bluuebunny/crossref_metadata_2025_split huggingface dataset:
Barrelettes—architectonic vibrissal representations in the brainstem trigeminal complex of the mouse. II. Normal post‐natal development
Authors: Ma Pokay M. 
Published: January 2005

AbstractVibrissal representations in the brainstem trigeminal complex (BTC) of rodents are manifested as architectural sub‐units called barrelettes. The development of barrelettes was studied by using Nissl staining, cytochrome oxidase histochemistry, and Golgi‐impregnation methods. On the day of birth (PND‐1), barrelettes are manifested as longitudinal, histochemical cylinders in sub‐nuclei principalis, interpolaris and caudalis of the BTC. One day later (PND‐2), fully formed histochemical barrelette formations are seen in the three sub‐nuclei. The development of cytoarchitectural barrelettes lags behind histochemical barrelettes by about two days. Between PND‐2 and PND‐3, longitudinal cytoarchitectonic cylinders begin to appear. By PND‐3, BTC neurons segregate into five rows of barrelettes in the coronal plane. Segmentation of rows into individual barrelettes begins on PND‐4, and complete cytoarchitectonic barrelette formations are seen by PND‐5. Golgi‐impregnation shows that on the day of birth, primary afferent terminals and dendritic arbors of second‐order trigeminal neurons within the BTC are short and poorly ramified. Over the next five post‐natal days, lengthening of these processes as well as elaboration into secondary and tertiary branches take place. Growth of these processes continues for two additional weeks, contributing to the increase in barrelette neuropils (hollows). As the neuropils expand, neuronal somata are pushed toward barrelette sides. Morphometric measurements show that there is a relatively constant rate of growth of barrelettes over the first three post‐natal weeks. The growth rate of the barrelette formations is identical to that of BTC as a whole. Thus, at the time of birth, the volume of neural tissue in the brainstem allotted to vibrissae is fixed relative to that allotted to other sensory receptors.Several features of the early development of barrelettes are identified: (1) Chemoarchitectural barrelettes appear before cytoarchitectural barrelettes, suggesting that terminal arbors of primary trigeminal afferents are organized before their target neurons form barrelettes. (2) Early cytoarchitecture is manifested in the form of unsegmented rows, suggesting that rough, row‐based topological maps are first formed, which are then fine‐tuned into individual sub‐units. Recent evidence shows that other vibrissal representations—thalamic barreloids and cortical barrels—also follow these “afferent‐before‐target” and “row‐before‐individual units” sequences of development. This gradual, afferent‐dependent fine‐tuning of topological organization is analogous to similar events during the early development of the visual system, and may be a general feature of developing sensory systems. In the visual system, sensory input plays an important role in fine‐tuning centers in the brain; the mechanisms by which barrelettes are organized and fine‐tuned are still unknown. 1993 Wiley‐Liss, Inc.
Distribution, parabrachial region projection, and coexistence of neuropeptide and catecholamine cells of the nucleus of the solitary tract in the pigeon
Authors: Berk Mitchell L. , Smith Stacy E. , Mullins Lee A. 
Published: January 2005

AbstractThe chemical nature of the cells of the nucleus of the solitary tract (NTS) that project to the parabrachial nucleus (PB) was investigated in the pigeon by the use of fluorescent bead retrograde tracer and immunofluorescence for the detection of substance P (SP), leucineenkephalin (LENK), cholecystokinin (CCK), neurotensin (NT), somatostatin (SS), and tyrosine hydroxylase (TH). Cells immunoreactive for CCK were located in subnuclei lateralis dorsalis pars anterior (LDa) and medialis superficialis pars posterior, and caudal NTS (cNTS); 22–26.5% of these cells were double‐labeled bilaterally. Immunoreactive SP cells were found in ventral NTS subnuclei; 24–25% of these cells were double‐labeled bilaterally. Cells immunoreactive for LENK and NT were concentrated in the anterior NTS; 5.5–7.5% of the LENK cells were double‐labeled bilaterally, while 11% (ipsilateral) and 21% (contralateral) of the NT immunoreactive cells were double‐labeled. Many SS immunoreactive cells were found in peripherally located subnuclei; 5.5–6.5% of these cells were double‐labeled bilaterally. Catecholamine cells were distributed in LDa, peripheral subnuclei, and cNTS; 23% of these cells were double‐labeled ipsilaterally and 8.5% contralaterally. A two‐color double‐labeling immunofluorescence technique revealed many cells immunoreactive for both NT and LENK, only a rare cell immunoreactive for both SS and SP, and no cells immunoreactive for both TH and SP.Cells immunoreactive for SP, CCK, NT, and TH are major contributors to NTS projections to PB. The confinement of these substances to specific NTS subnuclei, which receive visceral sensory information from specific organs, may contribute to the chemical encoding of ascending visceral information. 1993 Wiley‐Liss, Inc.
Connections of somatosensory cortex in megachiropteran bats: The evolution of cortical fields in mammals
Authors: Krubitzer Leah A. , Calford Mike B. , Schmid Leisa M. 
Published: January 2005

