bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of high‐affinity choline transport sites in rat forebrain: A quantitative autoradiography study with [3H]hemicholinium‐3
Authors: Happe H. K. , Murrin L. C.
Published: January 2005

The development of cholinergic terminals in rat brain has been quantitatively analyzed by [3H]hemicholinium‐3 autoradiography. [3H]Hemicholinium‐3 binds to high affinity choline transport sites, a specific marker for cholinergic neurons. In neonatal animals, kinetic and pharmacologic binding characteristics and regional distribution of [3H]hemicholinium‐3 sites are consistent with specific cholinergic localization, as in the adult. The distribution of cholinergic terminals is described in the adult rat brain and during development, including heterogeneity of binding within several regions such as the striatum, nucleus accumbens, olfactory tubercle, cortex, and hippocampus. Early development and maturation vary greatly between brain regions. At embryonic day E18 and day 0, specific binding density is high only in the medial habenula. Development occurs primarily during the postnatal period in most brain regions examined. Many brain regions exhibit a lull in development between days 5 and 10, although the rate of development is highly region specific. Specific binding increases 2–12‐fold between day 5 and adult animals, with adult density being achieved anywhere from day 15 to after day 21. The ontogeny of [3H]hemicholinium‐3 binding sites generally occurs in a rostral to caudal direction. In the striatal body the characteristic lateral to medial gradient of binding site density is apparent by day 5, and development is more rapid in the lateral striatum. Patches of dense [3H]hemicholinium‐3 binding coincident with acetylcholinesterase are observed on day 5 in the caudal striatum. The various patterns of cholinergic terminal development suggest that factors regulating cholinergic development are regional and complex. © 1992 Wiley‐Liss, Inc.
Distribution of the mRNA for a metabotropic glutamate receptor (mGluR1) in the central nervous system: An in situ hybridization study in adult and developing rat
Authors: Shigemoto Ryuichi , Nakanishi Shigetada , Mizuno Noboru
Published: January 2005

Distribution of the mRNA for a metabotropic glutamate receptor (mGluR1), which is linked to phosphoinositide (PI) hydrolysis, was investigated in adult and developing rat central nervous system (CNS) by in situ hybridization. Transcripts of mGluR1 were specifically localized to neurons and widely distributed throughout the adult rat brain. Most intensely labeled neurons were Purkinje cells of the cerebellum, mitral and tufted cells of the olfactory bulb, and neurons in the hippocampus, lateral septum, thalamus, globus pallidus, entopeduncular nucleus, ventral pallidum, magnocellular preoptic nucleus, substantia nigra, and dorsal cochlear nucleus. Moderately labeled neurons were seen in high density in the dentate gyrus, striatum, islands of Calleja, superficial layers of the retrosplenial, cingulate and entorhinal cortices, mammillary nuclei, red nucleus, and superior colliculus. In the developing rat brain, the level of mGluR1 expression gradually increased during early postnatal days in accordance with the maturation of neuronal elements.

These results show prominent expression of mGluR1 in the major targets of putative glutamatergic pathways and unique distribution pattern of mGluR1 distinct from those reported for ionotropic subtypes of glutamate receptors, suggesting specific roles of mGluR1 in the glutamatergic system. © 1992 Wiley‐Liss, Inc.
Innervation of the amphibian and basilar papillae in the leopard frog: Reconstructions of single labeled fibers
Authors: Simmons D. D. , Bertolotto C. , Narins P. M.
Published: January 2005

Amphibians have two auditory organs specialized for reception of airborne sounds: the amphibian papilla and the basilar papilla. In this report we examine the morphology of the ganglion cells and the afferent innervation of the sensory epithelium in both auditory organs of the leopard frog, Rana pipiens pipiens. Extracellular injections of either biocytin or horseradish peroxidase (HRP) were made into the VIII nerve; they labeled ganglion cells, their axons, and their terminal fibers within the papillae. Ganglion cells that projected to either the amphibian papilla or basilar papilla had cell bodies that were morphologically distinct from other labeled cells. In the amphibian papilla thick fibers terminated in the rostral portion and thin fibers terminated in the caudal portion. Labeled fibers in the rostral portion traveled short distances before making contacts with up to nine hair cells whereas labeled fibers in the caudal portion traveled longer distances and contacted no more than five hair cells. In the basilar papilla labeled fibers were thick (around 4 μm) and terminated on as many as nine hair cells. Consistent with studies from the bullfrog, Rana catesbeiana, our results suggest that the amphibian papilla of R. pipiens pipiens has a convergent innervation (i.e., multiple hair cells provide input to a single ganglion cell) and is topographically organized. However, in contrast to reports in other ranid species, a highly convergent innervation like that found in the amphibian papilla is also found in the basilar papilla. © 1992 Wiley‐Liss, Inc.
Calcitonin gene‐related peptide in afferents to the cat's cerebellar cortex: Distribution and origin
Authors: Bishop Georgia A.
Published: January 2005

