bluuebunny/crossref_metadata_2025_split huggingface dataset:
3H‐nicotine‐ and 125I‐alpha‐bungarotoxin‐labeled nicotinic receptors in the interpeduncular nucleus of rats. II. Effects of habenular deafferentation
Authors: Clarke Paul B. S. , Hamill Geoffrey S. , Nadi N. Suzan , Jacobowitz David M. , Pert Agu 
Published: January 2005

AbstractThe cholinergic innervation of the interpeduncular nucleus (IPN) is wholly extrinsic and is greatly attenuated by bilateral habenular destruction. We describe changes in the labeling of putative nicotinic receptors within this nucleus at 3, 5, or 11 days after bilateral habenular lesions. Adjacent tissue sections of the rat IPN were utilized for 3H‐nicotine and 125I‐α‐bungarotoxin (125I‐BTX) receptor autoradiography.Compared to sham‐operated controls, habenular destruction significantly reduced autoradiographic 3H‐nicotine labeling in rostral (−25%), intermediate (−13%), and lateral subnuclei (−36%). Labeling in the central subnucleus was unchanged. Loss of labeling was maximal at the shortest survival time (3 days) and did not change thereafter. In order to establish whether this loss was due to a reduction in the number or the affinity of 3H‐nicotine‐binding sites, a membrane assay was performed on microdissected IPN tissue from rats that had received surgery 3 days previously. Bilateral habenular lesions produced a 35% reduction of high‐affinity 3H‐nicotine‐binding sites, with no change in binding affinity.Bilateral habenular lesions reduced 125I‐BTX labeling in the intermediate subnuclei, and a slight increase occurred in the rostral subnucleus. In the lateral subnuclei, 125I‐BTX labeling was significantly reduced (27%) at 3 days but not at later survival times.In view of the known synaptic morphology of the habenulointerpeduncular tract, it is conculded that a subpopulation of 3H‐nicotine binding sites within the IPN is located on afferent axons and/or terminals. This subpopulation, located within rostral, intermediate, and lateral subnuclei, may correspond to presynaptic nicotinic cholinergic receptors. Sites that bind 125I‐BTX may include a presynaptic subpopulation located in the lateral and possibly the intermediate subnuclei.
Development of projections from somatic motor‐sensory areas of neocortex to the diencephalon and brainstem in the North American opossum
Authors: Cabana T. , Martin G. F. 
Published: January 2005

AbstractThe development of projections from somatic motor‐sensory areas of neocortex to the diencephalon and brainstem was studied by using the orthograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) in a series of pouch‐young opossums. The opossum was chosen for study because it is born in a very immature state, 12 days after conception, and has a protracted postnatal development. Cortical axons form a cerebral peduncle by at least postnatal day (PD) 10, a medullary pyramid by estimated PD (EPD) 17, a pyramidal decussation by EPD 26, and reach the first cervical segment of the spinal cord by EPD 29. Cortical axons innervate diencephalic nuclei and perhaps the substantia nigra by EPD 17, but do not grow into more caudal brainstem nuclei until EPD 26. The first brainstem areas innervated by cortical axons are the mesencephalic and rostral pontine tegmentum and parts of the pontine gray adjacent to the pyramidal tract (EPD 29). By EPD 31, cortical axons project to additional areas of the pontine gray, the gigantocellular reticular formation, the medial accessory olive, and the cuneate nucleus. Cortical innervation of the red nucleus and superior colliculus begins at EPD 31 but is not well developed until EPD 35. Cortical axons do not innervate the parvicellular reticular formation or the sensory trigeminal nuclei until EPD 35. Evidence for transient cerebrocerebellar axons was also found.
A comparative light microscopic analysis of the sensory innervation of the mystacial pad. II. The common fur between the vibrissae
Authors: Rice Frank L. , Munger Bryce L. 
Published: January 2005

