bluuebunny/crossref_metadata_2025_split huggingface dataset:
An anatomical substrate for the inhibitory gradient in the VLVp of the owl
Authors: Takahashi Terry T. , Barberini Crista L. , Keller Clifford H. 
Published: January 2005

AbstractThe interaural difference in the level of sounds is an important cue for the localization of the sound's source. In the barn owl, a keen auditory predator, this binaural cue is first computed in the nucleus ventralis lemnisci laterale, pars posterior (VLVp), a cell group found within the fibers of the lateral lemniscus. Its neurons are excited by inputs from the contralateral ear and inhibited by inputs to the ipsilateral ear and are therefore sensitive indicators of interattral level difference. The excitation arrives by a direct input from the contralateral nucleus arigularis, a cochlear nucleus, and the inhibition is mediated by a commissural projection that interconnects the VLVps of the two sides. The dorsally located neurons in the VLVp are more heavily inhibited than those found more ventrally, thus giving rise to a gradient of inhibition. This inhibitory gradient plays a central role in recent models of VLVp function. We present evidence based on standard anterograde tracing methods that this gradient of inhibition is mediated by a dorsoventral gradient in the density of synaptic inputs from the contralateral VLVp, the source of inhibition. Specifically, injection of tracers into one VLVp, regardless of the position of the injection within the nucleus, produced a vertically oriented field of label that was densest along the dorsal margin of the contralateral VLVp and became sparser at more ventral levels. Furthermore, we found that injections into the medial and lateral aspects of the nucleus produced this dorsoventrally graded field of label along the medial and lateral aspects of the contralateral VLVp, respectively. Finally, we confirmed an earlier observation suggesting that the anterior and posterior aspects of one VLVp project to the anterior and posterior aspects of the contralateral nucleus, respectively. © 1995 Wiley‐Liss, Inc.
Colocalization of γ‐aminobutyric acid with vasopressin, vasoactive intestinal peptide, and somatostatin in the rat suprachiasmatic nucleus
Authors: Buijs Ruud M. , Wortel Joke , Hou Yang‐Xun 
Published: January 2005

AbstractThe seemingly contradictory observations in previous publications that γ‐aminobutyric acid (GABA) is detected in all cell bodies of the suprachiasmatic nucleus (SCN) and that terminals originating from the SCN are only 20–30% GABA positive prompted us to investigate whether this might be explained by a preference of colocalization in terminals of certain peptidergic neurons in the SCN or by a day/night rhythm in GABA synthesis. At three different circadian times, animals were perfusion fixed, and their SCNs were stained for vasopressin (VP), somatostatin (SOM), or vasoactive intestinal polypeptide (VIP). Subsequently, the number of GABA peptide‐positive terminals was determined using GABA postembedding staining in ultrathin sections. It appeared that the highest percentage of colocalization with GABA was detected in VIP terminals (38%) and the lowest in VP terminals (15%). No differences in colocalization percentages could be observed in any parameter at any circadian time. In the dorsomedial hypothalamus, one of the target areas of the VP and VIP fibers from the SCN, a colocalization of GABA within VP and VIP terminals was found similar to that in the SCN. In the region of the somatostatin‐containing neurons in the SCN, a number of axoaxonal contacts could be observed that sometimes exhibited synaptic specializations. In nearly all cases, the axoaxonic terminals contained GABA and/or SOM. The conclusion is that the high level of intrinsic GABAergic connections in the SCN represents a putatively powerful mechanism to synchronize or shut down the activity of the SCN. We discuss the possibility that, depending on the firing frequency of the neurons, the colocalization of GABA with all peptides under investigation allows for the selection of which transmitter is released, the peptidergic one or the amino acid. © 1995 Wiley‐Liss, Inc.
Long‐term sensory hyperinnervation following neonatal skin wounds
Authors: Reynolds M. L. , Fitzgerald M. 
Published: January 2005

