摘要:

AbstractThe functional organization of the visual system was studied in the albino rat. Metabolic differences were measured using the 14‐C‐2‐deoxyglucose (DG) autoradiographic technique during visual stimulation of one entire retina in unrestrained animals. All optic centers responded to changes in light intensity but to different degrees. The greatest change occurred in the superior colliculus, less in the lateral geniculate, and considerably less in second‐order sites such as layer IV of visual cortex. These optic centers responded in particular to on/off stimuli, but showed no incremental change during pattern reversal or movement of orientation stimuli. Both the superior colliculus and lateral geniculate increased their metabolic rate as the frequency of stimulation increased, but the magnitude was twice as great in the colliculus. The histological pattern of metabolic change in the visual system was not homogenous. In the superior colliculus glucose utilization increased only instratum griseum superficialeand was greatest in visuotopic regions representing the peripheral portions of the visual field. Similarly, in the lateral geniculate, only the dorsal nucleus showed an increased response to greater stimulus frequencies. Second‐order regions of the visual system showed changes in metabolism in response to visual stimulation, but no incremental response specific for type or frequency of stimuli.To label proteins of axoplasmic transport to study the terminal fields of retinal projections14C‐amino acids were used. This was done to study how the differences in the magnitude of the metabolic response among optic centers were related to the relative quantity of retinofugal projections to these centers. Fast and slow axoplasmic transport were studied using three separate amino acids. In each case over 64% of the radioactivity projecting contralateral from the eye was found in superior colliculus. Considerably less isotope was found in dorsal lateral geniculate (11–17%), ventral lateral geniculate (3.7–6.2%), pretectal nuclei (5–12%), and the accessory optic system (3–7%). The greatest concentration of radioactivity within each optic center was found in the visuotopic aspect subserving the superior visual field; particularly the medial aspects of the superior colliculus, olivary pretectal nucleus, and posterior pretectal nucleus, and the anterior portion of the nucleus of the optic tract. The representation of central vision in the colliculus was relatively pale, as was a zone within the middle of the contralateral dorsal lateral geniculate.The anatomical and physiological results of this study suggest that differences in deoxyglucose metabolismamongoptic centers are primarily related to the number of retinofugal endings and the kind of visual stimulation. Changeswithinany one center primarily reflect the density of retinal endings subservi

ISSN:0092-7317    

DOI:10.1002/cne.901990402

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe distribution of ganglion cells in the retina of the opossum was determined from whole‐mounted retinae stained with cresyl violet. Isodensity lines were approximately circular with a peak density of 2,000 to 2,700 cells/mm2in superior temporal retina (area centralis). The total number of retinal ganglion cells was estimated to be 72,000 to 135,000 (mean 101,026) in retinae ranging from 125 to 187 mm2in total area. Three groups of ganglion cells were distinguished on the basis of soma size and retinal topography. Large cells (24 to 32 μm diameter) were fairly evenly distributed across the retina. Medium cells (12 to 23 μm diameter) were more numerous in the superior temporal quadrant than in other regions of the retina. Small cells (7 to 11 μm diameter) were prominent in all retinal regions, but particularly in nasal and inferior retina. An analysis of topographical differences in soma size distribution suggests that the medium size cells can be further subdivided into small‐medium and large‐mediu

ISSN:0092-7317    

DOI:10.1002/cne.901990403

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe axonal conduction velocity groups in the optic nerve of the North American opossum were analyzed electrophysiologically and related to soma size groups of ganglion cells in terms of their retinal origin and laterality of projection. On the basis of analysis of field potentials and single unit responses recorded at the optic disc, three velocity groups were identified (d1, d2, and d3) and estimated to have average conduction velocities of 12, 8, and 5 meters/second. From recordings of the field potential around the perimeter of the optic disc, it was found that the d1group was equally represented at all points around the disc, whereas the d2group was largest in amplitude in superior temporal regions. Electrical stimulation of the optic tracts indicated that axons in the d1group project either ipsilaterally or contralaterally, whereas the d2group projects predominantly ipsilaterally, and the d3group projects predominantly contralaterally.In order to relate these physiological data directly to soma size groups, horseradish peroxidase (HRP) was injected into one optic tract, and subsequently the retinae were processed for peroxidase reaction product in the ganglion cells. Labeled cells were seen in contralateral nasal, contralateral temporal, and ipsilateral temporal retina. Cells in all size classes were labeled in contralateral nasal retina. In contralateral temporal retina, labeled cells were either 10–17 μm diameter (small and medium) or 23–27 μm diameter (large), whereas in ipsilateral temporal retina, most labeled cells (94%) were 15–30 μm diameter (medium and large). The correspondence between these conduction velocity groups and the soma size groups described in the preceding paper (Rapaport et al., '81) is d

