bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dorsal root and dorsal column mediated synaptic inputs to reticulospinal neurons in lampreys: Involvement of glutamatergic, glycinergic, and GABaergic transmission
Authors: Dubuc Réjean , Bongianni Fulvia , Ohta Yoshihiro , Grillner Sten 
Published: January 2005

AbstractThis study was aimed at characterizing the inputs from dorsal roots and dorsal columns to reticulospinal neurons within the posterior rhombencephalic reticular nucleus in the lamprey. The in vitro isolated brainstem and spinal cord preparation was used. Microstimulation of dorsal roots and columns on both sides induced, in identified reticulospinal neurons, synaptic responses which consisted of large IPSPs mixed with excitation, particularly from stimulation on the ipsilateral side. When the spinal cord was selectively exposed to kynurenic acid or to Ca2+, synaptic responses to stimulation of dorsal roots and columns were not modified, whereas the same responses were abolished when the brainstem was exposed selectively to kynurenic acid, thus suggesting that the responses were carried by long fibres ascending directly to the brainstem. The excitatory and inhibitory synaptic responses are relayed by interneurons located in the brainstem. The ascending excitatory inputs to inhibitory interneurons and, most likely, also to excitatory interneurons, use excitatory amino acid transmission. Inhibitory responses were abolished by adding the glycinergic antagonist strychnine (5 μM) to the physiological solution, thus suggesting that inhibitory interneurons use glycine transmission. The synaptic transmission was depressed by (−)‐baclofen, a GABAu agonist, probably acting at a presynaptic site.Taken together, the present results suggest that dorsal root and dorsal column stimulations give rise to disynaptic inhibition and excitation of reticulospinal neurons mediated by excitatory and inhibitory amino acid transmission via brainstem interneurons. © 1993 Wiley‐Liss, Inc.
Ultrastructure of the circuit providing, input to the crayfish lateral giant neurons
Authors: Lee Sunhee C. , Krasne Franklin B. 
Published: January 2005

AbstractLabeled or otherwise identified neurons of the crayfish lateral giant escape reaction circuit were examined electron microscopically and the findings compared to expectations from physiology.Terminals of primary afferents contained clear, approximately 45 nm, irregularly round synaptic vesicles, while sensory interneuron terminals had slightly larger, 50 nm, more strictly round vesicles, permitting tentative classification based on anatomical criteria.Excitatory synapses on the lateral giants, believed from physiology to be electrical, generally had some gap junctions, but these were almost invariably paralleled by more prominent chemical junctional regions of unknown function. There may also be a class of interneurons making purely chemical synapses on the lateral giants. Synapses from primary afferents to sensory interneurons, believed from physiology to be cholinergic, had purely chemical morphology.Synapses with narrow elongated vesicles, similar to GABAergic vesicles seen in other neurons, frequently occurred on terminals of primary afferents. These synapses provide a basis for known presynaptic inhibition of afferent input. Consistent with physiology, such inhibitors sometimes also contacted the postsynaptic targets of the primary afferents and sometimes received input from other primary afferents. Afferent terminals also received some input from profiles richin large dense cored vesicles.Presumptive inhibitory input found on proximal dendrites of lateral giants provides a basis for known recurrent inhibition. However, similar inhibitory synapses that sometimes received local input from excitors of the lateral giants were also found distally mixed with excitatory inputs. These provide a basis for recently discovered distal inhibitory input following excitation and for tonic inhibition. © 1993 Wiley‐Liss, Inc.
Vestibular primary afferent projection to the cerebellum of the rabbit
Authors: Barmack N. H. , Baughman R. W. , Errico P. , Shojaku H. 
Published: January 2005

