bluuebunny/crossref_metadata_2025_split huggingface dataset:
Double representation of the body surface within cytoarchitectonic area 3b and 1 in “SI” in the owl monkey (aotus trivirgatus)
Authors: Merzenich Michael M. , Kaas Jon H. , Sur Mriganka , Lin Chia‐Sheng 
Published: May 2005

AbstractMicroelectrode multiunit mapping studies of parietal cortex in owl monkeys indicate that the classical “primary” somatosensory region (or “SI”) including the separate architectonic fields 3a, 3b, 1, and 2 contains as many as four separate representations of the body rather than one. An analysis of receptive field locations for extensive arrays of closely placed recording sites in parietal cortex which were later related to cortical architecture led to the following conclusions: (1) There are two large systematic representations of the body surface within “SI”. Each is activated by low threshold cutaneous stimuli; one representation is coextensive with Area 3b and the other with Area 1. (2) While each of these representations contain regions of cortex with topological or “somatotopic” transformations of skin surface, the representations have many discontinuities where adjoining skin surfaces are adjoining in the representations. Thus, the representations can be considered as composites of somatotopically organized regions, but cannot be accurately depicted by simple continuous homunculi. Lines of discontinuity often cut across dermatomes and seldom follow dermatomal boundaries, i.e., neither cutaneous representation constitutes a systematic representation of dermatomal skin fields. (3) While the two cutaneous fields are basically similar in organization and are approximate mirror images of each other, they differ in important details, i.e., lines of discontinuity in the representations and the sites of representations of different specific skin surfaces differ significantly in the two representations. (4) The two cutaneous representations also differ in size and in the relative proportions in each representation differ, they cannot both be simple reflections of overall peripheral innervation density. (5) All or part of Area 2 contains a systematic representation of deep body structures.These conclusions are consistent with a view of the anterior parietal region as containing functionally distinct fields at least partially related to different subsets of receptor populations and coding or representing different aspects of somatic sensation. We suggest that the “SI” region of primates be redefined as a parietal somatosensory strip, the Area 1 representation as the posterior cutaneous field, and, for reasons of probable homology with “SI” of other mammals, the Area 3b representation as SI proper.
Postnatal synaptogenesis in the rat interpeduncular nucleus
Authors: Lenn Nicholas J. 
Published: May 2005

AbstractThe rat interpeduncular nucleus (IPN) was studied by electron microscopy from the day of birth to 33 days of age. The habenulointerpeduncular (H‐IPN) axons, the principal afferents to IPN, were prominent at birth, occuring in large groups. They formed occasional S synapses en passant at this time. S synapses subsequently increased progressively in number and maturity until 28 days of age. Crest synapses, also formed by the H‐IPN axons, appeared at eight days without a recognized formative stage. They exhibited their diverse adult morphology by 14 days of age. F synapses, endings of uncertain origin that contain flattened vesicles, were seen at 21 days, although endings containing small vesicles at 14 days represented the same population. Axosomatic synapses were first seen at four days and remained infrequent subsequently. Dendritic growth cones had their maximal prevalence at birth, decreased at four days and were absent by six days of age.Thus each of the four synaptic types previously described in the adult rat IPN exhibited a characteristic time of appearance and pattern of development in normal rat pups. This well‐ordered sequence of synaptogenesis makes the H‐IPN system well suited for a study of synaptic plasticity.
Smooth and sparsely‐spined stellate cells in the visual cortex of the rat: A study using a combined golgi‐electron microscope technique
Authors: Peters Alan , Fairén Alfonso 
Published: May 2005

AbstractThe visual cortex of the rat was impregnated by the rapid Golgi procedure. From these preparations, smooth (spine‐free) and sparsely‐spined multipolar stellate cells with well impregnated axons were selected and drawn in the light microscope using a camera lucida. Five suitably impregnated cells were then gold‐toned and deimpregnated by removal of the silver chromate produced by the Golgi impregnation, so that they could be examined in the electron microscope to determine both their cytological features and their pre‐ and postsynaptic relationships. A sixth neuron was not deimpregnated, and was examined in the electron microscope only to evaluate the types of synapses formed by its axons terminals. Five of these cells had extensive local axonal plexus and the sixth had a plexus which was less profuse.In the electron microscope the various portions of the deimpregnated neurons were readily identified by their content of fine gold particles, and it was found that their perikarya possessed a rather dark cytoplasm containing many ribosomes. Both symmetric and asymmetric synapses were present on the perikarya, and some of the perikarya had spines. The dendrites of the cells had relatively smooth contours and contained rather closely packed microtubules. The dendrites also had both symmetric and asymmetric synapses along their shafts, with the symmetric synapses being more frequent on the proximal portions of the dendrites.The axons of the neurons were unmyelinated and all of them formed symmetric synapses with their postsynaptic partners. The synapses occurred at dilatations of the axons at both en passant and terminal boutons. Neuronal elements identified as being postsynaptic to the axon terminals of the stellate cells included the perikarya and apical dendritic shafts of pyramidal neurons, the perikarya and dendritic shafts of other stellate cells, and an axons initial segment.Reasons are given for concluding that these multipolar, smooth and sparsely‐spined stellate cells are inhibitory in function, and their relationships with some other neuronal components of the rat visual cortex are considered.
A light and electron microscopic study of the pineal in the blind goby, Typhlogobius californiensis (Pisces: Gobiidae)
Authors: McNulty John A. 
Published: May 2005

AbstractThe pineal of the burrow‐inhabiting, blind goby, Typhlogobius californiensis, was studied by light and electron microscopy. The two predominant cell types were photoreceptor and supportive cells. Ganglion cells could not be positively identified. The majority of photoreceptor cells had well developed outer segments and made apparent synaptic contact with nerve process of unknown origin. Similar unmyelinated nerve fibers containing dense‐cored vesicles were seen descending the pineal stalk. The cytoplasm of supportive cells contained several Golgi zones, occasional dense aggregations of smooth endoplasmic reticulum, abundant quantities of glycogen, some dense‐cored vesicles and unusual rod crystalline inclusions measuring approximately 0.5 μm in width and 4–5 μm in length. These observations suggest that the pineal in this light‐deprived species has retained its photoreceptive function and is a metabolically active organ which may also function in secretion.
Histology and ultrastructure of the carotid sinus in experimental hypertension
Authors: Rees Peter M. , Sleight Peter , Robinson James L. , Bonchek Lawrence I. , Doctor Aspi 
Published: May 2005

AbstractHistological studies including electron microscopy were performed on the carotid sinuses of dogs with renal hypertension of 17 to 82 days duration or hypertension of two years secondary to aortic coarctation. Physiological abnormalities in the baroreceptors including resetting had been demonstrated before death. Histologically there were no qualitative or quantitative differences in the intrasinus nerve fibers of the hypertensive animals compared to controls with normal blood pressures, and there was no evidence that baroreceptor degeneration occurred as a consequence of the hypertension. Structural lesions confined to the intima were evident in the sinus walls of some of the renal hypertensive animals whereas the dogs with coarctation showed more advanced sinus wall changes including medial calcification and enlargement of the vascular lumen.
Observations on the development of brainstem‐spinal systems in the north american opossum
Authors: Martin G. F. , Beals J. K. , Culberson J. L. , Dom R. , Goode G. , Humbertson A. O. 
Published: May 2005

AbstractThe North American opossum is born 12 to 13 days after conception and is available for 90 days or more in an external pouch where it can be observed and experimentally manipulated. It is of particular interest that the hindlimbs of the newborn opossum are very immature and remain immobile for a week or more after birth.Degeneration techniques reveal that immature brainstem axons are present within the marginal zone of the lumbosacral cord before hindlimb movements begin (our stage I) and material processed for formaldehyde induced fluorescence shows that some of them transport monoamines. Several lines of evidence suggest that part of the fluorescent axons arise within the nucleus locus coeruleus. At this early stage the electron microscope reveals that all brainstem‐spinal axons are small (0.1‐0.4 μm in diameter) and unmyelinated. By the time random hindlimb movements can be observed (stage II), brainstem axons, including those transporting monoamines, can be demonstrated to have grown into limited areas of the intermediate zone of the lumbosacral cord and to arise from most of the areas contributing to them in the adult animal (horseradish peroxidase technique). Such axons are still immature and it is not yet clear that they have formed synaptic terminals. Brainstem axons continue to grow into the intermediate zone of the lumbosacral cord for some time and come to occupy all of their adult territories before thoracic transection produces obvious change in hindlimb motility (beginning of stage III). It is still another 20 days or so before thoracic transection produces spinal shock comparable to that in the adult animal. The relatively mature use of the hindlimbs and the full expression of spinal shock correlate with changes in the technique and survival time needed to demonstrate degenerating brainstem axons in experimental material.
Nuclei of the solitary tract: Efferent projections to the lower brain stem and spinal cord of the cat
Authors: Loewy A. D. , Burton H. 
Published: May 2005

AbstractThe efferent projections from the solitary complex to the lower brain stem and spinal cord were studied in the cat with the autoradiographic anterograde axonal transport and retrograde horseradish peroxidase (HRP) techniques. A revised cytoarchitectonic description of the caudal two‐thirds of the complex is presented in which the complex was subdivided into six nuclei: lateral, ventrolateral, intermediate, medial, parvocellular, and commissural solitary tract nuclei. Following injections of 3H amino acids into electrophysiologically defined regions of the complex in which cardiac or respiratory units were recorded, labeled fibers could be traced to a number of sites in the caudal brain stem including the medial and lateral parabrachial nuclei, Kölliker‐Fuse nucleus and the area ventral to this nucleus, lateral periaqueductal gray matter, ambiguus complex, which consists of the retrofacial, ambiguus and retroambiguus nuclei, ventrolateral reticular nucleus (in an area equivalent to the A1 cell group of Dahlström and Fuxe, '64), medial accessory olive, paramedian reticular formation, and lateral cuneate nucleus. Descending solitario‐spinal projections have been traced bilaterally, but predominantly to the contralateral side, to the region of the phrenic motor neurons in the C4‐C6 ventral horn, to the thoracic ventral horn, and intermediolateral cell column.Confirmatory evidence of some of these projections was obtained from a series of HRP experiments. Mainly small neurons of the parvocellular, medial and commissural solitary tract nuclei project to the region of the parabrachial and Kölliker‐Fuse nuclei. The lateral solitary nucleus projects almost exclusively to the ipsilateral medial accessory olive. It was not possible to interpret conclusively the labeling seen in the medium and large neurons of the ventrolateral solitary nucleus after HRP injections made in the region of the ambiguus‐retroambiguus complex due to the problem of fibers of passage. Following injections of HRP into the cervical, thoracic, lumbar, or sacral spinal cord, retrograde cell labeling was seen in the solitary complex. Cells in the intermediate and commissural nuclei were labeled after all four types of experiments. In the ventrolateral nucleus, medium sized neurons were predominantly labeled after the cervical spinal cord experiments, while large sized neurons were labeled mainly after the thoracic spinal cord injections. The potential physiological significance of these various connections is discussed in terms of central control of cardiovascular and respiratory functions.
Distribution of motoneurones to the neck muscles, biventer cervicis, splenius and complexus in the cat
Authors: Richmond F. J. R. , Scott D. A. , Abrahams V. C. 
Published: May 2005

AbstractThe distribution of motoneurones to the cat dorsal neck muscles biventer cervicis, splenius and complexus has been examined using the technique of retrograde horseradish peroxidase transport. A comparison was initially made of HRP uptake into motoneurones produced either by injecting HRP solution directly into a singly neck muscle or by exposing the cut ends of motor nerves to an HRP solution. The injection of HRP into single neck muscles was found to produce widespread labelling of motoneurones presumably due to diffusion of HRP into adjacent muscles. For the examination of individual motoneurone pools the technique of cut nerve exposure was therefore used.Labelled neck muscle motoneurones ranged from 10–70 μ in diameter, but the majority of cells had diameters which were less than 40 μ. Most cells were located in the ventromedial nucleus and along the medial border of the ventral horn. In these regions there was considerable overlap between the motoneurones pools of the three neck muscles examined. In addition, some splenius motoneurones were located in the nucleus of the spinal accessory nerve. Labelled neck muscle motoneurones were also located in areas not usually considered to contain motoneurones such as the commissural and centrodorsal nuclei and in the ventral commissure.
Afferent and efferent fiber connections of the carp torus longitudinalis
Authors: Ito Hironobu , Kishida Reiji 
Published: May 2005

AbstractThe efferent and afferent pathways of the carp torus longitudinalis were studied by means of degeneration and retrograde HRP methods. Efferent projections were only seen in the most superficial layer of the ipsilateral optic tectum (stratum fibrosum marginale).Afferent pathways to the torus longitudinalis were found to originate mainly in the valvula cerebelli. Degenerating fibers course in the tractus mesencephalocerebellaris posterior within the valvula, and join the tractus mesencephalocerebellaris anterior in the tegmentum. The fibers which ascend in the tract gradually invade the optic tectum through which they are distributed to the torus longitudinalis. The remaining fibers pass through the posterior commissure and terminate in the torus longitudinalis at the rostral end of the tract.Degenerating terminals were also seen in the torus longitudinalis when lesions were made in the optic tectum, tectal commissure, torus semicircularis, and in the area between the valvula and the corpus cerebelli. The possibility of projection from these areas is discussed depending upon the results of the retrograde HRP method.
Effects of early monocular lid suture upon neurons in the cat's medial interlaminar nucleus
Authors: Kratz Kenneth E. , Webb Sarah V. , Murray Sherman S. 
Published: May 2005

AbstractSingle unit extracellular recordings, cell size measurements, and cell packing density measurements were made in the medial interlaminar nucleus (MIN) of nine adult cats that had been monocularly deprived by lid suture prior to natural eye opening. The electrophysiological properties of neurons in the nondeprived regions of MIN (areas receiving input from the nondeprived eye) remained unaffected by monocular lid suture. The latencies to optic chiasm stimulation and receptive field properties, including receptive field center size, were essentially the same as those found for MIN neurons of normal adult cats. In contrast, cells in the deprived regions were severely affected by monocular deprivation. We encountered in the deprived regions of MIN only about one half as many active neurons per mm of electrode penetration as we did in the nondeprived regions. Of the physiologically active cells remaining, about one half had abnormal receptive field and/or response properties. This resulted in a sampling density of 5.1 normal Y‐cells per mm of penetration in nondeprived regions of MIN compared to 1.0 normal Y‐cell per mm in deprived regions of MIN.Histological effects of deprivation were also seen. Deprived regions of MIN were distinguished from nondeprived regions in four cats by autoradiography following intravitreal injection of tritiated proline into the deprived or nondeprived eye (2 cats each). The man cell size of deprived regions of MIN was 34% smaller than that of nondeprived regions. We did not find a difference in cell packing density between these two regions.It appears that the effects of monocular lid suture upon MIN are in most respects similar to the effects of monocular lid suture previously reported for the A laminae. Since MIN is composed solely of Y‐cells, these data support the idea that the Y‐pathways are more severely affected by visual deprivation than are the X‐pathways. Further, since MIN projects largely outside the striate cortex, these data give the first clear demonstration of a primary effect of early lid suture upon extrastriate visual pathways.
Brain stem origins of spinal projections in the lizard Tupinambis nigropunctatus
Authors: Cruce William L. R. , Newman Donald B. 
Published: May 2005

AbstractIn order to study brainstem origins of spinal projections, ten Tegu lizards (Tupinambis nigropunctatus) received complete or partial hemisections of the spinal cord at the first or second cervical segment. Their brains were processed for conventional Nissl staining. The sections were surveyed for the presence or absence of retrograde chromatolysis. Based on analysis and comparison of results from lesions in the various spinal cord funiculi, the following conclusions were reached:The interstitial nucleus projects ipsilaterally to the spinal cord via the medial longitudinal fasciculus, as does the middle reticular field of the metencephalon. The red nucleus and dorsal vagal motor nucleus both project contralaterally to the spinal cord via the dorsal part of the lateral funiculus. The superior reticular field in the rostral metencephalon and the ventrolateral vestibular nucleus project ipsilaterally to the spinal cord via the ventral funiculus. The dorsolateral metencephalic nucleus and the ventral part of the inferior reticular nucleus of the myelencephalon both project ipsilaterally to the spinal cord via the dorsal part of the lateral funiculus.Several brainstem nuclei in Tupinambis project bilaterally to the spinal cord. The ventrolateral metencephalic nucleus, for example, projects ipsilaterally to the cord via the medial longitudinal fasciculus and contralaterally via the dorsal part of the lateral funiculus. The dorsal part of the inferior reticular nucleus projects bilaterally to the spinal cord via the dorsal part of the lateral funiculus. The nucleus solitarius complex projects contralaterally via the dorsal part of the lateral funiculus but ipsilaterally via the middle of the lateral funiculus. The inferior raphe nucleus projects bilaterally to the spinal cord via the middle part of the lateral funiculus.These data suggest that supraspinal projections in reptiles, especially reticulospinal systems, are more highly differentiated than previously thought. On the other hand, recent findings in cat, opossum, and monkey reveal that the organization of supraspinal pathways in the Tegu lizard bears a striking resemblance to that observed in mammals.
Cell types of the auditory caudomedial neostriatum of the starling (Sturnus vulgaris)
Authors: Saini K. D. , Leppelsack H.‐J. 
Published: May 2005

AbstractCell types of the auditory neostriatum in the starling forebrain are described. This area in the caudal neostriatum is defined neurophysiologically by the appearance of auditory neurons.Through use of the rapid Golgi technique, four types of neurons are identified, mainly on the basis of their processes: Neurons with long descending axons and thick dendrites rich in spines (type 1), neurons with long ascending axons and thin dendrites poor in spines (type 2), short‐axon neurons (type 3), and microneurons (type 4).The axons of the long neurons pass outside the confines of the auditory neostriatum. Among neurons of type 1; some of the long descending axons directed toward the lower brain centers enter the capsula interna occipitalis (CIO). The descending axons give off many collaterals within the auditory neostriatum. With neurons of type 2; most of the ascending axons cross the lamina hyperstriatica, enter the hyperstraiatum ventrale, and arborize near its periventricular region. Some of the long ascending axons reach the overlying hyperstriatum ventrale, pars caudale (HVc, the vocal control area). Among neurons of types 3 and 4; the axons of short‐axon neurons and of microneurons end with fine branches within the auditory neostriatum.The dendrites of long‐axon neurons are oriented in specific directions, whereas those of short‐axon neurons and of microneurons do not show a definite pattern of orientation.In the region of the auditory neostriatum that lies immediately adjacent to the midline of the brain, the first three types of neurons are arranged around the central core known as field L, which is composed of the microneurons and the terminal ramifications of auditory afferents. Laterally the microneurons, along with the fibers of the input tract, undergo a rostral shift to occupy a more peripheral position within the auditory neostriatum.The neurons of the auditory neostriatum are compared with those of the mammalian auditory cortex, and a functional classification of nerve cells into projection neurons, association neurons, and interneurons is proposed.