bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topographic spinocerebellar mossy fiber projections are maintained in the Lurcher mutant
Authors: Vogel Michael W. , Prittle Jennifer 
Published: January 2005

AbstractA variety of recent studies of cerebellar development have focused attention on the role of Purkinje cells as organizing elements for the topography of afferent fiber connectivity in the cerebellum. We have investigated the involvement of Purkinje and granule cells in the maintenance of topographic spinocerebellar mossy fiber projections by analyzing the distribution of spinocerebellar mossy fiber terminals in lurcher(+/Lc) mutant mice. Purkinje cells in the +/Lc mutant degenerate starting after the first week of postnatal development because of an intrinsic genetic defect. The loss of their Purkinje cell targets also results in the death of 90% of the granule cells. We examined the distribution of spinocerebellar mossy fiber terminals in the juvenile and adult +/Lc mutant to determine how the pattern of afferent projections is affected by the loss of Purkinje cells shortly after innervation of the cerebellum. Labeling of spinocerebellar mossy fiber terminals with WGA‐HRP in the P38 and adult +/Lc mutant showed that, despite the loss of almost all Purkinje cells and 90% of the granule cells, spinocerebellar mossy fiber project to the appropriate folia and segregate into relatively normal parasagittal bands. While we cannot rule out the possibility that Purkinje cells may be involved in the initial establishment of topographic maps, our results indicate that Purkinje cells are not necessary for the maintenance of the normal spinocerebellar mossy fiber topographic map. © 1994 Wiley‐Liss, Inc.
Serotoninergic innervation of nonprincipal cells in the cerebral cortex of the lizard Podarcis hispanica
Authors: Martínez‐Guijarro F. J. , Blasco‐Ibáñez J. M. , Freund T. F. 
Published: January 2005

AbstractThe mechanism of serotoninergic transmission in the neo‐ and archicortex of mammals kis complex, including both synaptic and nonsynaptic components, direct actions on principal cells, and indirect effects mediated by GABAergic interneurons. Here we studied the termination pattern and synaptic organization of the serotoninergic afferents in the cerebral cortex of the lizard, Podarcis hispanica, which is considered to correspond in part to the mammalian hippocampal formation, with the aim of unraveling basic, phylogenetically preserved rules in the connectivity of this pathway. We demonstrate that serotoninergic afferents, visualized by immunostaining for serotonin itself, establish multiple synaptic contacts with different subpopulations of nonprincipal cells containing parvalbumin, neuropeptide Y, and opioid peptides. The former two subpopulations contain GABA, whereas the opioid‐ immunoreactive neurons are most likely GABA‐negative cells. Evidence is provided at the electron microscopic level that serotonin‐immunoreactive varicosities establish conventional asymmetric synaptic contacts with their nonprincipal targets, but nonsynaptic varicosities also exist. We conclude that, similarly to mammals, a selective synaptic innervation of nonprincipal, possibly inhibitory, neurons is among the mechanisms of serotoninergic modulation of cerebral cortical activity in the lizard. © 1994 Wiley‐Liss, Inc.
Cellular localization and laminar distribution of NMDAR1 mRNA in the rat cerebral cortex
Authors: Conti Fiorenzo , Minelli Andrea , Molnar Marcherita , Brecha Nicholas C. 
Published: January 2005