In the present study, the distribution and origin of calcitonin gene‐related peptide (CGRP) were analyzed in the cat's cerebellum. Following incubation in an antibody generated against rat CGRP and processing with the peroxidase anti‐peroxidase (PAP) technique, CGRP immunoreactivity (IR) is found in profiles that have morphological characteristics of both simple and complex mossy fibers. However, all mossy fibers are not CGRP‐positive. Further, CGRP‐IR mossy fibers have a heterogeneous distribution in the cerebellum. In the vermis, the majority of immunoreactive profiles are in lobules VII, VIII, and the dorsal folia of IX. In anterior vermal lobules, only scattered terminals, located primarily at the apex and along the shoulder of the folia, are present. Laterally, CGRP‐IR mossy fibers are located in the paramedian lobule, paraflocculus, and crus II. No CGRP fibers or varicosities are observed in any of the cerebellar nuclei. However, CGRP‐positive cell bodies are scattered throughout the nuclear neuropil. A double label technique revealed that CGRP‐IR mossy fibers arise from neurons located in the lateral reticular nucleus, external cuneate nucleus, inferior vestibular nucleus, and basilar pons. The present findings, taken together with previous data, indicate that cerebellar afferents are chemically heterogeneous. The findings of the present study suggest that precerebellar nuclei that give rise to the mossy fibers that contain CGRP have the potential for playing a complex role in modulating circuitry in the cerebellar cortex of the cat. © 1992 Wiley‐Liss, Inc.
Dynamic changes in the density of radial glial fibers of the developing murine cerebral wall: A quantitative immunohistological analysis
Authors: Gadisseux J. F. , Evrard Ph. , Misson J. P. , Caviness V. S.
Published: January 2005

The density of radial glial fibers in the developing murine cerebral wall decreases dramatically during the terminal week of gestation. The present analysis characterizes these variations of fiber density quantitatively. Radial glial fibers were stained with monoclonal antibody RC2. Fibers were counted in a standard area of 2,000 μm2, passing orthogonally to the fiber long axis.

At E14, fiber density is maximum and relatively uniform throughout the full width of the cerebral wall. Subsequently, the overall glial fiber density decreases and fiber density gradients emerge in the transmural span of fibers. These, radial fiber density gradients are marked by sharp declines at the level of the ventricular‐subventricular zone and in the zone of transition between intermediate zone (IZ) and cortical plate. In the interval E14‐P0, the decrease in densities of fibers crossing the IZ is commensurate with the predicted diluting effects of tissue expansion with growth. By contrast, the decrease in fiber densities in ascent across the cortical plate beyond E14 through E17 exceeds that predicted by growth. The observations suggest that a substantial population of radial glial fibers do not span the full ventricular zone to the cerebral surface. A major contingent appears to extend only as far as the external sagittal stratum/ subplate through E16.

Subsequently, at a time when supragranular cortical layers are being assembled, the full set of fibers appears to extend more uniformly through the cortical strata. The late surge of fibers would be appropriate to the intercalation of groupings of neurons of the supragranular layers. © 1992 Wiley‐Liss, Inc.
Time course of dorsal root axon regeneration into transplants of fetal spinal cord: I. A light microscopic study
Authors: Itoh Yasunobu , Sugawara Taku , Kowada Masayoshi , Tessler Alan
Published: January 2005

Cut dorsal root axons regenerate into intraspinal transplants of fetal spinal cord and establish synaptic connections there. The aims of the present study were to describe the progression of dorsal root growth within the transplants and the maturation of transplant morphology and to determine whether the regenerated dorsal root axons persist within the transplants or eventually withdraw.

Embryonic (E) day 14 spinal cord was grafted into the lumbar enlargement of adult Sprague‐Dawley rats, and the L4 or L5 dorsal root was cut and juxtaposed to the transplants. The morphology of the transplants was examined from 1 day to over 1 year after surgery, and the regenerated dorsal roots were labeled with immunohistochemical methods to study the subset that contains calcitonin gene‐related peptide (CGRP).

Embryonic spinal cord transplants survived and grew within the host spinal cord in over 90% of the animals. Transplant volume increased and the morphology of the transplants matured over the first 12 weeks and then did not change for 48–60 weeks. During the first week the transplants were composed of dissociated neurons, glia, and hematogenous cells with considerable extracellular space between them. Subsequently, the grafted neurons became densely aggregated, and non‐neuronal elements such as inflammatory cells and myelin debris disappeared. CGRP‐immunoreactive dorsal roots began to regenerate into the transplants within 24 hours, formed dense bundles by 4 days, and were still present at 60 weeks, the longest survival period examined. Myelination of axons within transplants began at 2 weeks. Quantitative analysis showed that the area of the transplants occupied by CGRP‐labeled axons and the distribution area of the labeled axons within the transplants increased until 12 weeks and persisted unchanged for over 48 weeks.

These results indicate that regenerated dorsal root axons are permanently maintained within transplants of embryonic spinal cord and suggest that the transplants can contribute to the permanent restoration of damaged intraspinal neural circuits. © 1992 Wiley‐Liss, Inc.
The auditory cortex of the mouse: Connections of the ultrasonic field
Authors: Hofstetter Kurt M. , Ehret G.
Published: January 2005

The cortical and subcortical connections of the ultrasonic field (UF) of the auditory cortex of the house mouse (Mus musculus) were studied by using retrograde and anterograde transport of horseradish peroxidase (HRP). Small amounts of HRP were locally injected into the electrophysiologically defined UF. Superficial (layer I–IV) and deep (layer IV–VI) injections were prepared.

