bluuebunny/crossref_metadata_2025_split huggingface dataset:
Afferent and efferent projections of the region in mouse sml cortex which contains the posteromedial barrel subfield
Authors: White Edward L. , DeAmicis Richard A. 
Published: December 2004

AbstractExperiments using anterograde and retrograde tracing techniques have been used to identify projections to and from the region of mouse SmI cortex which contains the posteromedial barrel subfield (PMBSF, Woolsey and Van der Loos, '70). Microinjections containing horseradish peroxidase (HRP) and tritiated amino acids were placed unilaterally into the topographic center of the PMBSF. Brains were perfuse‐fixed and frozen sectioned. All sections were reacted for HRP and alternate sections were autoradiographed. Examination of sections cut tangential to the pial surface in the region of the injection site showed that diffusion of the injection was limited to cortex above and below the PMBSF in layer IV (i.e., PMBSF cortex). A “column” of HRP reaction product and developed silver grains was present in ipsilateral cortical area 40, in the face area of SmII. HRP positive cell bodies were mainly in layer III and VI of this “column.” A similar “column” was present in ipsilateral cortical area 6, in a region which in the rat corresponds to the vibrissal area of MsI (Hall and Lindholm, '74), but here HRF positive cells bodies were situated mainly in layer V. HRP labeled cells bodies were also present in layer V of ipsilateral cortical area 29c. The ipsilateral nucleus ventralis thalami pars lateralis and the nucleus posterior thalami contained many HRP positive cell bodies and were associated with dense aggregations of developed silver grains. Numerous silver grains were also present over portions of the ipsilateral caudate, reticular nucleus of the thalamus and ventral pontine nuclei, but no HRP positive cell bodies occurred in these regions.HRP‐filled axons left the injection site and traveled via the corpus callosum to contralateral PMBSF cortex where HRF labeled cell bodies were present mainly in layers III and V. Usually only one or two labeled somata were located superficial or deep to a contralateral PMBSF barrel. A few HRF positive cell bodies were also present in layers II and III of contralateral pyriform cortex.These results indicate that PMBSF cortex is reciprocally connected with ipsilateral cortical areas 6 and 40 and with the ipsilateral ventral and posterior nuclei of the thalamus. A small, homotopic callosal connection with contralateral PMBSF cortex has been demonstrated, and it is presumed that this projection is also reciprocal. PMBSF cortex projects to, but receives no projections from the ipsilateral caudate, reticular nucleus of the thalamus and the ventral pontine nuclei. Thus, many of the same projections of primary somatosensory cortex in higher animals, such as the monkey have been shown to occur in the mouse.
The morphology of the spinal cord efferent and afferent neurons contributing to the ventral roots of the cat
Authors: Light Alan R. , Metz Carol B. 
Published: December 2004

AbstractHorseradish peroxidase was applied to proximal ventral roots of the coccygeal and sacral spinal cord of cats. Subsequent histochemical reaction resulted in extensive staining of spinal cord neurons that had processes in the ventral roots. This procedure was used to study four issues concerning ventral root neurons. (1) Extensive transverse dendritic arborizations were revealed for large and small neurons presumed to be α and γ motoneurons respectively. Dendrites from these neurons were found to project heavily into the ipsilateral white matter, both laterally and ventrally. Dendrites also projected extensively through the anterior commissure, attaining the contralateral grey and white matter. (2) Medially‐located efferent neurons were found to contribute the contralateral dendrites as well as some dorsally‐directed dendrites. Laterally‐located neurons projected dendrites extensively into the lateral and ventral white matter. (3) Stained neurons were found in the intermediolateral cell column, and were presumed to be preganglionic efferent neurons. Some of these neurons projected dendrites into the marginal zone of the dorsal horn, while others sent dendrites medially toward the central canal. (4) Stained fibers, presumed to be primary afferents, were found to enter from the ventral roots and course to the dorsal horn. Most of these fibers were small in diameter and distributed boutons predominantly to the substantia gelatinosa. A few large ventral root afferent fibers were observed that distributed boutons mostly to the nucleus proprius.
Transport of radioactivity from primary auditory neurons beyond the cochlear nuclei
Authors: Carpenter Malcolm B. , Batton Robert B. , Peter Philip 
Published: December 2004

