bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional distribution of GABAA receptor binding sites in cat somatosensory and motor cortex
Authors: Schwark Harris D. , Li Jianying , Fuchs Jannon L. 
Published: January 2005

AbstractInhibition in primary sensory cortex plays a role in neuronal response to periperal stimuli. For many neurons in cat primary somatosensory cortex, blockade of GABAA receptors by bicuculline results in receptive field enlargement. The magnitude of this effect varies with the neuron's adaption characteristics and its location in particular laminae and submodality regions. To test whether these variation are correlated with the distribution of GABAA receptors, we analyzed [3H] muscimol binding in cat primary somatosensory and motor cortical areas. The highest levels of binding were in layers IV was distinguished by highest levels were in layers V–VI. In somatosensory cortical areas, layer IV, levels of binding were significantly higher in posterior area 3b than in anterior area 3b. These difference may correspond to the rapidly adaption and slowly adapting submodality regions which have been described in this area. The laminar distribution of [3H] muscimol binding differed from that of [3H]flunitrazepam, and neither resembled the distribution of magnitude of bicuculline's effects on receptive field size. The laminar distribution of [3H] muscimol binding was highly correlated with the area density of GABA‐immunoreactive neurons described in a companion study. © 1994 Wiley‐Liss, Inc.
Synaptology of physiologically identified ganglion cells in the cat retina: A comparison of retinal X‐ and Y‐cells
Authors: Weber A. J. , Stanford L. R. 
Published: January 2005

AbstractIt has long been known that a number of functionally different types of ganglion cells exist in the cat retina, and that each responds differently to visual stimulation. To determine whether the characteristic response properties of different retinal ganglion cell types might reflect differences in the number and distribution of their bipolar and amacrine cell inputs, we compared the percentages and distributions of the synaptic inputs from bipolar and amacrine cells to the entire dendritic arbors of physiologically characterized retinal X‐ and Y‐ cells. Sixty‐two percent of the synaptic input to the Y‐cell was from amacrine and bipolar cells. We found no significant difference in the distributions of bipolar or amacrine cell inputs to X‐ and Y‐ cells, or ON‐center and OFF‐center cells, either as a function of dendritic branch order or distance from the origin of the dendritic arbor. While, on the basis of these data, we cannot exclude the possibility that the difference in the proportion of bipolar and amacrine cell input contributes to the functional differences between X‐ and Y‐ cells, the magnitude of this difference, and the similarity in the distributions of the input from the two afferent cell types, suggest that mechanisms other than a simple predominance of input from amacrine or bipolar cells underlie the differences in their response properties. More likely, perhaps, is that the specific response features of X‐ and Y‐ cells originated in differences in the visual responses of the bipolar and amacrine cells that provides their input, or in the complex synaptic arrangements found among amacrine and bipolar cell terminals and dendrites of specific types of retinal ganglion cells. © 1994 Wiley‐Liss, Inc.
Distinct spatiotemporal expressions of five NMDA receptor channel subunit mRNAs in the cerebellum
Authors: Watanabe Masahiko , Mishina Masayoshi , Inoue Yoshiro 
Published: January 2005

AbstractThe distribution of five NMDA receptor channel subunit mRNAs was examined in the mouse cerebellum from embryonic day 13 through postnatal day 56, by in situ hybridization with subunit‐specific oligonucleotide probes. At postnatal days 21 and 56, each cerebellar neuron displayed differential expressions of the ∈ subunit mRNAs. The granule cells showed hybridizing signals for the ∈1 and ∈3 subunit mRNAs, the molecular layer neurons for the ∈4 subunit mRNA, and the cerebellar nucleus neurons for the ∈1 and ∈4 subunit mRNAs, whereas the Purkinje cells did not express any ∈ subunit mRNAs. At early postmitotic stages of development, the ∈2 subunit mRNA appeared in each cerebellar neuron, including the Purkinje cells, and the ∈4 subunit mRNA appeared in neurons of the molecular layer and the cerebellar nuclei. The expression patterns in the cerebellum altered drastically during the first 2 postnatal weeks: the ∈1 and ∈3 subunit mRNAs appeared in the granule cells and the cerebellar nucleus neurons, whereas the ∈2 subunit mRNA disappeared from each neuron and the signal levels of the ∈4 subunit mRNA decreased remarkably. In contrast to the differential expressions of the four ∈ subunit mRNAs, intense signals for the ζ 1 subunit mRNA were observed in each cerebellar neuron from early postmitotic stages through the mature stage. These findings suggest that anatomical organization of the ∈ subunits is heterogeneous in the cerebellum both spatially and temporally, which would give rise to functional diversity of the NMDA receptor channel. © 1994 Wiley‐Liss, Inc.
Synaptic relationships between dopaminergic afferents and cortical or thalamic input in the sensorimotor territory of the striatum in monkey
Authors: Smith Y. , Bennett B. D. , Bolam J. P. , Parent A. , Sadikot A. F. 
Published: January 2005