Superficial injections led to labelling of both cells (retrograde) and terminals (anterograde) in areas of the ipsilateral primary and secondary auditory cortex and in its dorsoposterior field, in an ipsilateral dorsal association area (patches of label), probably in ipsilateral secondary somatosensory cortex, in the contralateral homotopic UF, and in the ipsilateral medial geniculate body (MGBv, MGBd, and MGBm) and caudal posterior nucleus complex.

Deep injections showed the same connectivities as superficial ones and, in addition, terminals in the very caudal caudatoputamen, in the nucleus limitans and the nucleus reticularis of the thalamus, in the rostral pole, the dorsomedial, and lateral nucleus of the inferior colliculus, in the stratum griseum intermediale of the superior colliculus, and in a pontine nucleus ventromedial of the lateral lemniscus. All these projections occurred only ipsilaterally.

The majority of connections, except those with the nucleus limitans, superior colliculus and pontine nucleus, suggest that UF is part of the primary anditory cortex (AI) and/or of the anterior anditory field (AAF) of the auditory cortex. Since UF has no regular tonotopy, this has important implications for the functional role that AI/AAF can have in communication‐sound analysis. © 1992 Wiley‐Liss, Inc.
Quantitative analysis of bulbospinal projections from the rostral ventrolateral medulla: Contribution of C1‐adrenergic and nonadrenergic neurons
Authors: Jeske Iwona , McKenna Kevin E.
Published: January 2005

The contribution of C1‐adrenergic and nonadrenergic neurons to the spinal projection from the rostral ventrolateral medulla (RVLM) and their relative innervation density throughout thoracic spinal segments were examined by combining the Fluorogold (FG) retrograde tracing technique with immunofluorescent labeling for the epinephrine‐synthesis enzyme phenylethanolamine N‐methyltransferase (PNMT). The results indicate that the RVLM‐spinal projection is comprised of both PNMT‐positive and PNMT‐negative neurons located in the subretrofacial area of the RVLM, approximately 1 to 1.7 mm rostral to obex. The bulbospinal projection from the RVLM is predominantly ipsilateral, and bulbospinal neurons do not appear to be organized within the RVLM in a manner indicating their segmental termination site. Eighty‐one percent (4%, n = 2) of the PNMT‐positive cells in the ipsilateral subretrofacial RVLM were retrogradely labeled after unilateral FG injections into multiple thoracic levels of the intermediolateral cell column (IML). Following, single level FG injections, the number of retrogradely labeled PNMT‐positive neurons in the subretrofacial RVLM decreased with injections in more caudal thoracic segments, indicating a heavier innervation of the upper thoracic IML by C1 neurons. PNMT‐negative neurons were the main component of the RVLM‐spinal population with 63 · 8% (n = 7) of the non‐PNMT‐containing neurons within the ipsilateral subretrofacial RVLM innervating all thoracic levels of the IML. The results indicate that both C1‐adrenergic and nonadrenergic neurons in the RVLM make a substantial contribution to the innervation of the IML.
The human transient subpial granular layer: An optical, immunohistochemical, and ultrastructural analysis
Authors: Gadisseux Jean‐François , Goffinet André M. , Lyon Gilles , Evrard Philippe
Published: January 2005

The cytological features, origin, migration, and fate of the subpial granular layer cells of the human embryonic cerebral cortex are studied with light and electron microscopy, Golgi impregnations, and immunocytochemical staining with the microtubule associated protein 2 and glial fibrillary acidic protein antibodies.

Subpial granular layer (SGL) cells form a distinct neuronal population in the molecular layer, characterized by a small dark nucleus with abundant chomatin clumps and prominent nucleoli, and a lightly stained cytoplasm containing few organelles. Somata and processes of SGL cells are intensively stained with microtubule‐associated protein 2 antibody but do not express glial fibrillary acidic protein antibody.

These cells apparently originate from the olfactory germinative zone. They follow two major strands from the olfactory subventricular zone to the subpial region. Subsequently, they migrate tangentially at the subpial level to all cortical regions, as is observed on Golgi and ultrastructural preparations.

They constitute a transient population that penetrates the deep molecular layer and subsequently disappear from it. Several cytological features of these cells suggest an inward migration with growth of a radial process toward the cortical plate and subsequent nuclear translocation. The fate and the role of this new phylogenetic neuronal population has yet to be determined although the abundance of degenerating SGL cells in the deep molecular layer suggests at least partial degeneration.
The afferent and efferent connections of the nucleus submedius in the rat
Authors: Yoshida Atsushi , Dostrovsky Jonathan O. , Chiang Chen Yu
Published: January 2005

The afferent and efferent connections of the nucleus submedius (Sm) in the medial thalamus of the rat were examined. Injections of wheat‐germ agglutinin conjugated horseradish peroxidase (WGA‐HRP) into the Sm resulted in dense terminal labeling in the middle layers of the ipsilateral ventrolateral orbital cortex (VLO). Less dense labeling was also observed in the superficial and deep layers of VLO and in the medial part of the lateral orbital cortex (LO) and in the contralateral VLO. Retrogradely labeled neurons were observed primarily in the deep layers of VLO and the dorsal peduncular cortex (DP). Labeled neurons were also observed bilaterally, in the nucleus of the horizontal limb of the diagonal band, the lateral hypothalamus, the thalamic reticular nucleus (Rt), medial parabrachial nucleus (MPB), and the laterodorsal tegmental nucleus (LDT). Many labeled neurons were also observed in the trigeminal brainstem complex. Injections of Fluoro‐Gold (FG) into Sm resulted in a very similar distribution of retrogradely labeled neurons.

