bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical matching in the mammalian CNS: Lack of a competitive advantage of early over late‐generated cerebellar granule cells
Authors: Vogel Michael W. , Herrup Karl 
Published: January 2005

AbstractIn this report we use postnatal 3H‐thymidine injections to test whether granule cells that are generated early in postnatal cerebellar development and whose axons have access to their Purkinje cell target beginning in the first postnatal week have an advantage over granule cells generated 9 days later in the competition for target‐related stabilization. In the wild‐type mouse, 3–5% of the adult granule cell population is labeled by injection of 3H‐thymidine at either postnatal day 4 (P4) or P13. In the lurcher mutant, however, over 40% of the surviving granule cells are labeled by P4 injection while less than 1% are labeled after a P13 injection. Together, these results suggest that time of target contact is a critical factor in the competition for neuronal survival. The results from the lurcher chimeras, however, reveal that the situation is likely to be more complicated. In all chimeras examined, with target sizes ranging from 3 to 108% of wild type, equivalent numbers of granule cells were labeled at P4 and P13. These data lead to the contradictory conclusion that, in this experimental situation, early generated granule cells do not have a competitive advantage over later‐generated granule cells. The results are discussed in terms of various models of target stabilization. We propose that, of the various hypotheses, our results are best explained by postulating two distinct mechanisms for developmental cell death. Supporting evidence for this hypothesis from other neuronal systems is also briefly reviewed.
Morphology of a new population of spiking local interneurones in the locust metathoracic ganglion
Authors: Nagayama Toshiki 
Published: January 2005

AbstractA new population of spiking local interneurones is described in the metathoracic ganglion of the locust. All have their cell bodies in a cluster at the ventral, anteromedial portion of the ganglion close to the inner edge of an anterior connective. Their branches are restricted to the same half of the ganglion as their cell bodies.Fifteen types of these unilateral interneurones have been characterized by their morphology, as revealed by intracellular injection of dye, and by their physiology, as revealed by intracellular recording. Each interneurone has a characteristic shape and physiological action, but they form three distinct subgroups according to their gross morphology and their mode of operation. Interneurones of the first subgroup have ventral branches that extend over most of one‐half of the metathoracic neuropil and receive inputs mainly from exteroceptors on the ipsilateral hind leg. Typically, they have extensive and reciprocal receptive fields along the dorsoventral axis of the hind leg. Interneurones of the second subgroup have two main ventral branches which extend either medially or laterally and receive inputs mainly from proprioceptors of the hind leg. Interneurones of the third subgroup have few ventral branches and are inhibited by inputs anywhere on the hind leg.
Effects of unilateral cochlea removal on anteroventral cochlear nucleus neurons in developing gerbils
Authors: Hashisaki George T. , Rubel Edwin W. 
Published: January 2005

AbstractAfferent regulation of neurons in the cochlear nucleus as a function of age was investigated at the light microscope level. Unilateral cochlea removal was performed on Mongolian gerbils of three age groups: 1, 8, and 20 weeks postnatal. Animals survived for either 2 days or 2 weeks. An additional group of neonatally operated animals had a prolonged survival of 9 weeks. The number of neurons in anteroventral cochlear nucleus (AVCN) was counted, and cross‐sectional area measurements of large spherical cells in AVCN were made.In animals 1 week old at the time of surgery, there was a 35% reduction in neuron number in AVCN after 2 days, a 58% reduction after 2 weeks, and a 59% reduction 9 weeks after inner ear destruction. However, in animals 20 weeks old at the time of surgery, there was no cell loss in AVCN either 2 days or 2 weeks after surgery. Animals in each age group showed a reduction in cross‐sectional area of large spherical cells in AVCN after cochlea ablation. The gerbils that underwent cochlea removal at 8 and 20 weeks showed an average decrease of 14–18%. This effect was seen as early as 2 days after cochlea removal. Animals that underwent cochlea removal at 1 week exhibited the greatest change; a 25% decrease at 2 days progressed to 38% at 2 weeks following cochlea removal. No appreciable further changes were seen at 9 weeks after neonatal cochlea removal.The results indicate greater susceptibility of 1‐week‐old gerbil cochlear nucleus neurons to peripheral loss than found in older animals. In all groups the changes in cell size and neuron number occurred considerably sooner after cochlea ablation than previously has been reported. Interestingly, these changes were seen before the onset of hearing and before the onset of measurable cochlear microphonic responses to sound.
Ultrastructural study of the GABAergic, cerebellar, and mesodiencephalic innervation of the cat medial accessory olive: Anterograde tracing combined with immunocytochemistry
Authors: de Zeeuw C. I. , Holstege J. C. , Ruigrok T. J. H. , Voogd J. 
Published: January 2005