AbstractThe innervation to the common fur between the vibrissae was examined in the hamster, mouse, rat, gerbil, rabbit, guinea pig, and cat. Samples were taken from central locations among the more caudal vibrissae in the mystacial pad and processed with Richardson's variant of the Bielschowsky silver techique or with Winkelmann's silver technique to selectively stain peripheral axons and terminals. Additional samples were taken among the rostral vibrissae in the rat. We found major unpredictable species‐related variations in the distribution of receptor types, innervation density, and the quantity of innervation in the skin between neighboring vibrissae. The common fur is composed of numerous larger guard hairs and even more numerous smaller vellus hairs. The guard hairs usually are richly innervated with fully developed piloneural complexes composed primarily of a pallisade of Ianceolate endings and a circumferential array of Ruffini and free nerve endings. The vellus hairs are usually innervated by individual or shared free nerve endings. The piloneural complexes in the cat, rat, and mouse are usually complete, whereas those in the other species were usually incomplete and lacked Ruffini endings. There is considerable interspecies variation in the relative quantity of innervation between homologous neighboring vibrissae. The quantity of innervation is related to a combination of receptor completeness, innervation density, and distance between vibrissae. The quantity of intervibrissal fur innervation is by far highest in the cat, relatively high in the rabbit, relatively low in the hamster and caudal mystacial pad of the rat, and lowest in the mouse, gerbil, guinea pig, and rostral mystacial pad of the rat. The differences in the innervation between the cat and the rabbit correlate well with published physiologic data on types of receptor units. Also, barrels are most prominent in species having relatively low quantities of intervibrissal innervation and are less prominent or absent in species having high quantities of intervibrissal innervation.
Reactive synaptogenesis in hippocampal area CA1 of aged and young adult rats
Authors: Anderson Kevin J. , Scheff Stephen W. , DeKosky Steven T. 
Published: January 2005

AbstractSelective lesions that result in a partial loss of neuronal input appear to signal residual, undamaged inputs to sprout and replace synaptic connections that have been lost. Previous investigations have compared this process of reactive synaptogenesis in young and old animals in the hippocampal dentate gyrus and have demonstrated that the aged brain has a diminished capacity for reinnervation following massive denervation of a target area. This investigation has focused on the lesion‐induced plasticity of an adjacent area of the hippocampal formation, area CA1 of regio superior, in young adult and aged rats.Young adult aged Fischer 344 rats were subjected to a unilateral, intraventricular injection of kainic acid that selectively destroyed the CA3‐CA4 hippocampal pyramidal neurons. Following a 2‐day interoperative interval, the rats sustained an ipsilateral transection of the fimbria‐fornix. Animals were killed at 4, 10, 30, and 60 days following the second transection and processed for electron microscopic analysis. Photographic montages were constructed of area CA1 extending from the alveus to the hippocampal fissure. The density of synapses, both intact and degenerating, was determined and analyzed as a function of age, days postlesion, and zone of analysis.Synaptic density decreased 30–40% contralaterally and 60–70% ipsilaterally in both aged and young adult rats. While both age groups restored synaptic density to preoperative levels, aged subjects required significantly more time. Aged rats appeared to be retarded in the initial phases of synaptic replacement. The delay in the aged animals' reactive response was not due to any differences in degeneration clearance between the age groups.
Genesis of interneurons in the dorsal lateral geniculate nucleus of the cat
Authors: Weber A. J. , Kalil R. E. , Hickey T. L. 
Published: January 2005

AbstractMost neurons in the A‐laminae of the cat's dorsal lateral geniculate nucleus (LGN) are born between embryonic days 22 and 32. Whereas approximately 78% of these cells are destined to become geniculocortical relay cells, the remaining 22% of LGN neurons do not appear to establish connections with visual cortex, and therefore can be considered interneurons. In the present study we have combined the 3H‐thymidine method for labeling dividing neurons with the retrograde horseradish peroxidase (HRP) method for identifying LGN relay cells in order to study specifically the genesis of interneurons in the cat's LGN.Developing LGN interneurons in 12 kittens were labeled with 3H‐thymidine by injecting the radioactive label into the allantoic cavity of their pregnant mothers on different embryonic days. Approximately 8–22 weeks after birth LGN relay cells in the A‐laminae were labeled retrogradely by injecting large volumes of HRP into visual cortex areas 17 and 18. LGN cells that could not be labeled retrogradely with HRP were considered to be interneurons.Our results show that interneurons are born on each of the embryonic days studied, E24–E30. This period represents approximately the middle two‐thirds of the entire period of LGN neurogenesis. Although the birth rate for interneurons is not uniform, there is no indication from our data that interneurons and relay cells in the cat's LGN are born at different times during LGN neurogenesis.
Thalamic afferents to cytoarchitectonic subdivisions of area 6 on the anterior sigmoid gyrus of the dog: A retrograde and anterograde tracing study
Authors: Stanton Gregory B. , Tanaka Duke , Sakai Sharleen T. , Weeks Ophelia I. 
Published: January 2005