AbstractThe cerebral cortex and the intralaminar thalamic nuclei are the major sources of excitatory glutamatergic afferents to the striatum, whereas the midbrain catecholaminergic neurones provide a dense intrastriatal plexus of dopamine‐containing terminals. Evidence from various sources suggests that there is a functional interaction between the glutamate‐ and dopamine‐containing terminals in the striatum. The aim of the present study was to determine the synaptic relationships between cortical or thalamic inputs and the dopaminergic afferents in the sensorimotor territory of the monkey striatum. To address this issue, anterograde tracing in combination with immunocytochemistry for tyrosine hydroxylase (TH) was carried out by light and electron microscopy.Squirrel monkeys received injections of biocytin in the primary motor and somatosensory cortical areas or injections of eitherPhaseolus vulgaris‐leucoagglutinin (PHA‐L) or biocytin in the centromedian nucleus (CM) of the thalamus. Sections that included the striatum were processed to visualize the anterograde tracers alone or in combination with TH immunoreactivity. The anterogradely labelled fibres from the cerebral cortex and CM display a band‐like pattern and are exclusively confined to the postcommissural region of the putamen, whereas TH‐immunoreactive axon terminals are homogeneously distributed throughout the entire extent of the striatum. Electron microscopic analysis revealed that the anterogradely labelled terminals from the cerebral cortex form asymmetric synapses almost exclusively with the heads of dendritic spines. The thalamic terminals also form asymmetric synapses, but in contrast to cortical fibres, predominantly with dendrites (67.4%) and less frequently with spines (32.6%). The TH‐immunoreactive boutons are heterogeneous in morphology. The most common type (84% of the total population) forms symmetric synapses; of these the majority is in contact with dendritic shafts (72.1%), less with spines (22.5%) and few with perikarya (5.4%). In sections processed to reveal anterogradely labelled cortical fibres and TH‐immunoreactive structures, individual spines of striatal neurones were found to receive convergent synaptic inputs from both cortical and TH‐immunoreactive boutons. In contrast, anterogradely labelled thalamic terminals and TH‐immunoreactive boutons were never seen to form convergent synaptic contacts on the same postsynaptic structure.These findings suggest that the dopaminergic afferents are located to subserve a more specific modulation of afferent cortical input than afferent thalamic input in the sensorimotor territory of the striatum in primates. © 1994 Wiley‐Liss, Inc.
Changes in fiber order in the optic nerve and tract of rat embryos
Authors: Chan S. O. , Guillery R. W. 
Published: January 2005