AbstractThe rostral medial accessory olive (MAO) of the cat was studied by using an ultrastructural technique combining wheat germ agglutinin–coupled horseradish peroxidase (WGA‐HRP) anterograde tracing and postembedding GABA immunocytochemistry. One group of cats received a WGA‐HRP injection in the posterior interposed nucleus of the cerebellum and another group received an injection in the nucleus of Darkschewitsch.Based on differences in their morphology three types of GABAergic and three types of nonGABAergic terminals were observed. One type of GABAergic terminal was often GABA/WGA‐HRP double‐labeled in the cerebellar experiments, and one type of nonGABAergic terminal was often WGA‐HRP‐labeled in the mesodiencephalic experiments.Following injections of WGA‐HRP in the cerebellar nuclei virtually all WGA‐HRP‐labeled terminals were GABA positive. Quantification of these GABA/WGA‐HRP‐double‐labeled terminals showed that (1) 30% of the GABAergic terminals randomly selected from the entire neuropil were double‐labeled, (2) 13% of the GABAergic terminals adjacent to perikarya were double‐labeled, and (3) 34% of the GABAergic terminals strategically located next to both of the dendritic elements linked by a gap junction were doublelabeled. Statistical analysis of the above data showed that significantly fewer GABAergic terminals adjacent to perikarya were double‐labeled (P < .001) than would be expected from the double‐labeled proportion of the randomly selected GABAergic terminals.Following injection of WGA‐HRP in the nucleus of Darkschewitsch, all WGA‐HRP‐labeled terminals were GABA‐negative. Quantification of these terminals showed that (1) 26% of the randomly selected nonGABAergic terminals were WGA‐HRP labeled, (2) 20% of the nonGABAergic terminals adjacent to perikarya were WGA‐HRP labeled, and (3) 23% of the nonGABAergic terminals strategically located next to a gap junction were WGA‐HRP labeled. No significant differences were found among these populations.Quantification of terminals of both groups of experiments mentioned above showed that GABAergic terminals composed (1) 38% of the randomly selected terminals, (2) 64% of the terminals apposed to perikarya, and (3) 53% of the terminals strategically located next to gap junctions. Statistical analysis of the above data showed that significantly more GABAergic terminals were located adjacent to perikarya (P < .001) and strategically next to a gap junction (P < .05) than would be expected from the random GABAergic innervation.The above findings of the GABAergic, cerebellar, and mesodiencephalic input are discussed with regard to their functional role in the neuronal cir‐ cuitry of the rostral MAO. In addition, the possible noncerebellar origins of the GABAergic inputs to the inferior olive are discussed.
Functional organization of mustached bat inferior colliculus: II. Connections of the FM2 region
Authors: Frisina Robert D. , O'Neill William E. , Zettel Martha L. 
Published: January 2005

