摘要:

AbstractIn the rufous horseshoe bat (Rhinolophus rouxi), the superior olivary complex contains four main divisions. In comparison with other species, the most lateral division is clearly homologous to the lateral superior olive (LSO); the most medial division is homologous to the medial nucleus of the trapezoid body (MNTB). Lying between these landmarks, in approximately the position of the medial superior olive (MSO) of other mammals, are two additional divisions that are cytoarchitecturally distinct from one another yet do not greatly resemble the MSO of nonecholocating mammals such as the cat. We refer to these nuclei as the dorsal medial superior olive (DMSO) and the ventral medial superior olive (VMSO). We examined the afferent and efferent connections of all of these cell groups with retrograde and anterograde transport of WGA‐HRP from the superior olivary complex. In the same animals we recorded the binaural response properties of single units in the superior olivary complex. Virtually all units recorded in LSO were excitatory to the ipsilateral ear and inhibitory to the contralateral ear (EI); all of the units sampled in the MNTB and most of those sampled in the VMSO responded only to the contralateral ear (OE). In DMSO the binaural properties of units were varied: the number of units that were inhibitory to the ipsilateral ear and excitatory to the contralateral ear (IE) was about equal to the number of units excitatory to both ears (EE); a few units had OE responses; no units had EI responses. Connectional correlates for these binaural response properties are seen in the patterns of retrograde transport from WGA‐HRP injections in the divisions of the superior olive. The LSO receives projections from the ipsilateral cochlear nucleus and MNTB; MNTB receives projections from the contralateral cochlear nucleus. The DMSO and VMSO both receive bilateral projections from the cochlear nuclei. The results of retrograde and anterograde transport suggest that VMSO, in addition, receives projections from the ipsilateral MNTB. The LSO, DMSO, and VMSO all project to the ventral two‐thirds of the central nucleus of the inferior colliculus, and their targets are approximately coextensive. However, the LSO projects bilaterally to the inferior colliculus, whereas the medial cell groups project mainly ipsilate

ISSN:0092-7317    

DOI:10.1002/cne.902780302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this study we characterized the distribution of glycine receptor immunoreactivity in the spinal cord of the rat by using monoclonal antisera directed against the purified glycine receptor. There was dense, punctate glycine receptor immunoreactive staining in all regions of the gray matter ventral to the substantia gelatinosa. The densest staining was found in laminae III and IV of the dorsal horn. There were also distinct, tributarylike bands of punctate staining that extended well into the white matter of the lateral and ventral funiculi. The only consistent cell body staining was found in small neurons of the ventral horn. The labelled neurons were distributed among larger, unlabelled motoneurons.In general, the pattern of glycine receptor immunoreactivity was similar at all levels of the spinal cord and was comparable to that seen with binding of a tritiated glycine receptor antagonist, strychnine, to sections of rat spinal cord (Zarbin et al.:J. Neurosci. 1:532–547, '81). Two important exceptions, however, were observed. In contrast to the high levels of strychnine binding reported in the substantia gelatinosa, we found almost no glycine receptor immunoreactivity in laminae I and II of the superficial dorsal horn of the spinal cord or of the trigeminal nucleus caudalis. There was also a notable absence of antibody staining in the intermediolateral cell column of the thoracic cord.The presence of dense glycine receptor immunoreactivity in the region of lamina V and its absence in the superficial dorsal horn are discussed in terms of a possible differential glycinergic control of nociceptive neurons of laminae I and

ISSN:0092-7317    

DOI:10.1002/cne.902780303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractAn ultrastructural study of the organization and fine structure of the nervous system of the parasitic flatwormFasciola hepaticawas undertaken. The brain consists of paired cerebral ganglia, located just posterior to the oral sucker, that are connected by a transverse commissure which crosses over the dorsal surface of the pharynx. The cell bodies of the cerebral ganglia are not organized into a clearly defined rind around the neuropile but are loosely scattered around and within the neuropile area. The neuropile consists of two morphologically distinct types of unmyelinated nerve processes. The small nerve processes, with smooth cell membranes, are less than 2 μ in diameter, whereas the “giant” processes are greater than 12 μ in diameter and have extensively invaginated cell membranes. Giant processes make up the bulk of the nerve fibers in the transverse commissure and longitudinal nerve cords. Four morphological types of vesicles are present in the small processes; small clear vesicles (which were found associated with synapses), spheroidal and ellipsoidal dense vesicles, and dense‐core vesicles. Two types of synapses are found in the neuropile: simple synapses characterized by pre‐ and postsynaptic membrane densities, clusters of small clear vesicles, and a clear synaptic cleft; and wedge‐shaped synapses or divergent diads each having one presynaptic process synapsing onto two postsynaptic processes. Synaptic contacts were observed only between small processes; no synapses were observed on the cell bodies or on gian

