摘要:

AbstractThe distribution of corticothalamic projections from lateral suprasylvian areas AMLS, PMLS, ALLS, and PLLS was investigated with the autoradiographic method. Areas AMLS and PMLS were both found to project retinotopically upon the medial interlaminar nucleus and the lateral and pulvinar zones of the lateral posterior complex, as well as to the ventral lateral geniculate nucleus, intralaminar nuclei, and thalamic reticular complex. Retinotopic projections to the dorsal lateral geniculate nucleus were demonstrated from PMLS but not AMLS, and projections to zona incerta were demonstrated from AMLS but not PMLS. Areas PLLS and ALLS were both found to project retinotopically upon the interjacent zone of the lateral posterior complex, as well as to the intermediate and suprageniculate divisions of the posterior nuclear group, the magnocellular division of the medial geniculate complex, the thalamic reticular complex, and central lateral nucleus. Area ALLS was also found to project onto the dorsal division of the medial geniculate complex and lateral division of the posterior nuclear group. Differences between the four cortical areas in the pattern and density of their thalamic projections supports the parcellation of these areas as proposed by Palmer et al. ('78).The projection patterns of areas PMLS, AMLS, PLLS, and ALLS were found to respect the boundaries of the zones of the lateral posterior complex, which had been identified and defined previously (Updyke, ′77), and the results thus support the hypothesis that these zones are the functional units of organization for visual traffic between the cat's extrastriate visual area

ISSN:0092-7317    

DOI:10.1002/cne.902010403

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe object of this study was to describe the embryonic and postembryonic morphogenesis of a grasshopper interneuron in order to determine how, and when, this cell comes to assume its mature form. DCMD is an intensively investigated interneuron whose morphology, input and output physiology, and role in behavior are relatively well‐known in the adult. We examined the morphology of DCMD in the brain at each stage of its development with silver‐intesified cobalt‐fills. It arises at 40 ± 4% of embryogenesis and is probably one of the early progeny from its stem cell. In the ensuing 40% of development, its brain arborization grows quite directly into its mature form. Branches appear first and are always longest and densest in the brain region where the adult arborization is found. Thus, the adult form arises by initially directed growth and not by secondary selection of branches from a diffuse or overgrown arborization. Restricted secondary branch loss of lateral filopodia and probably of a few early branches does occur.Embryonic and postembryonic development of the cell are distinctly different. Embryogenesis is the period of morphological differentiation as indicated by the growth and shaping of the brain and also thoracic (axonal) arborizations, the appearance of cytological specializations, and the logarithmic growth of the neurite and soma. The brain arborization has its mature form, although not size, by the completion of embryogenesis. Postembryonic development is a period of substantial, but primarily allometric, growth. The soma and neurite grow linearly (with time), and the arborization grows in proportion to brai

ISSN:0092-7317    

DOI:10.1002/cne.902010404

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe representation of the visual field in the area adjacent to striate cortex was mapped with multiunit electrodes in the macaque. The animals were immobilized and anesthetized and in each animal 30 to 40 electrode penetrations were typically made over several recording sessions.This area, V2, contains a topographically organized representation of the contralateral visual field up to an eccentricity of at least 80°. The representation of the vertical meridian is adjacent to that in striate cortex (V1) and forms the posterior border of V2. The representation of the horizontal meridian in V2 forms the anterior border of V2 and is split so that the representation of the lower visual field is located dorsally and that of the upper field ventrally. As in V1, the representation of the central visual field is magnified relative to that of the periphery. The area of V2 is slightly smaller than that of V1. At a given eccentricity, receptive field size in V2 is larger than in V1.The myeloarchitecture of V2 is distinguishable from that of the surrounding cortex. The location of V2 corresponds, at least approximately, to that of cytoarchitectonic Area OB. V2 is bordered anteriorly by several other areas containing representations of the visual field

ISSN:0092-7317    

DOI:10.1002/cne.902010405

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractIn many animals the sensory hair cells of the inner ear are ultrastructurally variable within individual epithelia. This variation has been hypothetically related to both the function and the age of the individual cells. In this study, growth‐related changes in hair cell populations were examined in the macula neglecta sensory epithelia of juvenile and adult sharks. Scanning electron microscopy demonstrated that more than 80% of the 200,000 hair cells in the adult's macula neglecta are produced postembryonically. Tritiated thymidine autoradiography and histological descriptions of the hair cells in this sound detector indicate that new sensory cells are produced in growth zones at the edges of the epithelia. The hair cells in those zones have small cell bodies, small and heterogeneous cilia complexes, and associations with small numbers of particularly thin nerve terminals. Their cytological features and their sparse innervation contrast with the features of the more numerous central cells in each epithelium, but appear to resemble the published descriptions of embryonically developing hair cells. Thus, a germinal zone at the leading edge of sensory epithelium growth appears to persist into adult life in sharks. Published reports reinterpreted in light of this evidence suggest that such hair cell population growth may be expected in other anamniotes and that latent growth zones might persist in the ears of amniote

ISSN:0092-7317    

DOI:10.1002/cne.902010406

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe developmental abnormality caused by the autosomal recessive mutation reeler leads to a systematic inversion in the depth distribution of morphologically defined cell classes in the cortex and to an abnormal course taken by thalamocortical projections (Caviness, '77). The course of the geniculocortical projections was visualized in reeler through transneuronal autoradiography. After traveling under the pial surface, the fibers terminate in a slightly patchy manner at intermediate levels of the primary visual cortex. As in the normal mouse, there is a weaker projection to the lateral part of area 17 ipsilateral to the injection. The retinal ganglion cells giving rise to the ipsilateral projection in reeler were labeled with horseradish peroxidase and were found to be located at normal positions in the retina.The functional competence of the primary visual cortex in reeler was studied by recording the response properties of single cells. In most respects the reeler cortex appeared remarkably normal: the cortical topography of the visual‐field representations was normal overall, all receptive field types seen in the normal mouse were present, and cells within the binocular region received normally convergent input from the two eyes. The reeler differed from normal in having a greater number of poorly responding cells and a lower fraction of cells with oriented receptive fields. The tendency for oriented cells to occur preferentially in upper cortical layers in the normal mouse was not present in reeler.These results imply that the cells in the reeler cortex are connected in a largely normal manner despite the gross malformation. Thus it appears that the specificity of intercellular connections, in reeler and in normal cortex, does not depend crucially upon the position of the cells in the corte

ISSN:0092-7317    

DOI:10.1002/cne.902010407

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe three‐dimensional structure of the ruffed cell dendrite in the olfactory bulb of the goldfish (Carassius auratus) was studied by means of light and high‐voltage electron microscopy of Golgi‐impregnated material, combined Golgi‐electron microscopy, and electron microscopy of serial thin sections.Ruffed cell dendrites ramify in the glomerular area with tufted branching patterns. They give rise to many appendages of various shapes and sizes: sheetlike processes, fingerlike projections, or small tuftlike appendages. These appendages, singly or together, appear to entwine or cover other neuronal processes. In thin sections ruffed cell dendritic appendages frequently look like glial processes; that is, they appear to conform in shape to the contours of surrounding neuronal elements, such as mitral and granule cell dendrites.Ruffed cell dendrites display intimate relationships with mitral cell dendrites. The former appear to coil around and cover the latter. Notwithstanding the intimate relationship between ruffed cell dendrites and mitral cell dendrites, there seem to be no synaptic connection between them. Ruffed cell dendrites bear a rather small number of presynaptic and postsynaptic sites, most of which are with granule cell dendrites. Ruffed cell dendrites seem to receive no synapses from olfactory nerve te

ISSN:0092-7317    

DOI:10.1002/cne.902010408

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractNeurons in the hypothalamus, other diencephalic regions, and the telencephalon which project to the mesencephalic central gray (CG) and the region lateral to it were demonstrated, in the rat, by the horseradish peroxidase retrograde neuroanatomical tracing method with diaminobenzidine and tetramethyl benzidine visualization reactions. The greatest concentrations of neurons that project to the dorsal mesencephalon were found in the ventromedial nucleus, particularly the anterior and ventrolateral subdivisions, in the dorsal premammillary nucleus, and in the zona incerta. Neurons that project to or lateral to the CG were also found in the laterocaudal hypothalamus, the dorsomedial hypothalamus, regions of the anterior hypothalamic area, specific areas of the cerebral cortex (32, 29, 8, 8A, 13, 14), and the central nucleus of the amygdala. Some neurons that project were also found in the preoptic area, septum, bed nucleus of the stria terminals, and the habenula.More neurons in the mediocaudal quadrant of the hypothalamus project to the mesencephalon than do those in laterocaudal, mediorostral, or laterorostral quadrants. More neurons in the medial than the lateral half, and more in the caudal than the rostral half of the hypothalamus project to the mesencephalon. More neurons project to the central gray, or the region lateral to it, at the inferior colliculus.These descending connections to the midbrain, particularly from the hypothalamus and zona incerta, are probably components of neural networks that regulate nociception, certain neuroendocrine functions, sexual and other behaviors, and certain autonomic functions.

ISSN:0092-7317    

DOI:10.1002/cne.902010409

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902010402

出版商:Alan R. Liss, Inc.    

年代:1981

数据来源: WILEY