bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visual and auditory association areas of the cat's posterior ectosylvian gyrus: Cortical afferents
Authors: Bowman E. M. , Olson C. R. 
Published: May 2005

AbstractIn a preceding report, we described patterns of thalamic retrograde labeling following 17 tracer deposits on the cat's posterior ectosylvian gyrus and concluded, on the basis of patterns of thalamic connectivity, that the posterior ectosylvian gyrus is composed of three major divisions: a tonotopic auditory zone located anteriorly, a belt of auditory association cortex occupying the gyral crown, and a visual belt located posteriorly. We describe here patterns of transcortical retrograde labeling obtained from tracer deposits in the three zones so defined. Our results indicate that the tonotopic auditory strip is innervated primarily by axons from low‐order auditory areas (AAF, AI, P, VP, and V), that the auditory belt receives its strongest input from nontonotopic auditory fields (AII, temporal cortex, and other parts of the auditory belt), and that projections to the visual belt derive primarily from extrastriate visual areas (ALLS, PLLS, DLS, 19, 20, and 21) and from association areas affiliated with the visual system (insular cortex, posterior cingulate gyrus, area 7p, and frontal cortex). We discuss the results in relation to previous systems for parcellating the posterior ectosylvian gyrus of the cat and consider the possibility that divisions of the feline posterior ectosylvian gyrus correspond directly to areas making up the superior temporal gyrus in primates.
Dendritic morphology and axon collaterals of corticotectal, corticopontine, and callosal neurons in layer V of primary visual cortex of the hooded rat
Authors: Hallman L. Eric , Schofield Brett R. , Lin Chia‐Sheng 
Published: May 2005

AbstractRecent evidence indicates that corticotectal neurons belong to only one of the three morphological classes of pyramidal cells in layer V. The present study compares the dendritic morphology and axon collaterals of corticotectal, corticopontine, and layer V callosal neurons by using techniques based on the retrograde transport of horseradish peroxidase and fluorescent dyes as well as in vitro intracellular dye injections. Our results indicate that corticotectal and corticopontine neurons are located predominantly in the upper middle part of layer V. These neurons have medium to large somas with 5 or 6 primary basal dendrites and a single apical dendrite ascending to layer I. Approximately 60% of these cells send axon collaterals to both the superior colliculus and the pons. In contrast, callosal neurons form a heterogeneous group. In general, they have small pyramidal or ovoid cell bodies which give rise to 3 or 4 primary basal dendrites. Many cells have an apical dendrite that bifurcates and terminates in layer V or IV. We find that callosal neurons do not send an axon collateral to either the superior colliculus or the pons.We conclude that the corticotectal and corticopontine systems are similar in their intralaminar distribution, dendritic morphology, and pattern of axon collaterals, whereas the callosal system differs in these characteristics.
Death of the subcallosal glial sling is correlated with formation of the cavum septi pellucidi
Authors: Hankin Mark H. , Schneider Bernard F. , Silver Jerry 
Published: May 2005

AbstractIn this study we have examined the developmental fate of a population of cells that is located beneath the rostral corpus callosum during the perinatal period. These cells form a distinct slinglike structure along the geographically defined corticoseptal boundary (CSB) and may play a role in guiding callosal axons across the midline. The sling is a transient structure present in fetal and neonatal animals but not in adults.Here we show that the CSB cells die and that this debris is removed by macrophages. The sequence of cell degeneration in the CSB is highly stereotyped and follows a spatiotemporal pattern that is correlated with fusion of the cerebral hemispheres and subsequent growth across the midline of the callosal axons. The subcallosal location of the resorbing CSB is found in the exact place in which a fluid‐filled cavity (the cavum septi pellucidi) is transiently found during the perinatal period.The tight temporal and spatial correlation between callosal axon decussation, degeneration of the CSB, and cavum septi formation suggests that these three phenomena may be causally related.
Organization of cortical and subcortical projections to anterior cingulate cortex in the cat
Authors: Musil S. Y. , Olson C. R. 
Published: May 2005