AbstractIn order to define the extent to which retinotopic order in the optic pathways may contribute to fiber segregation at the chiasm or to the formation of central maps, the arrangement of fibers in the optic nerve and tract of rat embryos, on embryonic days 16.5 and 18.5, has been studied by placing a small granule of Dil in one of the four quadrants of the retina and tracing the filled fibers through transverse sections of the retinofugal pathway with confocal microscopy. There is a distinct quadrant‐specific order in the optic stalk immediately behind the eye, with fibers from the ventral nasal, dorsal nasal, dorsal temporal, and ventral temporal retina arranged sequentially across the rostrocaudal axis of the cross section of the stalk. However, this distinct order is not maintained very far. There is a gradual increase in the degree of overlap between fibers from the different quadrants as the fibers pass towards the chiasm. The dorsal groups of fibers intermingle extensively along almost the entire length of the stalk, but the fibers from ventral sectors remain separate until they reach the prechiasmatic region, where the ventral temporal and the ventral nasal fibers spread the throughout the rostrocaudal extent of the stalk and the chiasm. The initial quadrant‐specific order is completely lost at the chiasm. However, beyond the optic chiasm, the fibers are reorganized into another distinct order. In the optic tract, there is a segregation of dorsal from ventral fibers, but the nasal and temporal groups remain intermingled.The results of this study indicate that the earliest fibers in the developing optic tract are arranged according to topographical rules that differ from those obtaining behind the eye. Since all topographical order is lost between these two levels, there must be an active storing mechanism in the region where the chiasm joins the tract. Possibly this mechanism is related to the development of the dorsoventral axis of the topographic maps in the central visual targets. © 1994 Wiley‐Liss, Inc.
Extent and time course of restoration of descending brainstem projections in spinal cord‐transected lamprey
Authors: Davis G. R. , McClellan Andrew D. 
Published: January 2005

AbstractThe purpose of the present study was to determine the numbers of descending brainstem projections to different levels of the spinal cord in normal larval sea lamprey (Petromyzon marinus) and to examine the restoration of these projections in animals 3–32 weeks after transection of the rostral spinal cord ( ∼ 10% of body length). In normal animals approximately 1, 250, 900, and 825 brainstem neurons projected to 20%, 40%, and 60% of body length, respecively. Spinal projections originated from the diencephaln, mesencephalon, three rhombencephalic reticular nuclei, Müller and Mauthner neurons, and four cell groups in the caudal rhombencephalon. In spinal cord‐transected animals the number of brainstem neurons projecting to 20% of body length increased with recovery time, and at 32 weeks post‐transection the total number and distribution of brainstem neurons was not significantly differnt from normal animals. Brainstem projections first appeared at 40% of body length by 8 weeks post‐transection, and were present at 60% of body length by 32 weeks post‐transection. There was substantial restoration of brainstem projections to 40% of body length but limited restoration to 60% of body length. The ∼ 50 brainstem neurons, including some Müller cells, that projected to 60% of body length at 32 weeks post‐transection indicate that restoration of descending projections in excess of 50 mm can occur within the central nervous system of this vertebrate. These anatomical results are discussed in relation to the time course of recovery of locomotor functions in spinal cord‐transected lampreys. © 1994 Wiley‐Liss, Inc.
Anatomical organization of the limb premotor network in the turtle (Chrysemys picta) revealed by in vitro transport of biocytin and neurobiotin
Authors: Sarrafizadeh Ramin , Houk James C. 
Published: January 2005

AbstractThe in vitro turtle brainstem‐cerebellum preparation has been a valuable tool in the study of central motor programs. In the present study, we investigate the anatomical organization of the turtle rubrocerebellar limb premotor network and its sensory connections in vitro by combining the rapid anterograde and retrograde transport of neurobiotin and biocytin with the extended viability of the isolated turtle brainstem‐cerebellum. These compounds retrogradely labeled soma, dendrites, and axons, and orthogradely labeled axons and, to a lesser extent, terminals.The chelonian red nucleus receives a dense input form the contralateral lateral cerebellar nucleus and projects heavily to the contralateral spinal cord. Rubral axons sparsley innervate the lateral cerebellar nucleus and project heavily to the lateral reticular nucleus. Lateral reticular axons heavily innervate the lateral cerebellar nucleus before terminating in the pars laterlalis of the cerebellar cortex as mossy fibers. These prominent, recurrent loops among the lateral cerebellar nucleus, red nucleus, and lateral reticular nucleus constitute the turtle rubrocerebellar limb premotor network.Sensory inputs to the red nucleus orginate in the contralateral dorsal column nuclei, the principle trigeminal nucleus, and the spinothalamic system. These sites project bilaterally to the lateral reticular nucleus. The lateral cerebellar nucleus receives a contralateral input from the dorsal column nuclei. The red nucleus projects sparsely to the dorsal column nuclei.The red nucleus also receives an ipsilateral descending projection from the suprapeduncular nucleus, located in the diencephalon, and an ascending input from the rostral rhombencephalic reticular formation. An ipsilateral descending pathway originating in the red nucleus is likely to be the rubro‐olivary tract. © 1994 Wiley‐Liss, Inc.
Distributions of GABAA, GABAB, and benzodiazepine receptors in the forebrain and midbrain of pigeons
Authors: Veenman C. Leo , Albin Roger L. , Richfield Eric K. , Reiner Anton 
Published: January 2005