AbstractSkin innervation during wound healing was investigated using immunocytochemical staining with the panneuronal marker antiprotein gene product (PGP) 9.5, which labels the entire innervation of the skin throughout development and in the adult. Full‐thickness skin wounds in the hairy skin of the foot in neonatal rats result in pronounced hyperinnervation of the tissue that persists long after the wound has healed (at least 12 weeks). Quantification of this hyperinnervation by image analysis indicates that slcoin innervation density in the wounded area can increase up to 300%. The effect is greatest when wounds are performed at postnatal day (P) 0 or 7, declining when performed at P14 and P21 to resemble the weaker and transient effect in the adult. Staining with selective markers for different neuronal populations innervating skin (monoclonal anti‐RT97 staining the myelinated axons of large light sensory ganglion cells; anticalcitonin gene‐related peptide staining unmyelinated C axons, thinly myelinated Aδ axons, and a subpopulation of large A fibres) reveal that both A‐ and C‐fibre sensory axons contribute to this response. Destruction of the majority of the C‐fibre population with neonatal capsaicin pretreatment, which leaves large, A fibres intact, significantly reduces the hyperinnervation response at 14 days, confirming a major contribution from both A and C‐fibres. Sympathetic axons, stained with anti‐tyrosine hydroxylase, do not sprout into the wounded area. Furthermore, pretreatment of neonates with 6–hydroxydopamine, which destroys the sympathetic innervation, does not significantly reduce the overall sprouting response, as identified by anti‐PGP9. 5 staining. Behavioural sensory testing revealed a 50% drop in the mechanical threshold in the wounded area after 3 weeks. These remarkably long‐term and specific effects on sensory terminal axons following neonatal skin wounding indicate the plasticity of cutaneous innervation density following alterations in the target tissue at a critical stage of development. © 1995 Wiley‐Liss, Inc.
Trigeminal, vagal, and spinal projections of supramedullary cells in the puffer fish, Takifugu niphobles
Authors: Funakoshi Kengo , Abe Toshio , Kishida Reiji 
Published: January 2005

AbstractThe supramedullary cells (SMCs) of teleosts have been studied for nearly 100 years, but their peripheral connectional have remained obscure. We examined the supramedullary cells of the puffer fish, Takifugu niphobles, using horseradish peroxidase transport. Horseradish peroxidase labeling was found bilaterally after application to the trigeminal, the posterior branch of the vagal, and thee spinal nerves, No labeled neurons were found after application to the anterior or visceral branches of the vagal nerve. Thus, labeled SMCs were found only after application to the nerves containing cutaneous branches.Some rostrocaudal topographical labeling was found after selective application to each of the four branches of the trigeminal nerve. Labeled neurons were more common in the rostral than in the central or caudal part of the SMC region. Some topographical labeling was also found after application to the first, second, and third spinal nerves, but the topography was not very clear, and there was considerable overlap in the distribution of labeled cells. The sum total of labeled SMCs after unilateral horseradish peroxidase application to each peripheral nerve was more than three times the total number of ipsilateral SMCs, indicating that a single SMC projects several peripheral processes into different nerves.From these results, and taking previous studies into consideration, we propose that supramedullary neurons have a phylogenetic relationship with the spinal dorsal cells of the lamprey and with the extramedullary cells of the amphibian embryo. © 1995 Wiley‐Liss, Inc.
Dark‐rearing changes dendritic microtubule‐associated protein 2 (MAP2) but not subplate neurons in cat visual cortex
Authors: Reid S. N. M. , Daw N. W. 
Published: January 2005

AbstractSensory‐dependent modification of cortical morphology is one component of the cortical plasticity that occurs during the critical period for ocular dominance changes. In this study, we used dark‐rearing to examine the sensory dependency of subplate neuron death and the quantity of microtubule‐associate protein 2 (MAP2)‐positive dendrites. Kittens reared in total darkness until the peak of the critical period had fewer laterally extended MAP2‐positive dendrites than age‐matched normal kittens. This reduction was found in layer IV but not in layer V. Subsequent exposure to light for 10 days after dark‐rearing was sufficient to bring the number of MAP2‐positive dendrites to the normal level. Contrarily, dark‐rearing did not prevent subplate neurons from dying. Exposure to light after dark‐rearing did not increase the number of potential dying neurons. These results show that the quantity of MAP2‐positive dendrites is sensory‐dependent; however, the death of the subplate neurons is not. Therefore, the death of subplate neurons is probably not directly involved in sensory‐dependent modifications of synaptic connections. The possible involvement of laterally extended MAP2‐dendrites in visual plasticity is discussed. © 1995 Wiley‐Liss, Inc.
Cajal‐Retzius neurons in human cerebral cortex at midgestation show immunoreactivity for neurofilament and calcium‐binding proteins
Authors: Verney Catherine , Derer Paul 
Published: January 2005