AbstractThe aim of the experiments reported here was to identify cortical and subcortical forebrain structures from which anterior cingulate cortex (CGa) receives input in the cat. Deposits of retrograde tracers were placed at nine sites spanning the anterior cingulate area and patterns of retrograde transport were analyzed.Thalamic projections to CGa, in descending order of strength, originate in the anteromedial nucleus, lateroposterior nucleus, ventroanterior nucleus, rostral intralaminar complex, reuniens nucleus, mediodorsal nucleus, and laterodorsal nucleus. Minor and inconsistent ascending pathways arise in the paraventricular, parataenial, parafascicular, and subparafascicular thalamic nuclei. The basolateral nucleus of the amygdala, the hypothalamus, the nucleus of the diagonal band, and the claustrum are additional sources of ascending input.Cortical projections to CGa, in descending order of strength, derive from posterior cingulate cortex, prefrontal cortex, motor cortex (areas 4 and 6), parahippocampal cortex (entorhinal, perirhinal, postsubicular, parasubicular, and subicular areas), insular cortex, somesthetic cortex (areas 5 and SIV), and visual cortex (areas 7p, 20b, AMLS, PS and EPp).In general, the limbic, sensory, and motor afferents of CGa are weak. The dominant sources of input to CGa are other cortical areas with highorder functions. This finding calls into question the traditional characterization of cingulate cortex as a bridge between neocortical association areas and the limbic system.
Organization of cortical and subcortical projections to medial prefrontal cortex in the cat
Authors: Musil S. Y. , Olson C. R. 
Published: May 2005

AbstractWe have analyzed the cortical and subcortical afferent connections of the medial prefrontal cortex (MPF) in the cat with the specific aim of characterizing subregional variations of afferent connectivity. Thirteen tracer deposits were placed at restricted loci within a cortical district extending from the proreal to the subgenual gyrus. The distribution throughout the forebrain of retrogradely labeled neurons was then analyzed.Within the thalamus, retrogradely labeled neurons were most numerous in the mediodorsal nucleus and in the ventral complex. The projection from each region exhibited continuous topography such that more medial thalamic neurons were labeled by tracer from more ventral and posterior cortical deposits. Marked retrograde labeling without any sign of topographic order occurred in a narrow medioventral sector of the lateroposterior nucleus. Several additional thalamic nuclei contained small numbers of labeled neurons. In a subset of nuclei closely affiliated with the limbic system (the parataenial, paraventricular, reuniens, and basal ventromedial nuclei), retrograde labeling occurred exclusively after deposits at extremely ventral and posterior cortical sites.Within the amygdala, retrogradely labeled neurons occupied the anterior basomedial nucleus, the posterior basolateral nucleus, and a narrow strip of the lateral nucleus immediately adjoining the basolateral nucleus. The number of labeled neurons was greater after more ventral deposits. Very ventral deposits resulted in extensive labeling of the cortical amygdala.Within the cerebral cortex, the distribution of labeled neurons depended on the location of the tracer deposit. Comparatively dorsal deposits produced prominent retrograde transport to the anterior and posterior cingulate areas, to the agranular insula, and to lateral prefrontal cortex. Comparatively ventral deposits gave rise to prominent labeling of the hippocampal subiculum, various parahippocampal areas, and prepiriform cortex.On the basis of afferent connections, it is possible to divide the cat's medial prefrontal cortex into an infralimbic component, MPFil, marked by strong afferents from prepiriform cortex and the cortical amygdala, and a dorsal component, MPFd, without afferents from these structures. Further, within MPFd, it is possible to define an axis, running from ventral and posterior to dorsal and anterior levels, along which limbic afferents gradually become weaker and projections from cortical association areas gradually become stronger.
Calcitonin gene‐related peptide immunostained axons provide evidence for fine primary afferent fibers in the dorsal and dorsolateral funiculi of the rat spinal cord
Authors: McNeill D. L. , Chung K. , Carlton S. M. , Coggeshall R. E. 
Published: May 2005