AbstractN‐Methyl‐D‐aspartate (NMDA) receptors, which play a critical role in many cortical functions, are composed of a heteromeric assembly of different subunits: of these, the NMDA receptor subunit 1 (NMDAR1) is a constant component of, and thus an excellent marker for, NMDA receptors. In this study, we have investigated the cellular localization and laminar distribution of NMDAR1 mRNA in the cerebral cortex of adult rats by in situ hybridization histochemistry with a 35S‐labeled cRNA probe. Specificity and background levels were determined in adjacent sections incubated with a 35S‐labeled sense RNA. In sections incubated with the antisense RNA probe, specific hybridization signal was observed in a large number of cells. Some cells, however, did not appear to contain NMDAR1 mRNA. The vast majority of these unlabeled cells were small, suggesting that they are astrocytes or other small nonneuronal cells. Double‐labeling studies with in situ hybridization histochemistry and immunocytochemistry with antibodies to glial fibrillary acidic protein (GFAP) showed that about 95.7% of the GFAP‐positive cells did not express NMDAR1 mRNA, indicating that virtually all astrocytes do not contain this transcript.A semiquantitative evaluation of cortical neurons, defined as those cells larger than the GFAP‐positive astrocytes, revealed that about 80% were associated with silver grains. The number of silver grains associated with every neuron was determined from sections exposed for 15 days, the background level was subtracted, and all labeled neurons were grouped into five groups: A (≤10 grains), B (11–20 grains), C (21–30 grains), and E (>40 grains). The number of neurons belonging to each group was then evaluated according to their occurrence in each cortical layer. In layer I all labeled neurons were in group A, whereas in layers II–III and V–VI positive neurons were in groups A‐E. In layer IV most neurons were in groups A and B, whereas only a few were in group E.These observations indicate that (1) virtually all cortical cells containing NMDAR1 mRNA in adult rats are neurons; (2) about 80% of all cortical neurons express NMDAR1 mRNA;and (3) labeled neurons can be divided into several groups on the basis of NMDAR1 mRNA levels expressed, which presumably reflect the number of NMDA receptors. The existence of neurons with a different number of receptors may be a critical factor for determining the physiological effect of NMDA receptor activation. In addition, the differential laminar distribution of neurons with different intensities of hybridization signal suggests that NMDA receptors have a different influence at different stages of cortical processing. © 1994 Wiley‐Liss, Inc.
Topographical relations between ipsilateral cortical afferents and callosal neurons in the second somatic sensory area of cats
Authors: Barbaresi Paolo , Minelli Andrea , Manzoni Tullio 
Published: January 2005

AbstractExperiments were carried out on the second somatic sensory area (SII) of cats to study (1) the laminar distribution of axon terminals from the ipsilateral first somatic sensory cortex (SI); and (2) the topographical relations between their terminal field and the callosal neurons projecting to the contralateral homotopic cortex. To label simultaneously in SII both ipsilateral cortical afferents and callosal cells, cats were given iontophoretic injections of Phaseolus vulgaris‐leucoagglutinin (PHA‐L) in the forepaw zone of ipsilateral SI, and pressure injections of horseradish peroxidase (HRP) in the same zone of contralateral SII. The possibility that ipsilateral cortical axon terminals synape callosal neurons was investigated with the electron microscope by combining lesion‐induced degeneration with retrograde HRP labelling.Fibers and terminations immunolabelled with PHA‐L from ipsilateral SI were distributed in SII in a typical patchy pattern and were mostly concentrated in supragranular layers. Labelled fibers formed a very dense plexus in layer III and ramified densely also in layers I and II. Labelled axon terminals were both en passant and single‐stalked boutons. Counts of 8,303 PHA‐L‐labelled terminals of either type showed that 82.40% were in supragranular layers. The highest concentration was in layer III (43.99%), followed by layers II (30.22%) and I (8.09%). The remaining terminals were distributed among layers IV (6.96%), V (4.93%), and VI (5.68%). The same region of SII containing anterogradely labelled axons and terminals also contained numerous neurons retrogradely labelled with HRP from contralateral SII. Callosal projection neurons were pyramidal, dwelt mainly in layer III, and were distributed tangentially in periodic patches. Patches of anterograde and retrograde labelling either interdigitated or overlapped both areally and laminarly. In the zones of overlap, numerous PHA‐L‐labelled axon terminals were seen in close apposition to HRP‐labelled pyramidal cell dendrites. Combined HRP‐electron microscopic degeneration experiments showed that in SII axon terminals from ipsilateral SI form asymmetric synapses with HRP‐labelled dendrites and dendriticc spines pertaining to callosal projection neurons.These results are discussed in relation to the layering and function of the SI to SII projection, and to the evidence that SII neurons projecting to the homotopic area of the contralateral hemisphere have direct access to the sensory information transmitted from ipsilateral SI. © 1994 Wiley‐Liss, Inc.
Pedunculopontine nucleus in the squirrel monkey: Projections to the basal ganglia as revealed by anterograde tract‐tracing methods
Authors: Lavoie Brigitte , Parent André 
Published: January 2005

