
Authors: Opdam Paul , Nieuwenhuys Rudolf 
Published: May 2005

AbstractThe ventricular sulcal pattern and the cellular structure of the brain stem of the axolotl Ambystoma mexicanum have been studied in transversely cut Nissl and Bodian stained serial sections. Six longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, the sulcus medianus superior and the sulcus lateralis mesencephali could be distinguished. A seventh groove, the sulcus isthmi, clearly deviates from the overall longitudinal pattern of the other sulci. Although most neuronal perikarya are contained within a diffuse periventricular gray, 19 cell masses could be delineated: seven of these are primary efferent or motor nuclei, four are primary afferent or sensory centers, four nuclei are considered as components of the reticular formation, and the remaining four cell masses can be interpreted as “relay” nuclei.In order to study the zonal pattern of the brain stem, this structure was subjected to a topological analysis )cf. Nieuwenhuys, '74 and fig. 13(. This analysis yielded the following results. In the rhombencephalon the grisea are arranged in four longitudinal zones which, following Kuhlenbeck, have been termed: area ventralis, area Intermedioventralis, area intermediodorsalis and area dorsalis. Where present the sulcus intermedius ventralis, the sulcus limitans and the sulcus intermedius dorsalis mark the boundaries between these four morphological entities. The zonal areas in question coincide largely, but not sntirely, with the so‐called functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the nucleus fasciculi solitarii and the nucleus visceralis secundarius, two non‐visceral sensory cell masses, namely the nucleus vestibularis magnocellularis and the nucleus cerebelli. The four morphological zones delineated in the rhombencephalon cannot be distinguished in the mesencephalon and it is of particular importance that the sulcus limitans does not extend into this part of the brain. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extreme of the somatic motor column, whereas the tectum primarily represents a somatic sensory correlation area.
The synaptic cluster )glomerulus( in the inferior olivary nucleus
Authors: King James S. 
Published: May 2005

AbstractThis report describes the fine structural features and distribution of the synaptic cluster )glomerulus( within the inferior olivary nucleus of the opossum. The postsynaptic elements typically include spiny appendages and small diameter dendrites which exhibit attachment plaques and gap junctions. Profiles presynaptic to the central core of postsynaptic elements were differentiated on the basis of vesicle shape, vesicle size, as measured by a computer system, and junctional characteristics. Three categories of terminals with clear vesicles are present within the synaptic clusters in all nuclear divisions of the olive, whereas a fourth with large dense core vesicles is restricted primarily to the principal nucleus. The groups of pre and postsynaptic elements are surrounded by astrocytic lamellae and are most frequently encountered in the principal and rostral portions of the medial accessory nuclei. Possible identification of the sources of the synaptic components is discussed in relation to data available from Golgi impregnations, physiological reports and hodological evidence.
Autoradiographic studies of the projections of the midbrain reticular formation: Ascending projections of nucleus cuneiformis
Authors: Edwards Stephen B. , de Olmos José S. 
Published: May 2005

AbstractThe ascending projections of the cuneiform nucleus in the cat were traced by autoradiography in the transverse and sagittal planes following stereotaxically placed injections of 3H‐leucine. The ascending fibers are almost exclusively ipsilateral and enter the diencephalon as a wide radiation. At the mesodiencephalic junction fibers enter the nucleus of the posterior commissure and pretectal nuclei, and others cross in the posterior commissure to distribute to these structures on the contralateral side. More ventrally directed fibers distribute to the fields of Forel and then spread into the posterior hypothalamus and zona incerta. At the caudal level of the ventral thalamic group, the ascending fibers diverge and follow two separate courses. One division of fibers continues forward beneath the ventral thalamic group and distributes to the zona incerta and dorsal hypothalamic area. It rapidly diminishes in size as it attains more rostral levels where it is found in the bed nuclei of the stria terminalis and the anterior commissure. Other fibers of this division spread laterally to innervate the ventral lateral geniculate nucleus, the lateral hypothalamus, and preoptic area, and still others follow the entire conformation of the thalamic reticular nucleus. The second division of fibers ascends through midline and intralaminar nuclei, completely encircling the mediodorsal nucleus, which is uninnervated except for a small ventral region. The distribution of this division is heaviest to the paraventricular, parafascicular, and central dorsal nuclei. Neither division is conspicuous rostral to the anterior commissure. No projections to neostriatum or specific thalamic nuclei were evident.
Gustatory pathways in the bullhead catfish. I. Connections of the anterior ganglion
Authors: Finger Thomas E. 
Published: May 2005

