bluuebunny/crossref_metadata_2025_split huggingface dataset:
Afferents to the trigeminal and facial motor nuclei in pigeon (Columba livia L.): Central connections of jaw motoneurons
Authors: Berkhoudt Herman , Klein Bradley G. , Zeigler H. Philip 
Published: January 2005

AbstractTrigeminal and facial motor nuclei innervating the pigeon's jaw muscles were identified using a combination of microstimulation and EMG recording and HRP injections were made iontophoretically. The trigeminal motor nucleus receives an ipsilateral projection from sensory neurons in the trigeminal mesencephalic nucleus which forms the afferent limb of the monosynaptic stretch reflex of the jaw‐closers. Both the trigeminal and facial motor nuclei receive bilateral projections from interneurons in the intertrigeminal area and the lateral (parvocellular) reticular formation of the pons and medulla. These neurons serve as premotor elements in the control of jaw movements, mediating ascending, descending and internuclear connections. The similarity of inputs to the trigeminal and facial nuclei may reflect their common function as jaw motoneurons in this species.
Parasagittal organization of the olivocerebellar projection in the mouse
Authors: Beyerl Brian D. , Borges Lawrence F. , Swearingen Brooke , Sidman Richard L. 
Published: January 2005

AbstractThe inferior olivocerebellar projection of the normal inbred C57BL/6J mouse was visualized after anterograde transport of horseradish peroxidase conjugated to the lectin wheat germ agglutinin (HRP‐WGA conjugate). Following injections of HRP‐WGA conjugate which filled the entire inferior olivary nucleus on one side, olivocerebellar fibers were followed across the midline of the medulla and into the contralateral cerebellar cortex via the inferior cerebellar peduncle. The molecular layer was heavily but nonuniformly labeled in all cortical lobules. Labeled olivocerebellar fibers within the contralateral cerebellar molecular layer were grouped into distinct bands separated by regions of molecular layer containing no labeled fibers. The bands of olivocerebellar terminals in the molecular layer were in turn organized into distinct sets of bands oriented in parasagittal planes. The organizational basis for this banding pattern, previously recognized by other workers in other mammalian and avian species, remains unknown.
Failure of host axons to regenerate through a once successful but later rejected long nerve allograft
Authors: Zalewski Andrew A. , Silvers Willys K. , Gulati Adarsh K. 
Published: January 2005

AbstractHost axons will regenerate through a long nerve allograft in an immunologically tolerant rat. However, if tolerance is abolished, rejection occurs and allogeneic cells (e.g., Schwann, vascular, perineurial, etc.) as well as regenerated host axons disappear from the allograft. Because following tolerance abolition host axons begin to regenerate into the connective tissue remnants of the rejected nerve allografts, the extent of this renewed axonal growth was investigated. It was found that in a tolerance‐abolished rat, host axons only regrew into the proximal 1 cm of a 4‐cm allograft which in a fully tolerant recipient would have had numerous allogeneic Schwann cell‐myelinated axons throughout its length. It is concluded that viable allogeneic cells (i.e., Schwann, fibroblast, and vascular) together with their connective tissue matrix provide the best way to aid host nerve fiber regeneration through a long nerve allograft.
Spinal cord development in anuran larvae: II. Ascending and descending pathways
Authors: Forehand Cynthia J. , Farel Paul B. 
Published: January 2005