AbstractAutoradiographic and immunohistochemical methods were used to study the distributions of GABAA, GABAB and benzodiazepine(BDZ) receptors in the pigeon fore‐ and midbrain. GABAA, GABAB and BDZ binding sites were found to be abundant although heterogeneously distributed in the telencephalon. The primary sensory areas of the pallium of the avian telencephalon (Wulst and dorsal ventricular ridge) tended to be low in all three binding sites, while the surrounding second order belt regions of the pallium were typically high in all three. Finally, the outermost rind of the pallium (termed the pallium externum by us), which surrounds the belt regions and projects to the striatum of the basal ganglia, was intermediate in all three GABAergic receptors types. Although both GABAA and benzodiazepine receptors were abundant within the basal ganglia, GABAA binding sites were densest in the striatum and BDZ binding sites were densest in the pallidum. Among the brainstem regions receiving GABAergic basal ganglia input, the anterior and posterior nuclei of the ansa lenticularis showed very low level of all three receptors, while the lateral spiriform nucleus and the ventral tegmental area/substantia nigra complex contained moderate abundance of the three binding sites. The dorsalmost part of the dorsal thalams (containing nonspecific nuclei) was rich all three binding sites, while the more ventral part of the dorsal thalamus (containig specific sensory nuclei), the ventral thalamus and the hypothalamus were poor in all three binding sites. The pretectum was also generally poor in all three, althrough some nuclei displayed higher level of one or more binding sites. The optic tectum, inferior colliculus, and central gray were rich in all three sites, while among the isthmic nuclei, the parvicellular isthmic was nucleus was conspicuously rich in BDZ sites. The REsults show a strong correlation of the regional abundance of GABA binding sites with previously described distributions of GABAergic fibers and terminals in the avaian forebrain and midbrain. The distribution of these binding sites is also remarkably similar to that in mammals, indicating a conservative evolution of forebrain and midbrain GABA systems systems among amniotes. © 1994 Wiley‐Liss, Inc.
Catecholaminergic systems in the zebrafish. II. Projection pathways and pattern of termination of the locus coeruleus
Authors: Ma PoKay M. 
Published: January 2005

AbstractThe locus coeruleus is a widely projecting isthmal noradrenergic nucleus. In the zebrafish, it consists of between three and ten neurons, most of which have multiple, bilaterally projecting axons. Immunohodolgical studies show that the locus coeruleus provides most, if not all, of the noradrenergic innervation of the brain rostral to the isthmus. The pathways and targets in the zebrafish are similar to ascending coeruleal projections of other vertebrates. Axons ascend through two amin pathways: the longitudinal catecholamine bundle and the periventricular catecholamine pathway. The former is a dense meshwork of varicosity‐bearing axons which ascends along the lateral longitudinal fasciculus into the mesencephalon. In the posterior tuberal area, this bundle dives ventrally and assumes a lateral position. In the diencephalon, it takes up a position ventral to the medial forebrain bundle, and follows this bundle into the telencephalon, where it joins the medial olfactory tract to enter the olfactory bulb. The periventricular catecholamine pathway is a diffuse pathway consisting of thick, smooth axons. It is associated with the medial longitudianl fasciculus. Rostral to the nucleus of the medial longitudinal fasciculus, this pathway joins the longitudinal catecholamine bundle around the medial forebrain bundle. The Periventricular pathway gives rise to coarse terminal arbors with large but sparse varicosities, whereas the longitudinal catecholamine bundle gives rise to terminal plexuses with fine and dense fibers and varicosities. Among the more densely innervated regions are the raphé nucleus, the interpeduncular nucleus, the torus semicircularis, parts of the hypothalamus, and the suprachiasmatic and preoptic areas. The tours longitudinalis, optic tectum, cerebellum, habenular complex, the dorsomedial zone of area dorsalis telencephali, and the olfactory bulb are moderately innervated. The nucleus glomerulosus, the torus lateralis and lateral subnuclei of the nucleus diffusus, and the anterior tuberal nucleus are devoid of noradrenergic innervation. © 1994 Wiley‐Liss, Inc.
Developmental distribution of GFAP and vimentin in the Brazilian opossum brain
Authors: Elmquist Joel K. , Swanson Jack J. , Sakaguchi Donald S. , Ross Lynne R. , Jacobson Carol D. 
Published: January 2005

