bluuebunny/crossref_metadata_2025_split huggingface dataset:
An analysis of the origins of the cholinergic and noncholinergic septal projections to the hippocampal formation of the rat
Authors: Amaral D. G. , Kurz J. 
Published: May 2005

AbstractThese experiments were directed at determining the proportion and distribution of cholinergic septal cells which project to the rat hippocampal formation. Injections of WGA‐HRP were placed into different regions of the hippocampal formation and sections through the septal complex were processed for the simultaneous demonstration of the retrogradely transported marker and for choline acetyltransferase (ChAT) immunoreactivity. Preliminary analysis of adjacent normal series prepared either for the demonstration of ChAT or stained by the Nissl method demonstrated several distinct cell groups in the classically defined medial septal nucleus and vertical limb of the nucleus of the diagonal band. The groups of cells ranged from almost entirely ChAT‐positive to entirely noncholinergic. On the basis of shape and size of the constituent cells, the ChAT‐positive cells of the septal complex were divided into dorsal, intermediate, and ventral subdivisions.The proportion of retrogradely labeled cells that were also ChAT positive ranged from 22.8% to 77.4% in different experiments. When only the hippocampus and dentate gyrus are considered, this variation can largely be accounted for by the topographic organization of the septohippocampal projection. The medial, noncholinergic half of the medial septal nucleus projects primarily to the rostral or septal portions of the dentate gyrus and hippocampus, whereas the lateral half, in which the dorsal ChAT group is located, projects heavily to more temporal levels. Rostral portions of the hippocampus and dentate gyrus receive most of their cholinergic input from the ventral ChAT cell group which forms a major component of the vertical limb of the nucleus of the diagonal band. While some ChAT‐positive cells in the intermediate group project to the hippocampal formation, they are generally less numerous than those from the dorsal and ventral groups. However, in a control experiment in which the WGA‐HRP injection was placed into the cingulate cortex overlying the rostral hippocampal formation, the intermediate ChAT group accounted for 71.2% of the double‐labeled cells.
Ultrastructural characterization of synaptic terminals formed on newly generated neurons in a song control nucleus of the adult canary forebrain
Authors: Burd Gail D. , Nottebohm Fernando 
Published: May 2005

AbstractThe fine structure of synaptic terminals contacting neurons generated in the forebrain of adult male canaries was investigated by autoradiography and electron microscopy. The procedure for labeling the new neurons included pretreating adult canaries with 3H‐thymidine and sacrificing them 23–45 days later. Neurons were identified as newly generated by the presence of 3H‐thymidine in the cell nucleus. The new neurons in the nucleus hyperstriatum ventralis, pars caudalis (HVc) were identified by autoradiography and light microscopy and examined with electron microscopy.Several types of synaptic terminals contacted the cell body and proximal dendrites of the newly formed neurons. Synaptic junctions were formed by terminals that contained (1) spherical, agranular vesicles, (2) large densecore vesicles and spherical, agranular vesicles, and (3) pleomorphic or flattened synaptic vesicles. Terminals that contained spherical vesicles were most often associated with asymmetric synaptic densities, and terminals that contained pleomorphic or flattened vesicles formed symmetric junctions. New neurons were also contacted by small terminals that contained few vesicles and had little pre‐ or postsynaptic density associated with the junction; these terminals may be a special type or may be in the process of developing their synaptic contact with the new neuron. In addition, rare terminals that appeared to be degenerating or to contain debris from other degenerating neural elements contacted new neurons. In summary, these data indicate that the new neurons, which are known to be inserted into existing neural networks, receive synaptic input from at least three different sources.
The distribution of synapses on the two fields of neurites of spiking local interneurones in the locust
Authors: Watson A. H. D. , Burrows M. 
Published: May 2005

