bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventromedial mesencephalic tegmental (VMT) projections to ten functionally different cortical areas in the cat: Topography and quantitative analysis
Authors: Scheibner Tethys , Törk István 
Published: January 2005

AbstractThe cortical projections of the ventromedial mesencephalic tegmentum (VMT) were studied in the cat by the retrograde transport of wheat germ agglutinin‐conjugated HRP (WGA‐HRP). The following cortical regions were injected: prefrontal, cingulate, motor, somatic sensory, auditory, primary visual, secondary visual, parasplenial, insular, and entorhinal. Labelled cells in the five component nuclei of the VMT (rostral linear, parabrachial pigmented, central linear, interfascicular, and paranigral nuclei) were counted and the numbers correlated with the total cell populations of the nuclei.In all experiments large numbers of cells were labelled in the VMT, particularly in the rostral linear and parabrachial pigmented nuclei. Following entorhinal cortical injections, significant labelling occurred in the interfascicular and central linear nucleus, although some cells of these nuclei were labelled in every experiment. The cells of the paranigral nucleus remained unlabelled in all experiments. Several hundred VMT cells were labelled in most experiments, over 1000 in the case of the parasplenial and over 2000 in the case of prefrontal injections. The most strongly labelled nucleus was the rostral linear, in which up to 36% of the total cell population could be labelled in a single experiment.These results indicate that the VMT of the cat is a major source of brainstem projections to the cerebral cortex and that all cortical areas are reached by this system. Although the projections to the prefrontal and limbic cortical areas are particularly prominent, there appears to be a consistent and significant projection to all areas. Further, the projection of the VMT to the cortex is topographically organized, indicating that the functional roles of the component nuclei of the VMT may be substantially different.
Cobaltic lysine study of the morphology and distribution of the cranial nerve efferent neurons (motoneurons and preganglionic parasympathetic neurons) and rostral spinal motoneurons in the Japanese toad
Authors: Oka Yoshitaka , Takeuchi Hiroaki , Satou Masahiko , Ueda Kazuo 
Published: January 2005

AbstractThe morphology and distribution of the cranial nerve motoneurons (except III, IV, and VI) and rostral spinal motoneurons were systematically studied in the Japanese toad (Bufo japonicus) by retrograde labelling with cobaltic lysine complex. The cobaltic lysine clearly labelled whole neurons, i.e., cell bodies, proximal and distal dendrites, and axons. The branchial motoneurons (V, VII, IX, and X) had similar morphological characteristics and formed a more‐or‐less continuous cell column through the brainstem. The dendrites could be grouped mainly into the dorsomedial and the ventrolateral dendritic arrays. The dorsomedial dendrites formed a dendritic plexus in the subependymal gray matter, which extended as far peripherally as beneath the ependymal layer. The ventrolateral dendrites formed a broom‐like dendritic plexus in the lateral to ventrolateral white matter. They usually extended as far peripherally as the pial surface. The rostrocaudal extent of the dendritic field was also wide and usually exceeded the motor nuclear boundaries. The hypoglossal motoneurons were grouped into the dorsomedial and ventrolateral cell groups, and the latter was considered to be part of the rostral spinal motoneuron column, from their morphology and distribution. The former had well‐differentiated dendrites and occupied a more medial position than the branchial motoneurons. Besides the equivalent of the dorsomedial and ventrolateral dendritic arrays of the branchial motoneurons, they had dorsal and commissural dendrites. The accessory motoneurons had morphological characteristics and a distribution pattern similar to those of the rostral spinal motoneurons rather than the branchial motoneurons. The rostral spinal motoneurons had morphological characteristics somewhat different from the branchial motoneurons and the hypoglossal motoneurons (dorsomedial group). Functional implications of the motoneuron morphology are discussed, mainly based on the present results and earlier anatomical and physiological studies of the spinal motoneurons.The present study also revealed the anatomical features of the preganglionic parasympathetic neurons supplying some cranial nerves. These neurons had small somata with less elaborate dendrites and formed an almost continuous cell column that occupied a more dorsal position than the motoneurons of the corresponding nerve. They are thought to be homologous to the salivatory nucleus and the dorsal motor nucleus of the vagus. The basic anatomical organization of the general visceral efferent column seems to be similar throughout vertebrates.
Pedunculopontine tegmental nucleus of the rat: Cytoarchitecture, cytochemistry, and some extrapyramidal connections of the mesopontine tegmentum
Authors: Rye David B. , Saper Clifford B. , Lee Henry J. , Wainer Bruce H. 
Published: January 2005