AbstractThe central projections of the external gustatory system in bullhead catfish were examined using orthograde degeneration and retrograde transport of horseradish peroxidase (HRP) techniques.Both large and small cells were observed in the anterior ganglion which contains a mixture of elements from the trigeminal, facial and anterior lateral line nerves. Some of the large cells on the lateral margin of the ganglion were found to belong to the lateral line system. No separation of trigeminal and facial nerve connections could be made.Using HRP, the relation between the barbels and specific ganglion regions was determined. The dorsalmost portion of the ganglion received recurrens nerve inputs (from taste buds on the trunk); the rostromedial portion of the ganglion, from the nasal barbel nerve; and the ventral portion of the ganglion, from the maxillary and mandibular barbel nerves.The facial lobe (similar to part of the n. solitarius) was found to be divided into lobules by fascicles of nerve fibers. The lateral lobule received input only from the dorsal‐most part of the ganglion (recurrens nerve: trunk receptors); the intermediate lobule from the rostro‐lateral part of the ganglion (nasal barbel); and the medial lobule from the ventral areas of the ganglion (maxillary and mandibular barbels).Thus a topographical relationship exists between the different taste receptor groups and their locus of representation in the facial lobe. The trunk receptors connect to the lateral lobule; the nasal barbel receptors to the intermediate lobule, and the maxillo‐mandibular receptors to the medial lobule.
The rabbit optic nerve: Fibre diameter spectrum, fibre count, and comparison with a retinal ganglion cell count
Authors: Vaney D. I. , Hughes A. 
Published: May 2005

AbstractThis electron microscopic study indicates that the rabbit optic nerve contains 394,000 ± 20,000 (p < 0.05) nerve fibres, of which at least 98% are myelinated. The fibre diameter spectrum of the nerve is unimodal and ranges from 0.25–7 μm with its peak at 0.75 μm. The projection of the visual streak fibres is not apparent in local diameter spectra near the optic nerve head. Integration of a ganglion cell density map of the retina from another rabbit indicates a total ganglion cell count lying between 455,000 and 547,000. The optic nerve fibre and ganglion cell counts are both substantially greater than the maximum fibre count previously reported.
Structural and functional changes in an identified cricket neuron after separation from the soma. I. Structural changes
Authors: Clark Richard D. 
Published: May 2005

AbstractThe morphological effects of separation from the soma were examined in isolated arborization and isolated axon segments of an identified motor neuron in the Polynesian field cricket, Teleogryllus oceanicus. The identified neuron, the contralateral dorsal longitudinal motor neuron of the metathoracic ganglion (CDLM), possesses an arborization most of which lies contralateral to its soma within the metathoracic ganglion. Midline surgical lesions in the metathoracic ganglion separated CDLM into a distal segment composed of the axon and most of the arborization, and a proximal segment comprised of the remaining arborization, neurite, and soma. Isolated axonal segments were produced by cutting the nerve root containing the axon of CDLM close to the ganglion.The normal anatomy of CDLM was determined by axonal dye‐fills using cobaltous chloride. Morphological changes in the isolated arborization of CDLM were examined by axonal dye‐fills at successive time intervals. Changes in the isolated CDLM axon were examined via dissection and histological cross‐sections of the distal nerve at graded time intervals.In one example, a remnant of the isolated CDLM arborization survived to 168 days postoperative, a time comparable to the longest previously‐reported physiological and morphological survival times of distal axonal segments of invertebrates. In general the isolated arborization does not survive this long. Normally occurring branches of the arborization can be preserved about 0 to 50 days. After this period branches of the arborization seem to be lost in progressive fashion from smaller to larger, leading to complete loss of the arborization and axon in most cases at 100 or more postoperative days. There is evidence for the presence of supernumerary fibers in the isolated CDLM arborization between 0 to 63 days postoperative. Such supernumerary fibers indicate an independent capacity for outgrowth of the isolated arborization without connection to the nucleus.The distal axonal segment of CDLM degenerates physiologically and morphologically within 4 to 15 days after peripheral nerve section. This time course is close to that of Wallerian degeneration of vertebrate peripheral nerve axons.
Three bulbospinal pathways from the rostral medulla of the cat: An autoradiographic study of pain modulating systems
Authors: Basbaum Allan I. , Clanton Charles H. , Fields Howard L. 
Published: May 2005