AbstractEcholocating bats estimate target distance by analyzing the time delay between frequency‐modulated portions of their emitted ultrasonic vocalizations and the resultant echoes. In the companion paper we investigated, in the central nucleus of the inferior colliculus, the representation of the predominant second‐harmonic frequency‐modulated component (FM2) of the mustached bat biosonar signal (O'Neill et al.: J. Comp. Neurol. 283:000–000, '89). In the present paper we report the connections of this part of the colliculus, as determined by focal, iontophoretic injections of HRP following single‐unit mapping of the FM2 representation. It was found that the major inputs to the FM2 region of the inferior colliculus come from the contralateral cochlear nucleus; ipsilaterally from the medial superior olive, periolivary nuclei, and ventral and intermediate nuclei of the lateral lemniscus; and bilaterally from the lateral superior olive and dorsal nucleus of the lateral lemniscus. This study identifies for the first time those specific regions of brainstem nuclei providing input to the central nucleus of the inferior colliculus that process FM2 information in the mustached bat. The primary outputs of the FM2 region project to the medial and dorsal divisions of the medial geniculate body. In sharp contrast to other mammals, we found little evidence of connections to the ventral division of the medial geniculate. Other regions receiving significant inputs from the FM2 area include the deep superior colliculus ipsilaterally and the ipsilateral lateral pontine nuclei. Some fibers also terminated near the midline in the dorsal midbrain periaqueductal gray. Sparse intrinsic connections were also seen to the ipsilateral dorsoposterior division of the central nucleus and to the contralateral inferior colliculus at a location homologous to the injection site in the anterolateral division. The finding that FM2 projections to the medial geniculate heavily favor the medial and dorsal divisions is consistent with the location of “FM‐FM” delay‐dependent facilitation neurons found by Olsen (Processing of Biosonar Information by the Medial Geniculate Body of the Mustached Bat, Pteronotus parnellii. Dissertation, Washington Univ., St. Louis, '86) in these divisions, and with thalamocortical projection patterns in this species. These findings demonstrate that for the FM portions of the biosonar signal, a transformation from a tonotopic form of processing to a more specialized, convergent pattern of organization occurs at the level of the inferior colliculus outputs.
Retinogeniculate projection fibers in the monkey optic nerve: A demonstration of the fiber pathways by retrograde axonal transport of WGA‐HRP
Authors: Naito Jumpei 
Published: January 2005

AbstractSeven Japanese monkeys (Macaca fuscata) were used to investigate the fiber pathways of the optic nerve. Optic nerve fibers and retinal ganglion cells were retrogradely labeled by iontophoretic injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) into electrophysiologically defined positions of the lateral geniculate nucleus (LGN). By gross anatomical observation, the optic nerve usually had one distinct bend, which flexed dorsally 3‐4 mm from the eyeball, and occasionally another ventrally directed bend was found just behind the eyeball. In the optic nerve head, fibers from the various retinal areas were arranged in a wedge according to the fiber trajectory on the retinal surface. For about a 3 mm distance from the disc, fibers rapidly spread out radially. Subsequently, rather than scattering dorsoventrally, they progressed to the chiasm with a gradual increase in the degree of mediolateral (nasotemporal) scatter. The degree of the scatter was different depending on the retinal site from which the axons originated. Fibers from the peripheral retina spread out widely for a few millimeters behind the eyeball. Thereafter the scatter was rather limited until the chiasm. On the other hand, the scatter of fibers from the foveal and parafoveal areas progressed gradually through the nerve. The present study also suggests that the difference in scatter depends on the types of cells of origin. Fibers from large ganglion cells displayed more extensive scatter than fibers from medium‐sized cells. In spite of the extensive scatter of fibers, two clear segregations were found; one was a dorsoventral segregation, which was displayed by both central and peripheral retinal fibers, and the other was a center‐peripheral segregation in which the fibers from the nasal central (papillomacular) retina were located almost exclusively in the central part of the optic nerve surrounded by peripheral retinal fibers. However, the temporal central retinal fibers were located in the lateral periphery of the nerve, and they overlapped significantly with fibers from the temporal peripheral retina. Furthermore, a broad intermingling was found between nasal and temporal peripheral retinal fibers owing to their mediolateral scatter. Thus, the present findings based on more precise anatomical techniques indicate that the classical notion of the retinal quadrant topography in the monkey optic nerve probably is suspect. In addition, the “rotation” of the fiber arrangement was not demonstrated.
Olivocerebellar and cerebelloolivary connections of the oculomotor region of the fastigial nucleus in the macaque monkey
Authors: Ikeda Yoichi , Noda Hiroharu , Sugita Shoei 
Published: January 2005