Injections of WGA‐HRP and FG in the orbital cortex confirmed the ipsilateral Sm projection to VLO and suggested that the middle and deep layers of VLO receive a specific ipsilateral projection from the dorsal Sm and that the superficial layers receive a projection primarily from the ventral Sm. Injections of WGA‐HRP into the lateral hypothalamus, LDT, and MPB confirmed the retrograde labeling findings; the lateral hypothalamus was found to send a projection to the medial Sm, the LDT region to the ventromedial Sm and the MPB to the medial and dorsal Sm.

These findings confirm and extend the results of previous studies in cat and rat indicating that Sm has a major and specific reciprocal connection with VLO. This finding, in conjunction with previous studies showing direct spinal and trigeminal inputs and the existence of nociceptive neurons in Sm and VLO, provides further support for a role of Sm in nociception.
Topographic organization of cortical and subcortical projections to posterior cingulate cortex in the cat: Evidence for somatic, ocular, and complex subregions
Authors: Olson C. R. , Musil S. Y.
Published: January 2005

The posterior cingulate area (CGp) of the cat consists of cortex on the exposed cingulate gyrus and in the adjacent ventral bank of the splenial sulcus. We have placed deposits of distinguishable fluorescent tracers at multiple restricted sites in CGp and have analyzed the distribution throughout the forebrain of neurons labeled by retrograde transport.

Cortical projections to CGp arise (in approximately descending order of strength) from anterior cingulate cortex; prefrontal cortex and premotor areas including the frontal eye fields; visual areas including especially areas 7 and 20b; parahippocampal areas; insular cortex; somesthetic areas; and auditory areas. Corticocortical pathways are organized topographically with respect to the posterior‐anterior axis in CGp. Projections from prefrontal cortex and other areas with complex (as opposed to sensory, motor, or limbic) functions are concentrated posteriorly; projections from visual and oculomotor areas are concentrated at an intermediate level; and projections from areas with somesthetic and somatomotor functions are concentrated anteriorly.

Thalamic projections to CGp arise from the anterior nuclei (AD, AV, and AM), from restricted portions of the ventral complex (VAd, VAm, and VMP), from discrete sectors of the lateral complex (LD, LPs, and LPm), from the rostral crescent of intralaminar nuclei (CM, PC, and CL), and from the reuniens nucleus. Projections from AM, VAd, LD, and LPs are spatially ordered in the sense that more ventral thalamic neurons project to more anterior cortical sites. Projections from AV and AD are stronger at more posterior cortical sites but do not show other signs of topographic ordering. Projections from LPm, CM, PC, CL, and RE are diffuse.

We conclude (1) that cortical afferents of CGp derïve predominantly from neocortical areas including those with well established sensory and motor functions; (2) that limbic projections to CGp originate primarily in structures, including the hippocampus, which are associated with memory, as opposed to structures, including the amygdala, which are associated with emotional and instinctual behavior; and (3) that CGp contains subregions in which complex, ocular, or somatic afferents predominate. © 1992 Wiley‐Liss, Inc.
Expression of connexins in the developing olfactory system of the mouse
Authors: Miragall Fernando , Hwang Theng‐Khing , Traub Otto , Hertzberg Elliot L. , Dermietzel Rolf
Published: January 2005

To gain insight into the function of gap junctions' connexin43, connexin32 and connexin26 in a neural structure that retains neuronal turnover capacities throughout adulthood, the expression of these molecules has been investigated in the developing and adult olfactory system by immunocytochemical and biochemical methods.

Connexin43 was detectable from the olfactory placode stage. During early embryonic development, the levels of connexin43 expression remained low. An increase in the expression of this connexin occurred perinatally. Expression of connexin43 became very high during the postnatal stages and adulthood. Electron microscopy (EM) immunocytochemistry of the olfactory system showed connexin43 expression in non‐neuronal cells. Strong regional differences in the expression of connexin43 in the olfactory epithelium were observed. No apparent relationship between connexin43 expression and turnover activity of olfactory neurons was detected. Western blots of olfactory tissues revealed the presence of three different isoforms of connexin43.

Connexin32 was detected in the olfactory bulb at late postnatal stages including adulthood. Connexin32 was observed on some cells tentatively identified as oligodendrocytes.

Connexin26 was localized onto leptomeninges. Some immunofluorescence was also obtained in the periglomerular region and in the subependymal layer of the bulb. Northern blot analysis revealed the presence of mRNA of connexin32 and connexin26 in the adult olfactory system. Our results substantiate the cell specific expression of these three types of connexins and they document the primacy of connexin43 in olfactory tissues. Moreover, our findings indicate that although expression of connexin43 in the olfactory system is developmentally regulated, it is not directly associated with the neuronal cell turnover of the olfactory epithelium. © 1992 Wiley‐Liss, Inc.
Nerve ring of the hypostome in Hydra. I. Its structure, development, and maintenance
Authors: Koizumi Osamu , Itazawa Motoko , Mizumoto Hiromi , Minobe Sumiko , Javois Lorette C. , Grimmelikhuijzen Cornelis J. P. , Bode Hans R.
Published: January 2005