AbstractAlong with subplate neurons, Cajal‐Retzius cells (CRc) are the first neurons to be generated in the cortical anlage. Studies of their chemical content, such as neurofilament and calcium‐binding proteins, might give indications on their role in cortical development at midgestation in human fetuses (20–24 gestation weeks), when the CRc are morphologically mature. Cajal‐Retzius cells were immunolabeled with antibodies to subunits of neurofilament proteins SMI31 and SMI32. The SMI32 antibodies (directed against the nonphosphorylated epitope) specifically labeled the CR cell bodies, dendrites, and proximal axons in a Golgilike fashion. Specific acetylcholinesterase activity is known to be typical of all the CRc, and double labeling for SMI32 immunoreactivity and acetyleholinesterase histochemistry demonstrated that all the CRc exhibited SMI32 immunoreactivity. The SMI31 antibodies (directed against the phosphorylated epitope) exclusively labeled the CRc axons, forming a dense positive network in the deep one‐half of layer 1. This plexus was much denser than the one described with the Golgi method (Marin‐Padilla, 1990: J. Comp Neurol 239:89–105). Calbindin D28k, parvalbumin, and calretinin immunoreactivities were visualized in the CRc. Double‐labeling experiments showed that most of the CRc contained both calbindin and calretinin and sometimes parvalbumin. These colocalizations revealed a chemical heterogeneity within the CRc population even though they were described as morphologically homogeneous. These colocalizations of calcium‐binding proteins in the CRc differed from the other nonpyramidal neurons where calbindin, calretinin, and parvalbumin are contained in different (mutually exclusive) neuronal populations.Based on the morphological features and differential chemical contents described for the CRc, different hypotheses on their possible role and fate are discussed. © 1995 Wiley‐Liss, Inc.
Efferent projections of the paraventricular thalamic nucleus in the rat
Authors: Moga Margaret M. , Weis Roger P. , Moore Robert Y. 
Published: January 2005

AbstractThe paraventricular nucleus of the thalamus (PVT) receives input from all major components of the circadian timing system, including the suprachiasmatic nucleus (SCN), the intergeniculate leaflet and the retina. For a better understanding of the role of this nucleus in circadian timing, we examined the distribution of its efferent projections using the anterograde tracer Phaseolus vulgarl's leucoagglutinin (PHA‐L). The efferent projections of the PVT are loosely organized along its dorsal‐ventral and anterior‐posterior axes. The anterior PVT sends projections to the SCN; the dorsomedial and ventromedial hypothalamic nuclei; the lateral septum; the bed nucleus of the stria terminalis; the central and basomedial amygdaloid. nuclei; the anterior olfactory nucleus; the olfactory tubercle; the nucleus accumbens; the infralimbic, piriform, and perirhinal cortices; the ventral subiculum; and the endopiriform nucleus. A small PHA‐L injection, restricted to the ventral portion of the anterior PVT, produces a similar pattern of labeling, except for a marked decrease in the number of labeled fibers in the hypothalamus, cortex, and lateral septum and an increase in labeling in the endopiriform nucleus and basolateral amygdaloid nucleus. The posterior PVT has a more limited efferent distribution than the anterior PVT, terminating in the anterior olfactory nucleus; the olfactory tubercle; the nucleus accumbens; and the central, basolateral, and basomedial nuclei of the amygdala. Our results show that the anterior PVT is ideally situated to relay circadian timing information from the SCN to brain areas involved in visceral and motivational aspects of behavior and to provide feedback regulation of the SCN. © 1995 Wiley‐Liss, Inc.
Afferent influences on brainstem auditory nuclei of the chicken: Regulation of transcriptional activity followiqg cochlea removal
Authors: Garden Gwenn A. , Redeker‐DeWulf Valerie , Rubel Edwin W 
Published: January 2005