ISSN:0092-7317    

DOI:10.1002/cne.902780304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWe introduce a way to count and measure cells in an optically defined volume of tissue called acounting box. This method—direct three‐dimensional counting (3DC)—eliminates the need for correction factors, such as that introduced by Abercrombie (Anat. Rec. 94:239–247, '46), to determine the number of cells per unit volume (Nv). Problems caused by irregular cell shape and cell size, nonrandom orientation, and splitting of cells by the knife during sectioning are overcome. Furthermore, 3DC is insensitive to large variations in section thickness.The innovative feature of 3DC is the definition of a counting box with top and bottom sides located inside the section a precise distance away from the cut surfaces of the tissue. The positions of the top and bottom sides of the counting box are delimited by using a digital length gauge and a Z‐axis control unit.Sections of tissue between 8 and 100 μ thick are examined with a high numerical aperture objective in combination with video‐enhanced differential interference contrast optics (DIC). Cells are marked on a television screen while the microscopist scans systematically from the top to the bottom of the counting box. Cells that are located completely inside the box and cells that only cross through its top, right, or back sides are counted. All cells that cross the planes that define the bottom, left, and front sides of the counting box are not counted.Direct 3DC provides an accurate, simple, and reliable way to count cells, nuclei, nucleoli, or other objects in sectioned material. To build the counting system requires a standard transmitted light microscope equipped with DIC optics, a video camera, a position sensor, and a Z‐axi

ISSN:0092-7317    

DOI:10.1002/cne.902780305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractHorseradish peroxidase tracing and extracellular electrophysiological recording techniques were employed to delineate prosencephalic connections of the gustatory system in ictalurid catfishes. The isthmic secondary gustatory nucleus projects rostrally to several areas of the ventral diencephalon including the nucleus lobobulbaris and the nucleus lateralis thalami. Injections of HRP in the vicinity of the nucleus lobobulbaris reveal an ascending projection to the telencephalon terminating in the area dorsalis pars medialis (Dm) and the medial region of area dorsalis pars centralis (Dc). Conversely, injections of HRP into the gustatory region of area dorsalis pars medialis label small neurons in the nucleus lobobulbaris. Gustatory neurons in the telencephalon send descending projections via the medial and lateral forebrain bundles to several nuclei in the anterior and ventroposterior diencephalon. The nucleus lateralis thalami, a diencephalic nucleus, receives ascending gustatory projections from the secondary gustatory nucleus but does not project to the telencephalon. Neurons in both the nucleus lateralis thalami and the telencephalic gustatory target exhibit multiple extraoral and oral receptive fields and complex responses to chemical (taste) and tactile stimulation.

ISSN:0092-7317    

DOI:10.1002/cne.902780306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPrevious observations (Oland and Tolbert:J. Comp. Neurol. 255:196–207, '87,Soc. Neurosci. Abstr. 13:1144, '87; Oland et al.:J. Neurosci. 8:353–367, '88) have provided evidence that the afferent‐axon‐induced development of synaptic glomeruli in the antennal lobe of the mothManduca sextadepends upon an interaction between ingrowing sensory axons and the glial cells of the antennal lobe. In order to differentiate between the roles of glial cells and of afferent axons on the partitioning of the lobe into glomeruli, we have used the antimitotic agent hydroxyurea to produce lobes deficient in glial cells but retaining sensory input. The resulting lobes were analyzed in the light and electron microscopes, and the integrity of their antennal input was evaluated by examining the gross and microscopic structure of the antennae, the number of antennal afferent axons, and electroantennogram responses to odors. Our results with hydroxyurea show that in treated animals with adequate antennal input the degree to which the antennallobe neuropil becomes glomerular varies with the number of glial cells remaining in the lobe; when less than approximately one‐quarter of the normal glial complement is present, glomeruli do not develop at all. These experiments complement and extend previous experiments in which the number of glial cells was reduced with radiation (Oland et al.:J. Neurosci. 8:353–367, '88). The fact that the present results mimic the previous results with radiation strongly suggest that glial cells do mediate the afferent‐axon‐induced formation of olfactory glomer

ISSN:0092-7317    

DOI:10.1002/cne.902780307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe somal shapes, dendritic features, and orientations of the neurons within the gustatory zone of the nucleus of the solitary tract were studied with the rapid Golgi method in the adult hamster. These Golgi studies complement previous quantitative morphometric analyses of the distributions of large and small neurons within the gustatory zone. Class 1 neurons are usually fusiform and possess long, relatively unbranched dendrites that often extend beyond the cytoarchitectonic boundaries of the gustatory zone. Class II neurons are multipolar and possess more dendrites that are significantly shorter than those of class I neurons. Both classes of neurons are spine poor. Computer‐generated three‐dimensional rotational analyses demonstrate that the dendritic arborizations of neurons of the gustatory zone are oriented preferentially in the horizontal plane. Dendrites extend in parallel or perpendicular to the solitary tract, the source of peripheral gustatory inputs, and appear to be positioned spatially to maximize synaptic interactions with these peripheral fibers. These Golgi studies also suggest that individual gustatory neurons may be influenced by incoming gustatory fibers that innervate separate populations of taste buds, a finding that is not predictable from the topographical organization of the gustatory z