The anatomy and developmental dynamics of the nerve ring in the hypostome of Hydra oligatis were examined immunocytochemically with an antiserum against a neuropeptide and with neuron‐specifie monoclonal antibodies. The nerve ring is unique in the mesh‐like nerve net of hydra. It is a distinct neuronal complex consisting of a thick nerve bundle running circumferentially at the border between the hypostome and tentacle zone. Immunostaining showed that the nerve ring was heterogeneous and contained at least four different subsets of neurons. During head regeneration and budding, the nerve ring appeared only after the nerve net of ganglion and sensory cells had formed. Every epithelial cell is continuously displaced with neurons toward either head or foot in an adult hydra. However, the ectoderm in the immediate vicinity of, and including, the nerve ring constitutes a stationary zone that is not displaced. Tissue immediately above this zone is displaced toward the tip of the hypostome, while tissue below is displaced along the tentacles. Correspondingly, the production of new neurons in the ring as measured by their differentation kinetics is much slower than in surrounding areas. Thus, the nerve ring is static and stable in contrast to the dynamic features of the nerve net of hydra. © 1992 Wiley‐Liss, Inc.
Neuronal and synaptic composition of the mediodorsal thalamic nucleus in the rat: A light and electron microscopic golgi study
Authors: Kuroda Masaru , López‐Mascaraque Laura , Price Joseph L.
Published: January 2005

The distribution and dendritic domain of neurons in each segment of the mediodorsal thalamic nucleus (MD) have been studied in the rat with the Golgi technique. In addition, a combined Golgi method‐electron microscopic (Golgi‐EM) study was undertaken to determine the distribution of morphologically distinct synapse types along the dendrites of individual identified neurons in MD.

All the subdivisions or “segments” of MD (medial, central, lateral) contained both stellate and fusiform cells. The dendritic domain of both types of cells was predominantly restricted to the same segment of MD that contained the cell body of the neuron. Typical stellate neurons were found near the center of each segment, with radiating dendrites that extended to but not across the boundaries of the segment. Fusiform cells were usually located close to the segmental or nuclear boundaries and tended to have dendrites oriented parallel to those borders; again, the dendrites tended not to extend across borders between segments or at the outer edge of MD. In the medial segment of MD many fusiform cells had especially bipolar dendritic configurations, generally with a dorsoventral orientation. Because no small neurons were identified that might correspond to thalamic interneurons, all the impregnated cells in MD are presumed to be thalamocortical projection neurons. These results indicate that cells and their major dendrites are confined to a single segment of MD, with little dendritic overlap across segmental or nuclear borders. The segments of MD may therefore be considered to be relatively independent subnuclei.

The distribution of the four types of synapses previously identified in MD (Kuroda and Price, J. Comp. Neurol., 303:513–533, 1991) was determined along several identified dendrites studied with the Golgi‐EM method. Primary dendrites were contacted mostly by large axon terminals, including both large, round vesicle (LR) terminals and large, pleomorphic vesicle (LP) terminals, as well as a few small to medium sized terminals with pleomorphic vesicles (SMP). No small terminals with round vesicles (SR terminals) were observed to make synapses with primary dendrites. Secondary and tertiary dendrites received synapses from all types of axon terminals. Higher order dendrites were contacted predominantly by SR boutons, but they also carried some LR and SMP terminals. In addition, SMP boutons were often found to form symmetric contacts with cell somata. © 1992 Wiley‐Liss, Inc.
Direct observations of synapses between L‐glutamate‐immunoreactive boutons and identified spinocervical tract neurones in the spinal cord of the cat
Authors: Maxwell D. J. , Christie W. M. , Brown A. G. , Ottersen O. P. , Storm‐Mathisen J.
Published: January 2005

Four spinocervical tract cells in lumbosacral spinal cords of adult cats were physiologically characterized and intracellularly labelled with horseradish peroxidase. The neurones were examined with a light microscope and reconstructed. Selected regions were chosen for ultrastructural analysis. Thin sections were treated to reveal the presence of L‐glutamate by using the postembedding immunogold method. Two antisera, which specifically recognise the presence of fixed glutamate in tissue, were used in the study. Somata, proximal, and distal dendrites of all four neurones received synaptic contacts from boutons which displayed an obvious immunogold reaction. These boutons formed between 35% and 48% of all synaptic contacts onto spinocervical tract cells. Glutamate‐enriched boutons were associated with gold particle densities which were 2–3 times greater than the average densities associated with the surrounding neuropil. Their profiles had a mean diameter of 1.68 μm, contained round agranular synaptic vesicles, and formed asymmetrical synaptic junctions. However, not all boutons displaying these characteristics were enriched with glutamate.

Immunogold studies of alternate thin sections, which were incubated with glutamate or GABA antiserum, demonstrated that synaptic boutons on spinocervical tract cells were either enriched with GABA or with glutamate and formed two separate populations which had distinct morphological characteristics. GABA‐containing boutons contained irregularly shaped agranular vesicles and formed symmetrical synaptic junctions, whereas glutamate‐enriched boutons corresponded to those described above. A further population of boutons, containing highly flattened vesicles, was not immunoreactive for GABA or glutamate.