AbstractNeuronal survival in the cochlear nucleus of young animals is regulated by afferent activity. Removal or blockade of nerve VIII input results in the death of 20–40% of neurons in the cochlear nucleus, nucleus magnocellularis (NM), of the 10–14 days posthatch chick. Neuronal death in NM is preceded by complete failure of protein synthesis and degradation of ribosomes. In addition, there is a biphasic change in the immunoreactivity of ribosomes for a monoclonal antiribosomal RNA antibody, Y10B. Initially, the entire population of afferentdeprived NM neurons loses Y10B immunoreactivity, but, after 6 or 12 hours of afferent deprivation, lack of Y10B immunoreactivity specifically marks dying NM neurons. Whether RNA synthesis is also altered in afferent‐deprived NM neurons has not previously been studied. To determine whether RNA synthesis in NM neurons is regulated by loss of afferent activity, we injected chicks with 3H‐uridine following unilateral cochlea removal and measured the incorporation of RNA precursor with tissue autoradiography. As early as 1 hour after cochlea removal, there was a significant decrease in 3H‐uridine incorporation by afferent‐deprived NM neurons. After longer periods of afferent deprivation (6 or 12 hours), the majority of dying NM neurons (marked by loss of Y10B immunoreactivity) fail to incorporate RNA precursor. Six or 12 hours following cochlea removal, the subpopulation of surviving NM neurons incorporates 3H‐uridine at increased levels over those observed 1 or 3 hours after cochlea removal. These findings suggest that nuclear function is regulated by afferent synaptic activity and that failure of RNA synthesis occurs early in the cell death process. © 1995 Wiley‐Liss, Inc.
Caudal medullary pathways to lumbosacral motoneuronal cell groups in the cat: Evidence for direct projections possibly representing the final common pathway for lordosis
Authors: Vanderhorst Veronique G. J. M. , Holstege Gert 
Published: January 2005

AbstractThe nucleus retroambiguus (NRA) projects to distinct brainstem and cervical and thoracic cord motoneuronal cell groups. The present paper describes NRA projections to distinct motoneuronal cell groups in the lumbar enlargement. Lumbosacral injections of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) were made to localize and quantify the retrogradely labeled neurons in the caudal medullary lateral tegmentum. These injections were combined with spinal hemisections to distinguish between neurons having ipsi‐ or contralaterally descending axons. The NRA‐lumbosacral fibers descend almost exclusively contralaterally, but neurons in areas surrounding the NRA project mainly ipsilaterally.In an anterograde tracing study, injections of WGA‐HRP or tritiated leucine were made in the region of the NRA to determine the NRA targets in the lumbosacral cord. Hemisections in C2 made it possible to distinguish between NRA projections and projections from neurons in the adjoining lateral tegmentum. The results show delicate NRA projections to distinct lumbosacral motoneuronal cell groups innervating specific hindlimb muscles (iliopsoas, adductors, and hamstrings) as well as axial muscles (medial longissimus and proximal tail muscles). The projection is bilateral, with a contralateral predominance. Ipsilaterally terminating fibers are derived from NRA neurons whose axons cross the midline at the level of the obex, descend through the contralateral spinal white matter, and recross at the level of termination. A conceptual description is presented in which the periaqueductal gray‐NRA‐lumbosacral projections form the final common pathway for lordosis in the cat. © 1995 Wiley‐Liss, Inc.
Intratelencephalic projections of the visual wulst in pigeons (Columba livia)
Authors: Shimizu Toru , Cox Kevin , Karten Harvey J. 
Published: January 2005

AbstractThe visual wulst is the telencephalic target of the thalamofugal visual pathway of birds, and thus the avian equivalent of the striate cortex of mammals. The anterograde tracer Phaseolus vulgaris leucoagglutinin was used to follow the intratelencephalic connections of the major constituents of the visual wulst in pigeons. In particular, efferent pathways from the granular layer (Intercalated nucleus of the hyperstriatum accessorium, IHA), supragranular layer (hyperstriatum accessorium, HA), and infragranular layers (hyperstriatum intercalatus superior and/or hyperstriatum dorsale, HIS/HD) were investigated. These efferent projections were confirmed by injections of the retrograde tracer cholera toxin subunit B into their terminal fields.When a deposit of the anterograde tracer was centered in IHA, which receives the visual thalamic input, efferent fibers were seen to extend mainly dorsomedially to HA. When a deposit of the anterograde tracer was centered in HA, efferent fibers were seen to extend mainly in three directions: (1) medially to the tractus septomesencephalicus, which sends projections to extratelencephalic visual nuclei; (2) ventrolaterally to the lateral portion of the neostriatum frontale, where there were also labeled cells after the retrograde tracer was injected in HA; and (3) ventromedially to the paleosfriatal complex, which is the avian equivalent of the mammalian basal ganglia. Furthermore, relatively minor terminal fields were seen in (4) the neostriatum caudale, (5) neostriaturn intermedium, (6) archistriatum intermedium, and (7) hyperstriatum laterale. Finally, HIS/HD have projections predominantly to HA and the dorsocaudal telencephaion (area corticoidea dorsolateralis and area parahippocampalis), as well as relatively minor projections to the areas which also receive projections from HA. No anterogradely labeled fibers were seen in the tractus septomesencephalicus following the tracer injections in HIS/HD.These results indicate that the visual information from the granular layer is distributed via the supragranular layer HA to multiple areas within the telencephalon, such as the neostriatum frontale and paleostriatal complex. In addition, HA is the source of an extratelencephalic projection via the tractus septomesencephalicus. Thus, the avian supragranular layer HA contains neurons which are the source of both intratelencephalic and extratelencephalic projections, whereas neurons of the mammalian cortex are segregated into two distinct layers, supragranular and infragranular layers, based on the targets of their projections. The findings are further discussed and compared to the mammalian striate cortex. © 1995 Wiley‐Liss, Inc.
Cells of the perireticular nucleus project to the developing neocortex of the rat
Authors: Adams Niels C. , Baker Gary E. 
Published: January 2005