AbstractThe vestibular primary afferent projection to the cerebellum of the rabbit was studied with retrograde and orthograde tracers. We injected individual lobules of the cerebellum with horseradish peroxidase (HRP) or wheat germ agglutinin‐HRP (WGA‐HRP). Following these injections the numbers of labeled and unlabeled cells in Scarpa's ganglion were counted. Approximately 64–89% of the cells in Scarpa's ganglion were labeled retrogradely following uvula‐nodular injections. About 2% of the cells in the ipsilateral Scarpa's ganglion were labeled after injections of the flocculus. Virtually no cells were labeled following injections of the ventral paraflocculus.The vestibular primary afferent projection to the uvula‐nodulus is so extensive that it must be part of a collateral system that also innervates the vestibular nuclei. This collateral projection pattern was confirmed by using fluorescent tracers injected into the uvula‐nodulus and vestibular complex. Fluorogold was injected into the uvula‐nodulus and peroxidaserhodamine isothiocyanate was injected into the vestibular complex. More than 50% of the neurons in Scarpa's ganglion were double labeled by these subtotal injections.The dense vestibular primary afferent projection to the uvula‐nodulus was confirmed by using the C fragment of tetanus toxin (TTC) injected into the labyrinth as an orthograde tracer. With the TTC technique, the vestibular primary afferent projection to the uvula‐nodulus terminated exclusively in the ipsilateral granule cell layer of lobules 9d and 10. Much sparser vestibular primary afferent projections were found in the banks of major cerebellar sulci. A barely detectable projection was found to the flocculus and ventral paraflocculus. © 1993 Wiley‐Liss, Inc.
Localization of cardiac vagal preganglionic motoneurones in the rat: Immunocytochemical evidence of synaptic inputs containing 5‐hydroxytryptamine
Authors: Izzo P. N. , Deuchars J. , Spyer K. M. 
Published: January 2005

AbstractThe origin of cardiac vagal preganglionic motoneurones in the rat is still controversial and knowledge of the chemistry of synaptic inputs onto these neurones is limited. In this investigation vagal preganglionic motoneurones innervating the heart were identified by the retrograde transport of cholera toxin conjugated to horseradish peroxidase (CT‐HRP) combined with the immunocytochemical localization of 5‐hydroxytryptamine. Injection of CT‐HRP into the myocardium resulted in the retrograde labelling of neurones primarily in the ventral regions of the nucleus ambiguus (75.1%). Labelled neurones were also distributed in a narrow band through the reticular formation extending between the dorsal motor nucleus of the vagus nerve and the nucleus ambiguus (17.3%) as well as in the dorsal motor nucleus itself (7.6%).A combination of retrograde labelling with immunocytochemistry for 5‐hydroxytrypta‐mine revealed that the neuronal perikarya and the dendrites of cardiac vagal motoneurones in the nucleus ambiguus were often ensheathed in 5‐hydroxytryptamine‐immunoreactive axonal boutons. Electron microscopic examination of this material confirmed that there were synaptic specializations between these boutons and the cardiac vagal motoneurones. The identification of 5‐hydroxytryptamine‐containing synaptic inputs to this population of vagal motoneurones provides further detail towards the understanding of the regulation of heart rate by the parasympathetic nervous system. © 1993 Wiley‐Liss, Inc.
Noradrenergic innervation of the hypothalamus of rhesus monkeys: Distribution of dopamine‐β‐hydroxylase immunoreactive fibers and quantitative analysis of varicosities in the paraventricular nucleus
Authors: Ginsberg Stephen D. , Hof Patrick R. , Young Warren G. , Morrison John H. 
Published: January 2005