AbstractThe hypothesis being tested in the present paper is that there are large numbers of fine primary afferent axons in the dorsal and dorsolateral funiculi of the lumbar spinal cord of the rat. The data show numerous calcitonin gene‐related peptide labeled fine myelinated and unmyelinated axons in these funiculi. Approximately 95% of the labeled axons disappear after dorsal rhizotomy. Accordingly, the hypothesis is confirmed. Thus it is becoming apparent that fine primary afferent fibers are more widely distributed in spinal white matter than had been previously recognized. Implications are that it is not possible to find areas in the spinal white matter that contain only large myelinated sensory axons and that significant numbers of fine primary afferent fibers will be lost even if lesions are restricted to the dorsal funiculus. The sizable population of fine myelinated primary afferent axons in the dorsal funiculus is emphasized. An obvious question, suggested by significant differences in average diameters of the axons in the different pathways, is whether there are differences in the types of information carried by the fine afferent fibers in their different locations in the white matter of the lumbar cord.
Light microscopic localization of putative glycinergic neurons in the larval tiger salamander retina by immunocytochemical and autoradiographical methods
Authors: Yang Chen‐Yu , Yazulla Stephen 
Published: May 2005

AbstractPutative glycinergic neurons in the larval tiger salamander retina were localized by a comparative analysis of high affinity 3H‐glycine uptake and glycine‐like immunoreactivity (Gly‐IR) at the light microscopic level. Commonly labeled neurons include at least three types of amacrine cell (Type IAd, Type IAb, Type IIAd; distinquished by soma location and dendritic ramification), cell bodies in the ganglion cell layer (GCL), and rarely observed Type II (inner) bipolar cells. With the increased resolution provided by Gly‐IR, we identified a Type IAa amacrine cell, two types of Type IIAd amacrine cells, and Gly‐IR interplexiform cells. Gly‐IR axons in longitudinal sections of the optic nerve indicate the presence of Gly‐IR ganglion cells. The percentage of labeled somas in the inner nuclear layer (INL) compared to all cells in each layer was similar for the two methods: 30‐40% in INL 2 (middle layer of somas), 30–40% in INL 3 (inner layer of somas), and about 5% in the GCL. Labeled processes were found throughout the full thickness of the inner plexiform layer (IPL), but with a much denser band in the proximal half (sublamina b). The only major difference between the two methods (3H‐glycine uptake vs. Gly‐IR) was that Type I (outer) bipolar cells were labeled only by 3H‐glycine uptake; these cells were more lightly labeled with silver grains than cell bodies in either INL 2 or INL 3. Postembed labeling of 1 μm Durcupan plastic sections for Gly‐IR showed the same pattern, but with much higher resolution, as obtained with 10 μm cryostat sections. This study indicates extensive colocalization of labeling by both probes in INL 2, INL 3, the IPL, and the GCL. We conclude that Gly‐IR can serve as a valid and reliable marker for glycine‐containing neurons in this retina and suggest that glycine serves as a transmitter for several morphologically distinct types of amacrine cell, an interplexiform cell, and perhaps a small percentage of Type II bipolar cells and ganglion cells.
Morphological and immunocytochemical observations on the visual callosal projections in the cat
Authors: Voigt Thomas , LeVay Simon , Stamnes Mark A. 
Published: May 2005

AbstractThe connections between the left and right 17‐18 border regions of the cat's visual cortex were labeled by axonal transport of peroxidase‐conjugated wheat‐germ agglutinin (WGA‐HRP) and examined by light and electron microscopy. The cells of origin of the pathway were further characterized by transport of fluorescent microspheres (“beads”) followed by in vitro injection of cells with Lucifer Yellow, and by beads transport followed by immunocytochemistry with antibodies to gamma‐aminobutyric acid (GABA).The cells of origin of the callosal pathway were located in the lower part of layer 2/3, the upper part of layer 4, and layer 6. In layers 2/3 and 6, they were pyramidal cells; in layer 4 they were star pyramids or spiny stellate cells. None of them were spinefree or sparsely spinous cells, and none were GABA‐positive. The axon terminals of the callosal pathway formed type 1 (asymmetric) synapses, and most of them contacted dendritic spines. Both the cells of origin and the terminals were arranged in patches.The findings suggest that the direct action of the callosal pathway is excitatory. The callosal system appears to represent only a subset of the cell types that have intrinsic horizontal projections within areas 17 or 18.
The nervous system of the male Dinophilus gyrociliatus (polychaeta, dinophilidae): II. Electron microscopical reconstruction of nervous anatomy and effector cells
Authors: Windoffer R. , Westheide W. 
Published: May 2005