AbstractSpiking local interneurones in the metathoracic ganglion of the locust have two fields of neuropilar branches linked by a single process. One, with numerous fine neurites of relatively uniform diameter, is in a ventral area of neuropile where the afferents from hairs on a hind leg also terminate. The other, with sparser and varicose neurites, is in a more dorsal area of neuropile where the motor neurones of the leg muscles have many neurites. Physiological studies have shown that these interneurones receive direct inputs from some hair afferents and in turn synapse directly upon some leg motor neurones (Burrows and Siegler, '82; Siegler and Burrows, '83). The distribution of synapses in these two fields was revealed by injecting HRP intracellularly into an interneurone following its physiological characterization. In the ventral field, the majority of synapses are input synapses. Many are from profiles with round agranular vesicles of similar diameter to those of known afferents. Other presynaptic profiles contain pleomorphic agranular, or large round granular, vesicles. There are also some output synapses, each with only a small population of vesicles. Most input synapses are made onto small‐diameter neurites, whereas the majority of outputs are made from the larger‐diameter neurites. In the dorsal field, the majority of synapses are output synapses. They are made from vesicle‐filled varicosities onto postsynaptic profiles of small diameter. A single varicosity can be the site of many output synapses. Input synapses are few in number, but occur close to the output synapses. The absence of varicosities in the ventral field cannot therefore be correlated with a lack of output synapses and while the dorsal varicosities can be the sites of output, they can also receive input synapses.
The structure of locust nonspiking interneurones in relation to the anatomy of their segmental ganglion
Authors: Watkins B. L. , Burrows M. , Siegler M. V. S. 
Published: May 2005

AbstractThe morphology of eight nonspiking local interneurones in the metathoracic ganglion of the locust is described in relation to known tracts, commissures, regions of neuropile, and identified motor neurones. They are compared with the spiking local interneurones in the same ganglion. Each nonspiking local interneurone was injected intracellularly with cobalt, following characterization of its physiological effects on identified leg motor neurones. The shapes of the nonspiking interneurones are diverse, although all have processes restricted to one ganglion and lack an axon. Their cell bodies are distributed in the ventral and dorsal cortex of the ganglion. Interneurones with cell bodies in similar places have similar basic structures, with primary neurites in the same commissure or tract, and major branches in the same tracts. The fine branches of all the interneurones have the same texture throughout, and occur in the same lateral region of neuropile, dorsal to the prominent neurite of the fast extensor tibiae motor neurone. Some interneurones have branches that extend both to the midline and to the dorsal boundary of the neuropile, but none have branches in the ventral, medial neuropile. This distribution of branches corresponds with two known features of the physiology of these interneurones: (1) they make what appear physiologically to be direct connections with motor neurones, and have branches in the same region of the neuropile as the motor neurones. (2) They do not appear to receive direct inputs from hair afferents, and they have no branches in the ventral neuropile to which these afferents project.
Origin of interhemispheric fibers in acallosal opossum (with a comparison to callosal origins in rat)
Authors: Granger Ellen Moreland , Masterton R. Bruce , Glendenning Karen K. 
Published: May 2005