AbstractThe ontogeny of ascending and descending spinal pathways was examined in bullfrog (Rana catesbeiana) tadpoles using the transported histochemical marker, horseradish peroxidase (HRP). The adult pattern of brainstem projections to lumbar spinal cord is evident as early as larval stage I (Taylor and Kollros, Anat. Rec., 94:7–24, 1946), although the number and size of projecting cells increases as the animal matures. These projections arise from presumptive hypothalamic neurons at the diencephalicmesencephalic border as well as from neurons of the vestibular nucleus, oculomotor nucleus, and reticular formation. In contrast to the stability of the pattern of descending projections, the sources of fibers ascending to the brainstem change during larval life. In early larval stages, brainstem projections from lumbar spinal cord arise primarily from Rohon‐Beard cells and neurons of the superficial dorsal horn. In later stages, neurons in the intermediate and ventral areas of the spinal gray can also be retrogradely labeled by HRP application to the brainstem at the level of the VIIIth nerve. Evidence of the existence of dorsal column and lateral cervical nuclei in adult frog and tadpoles older than stage VIII is presented.The ascending projections of embryonically born primary neurons were also investigated. Rohon‐Beard cells, which are sensory neurons with their cell bodies in the spinal cord, were found to send ascending processes as least as far rostral as the level of the VIIIth nerve entry zone. Anterolateral and dorsal marginal cells, probable homologs, respectively, of mammalian spinal border cells and cells of Waldeyer (1888), were also found to project rostrally at least to the rhombencephalon. These marginal cells persisted through metamorphosis into adulthood.
Gap junctions among the perikarya, dendrites, and axon terminals of the luminosity‐type horizontal cell of the turtle retina
Authors: Witkovsky P. , Owen W. G. , Woodworth M. 
Published: January 2005

AbstractGap junctions of the H1 horizontal cell of the turtle retina (Leeper, 1978) were studied in thin‐sectioned material and in freeze‐fracture replicas. Peri‐karyal gap junctions were extremely restricted, 0.02–0.07 μm2 in area, whereas those of axon terminals were much larger, most being 0.1–1.0 μm2. Both varieties, however, had the usual seven‐layered appearance in thin sec‐tion and measured 15 ± 1 nm in overall width between cytoplasmic faces. Freeze‐fractured views of the perikaryal junctions revealed roughly circular patches of P‐face 9‐nm particles and E‐face pits. The axon terminal gap junctions were seen as large areas of P‐face particles and E‐face pits containing occasional islands of unsnecialized membrane. Particle densities varied from 1, 455to 2, 448 μm−2 serial reconstruction was made or a portion of the axon terminal network in order to measure the surface areas of the axons con‐tained therein and the fraction occupied by gap junctions. These data demonstrated that the fractional area occupied by gap junctions was roughly in inverse proportion to the area of the axon region (tuberous core vs. terminal process). It is argued that this constitutes an impedance matching device to ensure adequate current flow through the axon processes. Assuming that each P‐face particle represents a connexon having a conductance of 10−10 and given the P‐face particle density and gap junctional areas determined in this report, we calculated that the gap junction distribution is adequate to account for the spatial properties of the horizontal cell axon network (Lamb, 1976).
Neural correlates of flight loss in a mexican grasshopper, Barytettix psolus. II. DCMD and TCG interneurons
Authors: Arbas Edmund A. 
Published: January 2005

AbstractComparison of the nervous systems of a flightless grasshopper (Barytettix psolus), and locusts (Schistocerca) is extended to include two large interneurons, the descending contralateral movement detector (DCMD) and the tritocerebral commissure giant (TCG). These interneurons are thought to play a role in locu st flight. Both were visualized in Barytettix with cobalt staining techniques.Most features of the two neurons are similar in both locusts and Barytettix. Yet, several differences were noted. In locusts, the dorsal DCMD branch in its metathoracic projection terminates in dorsolateral neuropile and synapses with flight motorneurons (Pearson and Goodman, 1979). In Barytettix, no branch terminates in the corresponding region. Of the animals examined, 52% lacked branches corresponding to locust dorsal branches. When present, they all had abnormal projections by comparison to their counterparts in locusts.The maintenance of the TCG in Barytettix with so similar a form to that of locusts suggests that the role of the cell in behavior other than flight should be examined. The differences in DCMD projection suggest that a discrete set of output connections may have been modified in Barytettix by the alteration of a single first‐order axonal branch.
Organization of the ascending projections from the ventral tegmental area: A multiple fluorescent retrograde tracer study in the rat
Authors: Albanese Alberto , Minciacchi Diego 
Published: January 2005