The evidence supports the idea that much of the excitatory transmission into the SCT is mediated by L‐glutamate. © 1992 Wiley‐Liss, Inc.
Direct and indirect “cortico”‐rubral and rubro‐cerebellar cortical projections in the pigeon
Authors: Wild J. Martin
Published: January 2005

In birds the red nucleus is the most rostral cell group in the brain having projections to all levels of the spinal cord (Cabot et al., Prog. Brain Res., 57:79–108, 1982), but its sources of afferents are incompletely known. In order to determine these, a series retrograde and anterograde tracing experiments was carried out, largely with cholera toxin B‐chain conjugated to horseradish peroxidase. The results show that a sparse and diffuse projection to the red nucleus arises from deep regions of the hyperstriatum accessorium (HA) of the anterior Wulst, and that a much more dense projection arises from the caudal part of the nucleus principalis precommissuralis and the medial part of the medial spiriform nucleus (SpMm). These last two sources were themselves shown to receive a substantial projection from HA of the anterior Wulst.

The red nucleus was also shown to project upon the cerebellar cortex of lobule VI, and SpM upon the cerebellar cortex of lobules VI through IX (Karten and Finger, Brain Res., 102:335–338, 1976; Clarke, J. Comp. Neurol., 174:535–552, 1977). Double retrograde labelling experiments with fluorescein and rhodamine labelled latex microspheres injected into the cerebellar cortex and spinal cord showed that the rubrocerebellar cortical neurons are a different population from, although intermixed with, the rubrospinal neurons. © 1992 Wiley‐Liss, Inc.
A quantitative dendritic analysis of wernicke's area in humans. II. Gender, hemispheric, and environmental factors
Authors: Jacobs Bob , Schall Matthew , Scheibel Arnold B.
Published: January 2005

This quantitative Golgi study extends our investigation of relationships between cortical dendrite systems in humans and higher cognitive functions. Here we examine the relationship between the basilar dendrites of supragranular pyramidal cells in Wernicke's area and selected intrinsic (i.e., gender and hemisphere) and extrinsic (i.e., education and personal history) variables. Tissue was obtained from 20 neurologically normal right‐handers: 10 males (Mage = 52.2) and 10 females (Mage = 47.8). Several independent variables were investigated: GENDER (male, female), HEMISPHERE (left, right), and EDUCATION (less than high school, high school, and university). These were evaluated according to Total Dendritic Length, Mean Dendritic Length, and Dendritic Segment Count. A distinction was made between proximal (1st, 2nd, and 3rd order) and ontogenetically later developing distal (4th order and above) branches.

There was significant interindividual variation in dendritic measurements, which roughly reflected individuals' personal backgrounds. Females exhibited slightly greater dendritic values and variability than males across the age range examined. On the whole, the left hemisphere maintained a slight advantage over the right hemisphere for all dendritic measures when all subjects were pooled, but these differences were not in a consistent direction across individuals. Education had a consistent and substantial effect such that dendritic measures increased as educational levels increased. Dendritic differences between independent variable levels were most clearly illustrated in the total dendritic length of 3rd and 4th order branches. Distal dendritic branches appeared to exhibit greater epigenetic flexibility than proximal dendrites. The present findings concur with environmental enrichment research results in animals and suggest that dendritic systems in humans function as a sensitive indicator of an individual's (a)vocational activities. © 1993 Wiley‐Liss, Inc.
Retinal projection to the olfactory tubercle and basal telencephalon in primates
Authors: Mick Gérard , Cooper Howard , Magnin Michel
Published: January 2005

The retinal projection to the basal telencephalon was studied in eight species of primates from the suborders Strepsirhini and Haplorhini, including one anthropoid primate, the gibbon. Animals received an intraocular injection of tritiated amino acids and the distribution of retinal fibers and terminals was demonstrated by autoradiographic techniques in horizontal and coronal sections. In all species a discrete group of labeled retinal fibers is observed to branch off from the dorsolateral aspect of the optic tract at the level of the suprachiasmatic nucleus. These fibers, destined to the basal telencephalon, are topographically distinct from the retinal fibers which innervate the suprachiasmatic nucleus and medial hypothalamic regions. The fibers of the retinotelencephalic tract course dorsally above the supraoptic nucleus through the lateral hypothalamic area and then proceed further rostrally and laterally below the diagonal band of Broca towards the olfactory tubercle. Within the olfactory tubercle, terminal distribution of label is observed in the mediocaudal region along the granular cell layer II. In the macaque this cellular layer shows a characteristic thickening in the region of retinal terminals which is evident in both coronal and horizontal section. In some species this labeled region is seen within the superficial bulge of the tubercle on the ventral aspect of basal telencephalon. In all Primates the retinal projection to olfactory tubercle is bilateral. In prosimians label is predominantly contralateral to the injected eye, in New World monkeys label is equally distributed on both sides of the brain and in Old World monkeys label is mainly found ipsilaterally. Retinal fibers were also seen in the periamygdaloid region but never extended as far as piriform cortex. These results, in addition to previous studies in other mammalian orders, confirm that the basal telencephalon, and in particular the olfactory tubercle, constitutes a region of visual and olfactory convergence. This sensory integration may be related to photic and chemosensory modulation of reproductive physiology and behavior. © 1993 Wiley‐Liss, Inc.
Synapsin I Gene expression in the adult rat brain with comparative analysis of mRNA and protein in the hippocampus
Authors: Melloni Richard H. , Hemmendinger Lisa M. , Hamos James E. , Degennaro Louis J.
Published: January 2005