AbstractThe cortical connections of the primary somatosensory area (SI or 3b), a caudal somatosensory field (area 1/2), the second somatosensory area (SII), the parietal ventral area (PV), the ventral somatosensory area (VS), and the lateral parietal area (LP) were investigated in grey headed flying foxes by injecting anatomical tracers into electrophysiologically identified locations in these fields. The receptive fields for clusters of neurons were mapped with sufficient density for injection sites to be related to the boundaries of fields, and to representations of specific body parts within the fields. In all cases, cortex was flattened and sectioned parallel to the cortical surface. Sections were stained for myelin and architectonic features of cortex were related to physiological mapping and connection patterns. We found patterns of topographic and montopographic connections between 3b and adjacent anterior parietal fields 3a and 1/2, and fields caudolateral to 3b (SII and PV). Area 1/2 had both topographic and nontopographic connections with 3b, PP, and SII. Connections of SII and PV with areas 3b, 3a, and 1/2 were roughly topographic, although there was clear evidence for nontopographic connections between these fields. SII was most densely connected with area 1/2, while PV was most densely connected with 3b. SII had additional connections with fields in lateral parietal cortex and with subdivisions of motor cortex. Other connections of PV were with subdivisions of motor cortex and pyriform cortex. Laminar differences in connection patterns of SII and PV with surrounding cortex were also observed. Injections in the ventral somatosensory area revealed connections with SII, PV, area 1/2, auditory cortex, entorhinal cortex, and pyriform cortex. Finally, the lateral parietal field had very dense connections with posterior parietal cortex, caudal temporal cortex, and with subdivisions of motor cortex. Our results indicate that the 3b region is not homogeneous, but is composed of myelin dense and light regions, associated with 3b proper and invaginations of area 1/2, respectively. Connections of myelin dense 3b were different from invaginating portions of myelin light area 1/2. Our findings that 3b is densely interconnected with PV and moderately to lightly interconnected with SII supports the notion that SII and PV have been confused across mammals and across studies. Our connectional evidence provides further support for our hypothesis that area 1/2 is partially incorporated in 3b and has led to theories of the evolution of cortical fields in mammals. © 1993 Wiley‐Liss, Inc.
Functional organization of the ventral lateral geniculate complex of the tree shrew (Tupaia belangeri): II. Connections with the cortex, thalamus, and brainstem
Authors: Conley Michael , Friederich‐Ecsy Beate 
Published: January 2005

AbstractConnections of the ventral lateral geniculate complex (GLv) in the tree shrew were traced by anterograde and retrograde transport of WGA‐HRP. The results buttress earlier findings that GLv in this species is composed of two main divisions, lateral and medial, each of which differs in its connections with the brainstem and cerebral cortex. The connections of the lateral division (GLv) suggest that it participates in visuosensory functions: it receives input from the retina, striate cortex, pretectum, and retino‐recipient layers of the superior colliculus. These connections help clarify the identification of the internal and external subdivisions of GLv inasmuch as projections from both the superior colliculus and pretectum terminate in the external subdivision and each, in turn, receives a projection from the internal subdivision.Connections of the medial division suggest that this part of the nucleus is involved with visuomotor functions. Thus, the medio‐caudal subdivision projects to the pontine nuclei, the prerubral field and the central lateral nucleus. The medio‐caudal subdivision also receives projections from the lateral cerebellar nucleus, so that the GLv‐ponto‐cerebello‐GLv loop involves mainly one subdivision of GLv. The medio‐rostral subdivision receives projections from the pretectum and parietal cortex. Its output is directed primarily at the intermediate and deep layers of the superior colliculus. All of these targets of GLv, the pons, prerubral field, and deep layers of the superior colliculus, are known to play a role in the coordination of head and eye movements.Additional connections of GLv with the vestibular nuclei, intralaminar nuclei, hypothalamus, and facial motor nucleus are also described. © 1993 Wiley‐Liss, Inc.
Regenerative outgrowth and distribution of the electroreceptive nerve fibers in the catfish Kryptopterus
Authors: Roth Anton 
Published: January 2005