AbstractThe pedunculopontine tegmental nucleus (PPTn) was originally defined on cytoarchitectonic grounds in humans. We have employed cytoarchitectonic, cytochemical, and connectional criteria to define a homologous cell group in the rat. A detailed cytoarchitectonic delineation of the mesopontine tegmentum, including the PPTn, was performed employing tissue stained for Nissl substance. Choline acetyltransferase (ChAT) immunostained tissue was then analyzed in order to investigate the relationship of cholinergic perikarya, dendritic arborizations, and axonal trajectories within this cytoarchitectonic scheme. To confirm some of our cytoarchitectonic delineations, the relationships between neuronal elements staining for ChAT and tyrosine hydroxylase were investigated on tissue stained immunohistochemically for the simultaneous demonstration of these two enzymes.The PPTn consists of large, multipolar neurons, all of which stain immunohistochemically for ChAT. It is present within cross‐sections that also include the A‐6 through A‐9 catecholamine cell groups and is traversed by catecholaminergic axons within the dorsal tegmental bundle and central tegmental tract. The dendrites of PPTn neurons respect several nuclear boundaries and are oriented perpendicularly to several well‐defined fiber tracts. Cholinergic axons ascend from the mesopontine tegmentum through the dorsal tegmental bundle and a more lateral dorsal ascending pathway. A portion of the latter terminates within the lateral geniculate nucleus.It has been widely believed that the PPTn is reciprocally connected with several extrapyramidal structures, including the globus pallidus and substantia nigra pars reticulata. Therefore, the relationships of pallidotegmental and nigrotegmental pathways to the PPTn were investigated employing the anterograde autoradiographic methodology. The reciprocity of tegmental connections with the substantia nigra and entopeduncular nucleus was investigated employing combined WGA‐HRP injections and ChAT immunohistochemistry.The pallido‐ and nigrotegmental terminal fields did not coincide with the PPTn, but, rather, were located just medial and dorsomedial to it (the midbrain extrapyramidal area). The midbrain extrapyramidal area, but not the PPTn, was reciprocally connected with the substantia nigra and entope‐duncular nucleus. We discuss these results in light of other cytoarchitec‐tonic, cytochemical, connectional, and physiologic studies of the functional anatomy of the mesopontine tegmentum.
Visual topography of V1 in the Cebus monkey
Authors: Gattass Ricakdo , Sousa Aglai P. B. , Rosa Marcello G. P. 
Published: January 2005

AbstractThe representation of the visual field in the striate cortex (VI) was mapped with multiunit electrodes in the Cebus monkey. Nine Cebus apella, anesthetized with N2O and immobilized with pancuromium bromide were studied in repeated recording sessions.In each hemisphere, VI contains a continuous representation of the contralateral visual hemifield. The representation of the vertical meridian (VM) forms the external border of V1 except at the anteriormost portion of the calcarine fissure. The representation of the horizontal meridian (HM) divides the area so that the representation of the lower visual field is located dorsally, and that of the upper field ventrally.The convoluted surface of VI can be only partially unfolded, and no precise “flattened” map can be obtained without introducing surface discontinuities. The visual topography of VI is presented in a series of coronal sections and in “flattened” maps.The representation of the central visual field is magnified relative to that of the periphery in VI. The evaluation of the cortical magnification factors measured along isoeccentric and isopolar dimensions in the partially unfolded model of VI revealed anisotropies in the representation of the visual field with larger magnification along isopolar lines than along isoeccentric lines. Receptive field size increases with increasing eccentricity, whereas point image size decreases with increasing eccentricity.
Increased electrotonic coupling in aged rat hippocampus: A possible mechanism for cellular excitability changes
Authors: Barnes C. A. , Rao G. , McNaughton B. L. 
Published: January 2005