AbstractAll neuronal cells in the dwarf male of the dimorphic polychaete species Dinophilus gyrociliatus were individually identified by means of serial ultrathin sections. Altogether 68 neural cells–including 40 sensory neurons and 2 glial cells–constitute a small but complex nervous system. Fifty‐three neural cells are located in three pairs of ganglia and connected by paired nerve cords. The prominent frontal ganglia, each consisting of a well‐developed neuropile and surrounded by 20 or 21 neural cells, represent the animal's brain. The ventral ganglia contain only 2 neurons each. The penis ganglia–four cells each–are associated with the copulatory organ. A conspicuous circumpenial fiber mass surrounds the basal part of the penis. The effector cells–22 multiciliated epidermal cells, 34 muscle cells, and different gland cells (?)–were also reconstructed and their innervation was partly elucidated. Sensory‐motor neurons were unambigously identified. They are discussed in regard to the small body size of the animal. The male's nervous organization resembles a very simple rope ladder and may represent a reduced derivative of a nervous system in normal‐sized males of monomorphic species. Similarities, however, also occur with the developing nervous system of a planktotrophic metatrochophore. The neuronal organization, with its two centers (frontal ganglia and ventral ganglia vs. penis ganglia and circumpenial fiber mass), accords well with the bipartite behavioral pattern, which is entirely devoted to locomotion and copulation, respectively.
GABAergic basal forebrain neurons project to the neocortex: The localization of glutamic acid decarboxylase and choline acetyltransferase in feline corticopetal neurons
Authors: Fisher R. S. , Buchwald N. A. , Hull C. D. , Levine M. S. 
Published: May 2005

AbstractOur objective was to determine whether GABAergic and cholinergic basal forebrain neurons project to the neocortex. The retrograde connectivity marker wheat germ agglutinin lectin‐bound horseradish peroxidase was injected into the neocortex of adult cats. Histo‐ and immunohistochemical methods were combined to label sequentially connectivity and transmitter markers (glutamic acid decarboxylase; choline acetyltransferase) in forebrain neurons. The labels of each marker were identified by correlative light and electron microscopy.Two principal types of doubly labeled neurons were demonstrated. The connectivity marker was colocalized with glutamic acid decarboxylase or choline acetyltransferase. The neurons were located in the basal forebrain. Their ultrastructural, cellular, and regional organization supported 2 conclusions. (1) GABAergic basal forebrain neurons project to the neocortex. This is important new morphological evidence for the origin of inhibitory neocortical afferents from a subcortical brain site. (2) The GABAergic and cholinergic basal forebrain neurons projecting to the neocortex exhibit remarkable structural similarities. The transmitter diversity of these intertwined neocortical afferents may be significant for the pathology and treatment of human neurological disorders such as Alzheimer's disease.
Auditory brainstem of the ferret: Effects of unilateral cochlear lesions on cochlear nucleus volume and projections to the inferior colliculus
Authors: Moore David R. , Kowalchuk Nancy E. 
Published: May 2005