AbstractThe distribution of noradrenergic processes within the hypothalamus of rhesus monkeys (Macaca mulatta) was examined by immunohistochemistry with an antibody against dopamine‐β‐hydroxylase. The results revealed that the pattern of dopamine‐β‐hydroxylase immunoreactivity varied systematically throughout the rhesus monkey hypothalamus. Extremely high densities of dopamine‐β‐hydroxylase‐immunoreactive processes were observed in the paraventricular and supraoptic nuclei, while relatively lower levels were found in the arcuate and dorsomedial nuclei and in the medial preoptic, perifornical, and suprachiasmatic areas. Moderate levels of dopamine‐β‐hydroxylase immunoreactivity were found throughout the lateral hypothalamic area and in the internal lamina of the median eminence. Very few immunoreactive processes were found in the ventromedial nucleus or in the mammillary complex. Other midline diencephalic structures were found to have high densities of dopamine‐β‐hydroxylase immunoreactivity, including the paraventricular nucleus of the thalamus and a discrete subregion of nucleus reuniens, the magnocellular subfascicular nucleus. A moderate density of dopamine‐β‐hydroxylase immunoreactive processes were found in the rhomboid nucleus and zona incerta whereas little dopamine‐β‐hydroxylase immunoreactivity was found in the fields of Forel, nucleus reuniens, or subthalamic nucleus. The differential distribution of dopamine‐β‐hydroxylase‐immunoreactive processes may reflect a potential role of norepineph‐rine as a regulator of a variety of functions associated with the nuclei that are most heavily innervated, e.g., neuroendocrine release from the paraventricular and supraoptic nuclei, and gonadotropin release from the medial preoptic area and mediobasal hypothalamus. Additionally, quantitative analysis of dopamine‐β‐hydroxylase‐immunoreactive varicosities was performed on a laser scanning microscope in both magnocellular and parvicellular regions of the paraventricular nucleus of the hypothalamus. The methodology employed in this study allowed for the high resolution of immunoreactive profiles through the volume of tissue being analyzed, and was more accurate than conventional light microscopy in terms of varicosity quantification. Quantitatively, a significant difference in the density of dopamine‐β‐hydroxylase‐immunoreactive varicosities was found between magnocellular and parvicellular regions, suggesting that parvicellular neurons received a denser noradrenergic input. These differential patterns may reflect an important functional role for norepinephrine in the regulation of anterior pituitary secretion through the hypothalamic‐pituitary‐adrenal stress axis. © 1993 Wiley‐Liss, Inc.
Fibronectin‐like immunoreactivity of the basilar membrane of young and aged rats
Authors: Keithley Elizabeth M. , Ryan Allen F. , Woolf Nigel K. 
Published: January 2005

AbstractDysfunction of cochlear mechanics has been hypothesized to be a source of age‐related hearing loss and the basilar membrane mass and stiffness contribute to normal cochlear mechanics. Fibronectin, a large, extracellular matrix protein and a major component of the basilar membrane, may contribute to both the mass and stiffness of the membrane. Mesothelial cells underlying the basilar membrane may produce the fibronectin and also contribute to the mass of the membrane. Changes in either the fibronectin or the mesothelial cells might, therefore, have an effect on cochlear mechanics. In order to assess basilar membrane changes in aged animals, young adult (2–4 months) and aged (24–26 months) Sprague‐Dawley rats were evaluated for the presence of fibronectin‐like protein and mesothelial cells. The basilar membrane in the young animals had strong fibronectin‐like immunoreactivity throughout its length. The old animals, on the other hand, showed normal fibronectin immunoreactivity in the basilar membrane of the basal turn, but little or no reactivity in the apical cochlear turn. The number of mesothelial cells was reduced throughout the length of the membrane in aged animals, with the greatest loss in the basal turn (60% fewer cells). These two degenerative changes, which appear to be independent of each other, may contribute to the observed threshold shifts in aged cochleas. © 1993 Wiley‐Liss, Inc.
Functional organization of the ventral lateral geniculate complex of the tree shrew (Tupaia belangeri): I. Nuclear subdivisions and retinal projections
Authors: Conley Michael , Friederich‐Ecsy Beate 
Published: January 2005

AbstractThis is the first of two papers describing the organization and connections of the ventral lateral geniculate complex (GLv) in the tree shrew. Using a combination of Nissl, Golgi, histochemical, and immunocytochemical methods, we have identified two major divisions (lateral and medial) of GLv, both of which can be further subdivided. The lateral division contains three subdivisions, external, internal and intergeniculate leaflet. The medial division contains two subdivisions, medio‐rostral and medio‐caudal. All three lateral subdivisions receive input from the retina, the densest terminations being in the external subdivision and intergeniculate leaflet. These projections originate primarily from small retinal ganglion cells, although a feẁ large retinal ganglion cells also project to GLv by way of collateral branches. Each subdivision of GLv has a distinct cytoarchitectonic and immunocytochemical make‐up. In general, the level of immunoreactive endings for glutamic acid decarboxylase (GAD), leuenkephalin (ENK), and choline acetyltransferase (ChAT) parallels the distribution of retinal projections. Thus, all three markers are particularly dense in the external subdivision and the intergeniculate leaflet. Cell bodies immunoreactive for ENK are restricted to the external and intergeniculate leaflet subdivisions. The medial subdivisions stain relatively poorly for GAD, ENK, and ChAT, although each has other cytological features that differentiate them from the lateral subdivisions and the adjacent thalamic reticular nucleus. © 1993 Wiley‐Liss, Inc.
Regional and laminar organization of projections from the presubiculum and parasubiculum to the entorhinal cortex: An anterograde tracing study in the rat
Authors: Caballero‐Bleda Maria , Witter Menno P. 
Published: January 2005