AbstractTransneuronal degeneration in secondary brainstem auditory nuclei has been described following cochlear lesions, and Marchi studies have revealed degeneration in the trapezoid body after such lesions. These findings support the view of some early neuroanatomists that primary auditory afferents project beyond the cochlear nuclei. Silver impregnation studies of degenerating cochlear afferents have failed to support this claim, leaving the question unresolved. Using [3H] amino acides auditory projections in the monkey were traced autoradiographically from labeled ganglion cells: (1) in all portions of the spiral ganglion, (2) in apical and middle turns of the cochlea and (3) primarily in the basal turn of the cochlea.Labeling of the entire spiral ganglion resulted in profuse transport of isotope to parts of all cochlear nuclei [anteroventral (AVCN), posteroventral (PVCN), and dorsal (DCN) cochlear nuclei]. Labeled axons entering the trapezoid body (TB) projected ipsilaterally to: (1) the lateral trapezoid nuclei (LTN), (2) the lateral superior olivary nucleus (LSO), (3) the dorsal dendritic zone of the medial superior olivary nucleus (MSO), and (4) the pericollicular or cortical nucleus of the inferior colliculus (IC). Auditory fibers crossing the midline in the TB projected contralaterally to: (1) the medial trapezoid nucleus (MTN), (2) the ventral dendritic zone of the MSO, (3) the ventral nucleus of the lateral lemniscus (VNLL), and (4) the central nucleus of the inferior colliculus (CNIC). Selective labeling of cells in the apical and middle ganglionic turns of the cochlea resulted in a similar pattern of centripetal transport.Selective [3H] uptake primarily by ganglion cells in the basal turn of the cochlea resulted in: (1) labeling of restricted parts of all cochlear nuclei, and (2) a considerable reduction of isotope transported beyond the cochlear nuclei. Labeled fibers in the TB were distributed sparsely in the ipsilateral LTN, LSO and dorsal dendritic zone of the MSO. Fibers in the TB were not labeled contralaterally in these animals.Interpretation of these data considers the possibility of transneuronal isotope transport. The pattern of isotope transported beyond the cochlear nuclei does not correspond to the secondary projections of any individual cochlear nucleus, although it bears some resemblance to that of the AVCN. The current study suggests that some primary auditory afferents project beyond the cochlear nuclei.
Horizontal cells of the turtle retina. I. Light microscopy of golgi preparations
Authors: Leeper Harold F. 
Published: December 2004

AbstractIn Golgi preparations of turtle retina, four types of horizontal cells were observed and their morphological characteristics determined in vertical thick sections, whole mount preparations, and reconstructions from serial 1‐μm sections.H1 consists of a nucleated, stellate cell body (H1CB) and an irregular, tuberous axon terminal (H1AT) connected by a slender axon. Both parts of these cells make contact with receptor cells. H1CB's appear to correspond to “L2‐type cells” while H1AT's correspond to “L1‐type cells” described in the physiological literature.H2 and H3 are axonless stellate cells which are similar to one another in vertical profile and may occasionally appear similar in horizontal view. In general, the dendritic tree is more densely branched and the density of receptor cell contacts is higher for H2 than for H3. H2‐type cells may correspond to “R/G C‐type cells.”H4 is also an axonless stellate cell type which is smaller than H2 or H3 at equivalent retinal locations.The dendritic fields of H1CB's vary widely, but systematically, in size and shape over the retina. Their size is inversely related to receptor cell density, and the shape of the dendritic tree varies from roughly circular in the central area to elliptical in the periphery of the retina.
Development of the diencephalon in the rat. II. Correlation of the embryonic development of the hypothalamus with the time of origin of its neurons
Authors: Altman Joseph , Bayer Shirley A. 
Published: December 2004