AbstractThe neocortical origins of the anterior commissure in the acallosal, marsupial opossum were studied with the horseradish peroxidase (HRP) method. Following complete surgical transection of the anterior commissure, HRP was applied directly to the cut fiber tips. This procedure resulted in very large numbers of vividly labeled cells within the neocortex. The labeled cells were plotted and counted for comparison among cytoarchitectonic areas and among cortical layers. For comparative purposes, the neocortical origins of the corpus callosum are studied with the same procedure in the rat.No cytoarchitectonic area was entirely devoid of labeled cells in either species. The concentration of labeled cells throughout the entire neocortex averaged 25.2 cells/0.05 mm3 in opossum and 31.2 cells/0.05 mm3 in rat. The concentrations of labeled cells were correlated for the eight cytoarchitectonic areas common to the two species, though they were different enough in number to be statistically reliable. The distribution of labeled cells both among and within cytoarchitectonic areas was often more homogeneous in opossum than in rat.Although cortical layer 1 had no labeled cells in either species, the distribution of labeled cells across the remaining cortical layers differed sharply between the two species. In opossum, layer 3 had the most labeled cells (averaging 55% of the total number) while layer 5 had considerably less (averaging 12%). In rat, layer 5 had as many labeled cells as layer 3–both layers averaging 43% of the total number of labeled cells.In both species, striate cortex deviated markedly from other cytoarchitectonic areas. Although both species had very few labeled cells in striate cortex, those that were labeled were invariably supragranular in opossum and infragranular in rat.The similarities and dissimilarities in the topographic distribution of the origins of the two types of interhemispheric fiber systems seem to parallel the degree of cortical (and thalamic) differentiation in the two animals. However, the differences in laminar distribution are much greater and in particular, the small contribution of layer 5 in opossum as opposed to rat may well be functionally significant.
Synaptic connections of intracellularly filled clutch cells: A type of small basket cell in the visual cortex of the cat
Authors: Kisvárday Z. F. , Martin K. A. C. , Whitteridge D. , Somogyi P. 
Published: May 2005

AbstractLight and electron microscopic quantitative analysis was carried out on a type of neuron intracellularly filled with horseradish peroxidase. Two cells were studied in area 17, one of which was injected intra‐axonally, and its soma was not recovered. One cell was studied in area 18. The two somata were on the border of layers IVa/b; they were radially elongated and received synapses from numerous large boutons with round synaptic vesicles. The dendrites were smooth and remained largely in layer IV.The cells can be recognised on the basis of their axonal arbor, which was restricted to layer IV (90–95% of boutons) with minor projections to layers III, V, and VI. Many of the large, bulbous boutons contacted neuronal somata, short collaterals often forming “claw”‐like configurations around cells. The name “clutch cell” is suggested to delineate this type of neuron from other aspiny multipolar cells. Computer‐assisted reconstruction of the axon showed that in layer IV the axons occupied a rectangular area about 300 × 500 μm, elongated anteroposteriorly in area 17 and mediolaterally in area 18. The distributions of synaptic boutons and postsynaptic cells were patchy within this area. A total of 321 boutons were serially sectioned in area 17. The boutons formed type II synaptic contacts. The postsynaptic targets were somata (20–30%), dendritic shafts (35–50%), spines (30%), and rarely axon initial segments. Most of the postsynaptic somata tested were not immunoreactive for GABA and their fine structural features suggest that they are spiny stellate, star pyramidal, and pyramidal neurons. The characteristics of most of the postsynaptic dendrites and spines also suggest that they belong to these spiny neurons. A few of the postsynaptic dendrites and somata exhibited characteristics of cells with smooth dendrites and these somata were immunoreactive for GABA.It is suggested that clutch cells are inhibitory interneurons exerting their effect mainly on layer IV spiny neurons in an area localised perhaps to a single ocular dominance column. The specific laminar location of the axons of clutch cell also suggests that they may be associated with the afferent terminals of lateral geniculate nucleus cells, and could thus be responsible for generating some of the selective properties of neurons of the first stage of cortical processing.
The optokinetic nystagmus and ocular pigmentation of hypopigmented mouse mutants
Authors: Mangini Nancy J. , Vanable Joseph W. , Williams Marilyn A. , Pinto Lawrence H. 
Published: May 2005