AbstractThe regional and laminar organization of the projections from the presubiculum and the parasubiculum to the entorhinal cortex was analyzed in the rat with the anterograde tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L). The projections from the presubiculum were bilateral and confined to layers III and I of the medial entorhinal area (MEA). Both the ipsi‐ and the contralateral projections showed similar distributions and were almost of equal density. Projections to layer III of the entorhinal cortex arose predominantly from superficial layers of the presubiculum, whereas the fibers that reach layer I of the entorhinal cortex appear to originate preferentially from the deep layers of the presubiculum. These fibers also appeared to innervate weakly layer II of MEA. The parasubiculum distributed projections not only to MEA but also to the lateral entorhinal area (LEA), innervating layer II selectively. The innervation of LEA was quite dense and extensive. Very weak projections from the parasubiculum to the contralateral entorhinal cortex were observed in this study.The position of the terminal plexus in the entorhinal cortex was determined by the point of origin along both the dorsoventral and transverse or proximodistal axes of the presubiculum and parasubiculum. Projections from the presubiculum and parasubiculum entered the entorhinal cortex at the level of the injection, or slightly ventral to it, and the main terminal field was always present ventrally to the injection site. The dorsoventral axis of origin thus corresponded to a similarly oriented axis of termination in the entorhinal cortex. The distribution in relation to the origin along the transverse axis was more complex, and differences between the presubiculum and parasubiculum were present. The proximal presubiculum, i.e., the part closest to the subiculum, projected to the most lateral part of MEA and the central part of the presubiculum sent fibers to the most medial part of MEA. The distal part of the presubiculum, i.e., the part that borders the parasubiculum, projected to the central part of MEA. Projections from the portion of the parasubiculum directly adjacent to the presubiculum, the so‐called proximal parasubiculum, reached medial parts of MEA, and those originating in the central part distributed preferentially to lateral parts of MEA and adjacent medial parts of LEA. The distal part of the parasubiculum that borders the entorhinal cortex projected mainly to almost the full mediolateral extent of LEA.The regional and laminar organizations of the projections from the presubiculum and parasubiculum to the entorhinal cortex suggest that information is selectively conveyed not only to different cell layers but also to restricted dorsoventral and mediolateral parts of the entorhinal cortex. © 1993 Wiley‐Liss, Inc.
Early pattern of neuronal differentiation in the Xenopus embryonic brainstem and spinal cord
Authors: Hartenstein Volker 
Published: January 2005

AbstractWholemount antibody labeling techniques and horseradish peroxidase backfilling were used to analyze the pattern of neuronal differentiation in the embryonic Xenopus central nervous system between stages 22 and 35/36. In the spinal cord, the first neurons to differentiate are the Rohon‐Beard neurons; they are followed by ventral neurons with descending axons (descending interneurons, motoneurons) and lateral interneurons with commissural axons. The somata and axons of these primary neurons form dorsal, ventral, and lateral columns, respectively; the ventral and lateral columns uninterruptedly continue forward into the brainstem. The distribution and projection patterns of spinal neurons were analyzed quantitatively. Rohon‐Beard neurons, commissural interneurons, and primary motoneurons vary in number from segment to segment. Thus, these neurons are not distributed in a segmental pattern. In each segment, neurons of a given type project axons whose length varies over a wide range. The numerical distribution of length of axons formed by a population of neurons of a given type was calculated and expressed as the projection profile of these neurons. For each type of neuron and spinal segment, the projection profile is different. Furthermore, the projection profiles change in a systematic way along the spinal cord. For example, the fraction of Rohon‐Beard neurons with long ascending axons steadily increases if one moves towards caudal spinal levels. The findings suggest that suprasegmental cues with a graded distribution along the spinal cord determine the number and projection profile of a particular cell type in a given segment. © 1993 Wiley‐Liss, Inc.
Sensory innervation in the inner conical body of the vibrissal follicle‐sinus complex of the rat
Authors: Mosconi T. M. , Rice F. L. , Song M. J. 
Published: January 2005