AbstractThe ampullary electroreceptors on the trunk of Kryptopterus bicirrhis are induced and continuously maintained by a trophic substance released by their afferent nerve fibers. When the fibers are transected and the proximal stumps deflected to a new place, the regenerating fibers grow along new routes to the old electroreceptor sites and again induce organs there. The new routes consist of two sections. The first goes from the deflected stump end to other nearby running intact or degenerated nerves and fibers. In the second section, the regenerating fibers grow along these nerves and fibers to their distal ends, i.e., to the old electroreceptor sites. If the path‐guiding nerves and fibers are experimentally removed, the displaced fibers grow to the normal receptor areas directly. Growing out from the displaced stump, they spread out over the trunk in a pattern similar to the pattern displayed formerly by the original nerve fibers at this place. It is concluded that the outgrowing fibers do not possess a specificity for a certain receptor site or skin area, but spread out according to epigenetic factors in the periphery. © 1993 Wiley‐Liss, Inc.
Intrinsic connections of layer III of striate cortex in squirrel monkey and bush baby: Correlations with patterns of cytochrome oxidase
Authors: Lachica E. A. , Beck P. D. , Casagrande V. A. 
Published: January 2005

AbstractThis study used biocytin and horseradish peroxidase (HRP) to examine the intrinsic connections of the cytochrome oxidase (CO) rich blob and CO poor nonblob zones within layer III of striate cortex in two primate species, nocturnal prosimian bush babies (Galago crassicaudatus) and diurnal simian squirrel monkeys (Saimiri sciureus). Our main objective was to determine whether separate classes of lateral geniculate nucleus (LGN) cells projected to separate superficial layer zones or layers in either species. There were three significant findings. First, we confirm that layer III consists of three sublayers, IIIA, IIIB, and IIIC in both species. Layer IIIA receives input from layers IIIB, IIIC, and V, with little or no input from LGN recipient layers IV and VI. Layer IIIB receives its input from nearly every cortical layer. Layer IIIC, receives input principally from layers IVα [which receives its input from magnocellular (M) LGN cells] and from layers V and VI. Taken together with other findings on the extrinsic connections of these layers, our data suggest that IIIA and IIIC provide output to separate hierarchies of visual areas and IIIB acts as a set of interneurons. Second, we find that, as in macaque monkeys, cells in both IVβ and IVα of bush babies and squirrel monkeys projct to layer IIIB, converging within the blobs. These results suggest that information from all LGN cell classes [parvocellular (P), M, and the Koniocellular (K) or their equivalents] may be integrated within the blobs. Thus, blobs in all of these primates may perform a function that transcends visual niche differences. Third, our data show a species specific difference in the connections of the IIIB nonblobs; nonblobs receive indirect input via IVα from the LGN M pathway in bush babies but receive indirect input via IVβ from the LGN parvocellular (P) pathway in squirrel monkeys. These findings indicate that the role of nonblob zones within striate cortex differs from that of blob zones and takes into account visual niche differences. © 1993 Wiley‐Liss, Inc.
Localization of tyrosine hydroxylase in neuronal targets and efferents of the area postrema in the nucleus tractus solitarii of the rat
Authors: Kachidian Philippe , Pickel Virginia M. 
Published: January 2005