AbstractAnatomical connections of the caudal portion of the fastigial nucleus (FN) with the inferior olive (IO) were studied in macaque monkeys with wheat‐germ‐agglutinin‐conjugated horseradish peroxidase (WGA/HRP) and HRP. When injected HRP was confined to a caudal portion of the FN, retrogradely labeled Purkinje cells (P cells) appeared in the oculomotor vermis. We defined the area that receives the projection from vermal lobule VII as the fastigial oculomotor region. The same HRP injection resulted in retrograde labeling of IO neurons in an area of group b (of Bowman and Sladek: J. Comp. Neurol. 152:299‐316, '73) of the contralateral medial accessory olive (MAO). This area was designated as the Z‐portion because in the coronal section it appears like the letter “Z.” Retrogradely labeled IO neurons were also found in the Z‐portion when HRP was injected into the oculomotor vermis, indicating that neurons in this portion project to both the fastigial and vermal oculomotor regions. Anterogradely labeled axons from the contralateral fastigial oculomotor region also terminated in the Z‐portion.When the effective site included a region anterior to the fastigial oculomotor region, labeled P cells appeared in lobule V and labeled IO neurons appeared in group a. Labeled terminals of fastigial fibers were also found in group a. When the effective site included a region ventral to the oculomotor region, labeled P cells appeared in vermal lobules VIII and IX and labeled IO neurons appeared in caudal parts of a and b, in addition to group c. HRP injection into the posterior interposed nucleus (PIN) resulted in labeling of P cells in the paravermal zone and of IO neurons in the rostral two‐thirds of the MAO and the dorsal accessory olive (DAO). The location of the labeled terminals coincided with the region where the densest labeling of IO neurons was found. Thus, the olivary projections to both the cerebellar cortex and deep cerebellar nuclei and the nucleoolivary projection exhibited a closely related topographical organization.
Sex‐specific neuronal respecification during the metamorphosis of the genital segments of the tobacco hornworm moth Manduca sexta
Authors: Thorn Robert S. , Truman James W. 
Published: January 2005

AbstractAt metamorphosis, the terminal abdominal segments of larvae of the moth Manduca sexta transform into either male or female genitalia. At the start of this transformation, the larval muscles degenerate but their remains may persist to form the scaffolding on which the new adult muscles differentiate. The survival and subsequent orientation of larval muscle remnants is determined by the sex of the individual and is independent of motor innervation at the start of metamorphosis. Many of the larval motoneurons persist through metamorphosis and innervate the skeletal muscle of the adult. The survival of particular motoneurons is also sex‐dependent and correlated with the survival of its respective muscle remnant. No new skeletal motoneurons arise postembryonically, so all of the adult skeletal muscle motoneurons are derived from preexisting larval skeletal muscle motoneurons.The fates during metamorphosis are more complex for the visceral muscle motoneurons. Those innervating the adult hindgut of both sexes are identical and are derived from the larval hindgut motoneurons. Other hindgut motoneurons in the larva switch targets during metamorphosis and come to innervate the oviduct in adult females or perish in adult males. Other regions of the reproductive tract become innervated by adult‐specific cells that differentiate during metamorphosis. These cells come from distinct lineages in males and females.
Development of vasoactive‐intestinal‐polypeptide‐immunoreactive neurons in the rat occipital cortex: A combined immunohistochemical‐autoradiographic study
Authors: Cavanagh Marion E. , Parnavelas John G. 
Published: January 2005

AbstractThe postnatal development of vasoactive intestinal polypeptide (VIP)‐immunoreactive neurons, previously labeled with [3H]thymidine on embryonic days E14‐E22, has been studied in the rat occipital cortex. Immunohistochemistry combined with autoradiography showed very little evidence of an “inside‐out” pattern of maturation. Most VIP neurons are generated between E17 and E21 and are found in layers II‐IV of the cortex, but their position within these layers is not dictated by their date of birth. There is evidence of a temporal maturation since E17 VIP neurons were seen first (at day 7) and E21 last. Peak numbers of VIP neurons were generated on E19. The numbers of VIP‐immunoreactive neuronal somata detected in the cortex increased from the first week after birth to the third week and declined thereafter. However VIP‐immunoreactive dendrites were still visible, suggesting that VIP levels in the cell bodies were very low, and not that there was a loss of neurons.
Enkephalin‐like immunoreactivity in the cat superior colliculus: Distribution, ultrastructure, and colocalization with GABA
Authors: Mize R. Ranney 
Published: January 2005