AbstractThe projections from the ventral tegmental area of Tsai (VTA) to the frontal cortex (FC), lateral septum (LS), nucleus accumbens (Acc), caudateputamen (CPu), and lateral habenula (LH) were investigated in the rat by means of the double retrograde fluorescent tracer technique.True blue and fast blue were used in combination with nuclear yellow as retrograde tracers. After combined injections placed into two different terminal fields, many singly and some doubly labeled neurons were seen in the midbrain. In all cases the labeled cells were observed in the ipsilateral VTA, while after injections placed into the LS and Acc some fluorescent neurons were also seen in the contralateral VTA. The patterns of distribution of the labeled neurons showed a topographic organization of the VTA efferent pathways. However, some degree of overlapping was evident in the distribution of cells retrogradely labeled from different terminal fields. The number of the doubly labeled neurons varied according to the sites of combined injections, but in each experiment it never exceeded 10% of the total number of labeled perikarya. Doubly labeled neurons were particularly numerous after combined injections placed into the FC, LS, or LH; on the contrary, very few doubly labeled cells were observed after combined injections placed into the CPu and LS or LH.The organization of the ascending VTA projections suggests that they are probably integrated into different anatomical sets.
The primary vestibular projection to the cerebellar cortex in the pigeon (Columba livia)
Authors: Schwarz Irmgard E. , Schwarz Dietrich W. F. 
Published: January 2005

AbstractThe cerebellar cortex of the pigeon receiving direct vestibular afferents was delineated by anterograde transport of [3H]‐amino acids injected the vestibular nerve. Labelled mossy fiber rosettes in the granular layer were concentrated in lobule X (nodulus) and to a lesser extent, in the ventral portion of lobule IXd (uvula and paraflocculus). A few solitary labelled rosettes were also found in more dorsal portions of lobule IX, as well as in the anterior lobe between lobule II and IV. The lingularernainedunlabelled. Dis‐crete injections of [3H]‐leucine into the cristae of each of the three semicircu‐lar canals or the utricular macula yielded a similar distribution of fewer labelled rosettes. A few primary mossy fiber terminals labelled after cochlear injections are attributed to afferents from the lagenar macula. Since effective diffusion of label from the injection site was excluded by controls, it is concluded that projection of individual canal and macula nerves to the ves‐tibulocerebellar cortex is not topographically separated. It is proposed that this extensive convergence of various afferents is required by the cerebellum to compute precise and directionally specific control signals during head rotation in all conceivable planes.
Subnuclear organization of the dorsal motor nucleus of the vagus nerve in the pigeon, Columba livia
Authors: Katz David Miles , Karten Harvey J. 
Published: January 2005

AbstractThe present study is the first of two papers describing the cytoarchitec‐tural and functional organization of the dorsal motor nucleus of the vagus nerve (DMN complex) in the pigeon. This paper describes the distribution of vagal motoneurons within the pigeon brainstem, and the cytoarchitectural organization of the DMN complex. Our description is based on studies of Nissl‐stained tissue from normal animals and on experimental studies using retrograde tracing techniques. Cells within the DMN complex were classified according to size, morphology, location, and staining characteristics.These studies demonstrate that vagal motoneurons are localized to (1) the DMN complex, (2) the region of the nucleus ambiguus, and (3) the region of the reticular formation extending between the dorsal motor nucleus and the nucleus ambiguus. Our cytoarchitectural studies indicate that the DMN complex is composed of at least 11 cytoarchitecturally distinct subnuclei. These subnuclei are evident in normal tissue and are especially prominent in cases where HRP backfilling produces a Golgi‐like staining of the motoneu‐rons. The subnuclei can be distinguished by their positions within the DMN complex and by the size, shape, and staining chracteristics of their constituent neurons. Comparison of these data with studies in other species indicates similar patterns of cytoarchitectural organization in the DMN com‐plex of some mammals. The diversity of nuclear subgroups within the DMN complex may be related to the heterogeneity of target organs innervated by these cells.
Postembryonic growth of the macula neglecta auditory detector in the ray, Raja clavata: Continual increases in hair cell number, neural convergence, and physiological sensitivity
Authors: Corwin Jeffrey T. 
Published: January 2005