AbstractCatecholamines in the nucleus tractus solitarii (NTS) have been implicated in autonomic responses to circulating hormones that act on neurons in the area postrema, the most caudal circumventricular organ in brain. We combined immunoperoxidase labeling of the anterograde tracer, Phaseolus vulgaris leucoagglutinin (PHAL) with immunogold‐siver labeling of tyrosine hydroxylase to determine whether this enzymatic marker for catecholamines was present in efferents from the area postrema or their targets in the rat NTS. At survival periods of 10–12 days after PHAL injections into the area postrema, light microscopy revealed numerous varicose processes containing peroxidase reaction product for PHAL in the dorsomedial, medial, and commissural NTS. Some of these labeled processes were located near neuronal perikarya and processes containing immunogold‐silver intensified reaction product for tyrosine hydroxylase. Electron microscopy of the commissural and dorsomedial NTS established that the majority of the labeling for PHAL was in axon terminals, whereas immunogold labeling for tyrosine hydroxylase was mainly in soma and dendrites. Only 3 out of 579 PHAL‐labeled terminals also contained detectable tyrosine hydroxylase immunoreactivity. Fifty‐eight percent (335/579) of the PHAL‐labeled terminals formed synapses with recognized symmetric junctions, whereas the remainder lacked synaptic specializations within the examined series of serial sections. Of those PHAL terminals forming recognized symmetric junctions, 22% were on tyrosine hydroxylase‐immunoreactive dendrites, 74% on unlabeled dendrites and 4% on unlabeled axon terminals. From a total of 1,250 observed contacts on tyrosine hydroxylase labeled dendrites, 88 (7%) contained PHAL, 9 (<1%) contained TH, and 1,180 (93%) lacked detectable immunoreactivity and formed primarily symmetric synapses. We conclude that a few catecholamine, but mainly noncatecholamine efferents from the area postrema provide a monosynaptic, and most likely inhibitory input to target neurons both with and without tyrosine hydroxylase immunoreactivity in the dorsomedial and commissural NTS. Synapses between the efferent terminals from the area postrema and tyrosine hydroxylase labeled and unlabeled dendrites as well as unlabeled axons in these specific subnuclei of the NTS suggest multiple sites for modulation of gastric and cardiovascular reflexes in response to circulating peptdies. © 1993 Wiley‐Liss, Inc.
Substance P‐like and serotonin‐like immunoreactivity in the lateral cervical nucleus of the raccoon
Authors: Broman Jonas , Pubols Benjamin H. 
Published: January 2005

AbstractThe distribution of substance P and serotonin in the lateral cervical nucleus (LCN) of the raccoon was examined by light microscopic immunohistochemistry.Substance P‐immunoreactive fibers were found to be clustered in the ventromedial part of the LCN, whereas only few such fibers appeared in the dorsolateral part of the nucleus. This organization is closely similar to that previously observed in the cat, and provides further evidence for an anatomic and functional segregation along the transverse axis of the LCN in carnivores. In some sections, substance P‐positive fibers were found primarily in areas of the ventromedial LCN containing small neurons, indicating that such fibers may be involved in functions of the LCN associated with nociceptive projection neurons and/or local circuit neurons.The raccoon LCN also received a relatively sparse innervation of serotonin‐positive fibers that were distributed throughout the nucleus, an organization similar to that previously observed in the cat. The functional role of the serotonergic fibers is unclear. However, their presence suggests that descending influences on transmission in the spinocervicothalamic pathway, in addition to the well‐documented descending control of spinocervical tract neurons, may be present also at the level of the LCN. © 1993 Wiley‐Liss, Inc.
Extra‐hypothalamic vasopressin neurons coexpress galanin messenger RNA as shown by double in situ hybridization histochemistry
Authors: Miller Margaret A. , Kolb Pamella E. , Raskind Murray A. 
Published: January 2005