AbstractThe effects of aging on the intercellular transfer of the low molecular weight fluorescent dye 5,6‐carboxyfluorescein was studied in subfields fascia dentata, CA1, and CA3 of rat hippocampal slices maintained in vitro. All three areas exhibited a statistically significant increase in dye coupling with age. The increased dye coupling was accompanied by an apparent increase in postsynaptic excitability as assessed by the ratio of the population spike to EPSP components of the extracellulary recorded field potential. The possibility that artifaciual dye coupling due to cell fusion contributed significantly to these results was ruled out by the demonstrations that a high molecular weight, dextran‐coupled fluorescein compound did not produce multiple fills and that dye coupling with carboxyfluorescein could be prevented by prior intracellular loading with Ca++, a procedure that decouples gap junctions in other tissue. The increase in extent of electrical coupling suggested by these data may largely account for the apparent increase in cellular excitability of this tissue with age and may reflect the mechanism by which the senescent hippocampus compensates for the loss of afferent input during the course of normal aging. The additional possibility is raised that increased electrical couping may reflect a mechanism for permanent associative storage of information in this system.
Neuropeptide Y‐immunoreactive perikarya and nerve terminals in the rat medulla oblongata: Relationship to cytoarchitecture and catecholaminergic cell groups
Authors: Häurfstrand A. , Fuxe K. , Terenius L. , Kalia M. 
Published: January 2005

AbstractThe aim of this study was to examine details of the distribution of neuropeptide Y (NPY)‐immunoreactive perikarya and nerve terminals in the medulla oblongata in relation to cytoarchitectonically and functionally distinct catecholaminergic regions. The immunoperoxidase method was combined with Nissl staining to determine nuclear boundaries of transmitter‐identified nerve cell bodies and to examine the relationship between populations of NPY‐immunoreactive neurons and catecholaminergic cell groups (A1, A2, C1, C2, and C3) in serial sections. Previous studies using immunofluorescence have described the existence of NPY catecholaminergic immunoreactive nerve cell bodies in the brainstem. No information is currently available with regard to details of the distribution of these peptidergic neurons and nerve terminals in the functional subnuclear units of the medulla oblongata. In this study we have delineated the anatomical association of NPY immunoreactivity with cardiovascular function. Neuropeptide Y‐immunoreactive neurons were found located in close association with noradrenergic neurons of the Al cell group in the caudal ventrolateral medulla oblongata, where they were usually found located dorsal to the lateral reticular nucleus (LRt). A second population of NPY‐immunoreactive neurons was found located medial to the Al cell group in the ventral subdivision of the reticular nucleus of the medulla (MdV). Neuropeptide Y‐immunoreactive neurons in the rostral medulla were found located in regions corresponding to the principal distribution of adrenergic neurons in the C1, C2, and C3 cell groups. In the dorsomedial medulla (A2 region) NPY‐immunoreactive neurons were localized in the area postrema (ap) and in a number of subnuclei of the nucleus of the tractus solitarius (nTS), i.e., the dorsal parasolitary region (dPSR), the dorsal strip (ds), the periventricular region (PVR), and the ventral parasolitary region (vPSR). The location of NPY‐immunoreactive perikarya and nerve terminals in the dorsal subnuclei of the nTS, i.e., the dPSR and ds, is of particular significance, since this distribution corresponds with the location of small adrenergic neurons as well as with the site of termination of aortic and carotid sinus nerve afferent fibers. NPY‐immunoreactive neurons in the dorsomedial medulla are ideally situated for receiving monosynaptic input from baroreceptor afferents and could play a key role in the central integration of cardiovascular reflexes.
Angioarchitecture of the CNS, pituitary gland, and intracerebral grafts revealed with peroxidase cytochemistry
Authors: Broadwell Richard D. , Balin Brian J. , Charlton Harry M. , Salcman Michael 
Published: January 2005