AbstractSmall amounts of 3H‐leucine were injected into discrete regions in the rostral medulla of the cat. Descending projections from these sites were studied with autoradiographic methods. On the basis of differential projections to the medulla and spinal cord, three distinct regions were delineated. Nucleus reticularis gigantocellularis (Rgc), located dorsally in the medullary reticular formation, projects primarily to “motor” related sites, including cranial motor nuclei VI, VII, XII, nucleus intercalatus, and a part of the ipsilateral medial accessory olive. The projection to the spinal cord is primarily via the ipsilateral ventrolateral and contralateral ventral funiculi. The Rgc terminal field is in lamina VII and VIII ipsilateral and lamina VIII contralateral to the injection site. In contrast, nucleus raphe magnus, (NRM) located ventrally, in the midline of the rostral medulla projects primarily to structures with known nociceptive and/or visceral afferent input. These sites include the solitary nucleus, the dorsal motor nucleus (X) and the marginal and gelatinous layers of the spinal trigeminal nucleus caudalis. The projection to the spinal cord is bilateral, via the dorsolateral funiculus. Terminal fields are found in the marginal zone and the substantia gelatinosa of the dorsal horn, and more deeply in lamina V, medial VI and VII. Nucleus reticularis magnocellularis (Rmc), located lateral to NRM and ventral to Rgc, has an overlapping projection with NRM, but the projection is ipsilateral. This difference between Rmc and Rgc is correlated with cytoarchitectural features of the two regions. The possibility that the raphe‐spinal pathway in the DLF mediates opiate and brain stimulation‐produced analgesia is discussed.
A description of the amygdaloid complex in the rat and cat with observations on intra‐amygdaloid axonal connections
Authors: Krettek J. E. , Price J. L. 
Published: May 2005

AbstractThe cytoarchitectonic structure and divisions of the amygdaloid complex are described in the rat and cat, with special reference to the axonal connections of each of the amygdaloid nuclei, and to interspecies variations and similarities. Several intra‐amygdaloid connections are also described, based on autoradiographic experiments with small injections of 3H‐amino acids into the individual nuclei. Although it has probably not been possible to determine all of the intra‐amygdaloid projections from these experiments, the connections which have been shown are very specific. The lateral nucleus projects to the basomedial nucleus, the lateral part of the central nucleus, and the periamygdaloid cortex, while the basolateral nucleus projects only to itself, the medial part of the central nucleus, and the nucleus of the lateral olfactory tract. The basomedial nucleus projects to the cellular layer of the medial nucleus and the amygdalo‐hippocampal area, while the molecular layer of these structures and of the posterior cortical nucleus, receives projections from the periamygdaloid cortex or from the endopiriform cortex. There are also interconnections between the medial and posterior cortical nuclei, and commissural connections between the posterior cortical nuclei of the two sides.
Spinal projections from the midbrain in monkey
Authors: Castiglioi A. J. , Gallaway M. C. , Coulter J. D. 
Published: May 2005

AbstractNeurons descending from the midbrain to the spinal cord in the monkey were identified with the retrograde horseradish peroxidase technique. Beginning in the caudal midbrain and extending anteriorly beneath the superior colliculus, large numbers of neurons of the nucleus cuneiformis and lateral central gray were found to project ipsilaterally to the spinal cord. In the posterolateral superior colliculus, neurons of the intermediate and deep layers, stratum griseum intermediale and stratum griseum profundum, were found to give rise to contralateral projections to the upper cervical spinal segments. An ipsilateral tectospinal projection from the anteromedial part of the collicus may also exist. In the red nucleus, neurons of the magnocellular division were shown to give rise to a somatotopically organized projection to the upper cervical cord and spinal enlargements. No neurons of the parvocellular red nucleus were labeled from the spinal cord. In the anterior midbrain, neurons of the interstitial nucleus of Cajal, nucleus of Darkschewitsch, and the adjacent dorsomedial and ventromedial midbrain tegmentum were found to give rise to an extensive ipsilateral descending spinal projection. Neurons located in various midline nuclei including the supratrochlear nucleus, oculomotor nucleus, Edinger‐Westphal nucleus, and the ventral part of the central gray were also labeled from the spinal cord. These findings indicate that the primate midbrain is the origin of an extensive system of descending spinal pathways, some of which are likely to be involved in mediating descending influences involved in complex motor and sensory behavior.
Thalamic projections to S‐I in macaque monkey
Authors: Whitsel B. L. , Rustioni A. , Dreyer D. A. , Loe P. R. , Allen E. E. , Metz C. B. 
Published: May 2005