AbstractThe efferent projections of the pedunculopontine nucleus (PPN) to the ganglia have been studied in the squirrel monkey (Saimiri sciureus) with [3H]leucine andPhaseolus vulgaris‐leucoagglutinin (PHA‐L) as anterograde tracers. Following unilateral injections of [3H]leucine or PHA‐L in the central portion of the PPN, numerous autoradiographic linear profiles or PHA‐L‐labeled fibers ascend to the forebrain, both ipsilaterally and contralaterally. These fibers form a compact bundle that courses in the central portion of the mesopontine tegmentum. At rostral mesencephalic levels, theis bundle splits into ventromedial and dorsolateral fascicles that arborize in basal ganglia and thalamic nuclei, respectively. The substantia nigra and the subthalamic nucleus are by far the most densely innervated structures of the basal ganglia. In these two nuclei, labeled fibers arborize profusely ipsilaterally and less abundantly contralaterally. The labeled fibers in the substantia nigra are thin and varicose and arborize almost exclusively in the pars compacta, where they closely surround the soma and proximal dendrites of dopaminergic neurons. In the subthalamic nucleus labeled fibers are also thin and appear to contact more than one neuron along their course. Numerous labeled fibers also occur in the pallidal complex, where they arborize most profusely in the internal segment. Several thick, labeled fibers oriented dorsolaterally in the pallidal complex give rise to thinner fibers that closley surround the soma and proximal dendrites of pallidal neurons. Some labeled fibers are also scattered in the striatum. These fibers abound in the peripallidal and ventral portions of the putamen, are more sparsely distributed in the remaining portion of the putamen as well as in the caudate nucleus, and are virtually absent in the ventral striatum. These results reveal that the PPN gives rise to a massive and highly ordered innervation of the basal ganglia in the squirrel monkey. This nucleus may thus act as an important relay in the basal ganglia circuitry in primates. © 1994 Wiley‐Liss, Inc.
Intergeniculate leaflet: An anatomically and functionally distinct subdivision of the lateral geniculate complex
Authors: Moore Robert Y. , Card J. Patrick 
Published: January 2005

AbstractThe intergeniculate leaflet (IGL) in the rat is a distinctive subdivision of the lateral geniculate complex that participates in the regulation of circadian function through its projections to the circadian pacemaker, the suprachiasmatic nucleus (SCN) of the hypothalamus. The present investigation was undertaken to provide a precise definition of the IGL and a characterization of its neuronal organization including neuronal morphology, chemical phenotype, connections, and synaptic organization. The IGL extends the entire rostrocaudal lenght of the geniculate complex and contains a distinct population of small to medium neurons. In Golgi preparations, the neurons are multipolar with dendrites largely confined to the IGL. The neurons can be subdivided into three groups on the basis of neurotransmitter content and projections: (1) neurons that contain GABA and neuropeptide Y and project to the SCN; (2) neurons that contain GABA and enkephalin and project to the contralateral IGL; and (3) a small group of neurons that projects to the SCN but not characterized as yet by neurotransmitter content. The IGL receives dense, bilateral input from retinal ganglion cells and dense substance P input of unknown origin. A number of neurons in the anterior hypothalamic area and, particualrly, the retrochiasmatic area project to the IGL, and there are sparse projections from brainstem monoamine and cholinergic neurons. The synaptic organization of the IGL is complex with afferents terminating in glomerular complexes that include axoaxonic synapatic interactions. Virtually all IGL afferents synapse upon dendrites and spines, with the densest synaptic input occurring on the distal portions of the dendritic arbor. The organization of the IGL and its connections as revealed in this analysis is in accord with its role in the integration of visual input with other information to provide feedback regulation of the SCN integration of visual input with other information to provide feedback regulation of the SCN pacemaker. © 1994 Wiley‐Liss, Inc.
Light and electron microscopic immunocytochemical localization of AMPA‐selective glutamate receptors in the rat spinal cord
Authors: Tachibana Masayoshi , Wenthold Robert J. , Morioka Hiroyuki , Petralia Ronald S. 
Published: January 2005