AbstractVasopressin (VP) neurons in the bed nucleus of the stria terminalis (BNST) and medial amygdala (AMe) exhibit sexual dimorphism and steroid dependency. VP neurons in the supraoptic nucleus and paraventricular nucleus have been shown to coexpress other transmitters including galanin (GAL). However, little is known about what other neurotransmitters may be colocalized with VP in the BNST and AMe. Here, we have used radio‐labeled and digoxigenin‐labeled cRNA probes to perform double in situ hybridization histochemistry for VP and GAL in the BNST and AMe of intact, adult male rats. We provide evidence that in the basal state, the majority of VP‐synthesizing cells in the BNST and AMe of the adult male rat also express galanin mRNA. Likewise, the majority of GAL‐expressing neurons in these regions also contain VP mRNA. These findings give further evidence for the similarity of the BNST and AMe and provide a rationale for studies investigating the role of GAL in functions involving extrahypothalamic VP pathways. © 1993 Wiley‐Liss, Inc.
Distribution of [3H]QNB and [125I]α‐bungarotoxin binding and acetylcholinesterase activity in visual system and hippocampal structures of eleven mammalian species
Authors: Fuchs Jannon L. , Schwark Harris D. 
Published: January 2005

AbstractThis study assessed interspecies differences in regional brain distribution of [3H]QNB binding, [125I]α‐bungarotoxin binding and acetylcholinesterase activity, by autoradiographic and histochemical methods. Eleven mammalian species were examined, including carnivores (cat, dog), a lagomorph (rabbit), and rodents (squirrel, guinea pig, gerbil, hamster, vole, lemming, rat, mouse). Comparisons were based on primary visual system structures (superior colliculus, lateral geniculate nucleus, primary visual cortex) and the hippocampal formation. The two radioligands differed greatly in the degree of interspecies variation: while the pattern of [3H]QNB binding was quite similar across species, [125I] α‐bungarotoxin showed striking interspecies diversity. This contrast was most obvious in laminar patterns of the visual cortex and hippocampal formation. Regional distributions of acetylcholinesterase staining were fairly diverse, and were unlike the patterns of either [3H]QNB or [125I]α‐bungarotoxin. The two ligands showed more consistency in overall levels across species than did acetylcholinesterase. Possible correlates of the differences in interspecies diversity are discussed. © 1993 Wiley‐Liss, Inc.
Synaptophysin immunohistochemistry reveals inside‐out pattern of early synaptogenesis in ferret cerebral cortex
Authors: Voigt Thomas , De Lima Ana D. , Beckmann Matthias 
Published: January 2005

AbstractSynaptogenesis in the ferret cerebral cortex was examined from the day of birth to adulthood with an antibody against synaptophysin at the light and electron microscopic levels. Due to the premature birth of ferrets, the generation of cells destined to the upper cortical layers and their subsequent migration to their final positions in the cortical plate are largely postnatal events.Throughout the newborn ferret cerebral cortex, a high amount of synaptophysin immunoreactivity was present within the marginal zone and subplate region. Staining was also conspicuous within the forming cortical plate. The typical layering pattern of synaptophysin immunoreactivity in the developing cortical plate correlated with the migration pattern of cortical neurons. The synaptic density was lowest directly below the marginal zone, where the youngest neurons just stopped their migration. Below this zone, the density of the synaptic staining increased gradually toward lower (and older) cortical plate layers. As the cortex expanded, the synaptophysin immunoreactivity pattern closely followed the expansion, suggesting that synapses were formed in a given layer shortly after the cells migrating to this layer reached their final position. As soon as cell migration had finished, the entire cortical plate contained dense synaptophysin immunoreactivity, in a pattern similar to that observed in the adult animal. During cortical development, a rostrocaudal and a laterodorsal gradient of synaptogenesis was observed. At any given time, rostral and lateral regions of the cerebral cortex were more advanced in their development than caudal and dorsal regions.Electron microscopic examination of synaptophysin immunoreactivity in the developing cerebral cortex of ferrets confirmed that labeling was solely associated with synaptic vesicles. These vesicles were typically, but not exclusively, confined to synaptic boutons. Especially around the end of the first postnatal week, long fiber profiles loaded with synaptic vesicles were occasionally detected. As some of these fibers also showed en passant synapses along their course, we concluded that synaptic vesticle labeling may be reliably used to study synaptogenesis at the light microscopic level. A systematic analysis of samples from postnatal days 0 and 7 corroborated this conclusion, showing that synaptic profile distribution completely matched the distribution of synaptophysin immunoreactivity seen in the light microscope.In conclusion, synaptogenesis begins as soon as migratory cells reach their final position in the cortical plate. As long as cell migration continues, synaptogenesis is under the constraints of neurogenesis, following its gradients.