AbstractThe innervation of the inner conical body of the vibrissal follicle‐sinus complex of the rat was examined by high‐voltage and conventional transmission electron microscopy of serial and semi‐serial sections. The inner conical body is innervated by axons supplied almost exclusively by several superficial vibrissal nerves that arise from the infraorbital branch of the trigeminal nerve and converge upon the neck of the follicle‐sinus complex. Each superficial vibrissal nerve contains a few Aδ myelinated axons and several bundles of 20–30 unmyelinated axons. These axons enter the inner conical body and distribute circumferentially within 7–10 ring‐like arrays that encircle the vibrissal follicle and are stacked through the superficial‐to‐deep extent of the inner conical body. Each ring consists of 1 or 2 myelinated axons and several small bundles of 2–15 unmyelinated axons enclosed in sheaves of parallel collagen fibrils. Myelinated axons provide exclusively lanceolate endings that may arise at the termination of the axon or at nodes of Ranvier. Within the small bundles, unmyelinated axons individually terminate in succession as abrupt cytoplasmic swellings referred to as cytoplasmic blebs, which contain mitochondria or clusters of clear or dense‐core vesicles. Because of their affiliation with collagen fibrils and the proximity of myelinated axons, the blebbed endings may have been misinterpreted as Ruffini endings in previous studies. Their structure, distribution, and origin from unmyelinated axons suggest that the blebbed endings may constitute a unique array of low‐threshold C‐mechanoreceptors. © 1993 Wiley‐Liss, Inc.
Cholinergic projection to the dorsal cap of the inferior olive of the rat, rabbit, and monkey
Authors: Barmack N. H. , Fagerson M. , Errico P. 
Published: January 2005

AbstractThe inferior olive is divided into several subnuclei that receive specific sensory information. The caudal dorsal cap of the medial accessory subdivision of the inferior olive receives horizontal optokinetic information from the nucleus of the optic tract. The immediately subjacent b̃‐nucleus receives vertical vestibular information mediated by a GABAergic pathway originating from the ipsilateral descending and medial vestibular nuclei. None of the transmitters to the dorsal cap have been identified.Using choline acetyltransferase (ChAT) immunohistochemistry, we have identified a cholinergic pathway that terminates exclusively in the dorsal cap of rats and monkeys. No other division of the inferior olive received a significant cholinergic innervation. In the rabbit, immunostaining for ChAT reveals a weaker and more diffuse cholinergic innervation of both the dorsal cap and the subjacent b̃‐nucleus.In rats and rabbits we injected iontophoretically the orthograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L) into the medial and descending vestibular nuclei (MVN, DVN) as well as the nucleus prepositus hypoglossi (NPH) in order to trace the possible origin of the cholinergic projection. PHA‐L injections into the NPH and medial aspect of the MVN labeled terminals within the contralateral dorsal cap. PHA‐L injections in the central and lateral aspects of the MVN as well as the DVN labeled the ipsilateral b̃‐nucleus.Pressure injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) in the caudal dorsal cap of the rabbit inferior olive demonstrated a predominantly contralateral projection to the dorsal cap from the lateral aspect of the NPH. However, pressure injections of HRP into the caudal dorsal cap combined with ChAT immunohistochemistry in the rabbit demonstrated that most of the neurons of the NPH that projected to the dorsal cap were not cholinergic, and that most of the ChAT‐positive neurons within the NPH occupied a more ventral location than the neurons within the NPH that were retrogradely labeled from the HRP injection into the contralateral dorsal cap.In the rat, we made lesions in the MVN, DVN and NPH by injection of ibotenic acid (0.3–0.5 m̈l), in an attempt to deplete the dorsal cap of the inferior olive of its cholinergic input. Lesions confined to the NPH and medial aspect of the MVN of the rat caused a loss of ChAT staining in the contralateral dorsal cap. Lesions placed more laterally within the MVN or DVN failed to deplete ChAT‐positive terminals in the contralateral or ipsilateral dorsal caps.The dorsal cap of the rat and monkey receives a discrete cholinergic projection. In the rat, this projection originates from the contralateral NPH. In the rabbit, the caudal inferior olive receives a weak cholinergic projection. The dorsal cap receives a projection from the contralateral NPH. However, this projection is mediated by a non‐cholinergic transmitter. © 1993 Wiley‐Liss, Inc.