AbstractCells of glial origin are involved in the morphogenesis of the mammalian central nervous system (CNS). Characterization of glial‐associated proteins during neurogensis and differentiation may aid in understanding the complexity of CNS development. We have utilized immunoblotting and immunohistochemistry to characterize the developmental profiles of glial fibrillary acidic protein (GFAP) and vimentin (VIM) in the brain of the Brazilian opossum, Monodelphis domestica. Typical of marsupials, CNS morphogenesis and neurogenesis in the opossum extend well into the postnatal period. Opossum GFAP and VIM were found as single bands at molecular weights consistent with those reported for other species, thus indicating conservation of the VIM and GFAO proteinns through mammalian evolution. Differential developmental trends were observed for both proteins with relative VIM levels decreasing and GFAP levels increasing with age. Vimentin‐like immunoreactivity (VIM‐IR) was present at day 1 of postnatal life throughout the brain. The density of VIM‐IR was maximal at 10 and 15 days postnatal (especially in radial glial elements) and decreased slightly by 25 days postnatal. In the adult brain, VIM‐IR was markedly reduced compared to that of younger ages. In contrast, GFAP‐like immunoreactivity (GFAP‐IR) in the brain of Monodelphis increased dramatically with age. No GFAP‐IR was observed in the 1 and 5 day postnatal brains. By 25 days postnatal, the pattern of GFAP‐IR in the brainstem resembled that of the adult. In the forebrain, more GFAP‐IR was present than at younger ages. The adult distribution of GFAP‐IR was very similar to that reported for other mammalian species. These results indicate that GFAP and VIM are reciprocally related during periods of morphogenesis and differentiation of the opossum brain. © 1994 Wiley‐Liss, Inc.
Functional architecture of vestibular primary afferents from the posterior semicircular canal of a turtle,Pseudemys (Trachemys) scripta elegans
Authors: Brichta A. M. , Peterson E. H. 
Published: January 2005

AbstractPhysiological studies inmany vertebrates indicate that vestibular primary afferents are not a homogeneous population. Such date raise the question of what structural mechanisms underlie these physiological differeneces and what functional role is played by afferents of each type. We have begun to answer these questions by characterizing the architecture of 110 afferents innervating the posterior canal ofPseudemys scripta.We emphasize their spatial organization because experimental evidence suggests that afferent physiological properties exhibit significant spatial heterogeneity.The sensory surface of the posterior canal comprises paired, triangular hemicristae, which are innervated by two afferent types. Bouton afferents (66% of total afferents) are found over the entire sensory surface. They differ significantly in the shape and size of their collecting areas, number of boutons, soma size, and axon diameter; this morphological variation is systematically related to the afferent's spatial postion. In addition, multivariate analyses suggest that bouton afferents may comprise two subtypes: α afferents have delicate processes and are found throughout the crista; β afferents are more robust and are concentrated preferentially toward the canal center. Calyx‐bearing afferents comprise two morphological subtypes: dimorphs (13% of total afferents) bear calyceal and bouton endings; calyceal afferents (21%) bear calyceal endings only. Both types occur exclusively in an elliptical region near the center of each hemicrista; their morphology varies with radial distance from the center of this elliptical region.Our data provide evidence that inPseudemys:(1) the classical vestibular afferents types (bouton, calyx, dimorph) are structurally heterogeneous, and (2) their spatial sampling characteristic are highly structured and distinctive for each type. These spatial patterns may shed light on regional differences in physiological profiles of vestibular afferents, and they raise questions about the role of this spatial heterogeneity in signaling head movement. © 1994 Wiley‐Liss, Inc.