AbstractWe tested the optokinetic nystagmus (OKN) reflex of various hypopigmented mutant mice and ultrastructurally examined the pigmentation of various ocular structures in these mutants.Using electron microscopy we examined the pigmentation of the choroid and retinal pigment epithelium (RPE) and measured the numerical density, volume density, and distribution of RPE melanosomes of mice with the following phenotypes: (1) wild type, (2) mutants that have abnormal or no OKN in response to horizontally moving, full‐field stimulation, and (3) other mutants that have normal OKN but reduced choroidal pigmentation. We also measured the OKN of all these mice in response to horizontally moving stimuli that were restricted to the nasal or to the temporal retina.We found that in the mutants with normal OKN the numerical density of melanosomes in the RPE was within the range found for wild type, while the numerical density was reduced for the mutants with abnormal OKN. For one mutant with normal RPE pigmentation and normal OKN, the choroidal pigmentation was nearly absent. For the genotypes with abnormal OKN the volume density of the RPE melanosomes and percent apical melanosomes were sometimes greater and sometimes less than normal.The OKN patterns of these mice fell into the following categories: (1) wild type; (2) field‐restriction dependent OKN with small following movements but no OKN in response to full‐field stimulation, normal OKN in response to stimulation of the nasal retina, and OKN of reversed direction in response to stimulation of the temporal retina; (3) oblique with slow oblique following movements and reduced numbers of OKNs with oblique quick phases in response to horizontally moving, full‐field stimulation, nearly normal OKN in response to stimulation of the nasal retina, and OKN of reversed direction in response to stimulation of the temporal retina. The horizontal component of the oblique response to full‐field stimulation was in the same direction for the two eyes, but the vertical component was in the opposite direction. (4) Slow, small amplitude, with no or very small following movements in response to full‐field stimulation, following movements in response to stimulation of the nasal retina and reversed “following” movements in response to stimulation of the temporal retina but few or no quick phases of the OKN for any stimulus condition.These results show that a variety of abnormalities of the OKN occur for hypopigmentation mutants of the mouse. Moreover, abnormality of the OKN is associated with a reduction of the numerical density of melanosomes in the RPE, but not with either a reduction of the volume of melanin in the RPE or hypopigmentation of the choroid.
Cytoarchitectonic development of the prefrontal cortex in the rat
Authors: van Eden C. G. , Uylings H. B. M. 
Published: May 2005

AbstractThis paper gives an account of the cytoarchitectonic characteristics that make it possible to delineate, from as early as day 6, different subareas of the prefrontal cortex of the rat. Three phases can be distinguished during postnatal development. The first phase (from day 1 until day 18) is dominated by differentiation of the neurons within the cortical plate and by the formation of the cortical layers. At day 1, regional differences are observed in the cytoarchitecture of the cortical plate which correspond to the future subareas of the prefrontal cortex. The formation of layer IV occurs in the dorsolateral cortex around day 6, and from this age the agranular prefrontal cortex is well demarcated from the other parts of the frontal cortex. Between day 6 and day 10, the cortical plate has disappeared and all cortical layers can be recognized in the prefrontal cortex. Differentiation of the cells within the cortical layers changes the cytoarchitectonic character of the layers through day 18. During the second phase (from day 18 until day 30) little change occurs in the cytoarchitectonic characteristics of the prefrontal subareas. During the third phase (from day 30 until day 90) the delineation of the cortical layers becomes less clear in Nissl‐stained sections, and the individual cytoarchitectonic variance increases. On the basis of cytoarchitectonic criteria it can be concluded that the orbital prefrontal cortex develops earlier than does the medial prefrontal cortex.
Funicular trajectories of brainstem neurons projecting to the lumbar spinal cord in the monkey (Macaca fascicularis): A retrograde labeling study
Authors: Carlton S. M. , Chung J. M. , Leonard R. B. , Willis W. D. 
Published: May 2005