AbstractBlood vessels of the fetal, neonatal, and adult subprimate and primate CNS, including circumventricular organs (e.g., median eminence, pituitary gland, etc.), and of solid CNS and nonneural (anterior pituitary gland) allografts placed within brains of adult mammalian hosts were visualized with peroxidase cytochemistry applied in three ways: (1) to tissues from animals injected systemically with native horseradish peroxidase (HRP) or peroxidase conjugated to the lectin wheat germ agglutinin (WGA) prior to perfusion fixation; (2) to tissues from animals infused with native HRP into the aorta subsequent to perfusion fixation; and (3) to tissues from animals fixed by immersion and incubated for endogenous peroxidase activity in red cells retained within blood vessels. In neonatal and adult animals receiving native HRP intravascularly, non‐fenestrated vessels contributing to a blood‐brain barrier were outlined with HRP reaction product when tetrarnethyl‐benzidine (TMB) as opposed to diaminobenzidine (DAB) was used as the chromogen; fenestrated vessels of circumventricular organs were not discernible due to the density of extravascular reaction product. Fenestrated and nonfenestrated cerebral and ext racer ebral blood vessels exposed to blood‐borne WGA‐HRP were visible when incubated in TMB and DAB solutions. Native HRP infused into the aorta of fixed animals likewise labeled nonfenestrated vessels throughout the brain upon exposure to TMB or DAB but obscured fenestrated vessels of the circumventricular organs. Endogenous peroxidase activity of red cells, seen equally well with TMB and DAB, outlined blood vessels throughout the cerebral gray and white matter and all circumventricular organs in fetal, neonatal, and adult animals.Application of the three peroxidase cytochemical approaches to study the development or absence of a blood‐brain barrier in intracerebral allografts demonstrated that the vascularization of day 16–19 fetal/1 day neonatal. Placement of the grafts. CNS allografts secured from donor sites expected to possess a blood‐brain barrier exhibited blood vessels that were not leaky to HRP injected intravenously in the host. Fenestrated blood vessels associated with anterior pituitary allografts were evident prior to 3 days posttransplantation within the host brain and permitted blood‐borne HRP in the host to enter the graft and surrounding host brain parenchyma.The three peroxidase cytochemical approaches are useful for visualizing CNS blood vessels that contribute or do not contribute to a blood‐brain barrier in fetal, neonatal, and adult laboratory animals; the three approaches have potential application to cerebrovascular studies of stroke, trauma, and neoplasia.
Ultrastructure of synapses from the A‐laminae of the lateral geniculate nucleus in layer IV of the cat striate cortex
Authors: Einste Gillian , Davis Thomas L. , Sterling Peter 
Published: January 2005

AbstractThe morphology of synapses in layer IV of the cat striate cortex was studied by electron microscope (EM) autoradiography of serial sections following injection of tritiated amino acids into the lateral geniculate nucleus. Of the terminals in the neuropil, 22% had 2 or more silver grains in 10 successive sections and were labeled at 8–80 times the background level. These terminals were considered to be specifically labeled and to be derived from the lateral geniculate. Two forms of geniculate synapse were observed. One had medium‐size, round vesicles and a modest postsynaptic asymmetry (RA); the other had smaller, pleomorphic vesicles and hardly any postsynaptic opacity; that is, it appeared symmetrical (PS). The geniculate RA terminals were presynaptic to dendritic spines, fine processes, and cell bodies; the geniculate PS terminals were presynaptic to dendrites and cell bodies but not to spines. The possible sources of geniculate PS terminals are discussed.
Pattern of lateral geniculate synapses on neuron somata in layer IV of the cat striate cortex
Authors: Einstein Gillian , Davis Thomas L. , Sterling Peter 
Published: January 2005

AbstractThe distribution of geniculate synapses on neuron cell bodies in layers IVab and IVc of cat area 17 was studied. Electron microscope autoradiography was used to identify geniculate terminals that were labeled by antero‐grade transport of radioactivity injected into the A‐laminae of the lateral geniculate nucleus. Thirty‐eight cell bodies (19 in layer PVab and 19 in layer IVc) were examined in a series of 138 consecutive sections. Two pyramidal somas were studied and had no geniculate contacts. All of the other somas studied were nonpyramidal, and of these, 85% received geniculate contacts. The proportion of somas receiving somatic geniculate input differed in layers IVab and IVc. In layer IVab, 70% of the nonpyramidal somas received geniculate contacts; in IVc, 100%. Such high percentages indicate that geniculate afferents synapse with more types of layer IV neuron than the aspinous neurons that synthesize gamma‐aminobutyric acid (GABA) (Freund et al., '85b).The pattern of input to somas was so diverse that it was impossible to form groups of neurons based on only this criterion. We wondered if it would be possible to form groups of neurons based on a range of characteristics among which would be pattern of synaptic input. To this end, pyramidal neurons and neurons that contained, a cytoplasmic laminated body (CLB) (Winfield, '79; Einstein et al., '84) were treated as two separate classes. We found fair agreement among the features of these neurons within their own classes, with the CLB‐cells in layer IVab and IVc forming separate groups. Among the remaining neurons there was too little agreement within the range of features to enable us to treat them in this manner.Geniculate somatic contacts in both sublayers were of 2 forms, those with round vesicles and asymmetric thickenings (RA) and those with pleomorphic vesicles and symmetric thickenings (PS) (Einstein et al., '87). The distribution of these forms varied: some cells received contacts exclusively from one form or the other; other cells received contacts from both. On one cell that bore 33 somatic geniculate terminals, 61% were RA and 39% were PS. Such substantial numbers of geniculate contacts located near the site of impulse initiation are likely to contribute significantly to the receptive field properties of this neuron, and the possible effects are discussed.
Neural induction of taste buds
Authors: Hosley Mark A. , Hughes Stephen E. , Oakley Bruce 
Published: January 2005