AbstractThe perireticular nucleus is a recently described thin sheet of small cells among the fibres of the internal capsule, lying lateral to the thalamic reticular nucleus and medial to the globus pallidus (Clemence and Mitrofanis [1992]. J. Comp. Neurol. 322:167–180). During development, the perireticular nucleus is relatively large, lying in the path of the growing corticofugal and thalamocortical axons and filling the area of the internal capsule lateral to the thalamic reticular nucleus. After these axons have formed their connections, the perireticular nucleus rapidly decreases in size, leaving only a few cells in the adult (Mitrofanis [1992] J. Comp. Neurol. 320:161–181).In this study, we aiwed to investigate the connections between the developing cortex and thalamus by making injections of tracer into the cortical plate. Injections of Horse Radish Peroxidase (HRP), Wheat Germ Agglutinin bound to HRP (WGA‐HRP) and l'dioctadecyl 3, 3, 3′, 3 tetramethycarbocyanine perchlorate (DiI) were made in vivo between embryonic day (E)18 and adult and DiI was placed in the fixed brains of rats aged between E16 and postnatal day (P)1.Between E17 and P10, the retrograde perikaryal labelling resulting from these injections revealed a transient projection from the perireticular nucleus to the ipsilateral cortical plate. No cells were labelled in the thalamic reticular nucleus.This suggests that the perireticular nucleus must be regarded as a group of cells distinct from the thalamic reticular nucleus and having a separate role in development. Comparisons between the perireticular cells and the cells of the cortical subplate suggest that both may be playing comparable roles in early development, possibly guiding fibres towards their end stations or serving to rearrange the complex mapped projections linking thalamus and cortex. © 1995 Wiley‐Liss, Inc.
Macrophages and glia participate in the removal of apoptotic neurons from the Drosophila embryonic nervous system
Authors: Sonnenfeld Margaret J. , Jacobs J. Roger 
Published: January 2005

AbstractCell death in the Drosophila embryonic central nervous system (CNS) proceeds by apoptosis, which is revealed ultrastructurally by nuclear condensation, shrinkage of cytoplasmic volume, and preservation of intracellular organelles. Apoptotic cells do not accumulate in the CNS but are continuously removed and engulfed by phagocytic haemocytes. To determine whether embryonic glia can function as phagocytes, we studied serial electron microscopic sections of the Drosophila CNS. Apoptotic cells in the nervous system are engulfed by a variety of glia including midline glia interface (or longitudinal tract) glia, and nerve root glia. However, the majority of apoptotic cells in the CNS are engulfed by subperineurial glia in a fashion similar to the microglia of the vertebrate CNS. A close proximity between macrophages and subperineurial glia suggests that glia may transfer apoptotic profiles to the macrophages. Embryos affected by the maternal‐effect mutation Bicaudal‐D have no macrophages. In the absence of macrophages, most apoptotic cells are retained at the outer surfaces of the CNS, and subperineurial glia contain an abundance of apoptotic cells. Some apoptotic cells are expelled from the CNS, which suggests that the removal of apoptotic cells can occur in the absence of macrophages. The number of subperineurial glia is unaffected by changes in the rate of neuronal apoptosis. © 1995 Wiley‐Liss, Inc.