ISSN:0092-7317    

DOI:10.1002/cne.901990404

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe longer connections of the entorhinal cortex have been studied autoradiographically in a series of rats, each of which received a small injection of3H‐amino acids in one of the various cytoarchitectonic subfields of the entorhinal cortex. The major findings can be summarized as follows. Whereas the projection of the lateral entorhinal area (LEA) to the dentate gyrus is broad in its longitudinal extent, the medial entorhinal area (MEA), and especially the ventral portion of this zone, projects in a more lamellar fashion. In the transverse plane the LEA preferentially projects to the inner (dorsal) blade of the dentate gyrus, while the MEA innervates both blades equally. Within the radial dimension, the entorhinal cortex projects to the dentate gyrus according to a medial to lateral gradient, with lateral portions of the LEA projecting along the pial surface and successively more medial portions of the entorhinal projecting closer to the granule cells. The commissural entorhinal to dentate projections are similar to the ipsilateral projections in location; however, they are considerably reduced in septotemporal extent and do not arise from cells in the ventral half of either LEA or the intermediate entorhinal area (IEA). The projection of the entorhinal cortex to Ammon's horn reflects the same longitudinal characteristics as the denate projections. An alvear input which extends only to the pyramidal cells at the CA1‐subicular junction was most noticeable at ventral hippocampal levels. Finally the extrahippocampal projections have been analyzed. These arise predominantly from cells in the LEA and project forward along the angular bundle to the piriform and periamygdaloid cortices, as well as the endopiriform nucleus, the lateral, basolateral, and cortical amygdaloid nuclei, the nucleus of the lateral olfactory tract, the olfactory tubercle, the anterior olfactory nucleus, the taenia tecta, and the indusium griseum. These extrinsic projections are to a large extent reciprocal to the major extrinsic inputs to the

ISSN:0092-7317    

DOI:10.1002/cne.901990405

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe distribution of Met‐enkephalin‐like immunoreactivity in the brains of 2‐week‐old domestic chicks was studied with immunohistofluorescence and the unlabeled antibody peroxidase‐antiperoxidase technique, using antibodies to Met‐enkephalin generated in rabbits. Immunoreactive cell bodies were found in the telencephalon, diencephalon, and mesencephalon in areas as yet uncharacterized as discrete nuclei in birds (E‐1, E‐2, E‐3, E‐4, E‐5); further cells were located in the diencephalic nucleus spiriformis lateralis, the midbrain medial intercollicular nucleus (E‐6), the nucleus mesencephalicus lateralis, pars dorsalis, the Edinger‐Westphal nucleus and dorsal occulomotor nucleus; and in the nucleus of cranial nerveXand an uncharacterized area in the dorsolateral medulla (E‐7). Immunoreactive fibers and/or terminals were located around the immunoreactive cell bodies and, in addition in the lateral septal area of the telencephalon; in the preoptic and hypothalamic areas of the diencephalon; in the anterior intercollicular area, periaqueductal central gray, area C, and the midventral tegmentum of the mesencephalon; in the nucleus solitarius, nucleusIX‐X, nucleus intercalatus, nucleus intermedius, and ventrolateral areas of the rhombencephalon. The pattern of distribution of met‐enkephalin in the chick is compared with that in the rat. A possible functional role for Met‐enkephalin in neural mechanisms mediating some be