AbstractQuantitative scanning electron microscopy in an age series demon‐strated that the macula neglecta auditory epithelium of the ray, Raja clavata, produces and accumulates sensory cells perpetually at 1–3 cells/ day, so that the total increases from approximately 500 cells at birth to 6,000 at 7 years of age. The shape of the macula also changes with growth, and changes in the marginal zones of small and intermediate size hair cells are consistent with this differential growth and their proposed role as hair cell production sites. The neurons contacting the epithelium do not increase in number as animals age; instead they hypertrophy, increasing axon diame‐ter and terminal field size. A hypothetical double‐gradient interaction be‐tween the growing nerves and new hair cells is proposed to explain the devel‐opment of synaptic connections and the continual production of individually oriented, functional hair cells. Electrophysiological recordings from the neu‐rons demonstrated best sensitivities between 40 Hz and 200 Hz, directional receptive fields, and little or no effect of changes in the ear's position relative to gravity. The convergence ratio from sensory cells to neurons increases because of their unequal patterns of growth, and physiological sensitivity improves 500‐fold and more as these animals age. These results contrast with current information on mammalian ears, where it appears that sensory cells are not produced at any time after birth.
Neocortical projections of the suprageniculate and posterior thalamic nuclei in the marsupial brush‐tailed possum, Trichosurus vulpecula(phalangeridae), with a comparative commentary on the organization of the posterior thalamus in marsupial and placental mammals
Authors: Neylon L. , Haight J.R. 
Published: January 2005

AbstractAxonal transport methods were used to determine the extent and organisation of neocortical projections from the Suprageniculate (SG) and posterior (PO) thalamic nuclei in the brush‐tailed possum. Our findings show that SG projects extensively to the auditory cortex, overlapping the cortical projection field of the modial geniculatc nucleus, and to the immediately neighbouring association cortex. Though the input relationships of SG appear similar to those reported for other mammals, placental and marsupial, a strong SG projection to auditory cortex has not been reported previously. Neocortical relationships of PO are characterised by an orderly point‐to‐point projection to all but the most rostral parts of the motor‐somaesthetic cortex. There is also a substantial projection to the entire posterior parietal association cortex. The PO‐neocortex projection is reciprocally organised. The PO‐neocortical projection in the possum is similar to that reported in the Virginia opossum, rat, and several other mammals. There is a major difference in organisation in comparison with certain monkeys where the PO projection is much more restricted and does not involve the motor and som‐aesthetic cortex. We conclude that PO is similarly organised in many, though not all, mammals, including the marsupials, rodents, insectivores, and prosimian primates. The possum SG, on the other hand, is clearly distinct from other mammals in its extensive projection to auditory cortex, though we cannot say at present whether this a general property of marsupial mammals or a peculiarity restricted to this species and possibly its close relatives.
Visceral representation within the nucleus of the tractus solitarius in the pigeon,Columba livia
Authors: Katz David Miles , Karten Harvey J. 
Published: January 2005

AbstractThis study describes the distribution of organ‐specific populations of vagal afferent fibers within the nucleus of the solitary tract (nTS) in the pigeon. The central projections of vagal sensory neurons were visualized by the centripetal and trans‐ganglionic transport of horseradish peroxidase from either the central cut ends of peripheral vagal branches or from HRP injection sites in peripheral vagal target tissues. This paper also includes a detailed description of the cytoarchitectural organization of the nTS in the pigeon based on studies of Nissl‐stained material.Vagal afferent fibers that innervate different peripheral target organs are partially segregated within cytoarchitecturally distinct subnuclei of the nTS. Gastrointestinal afferents, for example, project primarily to medial subnuclei. On the other hand, pulmonary, and on the basis of earlier studies, cardiovascular afferents, project primarily to lateral subnuclei, Moreover, the rostral to caudal distribution of gastrointestinal afferents corresponds to the rostrocaudal topography of the gastrointestinal tract. In addition, our data demonstrate a projection of gastrointestinal afferents to the lateral descending tract of the trigeminal nerve that appears to terminate in the external cuneate nucleus.The cytoarchitectural organization of visceral representations within the pigeon nTS corresponds closely to recent descriptions of this cell group in mammals. Comparison of our results with studies of the central connections of nTS neurons suggests that the subnuclear distribution of organ‐specific vagal afferents within nTS plays a critical role in the organization of ascending and descending visceral afferent pathways.
The islands of Calleja complex of rat basal forebrain. III. Histochemical evidence for a Striatopallidal system
Authors: Fallon James H. , Loughlin Sandra E. , Ribak Charles E. 
Published: January 2005