AbstractUnilateral lesions of the right cochlea were made in ferrets aged postnatal day (P)12 to P93. The extent of the lesions was assessed by counting remaining hair cells and ganglion cells in midmodiolar sections through the lesioned cochleas and by comparison with a sample of unlesioned cochleas. The neural effects of the lesions were assessed by measuring the volume of each cochlear nucleus (CN) and by counting the number of neurons in each CN that were retrogradely labeled following injections of WGA‐HRP in the left inferior colliculus (IC). Survival times between lesioning and injection of the tracer ranged from 11 to 98 days. CN volume and projections to the IC were also measured in a sample of normal adult ferrets and in normal infants aged P39 to P80.Cochlear lesions resulted in a reduction of the volume of the CN on the lesioned side, relative to the other CN, in animals of all ages and survival times. The extent of the CN volume reduction was negatively correlated with the number of remaining cochlear ganglion cells. However, even where the number of ganglion cells was within the normal range, significant volume reductions occurred. The ventral CN was more severely affected by the lesions than the dorsal CN, but no difference was found between the anteroventral and posteroventral divisions of the nucleus. There was no significant difference in the extent of CN volume reductions between animals of different ages or survival times.Lesions of the right cochlea in younger animals (P14 to P24) resulted, after 90 days survival, in an increase in the number of left CN neurons projecting to the left IC. No significant increase was seen following lesions in older (P90) ferrets or following short (11 or 30 days) survival times in young (P14 to P24) ferrets. The extent of the increase in the ipsilateral CN‐IC projection was not related to the number of remaining ganglion cells or to the division of the CN examined. Lesions did not affect the contralateral CN‐IC projection.We conclude that cochlear lesions in infant ferrets can alter auditory brainstem morphology and connectivity. The dependence of these alterations on the age of the animal, survival time following lesion, and extent of the lesion varies markedly with the index examined.
Monoamine innervation of the organum vasculosum laminae terminalis (OVLT): A high resolution radioautographic study in the rat
Authors: Bosler Olivier , Descarries Laurent 
Published: May 2005

AbstractThe monoamine innervation of the organum vasculosum laminae terminalis (OVLT) was examined in the adult rat by light and electron microscope radioautography after intraventricular administration of tritiated serotonin ([3H]5‐HT) or dopamine ([3H]DA). Radioautographic and biochemical controls after 5,7‐dihydroxytryptamine or 6‐hydroxydopamine lesioning established the respective serotonin (5‐HT) and catecholamine (CA) identities of the axonal varicosities labeled under the conditions of the present experiments. For descriptive purposes, the OVLT was subdivided in three parts: two parenchymal zones, one juxtaventricular, the other juxtavascular, and the vascular core. Almost 10% of all axonal varicosities in the OVLT were found to be labeled with [3H]5‐HT. This 5‐HT innervation was most prominent in the rostrocaudal and ventrodorsal portions of the juxtaventricular zone and the dorsal aspect of the juxtavascular zone; there was none in the vascular core. [3H]DA‐labeled varicosities were much less abundant and yet more numerous than earlier histofluorescent and immunohistochemical studies would have predicted. They predominated in the juxtavascular zone, where a majority presumably had a dopamine (DA) rather than a noradrenaline identity. Some were also found in the vascular core, where they most likely corresponded to peripheral autonomic noradrenaline endings. In the juxtaventricular zone of the OVLT, a significant proportion of the [3H]5‐HT‐labeled varicosity profiles could be observed to form axodendritic synapses, but in the juxtavascular zone no 5‐HT or any [3H]DA‐labeled ones were ever seen in synaptic junction. In the juxtavascular zone, the 5‐HT and the presumed DA endings established close relationships with neurosecretory axons, and with astrocytic or tanycytic processes on which they occasionally formed “synaptoid contacts.” A few endings of either type were also seen to abut directly on the outer basement membrane of the perivascular space. It therefore appears probable that in OVLT monoamines influence neural and nonneural elements. At a proximal level of regulation (juxtaventricular zone), 5‐HT could act both synaptically and nonsynaptically as an interneuronal transmitter or modulator. In contrast, distally (juxtavascular zone), both DA and 5‐HT could be released as neurohormones in addition to modulating neurosecretion. 5‐HT and DA varicosities in the OVLT could also behave as sensors for circulating factors that do not cross the blood‐brain barrier.