ISSN:0092-7317    

DOI:10.1002/cne.901990406

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe morphology of early interactions between neural tube and myotome in the amphibian embryo and tail regenerate was examined using the electron microscope. Two types of contacts were observed. At the most primitive level where the myotome was yet unsegmented, multiple adhesive‐type contacts linked neural tube and myotome. In newly segmented areas early ventral roots were recognizable as small bundles of one to five axons extending the short distance to the myotome. There was only one bundle per segment and in addition to axons, each bundle always contained one or more primitive glial cell processes which accompanied axons as they left the cord. At points of root exit primitive glial processes appeared to funnel axons into the root. The cytoarchitecture of the cord and the new roots suggested that the primitive glia may play a role in pathfinding for motor axons as they leave the cord and extend toward their target

ISSN:0092-7317    

DOI:10.1002/cne.901990407

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe intramembrane organization of outer segment (OS) membranes and pigment epithlial (PE) microvilli has been studied in rats (10–17 postnatal days) with inherited retinal degeneration (RCS) and in normal retinas from genetically controlled rats (RCS‐rdy +). The OS plasma membranes of both dystrophic and normal retinas are characterized by large particles surrounding circular, particle‐free zones on the P‐faces (cytoplasmic leaflets) and a sparse distribution of particles on the E‐faces (external leaflets). No regional differences in particle distribution are observed in either basal or distal plasma membrane regions. Outer segment disc membranes are characterized by large, densely packed P‐face particles and ridged E‐faces with very few particles. Small, particle‐free patches of membrane are present in the basal disc P‐faces of both normal and dystrophic retinas, which Andrews and Cohen (1979) have described as characteristic of newly added disc membrane. In dystrophic retinas, larger, particle‐free domains are observed in the distal disc membranes (P‐faces) and accumulating membranous debris. In older retinas, which have accumulated more debris, the particle‐free domains occupy vast areas of the membrane faces and it is not possible to identify these membranes as belonging to either discs or plasma membranes. No comparable areas of particle‐free membrane are observed in the distal discs and OS plasma membranes of normal retinas. Pigment epithelial microvillus membranes are characterized by an intermixture of large and medium‐sized particles surrounding irregular particleq‐free areas, but no differences between normal and dystrophic PE membranes are observed. The changes in particle distribution observed in the dystrophic retinas suggests that the intramembrane molecular composition of older disc membranes has become altered or rearranged as the OS m

ISSN:0092-7317    

DOI:10.1002/cne.901990408

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

年代:1981

数据来源: WILEY

摘要:

AbstractCorticothalamic projections from areas 5a, 5b, and 7 of cat parietal cortex were studied with autoradiographic techniques. Each cortical area was identified by its cytoarchitectural characteristics and the patterns of termination were related to the thalamic nuclear groups. Injections of3H‐leucine in cortical area 5a were associated with terminal labeling primarily in the spinal recipient zone of the ventral lateral nucleus (VLsp) and the medial division of the posterior group (POm). The corticothalamic projections of area 5a are loosely topographically organized; medial parts of 5a project heavily to rostral and lateral parts of VLsp and sparsely to POm, while lateral parts of 5a project to more medial and caudal parts of VLsp and heavily to POm. Cortical area 5b projects primarily to the rostral portions of the lateral posterior nucleus (LP). These projections also appear to be topographically organized. The part of area 5b on the marginal gyrus projects to more ventral parts of rostral LP, while area 5b on the middle suprasylvian gyrus projects to more dorsal and lateral parts of rostral LP. Cortical area 7 projects to LP and the pulvinar (Pul). Rostral parts of area 7 project heavily to dorsal and lateral parts of LP and lightly to Pul; more caudal portions of area 7 project relatively more heavily to Pul. The reticular, central lateral, and paracentral nuclei also receive projections, especially from the suprasylvian gyrus. The results are discussed with regard to putative sensory response characteristics of these cortical areas and to general thalamocortical organizatio

ISSN:0092-7317    

DOI:10.1002/cne.901990409

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

年代:1981

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901990401

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

年代:1981

数据来源: WILEY