Synapsin I is the best characterized member of a family of neuron‐specific phosphoproteins thought to be involved in the regulation of neurotransmitter release. In this report, we present the first extensive in situ hybridization study detailing the regional and cellular distribution of synapsin I mRNA in the adult rat brain. Both the regional distribution and relative levels of synapsin I mRNA established by in situ hybridization were confirmed by RNA blot analysis. Our data demonstrate the widespread yet regionally variable expression of synapsin I mRNA throughout the adult rat brain. The greatest abundance of synapsin I mRNA was found in the pyramidal neurons of the CA3 and CA4 fields of the hippocampus, and in the mitral and internal granular cell layers of the olfactory bulb. Other areas abundant in synapsin I mRNA were the layer II neurons of the piriform cortex and layer II and V neurons of the entorhinal cortex, the granule cell neurons of the dentate gyrus, the pyramidal neurons of hippocampal fields CA1 and CA2, and the cells of the parasubiculum. In general, the pattern of expression of synapsin I mRNA paralleled those encoding other synaptic terminal‐specific proteins, such as synaptophysin, VAMP‐2, and SNAP‐25, with noteworthy exceptions. To determine specificall how synapsin I mRNA levels are related to levels of synapsin I protein, we examined in detail the local distribution patterns of both synapsin I mRNA and protein in the rat hippocampus. These data revealed differential levels of expression of synapsin I mRNA and protein within defined synaptic circuits of the rat hippocampus. © 1993 Wiley‐Liss, Inc.
Two visual systems in one brain: Neuropils serving the principal eyes of the spider Cupiennius salei
Authors: Strausfeld Nicholas J. , Weltzien Peter , Barth Friedrich G.
Published: January 2005

Principal (anterior median) eyes of the wandering spider Cupiennius are served by three successive neuropils, the organization of which is distinct from those serving secondary eyes. Photoreceptors terminate in the first optic neuropil amongst second order neurons with overlapping dendritic fields. Second order neurons terminate at various depths in anterior median eye medulla where they are visited by bush‐like dendritic trees of third order projection neurons. These supply tracts which extend into the “central body.” This crescent‐shaped neuropil lies midsagittally in the rear of the brain near its dorsal surface. It is organized into columns and it supplies both columnar and tangential efferents to other brain centers. The supply to and organization of the “central body” neuropil is reminiscent of retinotopic neuropils supplying the lobula of insects. Channels to the “central body” comprise one of two concurrent visual pathways, the other provided by the secondary eyes supplying the “mushroom body.” We suggest that principal eye pathways may be involved in form and texture perception whereas secondary eyes detect motion, as is known for jumping spiders. Our data do not support Hanström's classical view that the “central body” is specifically associated with web‐building, nor that it is homologous to its namesake in insect brains. © 1993 Wiley‐Liss, Inc.
Physiological properties and morphological characteristics of cutaneous and mucosal mechanical nociceptive neurons with A‐δ peripheral axons in the trigeminal ganglia of crotaline snakes
Authors: Liang Yun‐Fei , Terashima Shin‐Ichi
Published: January 2005

Primary A‐δ nociceptive neurons in the trigeminal ganglia of immobilized crotaline snakes were examined by intrasomal recording and injection of horseradish peroxidase in vivo. Thirty‐four neurons supplying the oral mucosa or facial skin were identified as A‐δ nociceptive neurons which responded exclusively to noxious mechanical stimuli and had a peripheral conduction velocity ranging from 2.6 to 15.4 m/s. These neurons were subdivided into a fast‐conducting type (FC‐type) and a slowly conducting type (SC‐type). Neurons of both types had a receptive field limited to a single spot which responded to pin prick stimulus with a threshold of more than 5 g. The FC‐type neurons had a narrow spike followed by a shorter after‐hyperpolarization. In contrast, SC‐type neurons exhibited a broad spike with a hump on the falling phase and a longer after‐hyperpolarization. The diameters of the stem, central and peripheral axons of the FC‐type neurons were significantly thicker than those of the SC‐type neurons, but there was no statistical difference in the soma size of the two types. Central axons of both types of neurons were thinner than their stem and peripheral axons. Dichotomizing fibers of peripheral axons were observed within the ganglion on 3 neurons. Central axons of the FC‐type neurons terminated ipsilaterally in the nucleus principalis, the subnucleus oralis, interpolaris and caudalis and the interstitial nucleus, whereas those of the SC‐type neurons generally projected only to the caudal half of the subnucleus interpolaris, subnucleus caudalis and interstitial nucleus ipsilaterally. The present data showed for the first time the physiological and morphological heterogeneity of the primary trigeminal A‐δ nociceptive neurons and revealed that the trigeminal nucleus principalis and all the subdivisions of the trigeminal descending nucleus are involved in nociception as relay nuclei, but the subnucleus caudalis and the caudal half subnucleus interpolaris are the essential relay sites of the primary nociceptive afferents supplying the oral mucosa and facial skin. The interstitial nucleus also appears to play an important role in orofacial nociception. © 1993 Wiley‐Liss, Inc.
A nonrandom interneuronal pattern in the developing frog spinal cord
Authors: Heathcote R. David , Chen Aileen
Published: January 2005

In the developing spinal cord of the frog, Xenopus laevis, a population of interneurons assumes a pattern that represents a previously undescribed level of organization. Glyoxylic acid treatment and immunocytochemistry show that the neurons contain catecholamines and their synthetic enzyme, tyrosine hydroxylase. Cells are located within the ependymal layer of the floor plate region of the larval spinal cord. The cells have several processes including a long one that projects toward the brain without fasciculating with other labeled processes. In addition, the cytoplasm of the catecholaminergic cells extends into the central canal, showing that they are a population of cerebrospinal fluid‐contacting neurons.