AbstractBilateral innervation allows more than 80% of the 610 vallate taste buds to survive removal of one IXth nerve in adult rats. Removal of both IXth nerves in neonatal or adult rats results in the absence of taste buds. In studying development, we found that removing or crushing one IXth nerve in three‐day‐old neonates profoundly decreased the number of vallate taste buds that subsequently developed. Specifically, after removal of one IXth nerve at 3 days, only 228 taste buds formed, compared with 496 taste buds that one nerve would maintain in adults. Thus, during normal development, the right and left IXth nerves interact synergistically, as at least 150 more taste buds develop than predicted by the sum of the independent action of each IXth nerve. This suggests that vallate taste buds are induced by the IXth nerve. A second example of synergism, representing evidence for the neural induction of taste buds, came from experiments in which we crushed the left IXth nerve 3 days after birth and found that these regenerated IXth nerve axons induced 4 times as many taste buds in the presence of the normal right IXth nerve (118 taste buds) as in its early absence (30 taste buds).We conclude that taste buds are neurally induced and that axons of the IXth nerve interact synergistically in inducing them, rather than competing for targets. We propose that in development innervated progenitor cells form stem cells which lead to taste bud cells.
Corticotropin releasing factor‐like immunoreactivity in the rat brain as revealed by a modified cobalt‐glucose oxidase‐diaminobenzidine method
Authors: Sakanaka Masahiro , Shibasaki Tamotsu , Lederis Karl 
Published: January 2005

AbstractA cobalt‐glucose‐oxidase diaminobenzidine (Co‐GOD) method, employing a specific antiserum against rat corticotropin releasing factor (CRF), was applied to determine immunohistochemically a widespread and detailed localization of corticotropin releasing factor‐like immunoreactivity (CRFI) in the rat brain.Besides the CRFI cells in the paraventricular hypothalamic nucleus that project to the median eminence, CRFI cells were demonstrated in many brain regions, including the olfactory bulb, cerebral cortex, septal nuclei, hippocampus, amygdala, thalamic nuclei, medial hypothalamic nuclei, lateral hypothalamic area, perifornical area, central gray, cuneiform nucleus, inferior colliculus, raphe nuclei, mesencephalic reticular formation, laterodorsal tegmental nucleus, locus coeruleus, parabrachial nuclei, mesencephalic tract of the trigeminal nerve, pontine reticular formation, lateral superior olive, vestibular nuclei, prepositus hypoglossal nucleus, nucleus of the solitary tract, dorsal motor nucleus of the vagus, lateral reticular nucleus, nucleus of the spinal tract of the trigeminal nerve, external cuneate nucleus, inferior olive, and medullary reticular formation. CRFI‐reacting neural processes were also detected in these same areas. In particular, the median eminence, lateral septum, bed nucleus of the stria terminalis, mesencephalic reticular formation, parabrachial nuclei, and nucleus of the solitary tract contained large numbers of CRFI fibres.The widespread localization of CRFI demonstrated in the present study strongly suggests that CRF, like many other neurohormones and peptides, may act as a neurotransmitter and/or neuromodulator in numerous extra‐hypothalamic circuits, as well as participate in neuroendocrine regulation.