ISSN:0092-7317    

DOI:10.1002/cne.902780308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe present study provides detailed anatomical evidence that the strongly texture‐sensitive complex neurones of the cat's striate cortex constitute a discrete subset of all complex neurones, and lie in two bands, deep in lamina III and in lamina V.Physiological properties of simple and complex striate cortical neurones were characterized extracellularly in lightly anaesthetized cats by use of micropipettes filled with 12% Fast Green FCF dye in 2.0 M sodium chloride. Complex neurones were further subdivided on the basis of their length‐summating properties for an optimally oriented bar into “standard,” “special,” or “intermediate” categories and on the basis of their tuning and degree of sensitivity to motion of random texture.Extracellular dye marks were made at strategic locations along each microelectrode track, especially at the site of recording from strongly texture‐sensitive complex neurones. Tracks were reconstructed with the aid of the histologically recovered dye marks in sections counterstained with cresyl violet to reveal cortical lamination.The results confirm and refine the inference made by Hammond and MacKay (Exp. Brain Res. 22:427–430, '75;Exp. Brain Res. 30:275–296, '77) and the gross observations from 2‐deoxyglucose uptake studies by Wagner, Hoffmann, and Zwerger (Brain Res. 224:31–43, '81) concerning the laminar distribution of texture‐sensitive complex neurones

ISSN:0092-7317    

DOI:10.1002/cne.902780309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWith the aid of autoradiographic and histochemical (WGA‐HRP) tracing techniques, the projections of the nucleus of the nucleus of the tractus solitarius (nTS) in the pigeon have been delineated and related to the viscerotopic organization of the nucleus. As in mammals, nTS projects to both brainstem and forebrain structures. At medullary levels, projections were seen to nTS itself, to the dorsal motor nucleus of the vagus and to the subjacent and more ventral reticular formation. There is a substantial projection to the parabrachial nuclear complex with terminations in all its subnuclei and minor projections to locus coeruleus and several mesencephalic areas, including the ventral area of Tsai, the nucleus of the ascending brachium conjunctivum, and the compact portion of the tegmental pedunculopontine nucleus. At diencephalic levels, projections to the hypothalamus (magnocellular periventricular nucleus, stratum cellulare internum and externum) and dorsal thalamus were seen. Terminal fields within the basal telencephalon included the nucleus of the pallial commissure, the bed nucleus of the stria terminalis, and the nucleus accumbens.The organization of nTS projections in pigeons is correlated with the pattern of inputs to specific nTS subnuclei. Lateral tier subnuclei receiving cardiovascular and pulmonary inputs project upon the ventrolateral reticular formation and the ventrolateral parabrachial complex. Medial tier subnuclei receiving gustatory and gastrointestinal inputs project upon dorsal and medial parabrachial nuclei. Transparabrachial projections arise from nTS subnuclei receiving little or no primary input from the viscer

ISSN:0092-7317    

DOI:10.1002/cne.902780310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCell production and cell deaths were determined in larvalRana pipiensboth in control tecta and in tecta following unilateral eyeball removal in embryos and larvae. Such enucleations produce significantly reduced rates of cell division in the contralateral tecta for virtually the entire larval period (confirming studies with enucleation almost exclusively performed in embryos—Kollros:J. Exp. Zool. 123:153–187, '53, andJ. Comp. Neurol. 205:171–178, '82). Significant numbers of cell deaths in all nonependymal tectal cell layers were also observed. Control cell division rates peak at stage X, while cell death peaks are reached in stages XIII–XX. Overall, about 106nonependymal cells are produced in control tecta, and about 350,000 of them die by the end of metamorphosis. Control of cell numbers following enucleation is shown to depend mainly on reductions in cell division rates when the operation occurs early in development and mainly on increases in cell death rates are invariably present within 1 day of the operation whereas the reduced division rates ordinarily require several more days to be seen. The modified rates, both of cell divisions and cell death, are limited to tectal areas to which optic nerve fibers have already extended. Maps of the positions of tectal cell divisions in many larval stages provide the basis for modifying the current dogma that tectal formation occurs as a series of newly formed mediocaudal wedges pushing previously produced wedges rostrolaterad. All such “old” wedges receive substantial cell additions for many stages, with the rate of addition decreasing rostrad earlier

ISSN:0092-7317    

DOI:10.1002/cne.902780311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY