bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of denervation and stimulation upon synaptic ultrastructure
Authors: Rutledge L. T. 
Published: January 2005

AbstractQuantitative studies of synaptic ultrastructure were made in the upper layers of cat cerebral cortex. Tissues were from intact cortex and from long‐term (chronic) undercut cortex with or without electrical stimulation. The synaptic effects of chronic electrical stimulation of denervated cortex are most readily understood as growth and remodeling of synaptic elements. Associated with chronic stimulation were increases in: symmetric membrane contacts; areas of round and flat vesicle containing terminals; dendritic shaft contacts; and synaptic contact lengths. Even without stimulation there were indications of synaptic plasticity in denervated cortex; compared with intact cortex, synapses having symmetric membrane contacts showed an increase in bouton area and an increase in synaptic contacts on dendritic shafts. These data are consistent with the observations of others in which axonal terminal growth occurred after deafferentation. But it appears that chronic electrical stimulation in the adult nervous system promotes significantly more plasticity than occurs without stimulation. In a functional sense stimulation in the present experiments produced effective inhibition which did not occur with denervation alone. Thus the plasticity observed with stimulation had both structural and functional components.
The organization of olivo‐cerebellar projections in the opossum, Didelphis Virginiane, as revealed by the retrograde transport of horseradish peroxidase
Authors: Linauts M. , Martin G. F. 
Published: January 2005

AbstractThe retrograde transport of horseradish peroxidase was utilized to map olivo‐cerebellar projections in the Virginia opossum. The spinal cerebellum (anterior lobe, paramedian lobule and pyramis) receive input from several separate regions in the dorsal accessory nucleus, the medial accessory nucleus and portions of the principal nucleus. Evidence is present for a topographical organization whereby specific regions of the olive project to restricted longitudinal zones. The visual‐auditory region of the posterior vermis receives input from small areas within the caudal part of the medial accessory nucleus. From a distinctly separate region of the caudal part of the medial accesssory nucleus (as well as the principle nucleus), axons project to the uvula. The vestibulo‐cerebellum is the recipient of axons from the cap of Kooy and from two spatially separate regions of the medial accessory nucleus. The cerebellar hemisphere(Crus I and II, lobus simplex) is the target of axons from the different nuclei are targeted upon separate zones. The paraflocculus was found to receive an input from the rostral part of the medial accessory nucleus and from the principal nucleus.The present relsults suggest that a distinct olivary region may project to several widely separate areas of the cerebellum, and that one cerebellar region may revieve input from several areas of the olive. The organization of the olivocerebellar projection is highly complex, but when considered in light of known inputs to the olive, certain patterns emerge.
Distribution of catecholamine‐containing cell bodies in the rabbit central nervous system
Authors: Blessing W. W. , Chalmers J. P. , Howe P. R. C. 
Published: January 2005

AbstractA recently developed fluorescence histochemical technique, which both fixes the brain in situ and converts catecholamines to fluorescent derivatives, has been utilised to study the distribution of catecholamine‐conataining cell bodies in the central nervous system of the rabbit, a species particularly suited to cardiovascular investigation.Catecholamine‐conataining cells are widely distributed through the brain stem but are absent from the spinal cord, the cerbellum and the telencephalon. In the medulla the cells form separate ventrolateral and dorsomedial groups, while pontine cells form a continuous gruop, comprising cells of the locus coeruleus, the subcoeruleus and the ventrolateral pontine area. Fluorescent cella are widely distributed in the midbrain including an extensive group in the substantia nigra and a smaller dorsal group in the central gray matter just ventral to the aqueduct. Nearly all fluorescent forebrain cells are found in the hypothalamus, in the arcuate nucleus and in the more caudal reigons of the dorsal hypothalamus.Although the general arragement of the catecholamine‐containing cells is similar to that of the rat there are some readily appreciated differences. Ventrolateral medullary cells are more tightly grouped in the rabbit and dorsomedial medullary cells extend forther rostrally, some being found within the dorsal motor nucleus of the vagus. Locus coeruleus cells are more loosely arranged in the rabbit and the subcoeruleus group is more extensive. Midbrain cells are closely comparable but the caudal thalamic group described in the rat is less extensive in the rabbit.
Efferent projections of the subthalamic nucleus: An autoradiographic study in monkey and cat
Authors: Nauta Haring J. W. , Cole Monroe 
Published: January 2005

AbstractThe efferent projections of the subthalamic nucleus were studied with the autoradiographic tracing technique in Rhesus monkey and cat. From the data it appears that the major efferent projections of the nucleus are to the pallidal complex and the substantia nigra. In both monkey and cat, the projection to the pallidal complex is truly massive and is directed at both pallidal segments. The projection field includes an infracommissural part of the pallidal complex bordering on the substantia innominata. In the monkey the termination in the pallidal complex is organized in several characteristic bands oriented parallel to the medullary laminae. The subthalamo‐pallidal projection in monkey further appears to be topographically organized. The projections to the substantia nigra is prominent in both cat and monkey though not as massive as that to the pallidal complex. The distribution of termination in the substantia nigra favors the more ventral strata near the cerebral peduncle. In the monkey the terminal distribution appears to avoid regions of the substantia nigra containing pigmented neurons and it is suggested that the subthalamonigral pathway may prefer non‐dopaminergic neurons. In addition to the above major projections, sparse projections were noted to the thalamic nuclei ventralis lateralis and ventralis anterior, to the putamen, and to the mesencephalic nucleus tegmenti pedunculopontinus, pars compacta. The findings are discussed.
Organization and development of the brain stem auditory nuclei of the chicken: Primary afferent projections
Authors: Parks Thomas N. , Rubel Edwin W. 
Published: January 2005

AbstractThe pattern of primary auditory projections to the brain stem of young chickens was investigated using terminal degeneration methods and orthograde transport of horseradish peroxidase (HRP) or tritiated amino acid. Of particular interest was the question of whether nucleus laminaris (NL) receives primary afferents. A study of silver‐stained degeneration patterns in nucleus magnocellularis (NM) and NL at three intervals following unilateral interruption of the cochlear nerve revealed that by 48 hours after the lesion, degenerating terminals were found only in the ipsilateral nucleus angularis (NA), NM and lagenar projection areas but not in NL. Five‐ and eight‐day survival times, however, also revealed degeneration bilaterally in NL. The appearance of terminal degeneration in NL at the longer survival times is attributed to the previously‐reported severe and rapid transneuronal degeneration of neurons in NM following deafferentation and not to the presence of cochlear nerve terminals in NL. Injection of HRP or tritiated proline into the basilar papilla produced patterns of labeling similar to that seen in the 2‐day degeneration material; HRP reaction product or autoradiographic label were seen only in the ipsilateral NA and NM and in the ipsilateral projection areas of the macula lagena but not in either NL. The patterns of primary auditory projections revealed by the three methods were quite similar to each other and to that previously reported for the pigeon and confirm the conclusion that the laminar nucleus of chickens does not receive primary afferents.
Properties of the enteric nervous system: Limitation of access of intravascular macromolecules to the myenteric plexus and muscularis externa
Authors: Gershon Michael D. , Bursztajn Sherry 
Published: January 2005

AbstractThe possible presence of a blood‐myenteric plexus barrier similar to the blood‐ nerve and blood‐brain barriers was investigated. The myenteric plexus was found to be an enclosed tubular structure incompletely surrounded by a sheath of supporting cell processes. Capillaries do not enter the plexus. The capillaries which supply the myenteric layer differ in structure from capillaries of other layers of the gut and are non‐fenestrated. Tracers, Evans blue labeled albumin or horseradish peroxidase, readily leak out of fenestrated capillaries, but do not readily escape from myenteric capillaries. These capillaries have impermeable junctions that prevent the passage of tracer between endothelial cells. A slow leakage of macromolecules is probably accounted for by transport through endothelial cells within plasmalemmal vesicles. A backup system of phagocytic cells removes this material and prevents the tracers leaking from the vasculature from reaching detectable concentrations in the extracellular space. Neither tracer was ever found in the myenteric plexus. Therefore, there is a blood‐myenteric plexus barrier to macromolecules that resembles the bloodthymic barrier and may be functionally analogous to the blood‐brain barrier.
The localization of the motor neurons innervating the extraocular muscles in the oculomotor nuclei of the cat and rabbit, using horseradish peroxidase
Authors: Akagi Yoshio 
Published: January 2005

AbstractThe localization of the motor neurons innervating the extraocular muscles in the oculomotor nuclei of adult cats and rabbits was investigated by means of retrograde labelling with horseradish peroxidase (HRP).The groups consisting of the motor neurons innervating an individual muscle lay in the nucleus as elongated columns extending in a longitudinal direction. The position of each group in the transverse section varied according to the rostro‐caudal level of the nucleus. In the cat and rabbit, entire contralateral innervation of the superior rectus and entire ipsilateral innervation of three muscles of the inferior rectus, medial rectus and inferior oblique were similarly observed. However, the arrangement of individual motor groups differed considerably in both animals except for the group innervating the inferior rectus which was generally found in the ventral position running through the rostral two‐thirds of the oculomotor nucleus.In the case of cats, the central caudal nucleus bilaterally innervated the levator palpebrae superioris. The motor neurons innervating this muscle in the rabbit (which lacks the central caudal nucleus) formed a rostro‐caudal club‐shaped column close to the group innervating the superior rectus.The aberrant cellular mass in the adjoining medial longitudinal fasciculus which belongs to the medial rectus appears to play an important role in the eye movement, because it commonly appears in various animals.
A comparison of projections of entopeduncular neurons to the thalamus, the Midbrain and the habenula in the cat
Authors: Filion Michel , Harnois Carmen 
Published: January 2005

AbstractAnatomical studies have demonstrated that the output of the striopallidal system is distributed to two areas of the thalamus: the ventrolateral‐vertroanterior and the centromedian nuclei. The two areas are involved in different ways in the control of somatic motor activity. Pallidal efferents are also distributed to a still obscure tegmental area in the midbrain, the pedunculopontine nucleus, and to the lateral habenular nucleus, a structure of the limbic system. The present study compares the projections of entopeduncular neurons to the four sites in cats. The comparison is based on an estimation of the number of entopeduncular neurons sending fibers to each site and branching to more than one site. The four projection sites were stimulated electrically in anesthetized cats and the number of entopeduncular neurons excited antidromically were counted.At least 68% of entopeduncular neurons were excited antidromically by stimulation of the ventrolateral nucleus, an equal number were excited antidromically by stimulation of the nucleus centromedian and slightly fewer but still more than 50% by stimulation of the pedunculopontine nucleus. The three sites gave rise to antidromic responses of the same entopeduncular neuron in at least 33% of the cases. Only 25% of entopeduncular neurons responded antidromically to stimulation of the lateral habenular nucleus exclusively (one‐third) or not (two‐thirds). Some neurons recorded incidentally in the globus pallidus responded antidromically to the stimulation sites. Neurons were also recorded in the preoptico‐hypothalamic area and 67% responded antidromically exclusively to the stimulation of the lateral habenular nucleus.
Differential projections of cat medullary raphe neurons demonstrated by retrograde labelling following spinal cord lesions
Authors: Martin R. F. , Jordan L. M. , Willis W. D. 
Published: January 2005

AbstractNeurons of the medullary raphe nuclei in cats were retrogradely labelled following injection of horseradish peroxidase (HRP) into the L6 spinal cord segment. Brainstems were cut in sagittal section to facilitate examination of the rostral‐caudal extend of raphe neurons projecting to the spinal cord. Large numbers of HRP‐labelled neurons were found in nucleus raphe magnus, nucleus raphe pallidus, and nucleus raphe obscurus (as well as a few neurons in nucleus raphe pontis). Dorsal or ventral hemisections at the T12‐L1 level restricted HRP retrograde transport to those pathways within the intact portion of spinal cord, allowing a determination of the part of the cord through which raphe neurons project to the lumbar enlargement. Neurons of nucleus raphe magus were found to project primarily in dorsolateral fasciculus. A significant number of neurons of nucleus reticularis gigantocellularis also project in dorsolateral fasciculus. Nucleus raphe obscurus neurons were found to project primarily in ventral funiculus, while nucleus raphe pallidus neurons project in the ventrolateral fasciculi and ventral funiculus. The serotonergic (5HT) fibers described by Dahlström and Fuxe ('65) to terminate in the dorsal horn, intermediolateral cell column, and ventral horn are likely to coincide with the raphe‐spinal projections documented in this work.
Anatomical and physiological properties of ipsilaterally projecting spinothalamic neurons in the second cervical segment of the cat's spinal cord
Authors: Carstens Earl , Trevino Daniel L. 
Published: January 2005

AbstractAnatomical and electrophysiological methods were used to investigate the projections and response properties of neurons in the second cervical (C2) spinal segment of the cat giving origin to a previously undescribed projection to the ipsilateral thalamus.The method of retrograde axonal transport of horseradish peroxidase (HRP) was used to identify neurons in C2 giving rise to thalamic projections. Following large (3.0 μl) thalamic HRP injections, a large numbers of labeled neurons was observed in lateral laminae VII–VIII of C2 ipsilateral to the injections. They occurred as small clusters of cells along the longitudinal axis of C2. Labeled neurons were also observed contralaterally in the lateral cervical nucleus, dorsal horn (especially medial lamina VI), and loosely distributed in the ventral horn. The ipsilaterally projecting neurons were also labeled following small (0.2–0.5 μl) HRP injections restricted to individual spinothalamic terminal zones (intralaminar nuclei, ventrobasal complex‐nucleus ventralis lateralis border zone, medial division of the posterior nuclei), indicating that as a group they project widely throughout the thalamus.Single unit recording methods were used to obtain complementary information on the functional properties of these neurons. The antidromic stimulation method was applied to identify units in C2 projecting to the ipsilateral thalamus in anesthetized, paralyzed cats. Three categories of ipsilaterally projecting C2 units were identified: (i) units not driven by any type of natural stimulation; (2) units having large cutaneous receptive fields (RFs) and wide dynamic response ranges (“widefield”), and (3) units with smaller RFs and varied properties (“other”).Widefield units with bilaterally symmetrical and asymmetrical RFs were observed. Co‐stimulation of different portions of an excitatory RF produced summation of the unit response. Inhibitory RF components were identified in one third of the widefield units. Unit recordings after spinal tract lesions revealed that the afferent input passed via the ipsilateral lateral and/or ventral funiculi. Widefield unit responses to somatosensory stimuli could be inhibited by dorsal column conditioning stimulation. Several “other” units resembled widefield units, while a second group had small RFs restricted to the C2 dermatome.Possible functional roles of the projecting C2 neurons in somatosensory and non‐specific systems are discussed.
A histochemical study on the innervation of cerebral blood vessels in the bullfrog
Authors: Tagawa Takasuke , Andō Kōichi , Wasano Takeo , Iijima Tadahiko 
Published: January 2005

AbstractSpecific histochemical techniques for the demonstration of catecholamine and acetylcholinesterase have been used to study the distribution of adrenergic and cholinergic nerves on the cerebral blood vessels of bullfrog, Rana catesbeiana.The adrenergic nerve meshworks on the cerebral arteries of bullfrog were less dense, had a more elongate appearance along the arterial axis as compared with those of mammals and were rather similar to those of snakes. The nerve plex‐uses on the cerebral carotid artery and its main branches were somewhat denser than those on the basilar artery.The most characteristic feature of innervation in the bullfrog cerebral vessels was that no acetylcholinesterase‐positive fibres were observed on the extraparenchymal arteries, whereas, in all higher vertebrates investigated so far, the cerebral arteries have been found to be dually innervated although differences in the density of innervation of the two nerves may exist. This suggests that the peripheral adrenergic innervation on the cerebral blood vessels appeared earlier than the cholinergic one in the evolution of vertebrates.On the other hand, both adrenergic and acetylcholinesterase‐positive fibres were observed in close contact with parenchymal arterioles and capillaries suggesting the possible existence of a dual central innervation. This feature, however, was by no means common. Thus, the central neurons have a significant influence on the cerebral circulation in the bullfrog is somewhat equivocal.Most of the pial and the parenchymal small vessels and the parenchymal capillaries exhibited a heavy acetylcholinesterase activity on the vascular walls. Although the significance of the enzyme is obscure as yet, this has to be considered in relation to the regulatory mechanism of the cerebral circulation.
Quantitative analysis of nerve fibre densities in the cochlea of the house mouse (Mus musculus)
Authors: Ehret Günter 
Published: January 2005

AbstractTransverse sections of the cochlear nerve, silver‐stained surface preparations of the cochlea, and silver‐ and osmium‐stained tangential sections of the cochlea of the house mouse were made to determine the number and density of nerve fibres entering the organ of Corti and their distribution to inner and outer hair cells along the cochlear spiral. A number of 12,578 ± 819 fibres was counted within the cochlear nerve, which is almost equal to the total number of 12,350 ± 810 fibres entering the organ of Corti. The 12,350 fibres divide into 9,780 (≙ 79%) fibres running to the inner hair cells, 703 (≙ 6%) basilar (afferent) fibres and 1,867 (≙ 15%) upper tunnel radial (efferent) fibres innervating the outer hair cells. About 93% of all afferent fibres are connected to the inner hair cells, and only 7% innervate outer hair cells. The density of fibres running to the inner hair cells varies considerably and has a significant (p < 0.01) absolute and relative maximum 3.7 mm and 2.9 mm from the apex respectively (total length: 6.84 mm) and decreases toward apex and base. The density of afferent fibres running to the outer hair cells shows a slow increase up to 2 mm from the apex, and remains on a constant low level (5.5 fibres per 40 μm) down to the base. The density of efferent fibres running to the outer hair cells increases linearly up to about 2 mm from the apex, remains rather constant (10 fibres per 40 μm) from 2 mm to 4 mm, and then decreases toward the base. Generally, the outer hair cells show a convergent innervation pattern, the inner hair cells a divergent one. The significance of the present measurements is discussed in relation to respective results from other mammals and in relation to auditory thresholds.
The posterior lateral line lobe of certain gymnotoid fish: Quantitative light microscopy
Authors: Maler Leonard 
Published: January 2005

AbstractThe posterior lateral line lobe of the wave species of gymnotoid fish was investigated with the Golgi technique. The posterior lobe has a laminar structure and contains II cell types differentially distributed in the various laminae (fig. 13). The major laminae, from ventral to dorsal are the deep fiber layer, containing multipolar neurons; the deep neuropil layer, containing ovoid neurons and a sub‐lamina of spherical cells; the granule cell lamina, containing two types of granule cell; the plexiform laminae; the polymorphic cell lamina, containing basilar pyramids, non‐basilar pyramids, giant fusiform cells, and polymorphic cells; the stratum fibrosum; the molecular lamina, containing neurons of the ventral molecule layer and stellate cells.The spherical cells are regularly distributed in their sub‐lamina and appear to receive one type of primary afferent input. Another type of primary afferent input ends in the deep neuropil and granule layers, in proximity to the basilar dendrites of the granule cells and of the basilar pyramids. The basilar pyramidal cell spatially alternates with the non‐basilar pyramidal cell, so that the basilar dendritic trees of nearest‐neighbour basilar pyramids show almost no overlap.Descending input to the posterior lobe ends in the molecular layer, in proximity to apical dendrites of both pyramidal cells, giant fusiform cells, polymorphic cells, and one type of granule cell. There are three afferent fiber systems in the molecular layer, one running transversely, one longitudinally, and one vertically. Local circuitry in the posterior lobe is precisely organized and involves projections of granule cells onto overlying pyramidal cells. The polymorphic cell may also be involved in the intrinsic circuits of the posterior lobe.