Abstractα‐Amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA)‐type glutamate receptors are probably the most widespread excitatory neurotransmitter receptors of the central nervous system, and they play a role in most normal and pathological neural activities. However, previous detailed studies of AMPA subunit distribution have been limited mainly to the brain. Thus, a comprehensive study of AMPA receptor subunit distribution was carried out on sections of rat spinal cord and dorsal root ganglia, which were immunolabeled with antibodies made against peptides corresponding to C‐terminal portions of the AMPA receptor subunits: GluR1, GluR2/3, and GluR4. In the spinal cord. Labeling was most prominent in the superficial dorsal horn, motoneurons, and nuclei containing preganglionic autonomic neurons. Immunostaining also was observed in neurons in other regions including those known to contain Renshaw cells and Ia Inhibitory cells. Although overall immunostaining was lighter with antibody to GluR1 than with GluR2/3 and 4, there were neurons were neurons that preferentially stained with antibody to GluR1. These “GluR1 intense” neurons were usually fusiform and most concentrated in lamina X. In dorsal root ganglia, immunostaining of ganglion cell bodies was moderate to dense with antibody to GluR2/3 and light to moderate with antibody to GluR4. Possible neuroglia in the spinal cord (mainly GluR2/3 and 4) and satellite cells in dorsal root ganglia (GliR4) were immunostained. Electron microscopic studies of the the superficial dorsal horn and lateral motor column showed staining that was restricted mainly to postsynaptic densities and associated dendritic and cell body cytoplasm. In dorsal horn, colocalization of dense‐cored vesicles with clear, round synaptic vesicles was observed in unstained presynaptic terminals apposed to stained postsynaptic densities. Subsynaptic dense bodies (Taxi‐bodies) were associated with some stained postsynaptic densities in the superficial dorsal horn and lateral motor column. Based on several morphological features including vesicle structure and presence of Taxi‐bodies, it is likely that at least some of the postsynaptic staining seen in this study is apposed to glutamatergic input from primary sensory afferent terminals. © 1994 Wiley‐Liss, Inc.
Functional and antigenic maps in the rat cerebellum: Zebrin compartmentation and vibrissal receptive fields in lobule IXa
Authors: Chockkan Vijay , Hawkes Richard 
Published: January 2005

AbstractThe mammalian cerebellum is compartmentalized, both structurally and biochemically, into an array of parasagittal bands. In the adult rat, bands can be shown by immunocytochemical staining of a Purkinje cell subset with the monoclonal antibody antizebrin II. In contrast to the bands revealed by the zebrin II distribution, electrophysiological maps of tactile representations show an apparently quite different organization, a patchwork somatotopy of interwoven small receptive fields. We have compared zebrin II compartmentation with the distribution of vibrissal receptive fields in the dorsal face of lobule IXa. Nine adult rats were studied. Zebrin II immunocytochemistry revealed a zebrin II+ band at the midline (P1+) and three others (P2+, P3+, P4+) arrayed laterally, separated by the P1−, P2−, and P3− bands of unstained Purkinje cells. The only significant source of variability was that P3− was sometimes ill defined, making the P3+ and P4+ difficult to distinguish. Electrophysiological recording in the granular layer of lobule IXa identified two reproducible vibrissal receptive fields on each side of the midline (V1 and V2), with a third, more laterally, identified occasionally (V3). When receptive field maps were constructed and aligned with the zebrin II compartment maps from the same individuals, the V1 receptive field was centered on P1−, V2 on P2−, and V3 on P3−. However, the receptive fields typically extended beyond the P− band into the neighboring P+ to each side. Thus there is a simple, reproducible vibrissal receptive field organization in lobule IXa that bears a constant relationship to the Purkinje cell compartmentation revealed by zebrin II immunocytochemistry. The biochemical parcellation of the cortex may serve to organize the afferent and efferent projection topography and thus to align the sensory and motor maps in the cerebellum. © 1994 Wiley‐Liss, Inc.
NADPH‐Diaphorase in the central nervous system of the larval lamprey (Lampetra planeri)
Authors: Schober Andreas , Malz Cordula R. , Schober Wilfried , Meyer Dietrich L. 
Published: January 2005