AbstractThe development of the nuclei of the hypothalamus was examined in normal and X‐irradiated embryos from day 13 (E13) to the day before birth (E22). The diencephalic neuroepithelium was subdivided into three lobes (dorsal, medial, and ventral) and two lobules (superior and inferior). The hypothalamus is derived from the ventral lobe and the inferior lobule. The ventral neuropithelial lobe generates the neurons of most of the early arising hypothalamic structures, including those of the lateral tier nuclei associated with the medial forebrain bundle, and the heterogeneous intermediate tier nuclei. A specialized neuroepithelial region lining the diamond shaped ventricle produces the early neurohypophysial magnocellular neurons; the neurons of the paraventricular nucleus remain at the site, whereas the neurons of the supraoptic nucleus could be traced migrating laterally. The neurons of the late arising hypophysiotropic area of the posterior hypothalamus are derived from components of the inferior neuroepithelial lobule: the dorsomedial and ventromedial nuclei apparently from a shared matrix in the main portion of the inferior lobule; the tuberomammillary‐arcuate complex from its posteroventral recess. The triple‐decked and sequentially produced components of the mammillary system may arise from separate neuroepithelial sites. The autoradiographic results of the previous study (Altman and Bayer, '78a) showed that the structural and functional heterogeneity of the mature hypothalamus is paralleled by cytogenetic heterochronicity; the present embryonic observations indicate that many of the distinguishable components of the hypothalamus arise from a mosaic of heterogeneous neuroepithelial sites.
Projections from the subiculum to the deep layers of the lpsilateral presubicular and entorhinal cortices in the guinea pig
Authors: Sørensen Knud Erik , Shipley Michael T. 
Published: December 2004

AbstractProjections from the subiculum to retrohippocampal areas were studied by reduced silver impregnation of anterograde degeneration and by autoradiographic tracing of transported proteins following injections of radioactive amino acids. The subiculum was found to project to the presubiculum and to the medial and lateral parts of the entorhinal area. The projections are exclusively ipsilateral, and arranged in a dorso‐ventral topographical order with the terminations confined to the deep cortical layers. The projections form part of multisynaptic chains within the hippocampal region and must also be implicated in output routes for hippocampal activity additional to the fimbria‐fornix system.
A light microscopic and electron microscopic study of the superficial layers of the superior colliculus of the tree shrew (Tupaia glis)
Authors: Graham J. , Casagrande V. A. 
Published: December 2004

AbstractHistochemical, Golgi, and electron microscopic methods were used to study the superficial layers of the superior colliculus of the tree shrew. Following horseradish peroxidase injections in the dorsal lateral geniculate nucleus (LGd) and the pulvinar (Pul), retrogradely labeled somata were found in the upper two‐thirds and the lower third of the stratum griseum superficiale (SGS), respectively, as has been described by Albano et al. ('79). In tissue prepared with Golgi methods, somata, similar in location and shape to those projecting to the LGd, had narrow, vertically oriented dendritic arbors, which were confined to the upper two‐thirds of the SGS. Cells located in the lower third of the SGS had larger somata, similar to those projecting to the Pul, and wider dendritic arbors, which were confined to the lower two‐thirds of the SGS. Electron microscopic comparison of the number of degenerating terminals following enucleation and striate cortex lesion indicated that within the SGS terminals from the retina overwhelmingly outnumbered those from the cortex. In both types of material, degenerating terminals were observed throughout the SGS. However, the majority of the degenerating optic terminals were located in the upper SGS, whereas most of the degenerating striate terminals were found in the lower SGS. Thus, cells that project to the LGd and those that project to the Pul differ not only with respect to location, size, and dendritic morphology, but also with respect to the proportion of retinal and striate afferents which terminate in the region of their dendritic trees.
Morphological effects of monocular deprivation and recovery on the dorsal lateral geniculate nucleus in galago
Authors: Casagrande V. A. , Joseph Rhawn 
Published: December 2004

AbstractThe effects of monocular lid‐suture deprivation on development were evaluated by measurement of cell sizes in the lateral geniculate nuclei of six deprived and three normally reared galagos. In all animals autoradiographic demonstration of the retino‐thalamic projections from one eye was used to define the lamination and distinguish the monocular from the binocular segment of the nucleus. Our results indicate that monocular deprivation significantly affects cell growth in both the binocular and monocular geniculate segments, with the greater change occurring in the binocular segment, suggesting that both visual experience and binocular competitive interactions influence geniculate cell growth in these primates. In animals forced to use their deprived eye for 2 months or more by reverse suturing, disparity of cell sizes is reduced in the monocular segment, while differences in binocular segment cell sizes are maintained. Our results also show that monocular deprivation with or without later reverse suture has an unequal influence on different geniculate layers, such that cells in laminae 4 and 5 are not as severely affected as the remaining layers. This differential influence could relate either to the unique pattern of projection of these layers to cortex or to functional differences between layers.
Second somatic sensory area in the cerebral cortex of cats: Somatotopic organization and cytoarchitecture
Authors: Burton H. , Mitchell G. , Brent D. 
Published: December 2004

AbstractThe cortex of the anterior ectosylvian gyrus and adjoining ectosylvian and suprasylvian sulci was explored with tungsten microelectrodes to determine the distribution of responses to light cutaneous stimulation in barbiturate‐anesthetized cats. Recordings were spaced between 125 and 250 μm and, in several cases, nearly all of the somatic areas in this cortex were explored in the same brain. Four somatic sensory areas were identified on the basis of response properties, sequences of receptive fields, and cytoarchitecture.The largest area, which occupied the rostral and medial two‐thirds to three‐fourths of the exposed, relatively flat portion of the anterior ectosylvian gyrus, was called the second somatic sensory area (SII). Receptive fields in SII were primarily from the contralateral side of the body; they were well defined and somatotopically organized into an erect representation of the body. The top of the head was located next to similar representation of the periphery in a portion of the first somatic sensory area (SI)Individual distal digits and toes occupied discrete components of the SII map. Another representation for the distal forelimb and hindlimb was noted medially along the lateral bank of the anterior suprasylvian sulcus. Receptive fields and response properties in this region were equivalent to those seen in SII proper. However, only a crude anteroposterior, fore‐ to hindlimb topographical organization was noted, but with more distal parts of the limbs generally located closer to the fundus of the sulcus in this medial representation. As the cytoarchitecture in this medial region was similar to the rest of SII it was considered a medial subdivision of SII. A third, topographically organized zone was located lateral to SII largely within the upper bank of the anterior ectosylvian sulcus and adjoining lateral crest of the anterior ectosylvian gyrus. Large, stockinglike, contralateral receptive fields were common; ipsilateral components to the receptive fields were present. Some individual digit receptive fields were located in the rostral part of the forelimb zone within the anterior ectosylvian sulcus. This lateral somatic area is probably equivalent to a fourth somatic sensory area (SIV) recently identified by Clemo and Stein (1982). Posterior to the hindlimb zones of SII and medial to SIV was another region that responded to cutaneous plus auditory stimulation. There was no detectable topography in this area; nearly all of the receptive fields were large, frequently bilateral, and often involved the whole body or all four extremities. This area's cytoarchitecture was comparable to previous descriptions of the suprasylvian fringe (Rose, 1949). The location and physiology of these four areas were discussed in reference to previous controversies regarding the topography of the body representation in SII and the location of an acallosal zone in this region of cortex.
Studies of effects of kainic acid lesions in the dorsal lateral geniculate nucleus of rat
Authors: Woodward William R. , Coull Bruce M. 
Published: December 2004

AbstractKainic acid has been described as a highly specific neurotoxin that when injected locally into the nervous system destroys neuronal perikarya but spares axons of passage and terminals in the vicinity of the injection site. The effects of injection of this agent into the rat dorsal lateral geniculate nucleus on geniculocortical and corticofugal pathways have been examined. Neuronal perikarya were absent from injected geniculates, and products of neuronal degeneration were observed in the external stratum of the optic radiation and in layer IV of striate cortex. Furthermore, no visually driven units could bu found in physiological recordings from ipsilateral visual cortex, and no orthograde axonal transport of radioactivity to cortex was de tectable by autoradiography. These observations are consistent with the complete destruction of the geniculocortical pathway. On the other hand orthograde axonal transport appeared normal in corticogeniculate and cor‐ticotectal neurons on the injected side. In addition to silver grains appearing over the geniculate and superior colliculus label was observed over corti cofugal axons in the internal stratum of the optic radiation. It is noteworthy that axons of the corticofugal pathways are clearly segregated from geniculocortical axons over a part of their course through white matter. Corticogeniculate neurons on the injected side were able to transport D‐aspartate but not nuclear yellow retrogradely to cell bodies in layer VI. These results are consistent with the notion that cortical neurons terminating in and passing through the kainate lesion site survive but suggests, however, that corticogeniculate neurons may be functionally altered by these lesions.
Efferent projections of the posterior lateral line lobe in gymnotiform fish
Authors: Maler Leonard , Sas Emilia , Carr Catherine E. , Matsubara Joanne 
Published: December 2004

AbstractThe posterior lateral line lobe (PLLL) of gymnotoid fish has efferent projections to two midbrain regions: the nucleus praeeminentialis dorsalis (n.P.d.) and the torus semicircularis dorsalis (T.Sd.). Both ipsilateral and contralateral connections are present; the n.P.d. receives nearly equal input from both sides while the T.Sd. receives a stronger contralateral input. The PLLL projection to n.P.d. merely maps medial PLLL to ventral n.P.d. and lateral PLLL to dorsal n.P.d., thus preserving the separate topography and relative orientation of the four electrosensory maps found in the PLLL. Only PLLL pyramidal cells (basilar and nonbasilar pyramids) contribute to this projection. The four PLLL electrosensory maps converge onto T.Sd. so that they map the dorsal body surface onto medial T.Sd. and the ventral body surface onto lateral T.Sd. Pyramidal cells, spherical cells, and multipolar cells contribute to this projection.A small commiusural connection links homologous segments of the PLLL; these fibers arise from polymorphic cells of the PLLL.
Cortical and subcortical projections of the middle temporal area (MT) and adjacent cortex in galagos
Authors: Wall John T. , Symonds Laura L. , Kaas Jon H. 
Published: December 2004

AbstractProjections of the middle temporal visual area, MT, and of visual cortex adjoining MT were investigated with autoradiographic methods in the prosimian primate, Galago senegalensis. Ipsilateral cortical targets of MT included area 17, area 18, cortex caudal to MT, cortex ventral to MT, and parietal‐occipital cortex dorsal to MT. This pattern of projections suggests that extrastriate cortex contains a number of visual subdivisions in addition to MT. Contralateral projections were to MT and parietal‐occipital cortex. Projections from MT to areas 17 and 18 connected regions representing similar parts of the visual hemifield while the location of callosal projections in MT matched the location of the injection site in the other hemisphere. Label in area 17 wac concentrated in layers I, III, and VI whereas other cortical areas were most densely labeled in the granular and supragranular layers. Subcortical projections of MT included the reticular nucleus of the thalamus, the lateral posterior nucleus, the superior pulvinar, the inferior pulvinar, the superior colliculus, and the pontine nuclei. The projection pattern to the superior and inferior pulvinar nuclei suggests that MT projects in a topographic manner to two subdivisions within each of these structures.Injections in cortex just outside of MT labeled area 18, inferotemporal cortex, parietal‐occipital cortex, and, to a lesser extent, MT. The projections to inferotemporal cortex clearly distinguish the bordering cortex from MT. Contralateral cortical terminations were in locations corresponding to the injection site. Subcortical targets were generally similar to those seen after MT injections, although additional projections were observed depending on the location of the injection.Comparison of these results from the prosimian galago with studies in New and Old World monkeys indicates there are substantial similarities in projections. Thus, some of the cortical and thalamic subdivisions described for monkeys appear to exist in prosimians.