AbstractThe organization of thalamic input to functionally characterized zones in primary somatosensory cerebral cortex (S‐I) of macaque monkeys (Macaca mulatta) was investigated using the method of labelling by retrograde transport of horseradish peroxidase (HRP). It was found that the cell columns positioned at the posterior margin of the band of cortex representing a given body region receive thalamic input from a posterior level of the ventroposterior thalamic nucleus (VP), and that cell columns at successively more anterior positions within that band receive input from successively more anterior levels of VP. The extreme posterior and anterior margins of the S‐I hand, foot and face areas receive input from neuron populations which are not as widely separated in the anteroposterior dimension of VP as the neurons projecting to the extreme anterior and posterior margins of the proximal limb and trunk representations in S‐I. These characteristics of the organization of the projections from VP to S‐I are consistent with the view that the body representations in VP and S‐I have the same connectivity and differential submodality distribution; and with the idea that thalamocortical connections only exist between functionally equivalent neuron populations in VP and S‐I.
Acute whisker removal reduces neuronal activity in barrels of mouse sml cortex
Authors: Durham Dianne , Woolsey Thomas A. 
Published: May 2005

AbstractThe autoradiographic 2‐deoxy‐D‐glucose (2‐DG) method has been used to map relative changes in metabolic activity in the CNS during various functional states (Plum et al., '76). Here we describe the application of the 2‐DG method to assay regional activity in the posteromedial barrel subfield (PMBSF) region of the mouse SmI cortex after acute removal of mystacial vibrissae.One day prior to isotope injection, various combinations of vibrissae (e.g., all vibrissae, row‐C only, rows‐B and ‐D only) were plucked from adult male Swiss Webster mice under anesthetic. The next day, 5 μCi of 14C‐2‐DG were injected into a tail vein, and the mice were allowed to actively explore an empty cage for 45 minutes. The animals were then sacrificed, the brains quickly removed, frozen, and sectioned either parallel or perpendicular to the pia at 80 μm in a cryostat. The sections were mounted, dried on coverslips, and were used to expose X‐ray film, after which the sections were stained with thionin and the X‐ray film developed. The tissue sections and matching autoradiograms were compared directly from photomicrographs of each.The autoradiograms showed areas of higher activity in barrels for which corresponding vibrissae were present and lower activity in barrels for which appropriate vibrissae were missing. In tangential sections from animals with all vibrissae intact, the PMBSF was uniformly and consistently higher in activity than in cases with all vibrissae missing. The removal of row‐C or rows‐B and ‐D resulted in strips of decreased activity in the corresponding PMBSF rows. The same patterns of increased or decreased activity were also seen in sections normal to the pia, but the changes in activity, while greatest in layer IV, extended through all layers of the cortex. Finally, in a number of the autoradiograms, density patterns could be recognized which later were shown to relate directly to sides of individual barrels.The results indicate: (1) Acute removal of the peripheral vibrissal hairs is sufficient to deprive the related contralateral cortical barrel neurons of normal activity. Thus in the mouse somatosensory system it may be possible to determine the relative importance of sensory deprivation and neonatal peripheral lesions in normal cortical development. (2) The barrels are part of a functional cortical columnar organization similar to that in other sensory systems. And, (3) the 14C‐2‐DG‐X‐ray technique is sufficiently sensitive to reveal parts of individual barrels in autoradiograms and thus, with some modification, may be suitable for the study of small populations of neurons.
Temporal and spatial sequence of anterograde degeneration in the cochlear nerve fibers of the cat. A light microscopic study
Authors: Arnesen Atle Rønning , Osen Kirsten Kjelsberg , Mugnaini Enrico 
Published: May 2005

AbstractThis study deals with anterograde degeneration in the cochlear nerve fibers following cochlear lesions. The observations are based on 2‐μm thick sections of material embedded in resin according to procedures used in electron microscopy and stained with toluidine blue. Among the various operative approaches used in this study, sparing of the modiolus afforded the least local reaction and furnished the material best suited for anterograde degeneration studies in this nerve only 2 mm long. The anterograde degeneration of the cochlear nerve is characterized by segmental swelling of myelinated nerve fibers followed by shrinkage of the axoplasm and collapse of the distended myelin sheaths. The swelling, which begins at the nodal‐paranodal region of the axon, is preceded by accumulation in the cytoplasm of granular organelles, presumably mitochondria and lysosomes. The portions of the cochlear fibers situated in the nerve root, i.e., within the cochlear nuclei and including the axon terminals, follow essentially the same pattern of degeneration as those in the peripheral portion of the nerve. Both peripherally and centrally degenerative changes occur first in the basal, high frequency fibers and progress to the apical, low frequency fibers. The difference between the two extremes in the onset of degeneration is, approximately, 24 hours. Once initiated, however, the pace of degeneration is the same along the whole fiber spectrum.