AbstractThe characteristics of the islands of Calleja complex (ICC) in the basal forebrain of the rat were studied with immunohistochemistry, histofluorescence, acetylcholinesterase staining, India ink vascular perfusions, electron microscopy, and steroid autoradiography. The ICC contains clusters of granule cells and associated medium‐sized and large cells in the surrounding neuropil of the olfactory tubercle and septum‐nucleus accumbens interface. The ICCs were found to contain monoamine fibers (dopamine and norepi‐nephrine), neuroactive peptide fibers (leu‐enkephalin, met‐enkephalin, substance P, cholecystokinin, luteinizing hormone‐releasing hormone), acetyl‐cholinesterase‐containing somata and dendrites, and medium‐sized and large cells that concentrate [3H] estradiol.The specific overlap and combination of putative neurotransmitters in separate compartments of the ICC suggest that these structures contain striatum‐ and pallidumlike components. Striatumlike regions are defined as the zone in the rim regions of the ICC and are innervated predominantly by dopamine and cholecystokinin inputs. Pallidumlike regions are defined as the synaptic zone near the medium‐sized and large cells of the cap and core regions of the ICC and they are innervated predominantly by enkephalin, substance P, and gamma aminobutyric acid inputs. The morphology, connections, and neurotransmitter relationships of the ICC, therefore, resemble classical Striatopallidal systems.The additional presence of substances involved in the reproductive neuroendocrine systems (luteinizing hormone‐releasing hormone, estradiol‐binding cells), especially in the medial ICC, suggest that some ICC are involved in an endocrine corticostriatopallidal system. These endocrine systems resemble other neocortically and allocortically originating corticostriatopallidal systems in terms of their cell types, connections, and neurotransmitter systems. A functional role for the ICC in extrapyramidal motor systems is proposed.
Nongeniculate afferents to striate cortex in macaques
Authors: Doty Robert W. 
Published: January 2005

AbstractHorseradish peroxidase (HRP) was injected in relatively massive amounts to cover most, or portions, of opercular striate cortex in four macaques. Absence of transcallosal or circumventricular labelling, plus discrete and consistent retrograde labelling in other areas in the four cases, assured the validity and specificity of the observations. Numerous labelled cells in regions directly bordering striate cortex, however, were excluded from the analysis because of the possibility of uptake consequent to physical diffusion. With this exception, all labelled cells were counted at roughly 2‐mm intervals for one case with extensive unilateral injection of HRP. Even excluding the closely circumstriate population, the totals indicate that more than 30% of the afferent input to striate cortex arises from nongeniculate sources. Four areas of neocortex together make up about one‐fourth of the total afferents: superior temporal sulcus 17.1%;inferior occipital area, 6.1%; intraparietal sulcus, 0.4%;and parahippocampal gyrus, 0.3%. Other areas projecting to striate cortex include claustrum, pulvinar, nucleus paracen‐ tralis, raphe system, locus coeruleus, and the nucleus basalis of Meynert. Cells of the latter were particularly striking with their very heavy uptake of HRP, and, even in cases of minimal effective injection, were scattered throughout an extensive area from the posterior edge of the globus pallidus passing rostrally beyond the chiasm and into the nucleus of the diagonal band. On the basis of their distribution and known cholinergic affinity, it is argued that this group also includes the cells labelled in and around lateral hypothalamus and cerebral peduncle, and that as a whole the group constitutes a cholinergic counterpart of the diffusely projecting monoaminergic systems. It seems possible that the basalis projection at first follows a forni cal‐subcallosal pathway to reach striate cortex via callosoperforant fibers.