AbstractThe cytoarchitecture and thalamic afferents of cortical area 6 located on the anterior sigmoid gyrus were mapped and analyzed in the dog by means of cytoarchitectonic, horseradish peroxidase (HRP), and autoradiographic methods.Cytoarchitectonically, area 6 consists of medial and lateral subdivisions that correspond, respectively, to areas 6aα and 6aβ in the cat. In the dog, area 6aα is characterized by a wide layer III, the merging of borders between layers III and V, the presence of small‐to‐medium‐size pyramidal cells in layer V, and a pallisade arrangement of cells in layer VI. Area 6aβ appears more stratified, with a relatively acellular layer present between layers V and VI and the presence of large pyramidal cells in layer V. Neither area 6aα nor 6aβ contains a layer IV.Data obtained from injections of HRP into areas 6aα or 6aβ revealed that labeled thalamic neurons were distributed in a longitudinal band extending from the rostral part of the ventral anterior nucelus (VA) through the caudal part of the mediodorsal nucleus (MD). Labeled cells were observed in the ventral and ventral medial thalamic nuclei as well as in several of the intralaminar nuclei including the central lateral, central medial, parafascicular, and centrum medianum nuclei. A few labeled cells were also located in the suprageniculate nucleus. The densest thalamic labeling was present in VA and MD following injections into area 6aα. Equivalent or even larger injections into area 6aβ resulted in much less thalamic labeling. The band of labeled cells also extended into the hypothalamus, zona incerta, amygdala, claustrum, periaqueductal gray of the midbrain, and the nucleus of Darkschewitsch.Results from autoradiographic experiments showed that area 6 subdivisions receive a loosely organized topographic input from VA. Injections of tritiated amino acids were made into selected regions of VA and into the caudal part of MD, areas in which the largest numbers of HRP‐labeled cells were located. Area 6aα receives afferents primarily from the rostromedial part of VA and the caudal part of MD while area 6aβ receives its principal input from the caudal and lateral parts of VA with minimal input from MD. Axons originating from VA terminate in both layers I and III of area 6 while those originating from the caudal part of MD terminate only in layer III.The results of this study show that area 6 in the dog may be divided cytoarchitectonically into two distinct regions, each of which receives a characteristic pattern of thalamic inputs. The organization of these inputs, as well as those from other, nonthalamic subcortical areas, lends anatomical support for the functional division of area 6 into an electrophysiologically defined medial eye movement field and a lateral supplementary motor area.
A developmental study of the quantitative distribution of LHRH neurons within the central nervous system of postnatal male and female rats
Authors: Wray Susan , Hoffman Gloria 
Published: January 2005

AbstractThe quantitative distribution of LHRH neurons within the central nervous system of male and female rats during postnatal development was investigated with light microscopic immunocytochemistry. Approximately 1,300 immunoreactive LHRH cells were found within the forebrain at all ages. The topographic distribution of LHRH neurons was adultlike in the earliest neonatal stage examined (2 days postnatal) and remained similar throughout development. Two LHRH cell subtypes, smooth LHRH cells and LHRH cells with spinelike processes (irregular LHRH cells), were found throughout the entire extent of the LHRH neuronal field in both sexes. A sex difference in the number of LHRH cells anterior to the organum vasculosum lamina terminalis/preoptic area (a 20% greater number in this region in females) was observed. This sex difference was present throughout development and was not limited to one specific LHRH cell subtype. These data are consistent with the hypothesis that the LHRH system is established early in postnatal development, and that the signal for reproductive maturation is related to the development of synaptic inputs to the LHRH cells.
Morphology of rabbit retinal ganglion cells projecting to the medial terminal nucleus of the accessory optic system
Authors: Buhl Eberhard H. , Peichl Leo 
Published: January 2005