AbstractBrainstem nuclei projecting to the lumbar spinal cord in the monkey were identified by using horseradish peroxidase and the fluorescent dye granular blue. These retrogradely transported tracers were used in fluid and/or gel forms to determine the funicular trajectories of the brainstem‐spinal projections. The major descending components of the dorsal funiculus arose from the n. gracilis, n. cuneatus, and the n. of the solitary tract. Major components of the dorsolateral funiculus (DLF) came from the raphe complex, medullary and pontine reticular formation, locus coeruleus, Edinger‐Westphal n., and red n. Other nuclei giving rise to minor contributions to the DLF included n. gracilis, n. cuneatus, n. of the solitary tract, medial and spinal vestibular n., subcoeruleus, periaqueductal gray, interstitial n. of Cajal, n. of Darkschewitsch, and the anteromedian n. The major components of ventral cord paths (ventrolateral and ventral funiculi) arose from the raphe complex, the medullary and pontine reticular formation, lateral and spinal vestibular n., and the coerulean complex. Minor contributions to the ventral paths descended from the dorsal motor n. of X, n. of the solitary tract, medial vestibular n., paralemniscal reticular formation, dorsal parabrachial n., n. cuneiformis, periaqueductal gray, Kölliker‐Fuse n., and red n. The possible functional implications of the funicularr distribution of these descending pathways are discussed from the perspective of descending inhibition and pain modulation.
Dendritic plasticity in the early postnatal feline retina: Quantitative characteristics and sensitive period
Authors: Eysel U. T. , Peichl L. , Wáussle H. 
Published: May 2005

AbstractRetinal lesions were made in kittens between 3 and 60 days postnatal age and in adult cats. After postlesion survival times ranging from 4 to 11 months the dendritic morphology of retinal ganglion cells was revealed by retrograde labeling with horseradish peroxidase or with neurofibrillar staining techniques. After retinal lesions on the third postnatal day changes of dendritic morphology were observed in retinal ganglion cells adjacent to regions of retrograde degeneration. Originating from eccentrically positioned somata the dendritic fields extended into the regions that were free of neighboring cells. The dendrites oriented toward the ganglion‐cell‐free region were elongated and thicker than normal. The density of dendrites per unit area was increased in this part of the dendritic trees. Lesions on the 20th, 38th, and 56th postnatal days elicited increasingly weaker changes of dendritic morphology. The sensitive period for the type of dendritic plasticity described ends between 40 and 60 days postnatally.
Innervation of cat visual areas 17 and 18 by physiologically identified X‐ and Y‐ type thalamic afferents. II. Identification of postsynaptic targets by GABA immunocytochemistry and Golgi impregnation
Authors: Freund T. F. , Martin K. A. C. , Somogyi P. , Whitteridge D. 
Published: May 2005

AbstractThe precise location of physiologically identified specific afferent input on the different types of cell in the visual cortex and the identification of the neurotransmitters of these cells are essential to a better understanding of the first stage of cortical processing. A combination of anatomical, neurochemical, and physiological methods was used to identify the cortical neurones that receive synaptic input from X‐ and Y‐type afferents, which are thought to originate from cells of the lateral geniculate nucleus. One method relied on chance contacts made between single physiologically characterised axons, which had been injected with horseradish peroxidase (HRP), and the processes of cells impregnated by the Golgi method. These experiments revealed that both X and Y axons formed synapses on the dendrites of spiny stellate cells in layer 4. Y axons in both areas 17 and 18 established multiple synaptic contacts on basal dendrites of layer 3 pyramidal cells. One X axon contacted the apical dendrite of a layer 5 pyramidal cell and one Y axon contacted the dendrite of a large cell with smooth dendrites in layer 3. The maximum number of synapses made between one axon and a single postsynaptic cell was eight, although in most cases it was only one. It was concluded that one axon only provides a small fraction of the geniculate afferent input to an individual cell.A second method revealed that the somata in layer 4 in synaptic contact with the HRP‐filled axon terminals were GABA‐immunoreactive, and therefore might be involved in inhibitory processes. From light microscopic data it was found that somata receiving contacts from X axons in area 17 were significantly smaller (average diameter 15μm) than those contacted by the Y axons in areas 17 and 18 (average diameter 24 μm). Somatic contacts were extremely rare in layer 6. These data show that the X and Y afferents may activate separate subsets of inhibitory neurones.