AbstractThe distribution of enkephalin (ENK) immunoreactivity has been examined in the cat superior colliculus (SC) by means of light and electron microscope immunocytochemistry. The antisera were directed against leucine enkephalin but also recognized methionine enkephalin. Colocalization of ENK with gamma aminobutyric acid (GABA) was studied with a two‐chromagen double‐labeling technique. Enkephalin antiserum labeling was highly specific. Dense neuropil labeling was found only in a thin band 75–100 μm wide within the upper superficial gray layer of SC. Negligible neuropil labeling was seen deeper, except for patches of label within the intermediate gray layer. Intensely labeled neurons also had a specific distribution. Forty‐seven percent were located within the upper 200 μm of SC, 40% within the deep superficial gray layer, 11% in the optic layer, and only 2% below that layer. Almost all ENK‐labeled cells were small (mean area of 117 μm2). Some of these had horizontal fusiform cell bodies and horizontally oriented dendrites. Others had small round somata and thin, obliquely oriented dendrites. In double‐labeling experiments, 18% of anti‐ENK‐labeled cells were also immunoreactive for GABA.Four distinct types of ENK‐labeled profile were identified with the electron microscope. Presynaptic dendrites (PSD) with loose accumulations of synaptic vesicles were densely labeled with the antiserum. Conventional dendrites were also labeled. Both types of labeled profile received input from unlabeled synaptic terminals, including those from the retina that contained pale mitochondria and round synaptic vesicles and formed asymmetric synaptic contacts. Retinal terminals were never labeled with the antisera. However, some axon terminals with round synaptic vesicles, dark mitochondria, and symmetric synaptic densities were labeled by the antisera, as were some thinly myelinated axons. These results show that there is a small population of enkephalinergic neurons in the cat SC, some of which also contain GABA. Because not all cells with identical morphologies were double labeled, it appears that neurons of like morphology are chemically heterogeneous.
Nerve growth factor receptor immunoreactive profiles in the normal, aged human basal forebrain: Colocalization with cholinergic neurons
Authors: Mufson Elliott J. , Bothwell Mark , Hersh Louis B. , Kordower Jeffrey H. 
Published: January 2005

AbstractA monoclonal antibody raised against the receptor for nerve growth factor (NGF) has been used to map the distribution of NGF receptor‐containing profiles within the human basal forebrain of four male and three female elderly patients without neurologic or psychiatric illness. Immunohistochemically processed tissue reveals a continuum of NGF receptor‐positive neurons located within the medial septum, vertical and horizontal limb nuclei of the diagonal band, and nucleus basalis. NGF receptor‐containing neurons are also found within the bed nucleus of the stria terminalis, the anterior commissure, the internal capsule, and the internal and external medullary laminae of the globus pallidus. Virtually all (>95%) NGF receptor‐containing neurons colocalize with the specific cholinergic marker choline acetyltransferase (ChAT) or the nonspecific marker acetylcholinesterase (AChE). Conversely, a few cholinergic perikarya are found which are not NGF receptor positive (and vice versa). These findings demonstrate that human basal forebrain neurons on which NGF receptor immunoreactivity is detected are primarily cholinergic and analogous to the nonhuman primate Ch1–Ch4 subgroups of Mesulam et al. (J. Comp. Neurol., 214:170–197, '83). NGF receptor‐containing fiber tracts are observed emanating from the medial septum and vertical limb nucleus of the diagonal band coursing medially within the fornix. Another fascicle originating mainly from the nucleus basalis and travelling within the external capsule enroute to the cortex is observed innervating all cortical layers.Comparison of NGF receptor‐ and ChAT‐containing neurons reveals cholinergic perikarya within the striatal complex, whereas virtually no NGF receptor‐containing neurons are found in these structures. An occasional displaced NGF receptor‐containing neuron is seen in the ventrolateral portion of the putamen and the white matter underlying the nucleus accumbens. These data are discussed in terms of the relationship of NGF receptor‐ and ChAT‐ containing neurons within the basal forebrain and in terms of the possible functional significance of NGF in normal and diseased brain.