AbstractRabbit retinal ganglion cells were retrogradely labeled following injection of rhodamine‐labeled microspheres into the medial terminal nucleus. The small fraction of rhodamine‐labeled neurons reached their peak concentration within the visual streak and then decreased with increasing eccentricity until none were encountered in the far periphery. The same rabbits also received injections of the fluorescent tracer Fast Blue into the superior colliculus. No double‐labeled neurons were observed, i.e., ganglion cells projecting to the medial terminal nucleus (MTN) had no axon collaterals to the superior colliculus. In fixed retinae rhodamine‐labeled ganglion cells were intracellularly injected with the fluorescent dye Lucifer Yellow to reveal their full dendritic arborization. MTN‐projecting cells had mediumsized to large somata with thin and frequently branched dendrites. The large dendritic trees had a distinct morphology and were predominatly unistratified in a narrow band that presumably corresponded to the electrophysiologically determined on‐sublamina of the inner plexiform layer. Dendritic field sizes were inversely related to ganglion cell density, thus providing an eccentricity‐independent, constant dendritic coverage factor. Approximately five to six dendritic fields from neighboring cells cover every point of the retina. Published reports claim that the physiological class of on‐direction‐selective ganglion cells provides the sole retinal input to the MTN in the rabbit. In this context morphological features of MTN‐projecting cells and their presumed functional correlation with on‐direction‐selective ganglion cells are discussed.
Structural and functional characteristics of commissural neurons in the superior colliculus of the hamster
Authors: Rhoades Robert W. , Mooney Richard D. , Szczepanik Ann Marie , Klein Bradley G. 
Published: January 2005

AbstractIntracellular recording and horseradish peroxidase (HRP) injection techniques were employed to delineate the structural and functional properties of superior collicular (SC) neurons in the hamster that were antidromically activated by electrical stimulation of the contralateral tectum. A total of 39 such cells were completely characterized, injected, and recovered. In ten of these, the axonal filling allowed us to reconstruct at least a portion of the terminal arborization in the SC contralateral to the labelled cell. Two of the recovered neurons were located in the stratum griseum superficiale (SGS), three were in the stratum opticum (SO), ten were in the stratum griseum intermediale (SGI), 11 were in the stratum album intermedium (SAI), 11 were in the stratum griseum profundum (SGP) and two were located in the stratum album profundum (SAP). The recovered cells were highly varied in both their morphological and their physiological characteristics. Somal areas ranged between 74 μm2 and 364 μm2, and the sample of recovered neurons included horizontal cells, narrow field vertical cells, and a variety of other multipolar neurons. Over one‐third (38.5%) of the recovered cells were unresponsive, 2.6% were exlcusively visual, 33.3% responded only to innocuous cutaneous stimuli, 10.2% were bimodal, 7.7% were specifically nociceptive, and 7.7% had complex (Rhoades, Mooney, and Jacquin: J. Neurosci. 3:1342–1354, ′83) somatosensory receptive fields. We observed no clear‐cut correlations between the structural and functional characteristics of these neurons. The conduction latencies of the commissural SC neurons ranged between 0.8 and 14.0 ms. The most rapidly conducting cells were located in the SGP and SAP. Conduction latency had a significant negative correlation with soma area.Labelled axons, in many cases, had at least one terminal arbor in a portion of the SC that was mirror symmetric with the location of the cell from which it originated. In several cases, however, commissural axons gave off a number of collaterals across the mediolateral extent of the tectum. Commissural axonal terminations were visible only in the laminae ventral to the SO. Several commissural SC neurons also had extensive ipsilateral axon collaterals. Both the ipsilateral and commissural axon branches of these cells gave off en passant and terminal swellings.
Heterogeneity in the pattern of distribution of the axonal collaterals of Purkinje cells in zone b of the cat's vermis: An intracellular HRP study
Authors: Bishop Georgia A. , O'Donoghue Daniel L. 
Published: January 2005