The spatial domain of catecholaminergic neurons starts abruptly at the boundary between the hindbrain and spinal cord and continues to the tip of the tail. The neurons occupy two longitudinal columns within the sheet of floor plate cells, which includes cells that do not exhibit the catecholaminergic phenotype. Unlabeled cells are intercalated between catecholaminergic cells in each column, giving the labeled cells the appearance of being spaced along the length of the spinal cord. This general arrangement is evident at the time of hatching. Spatial analysis showed that the position of cells along a column is not random. The nonrandom behavior is due to cells being excluded from the area immediately surrounding other catecholaminergic cells. Further analysis showed that the cellular pattern lacks segmental or other periodic repeats. Ultimately, the location of a cell within a column depends upon the position of its closest catecholaminergic neighbor. © 1993 Wiley‐Liss, Inc.
Principal neurons as local circuit neurons in the rat superior cervical ganglion: The synaptology of the neuronal processes revealed by intracellular injection of biocytin
Authors: Kawai Yoshinori , Tamai Yasuhiko , Senba Emiko
Published: January 2005

To analyze the local circuitry of the sympathetic ganglion, the synaptic relations of the neuronal processes of the principal neurons in the rat superior cervical ganglion were investigated by correlated light and electron microscopy combined with intracellular injection of biocytin. Intracellular iontophoresis of biocytin followed by avidin‐biotinylated horseradish peroxidase cytochemistry allowed complete visualization of the neuronal processes of the principal neurons. The stained principal neurons have a single process (axon), which leaves the ganglion, and several intraganglionic processes (dendrites), some of which show specific terminal arborizations. Some terminals of the dendritic collaterals formed pericellular plexuses or intercellular glomerular plexuses. Electron microscopically, the dendrites and their collaterals contain numerous small vesicles. Synaptic membrane specializations were observed between the stained dendritic collaterals and unlabeled neurites. These may be both preganglionic axon terminals and processes of principal neurons. The likely direction of neurotransmission often could not be determined because of the bidirectional synaptic structures. Our findings show that the dendritic collaterals of principal neurons appear to make both post‐ and presynaptic contacts with both the principal neurons and the preganglionic axons. It is suggested that the principal neurons might participate in local circuits involving not only preganglionic axons but also neighboring principal neurons. © 1993 Wiley‐Liss, Inc.
OFF‐alpha and OFF‐beta ganglion cells in cat retina. I: Intracellular electrophysiology and HRP stains
Authors: Nelson Ralph , Kolb Helga , Freed Michael A.
Published: January 2005

Six OFF‐alpha ganglion cells and a single OFF‐beta ganglion cell were penetrated with intracellular microelectodes and marked with horseradish peroxidase (HRP) in a perfused cat eyecup. Gaussian center radii (Rc) ranging from 40 to 217 μm were measured for receptive fields mapped with slits, values in agreement with previous extracellular reports. ON and OFF response components revealed nearly identical Rc's and center locations. Although Gaussian diameters (2Rc) were about 80% of dendritic field diameters overall, in this sample dendritic and receptive fields were not well correlated. Spatial tuning of ganglion cells was evidenced in peaked amplitude‐vs.‐width functions, fit by difference‐of‐Guassians models. Such plots yielded Rc values about 40% less than position‐vs amplitude plots. Rs values for surrounds ranged from 200 to 1,700 μm.

Rod and cone signals were investigated with flicker. Rod flicker signals in OFF‐alpha cells were larger and of shorter latency than in either horizontal or AII amacrine cells. Cone flicker signals were also short in latency, with an ON response time constant of 9 msec, and an OFF response time constant of 3 msec. The OFF‐alpha rod‐cone transition involved a latency increase of 20–30 msec.

The spontaneous and light‐evoked impulse rates of OFF‐alpha responses varied linearly with extrinsic current, but the amplitude of ON hyperpolarization was little affected. After injection of staining current, the OFF‐beta cell transiently depolarized at ON, suggestive of ON inhibition with reversed chloride gradient, a result not seen in OFF‐alpha responses.

Events (peaked, depolarizing voltage fluctuations) of high, low, and intermediate amplitudes were studied in OFF‐alpha responses. High amplitude events (impulses), were OFF‐correlated with the stimulus, and exhibited mean rise times (transit time from 25 to 75% of peak amplitude) from 255 to 392 μsec. Intermediate level events (presumed synaptic origin) were also OFF correlated and had longer rise times (325 μsec to 1.56 msec). Low level events (234–685 μsec) revealed either ON, ON/OFF, or no stimulus correlation. Published in 1993 Wiley‐Liss, Inc.