AbstractThe distribution of nitric oxide synthase (NOS) in the lamprey brain was studied by using reduced nicotinamide‐adenine‐dinucleotide phosphate (NADPH)‐diaphorase histochemistry to further elucidate the evolution of neurons synthesizing nitric oxide. Intense labeling of fibers and/or neurons was found in portions of the lamprey central nervous system, such as the olfactory system, the pineal organ, the habenular region, the nervus stato‐acousticus (N. VIII), the brainstem, and the spinal cord, and also in the adenohypophysis.Labeled giant cells located at the floor of the 3rd, and 4th ventricle were recognized as reticulospinal neurons. Mauthner and Müller cells were identified according to morphological criteria. Eight pairs of Müller cells and one pair of Mauthner cells were labeled by NADPH histochemistry.None of these cells had, as yet, been described to display NOS activity in any vertebrate. The massive staining of these cells and the apparent lack of labeling, e. g., in teleost fishes, may be a histochemical correlate to already known differences of functions served by these cells in different species. In addition, our results suggest that the nitric oxide (NO) system has appeared early in vertebrate evolution. © Wiley‐Liss, Inc.
Information processing within the motor cortex. I. Responses of morphologically identified motor cortical cells to stimulation of the somatosensor cortex
Authors: Kaneko Takeshi , Caria Marcello A. , Asanuma Hiroshi 
Published: January 2005

AbstractInputs from the somatosensory cortex to the motor cortex have been proposed to function in learning of motor skills. In an attempt to analyze how these somatosensory inputs were processed in the motor cortex, neurons in the superficial layer of the cat motor cortex were classified into three groups on the basis of synaptic responses elicited by intracortical microstimulation (ICMS) of area 2. ICMS was delivered through seven electrodes implanted in area 2. When ICMS through one of the sevn sites produced a response that was greater than 50% of the response produced by stimulating the seven sites at time, the site was called a “dominant” site. Type I cells were those that had a dominant stimulation site and showed a constant response latency when examined by a double shock test. Type II cells were those that had a dominant site but displayed a variable latency. Type III cells had no dominant site and showed a variable latency. Latency of type I responses was 1.2–2.6 milliseconds, which was much shorter than that of type II and type III responses.Seventy‐nine neurons in layers II/III of the motor cortex, which responded to ICMS in area 2, were stained by intracellular injection of biocytin. From the presence of an apical dendrite and rich spines on the dendrites, 23 type I, 21 type II, and 15 type III cells were classified as pyramidal cells. Type II pyramidal cells were located more superficially than type I and type III pyramidal cells. On the basis of the absence or sparseness of dendritic spines, three type I and four type II cells in layers II/III were classified as nonpyramidal cells. These cells consisted of five small multipolar cells in layer II and a large multipolar cell and a small bitufted cell in layer III. The remaining 11 cells were not classified because of insufficient staining.Since type I and type II cells are considered to represent monosynaptic and polysynaptic responses to stimulation of area 2, respectively, information flow from type I cells to more superficially located type II cells is presumed in layers II/III of the motor cortex. Type III responses suggest tye presence of a convergent flow of impulses inside of and/or between areas 2 and 4. © 1994 Wiley‐Liss, Inc.