AbstractIntracellular recordings were obtained from Purkinje cells located in zone b of the vermis; all of the cells were located within lobule V. The ulnar and sciatic nerves were stimulated bilaterally in order to determine the input characteristics of each impaled neuron. Subsequent to recording physiological data the neurons were intracellularly labeled with horseradish peroxidase (HRP). At the conclusion of the experiment the animals were perfused and their brains were processed for HRP histochemistry. Zone b was divided histologically into five 200‐μm intervals and the location of each intracellularly injected Purkinje cell relative to these intervals was determined. The input characteristics of Purkinje cells within a single 200‐μm interval are not identical. Some Purkinje cells respond exclusively to input from a specific limb, whereas other Purkinje cells within the same interval are activated by both forelimb and hindlimb stimulation. The collaterals of a zone b Purkinje cell form a dense plexus at the Purkinje cell‐granule cell junction; branches also distribute to the superficial and deep granule cell layer, as well as to the lower molecular layer. Two patterns of collateral distribution were observed. In one pattern, the plexus has a single arbor confined to the vicinity of the cell body of origin. In the second pattern, at least two arborizations are present. One arbor remains within the vicinity of the cell body of origin whereas other arbors are distant from the parent cell; the two arbors are separated by areas devoid of collaterals. An analysis of the distribution of axonal varicosities shows that they are not uniformly distribution around the cell body of origin in either the sagittal or transverse plane. Cortical areas that contain numerous beads are interspersed between regions that contain few or no varicosities. The discontinuous pattern of distribution and the presence of varicosities in all three cortical laminae suggest that Purkinje cells in zone b have multiple discrete foci of influence on diverse populations of cerebellar neurons.These anatomical findings suggest that individual Purkinje cells may play different functional roles in the local circuitry of zone b. Cells with the spatially confined arbors may be involved with the integration of information within restricted sagittal intervals (approximately 200 μm in width) of the cerebellum. Purkinje cells with the dual arbors have the potential to integrate information over a greater extent of zone b or, in some cases, between zone b and adjacent cortical zones (e.g., c1 or x).
Restoration of neuromuscular specificity following ventral rhizotomy in the bullfrog tadpole, rana catesbeiana
Authors: Farel Paul B. , Bemelmans Sibyl E. 
Published: January 2005

AbstractThe specificity of hindlimb reinnervation following transection of lumbar ventral roots was investigated in adult and larval bullfrogs (Rana catesbeiana). Five to 6 weeks following ventral rhizotomy, the retrogradely transported marker horseradish peroxidase (HRP) was applied to circumscribed regions of the hindlimb. The location of labeled motoneuron somata within the lumbar lateral motor column was compared with that obtained in unoperated tadpoles. Reinnervation of the hindlimb was largely specific in tadpoles operated during the first third of larval life. However, localization was largely lost in older tadpoles and adult frogs. Repeated applications of 3H‐thymidine combined with retrograde labeling with HRP failed to provide evidence that newly born motoneurons contribute to reinnervation of the hindlimb. Hindlimb reinnervation thus appears to result from regeneration of transected motor axons.In contrast to the lack of neuromuscular specificity seen in older animals after transection of ventral roots, moteneuron axons disconnected from their targets by crush injury regenerate to the appropriate limb regions.
Distribution and ultrastructure of synapses on a premotor local nonspiking interneuron of the crayfish
Authors: Kondoh Y. , Hisada M. 
Published: January 2005

AbstractMany premotor local nonspiking interneurons are involved in the control of the uropod movements of a crayfish. One of these interneurons was impaled intracellularly, characterized physiologically, and then labeled by intracellular horseradish peroxidase (HRP) injection to examine the distribution and ultrastructure of synapses. Depolarization of this interneuron by a current injection excited the closer motoneurons of the uropod and inhibited its opener motoneurons, but hyperpolarization had no effect. Input and output synapses are distributed all over the major branches and the finer neurites except for the main neurite (7–10 μm in diameter), which runs near the dorsal surface of the neuropil. Both types of synapse are located on the same neurite and are often intermingled in close proximity, often less than 1 μm apart. Presynaptic terminals of the interneuron contain round, clear vesicles that are densely packed in fine branches and spines. The number of synaptic vesicles associated with a particular output synapse was estimated to be about 2,000. No dense‐cored granules are observed in the labeled neurites. Our results support the proposal that synaptic transmission in this class of interneurons of the crayfish can sometimes be restricted to a very small region of the branches and that, therefore, different regions of the interneuron can function independently.