摘要:

AbstractAnatomical and electrophysiological mapping techniques were used to determine topographic organization and arrangement of ocular dominance columns in the primary visual cortex of ferrets. From its border with area 18 on the posterior lateral gyrus, area 17 extends around the caudal pole of the hemisphere and over the splenial gyrus to the caudal bank of the splenial sulcus. The visuotopic map is oriented with the isoazimuth lines approximately parallel to the long axis of the posterior lateral gyrus and the isoelevation lines approximately perpendicular to the isoazimuths. Central azimuths are represented on the posterior lateral gyrus and peripheral azimuths are represented on the splenial gyrus; the inferior visual field maps medially and the superior visual field maps laterally. As in other species, the representation of the central visual field is expanded.The ferret has a considerable degree of binocular vision. Receptive fields driven through the ipsilateral eye extended more than 20° into the contralateral visual field. Within the region of area 17 corresponding to the binocular portion of the visual field, tritiated proline injected into one eye transneuronally labelled an ipsilateral projection as a series of patchy bands roughly complementary to gaps in the labelled contralateral projection. Physiological ocular dominance columns were evident as well in that neurons and groups of neurons recorded in this region showed clustered ocular dominance preferences. Most single neurons studied were binocularly driven

ISSN:0092-7317    

DOI:10.1002/cne.902780202

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe organization of the motor nuclei of cranial nerves V (including mesencephalic nucleus), VI, VII, IX, and X is described from HRP‐stained material (whole mounts and sections) for 25 species representing five families of salamanders, and the general topology of the brainstem is considered. Location and organization of the motor nuclei, cytoarchitecture of each nucleus, and target organs for nuclei and subnuclei are described. The trigeminal nucleus is separated distinctly from the facial and abducens nuclei and consists of two subnuclei. The abducens nucleus consists of two distinct subnuclei, one medial in location, the abducens proper, and the other lateral, the abducens accessorius. The facial nucleus has two subnuclei, and in all but one species it is posterior to the genu facialis. The facial nucleus completely overlaps the glossopharyngeal nucleus and partially overlaps that of the vagus. In bolitoglossine plethodontid salamanders, all of which have highly specialized projectile tongues, the glossopharyngeal and vagus nuclei have moved rostrally to overlap extensively and intermingle with the anterior and posterior subnuclei of the facial nerve. In the bolitoglossines there is less organization of the cells of the brainstem nuclei: dendritic trunks are less parallel and projection fields are wider than in other salamanders. Some aspects of function and development are discussed; comparisons are made to conditions in anurans; and phylogenetic implications are considere

ISSN:0092-7317    

DOI:10.1002/cne.902780203

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution and cytoarchitecture of motor nuclei of the cervical spinal cord were studied by using HRP techniques (whole mounts and sections) in 22 species of salamanders (families Hynobiidae, Dicamptodontidae, Ambystomatidae, Salamandridae, and Plethodontidae) representing a wide variety of life histories and functional modes of feeding. The nucleus of the first spinal nerve extends from the level of, or slightly caudad to, the root of the tenth cranial nerve, almost to the ventral root of the second spinal nerve. Approximately one‐half of this nucleus is situated in the brainstem. This anterior extension is longest in bolitoglossine plethodontids. The nucleus of the second spinal nerve extends from the root of the first spinal nerve to the dorsal root of the second spinal nerve.The nuclei of the first and second spinal nerves in all species except bolitoglossines have motor neurons arranged in two columns: a lateral one containing large spindle‐shaped cells and a medial one containing pearshaped or polygonal smaller cells. The primary dendrites of these lateral and medial cells are parallel and their arborization is relatively narrow. In contrast, bolitoglossines lack the lateral motor column. The nucleus of the first spinal nerve consists only of a medial band of pear‐shaped and sometimes polygonal cells, and the nucleus of the second spinal nerve is a wider band of pear‐shaped and polygonal cells which are always situated inside the periventricular gray matter. The arrangement of the somata in bolitoglossines is less organized and the primary dendrites are less parallel and have a broader arborization than in other salamanders. In all species, cells in the second spinal nucleus are arranged in a less orderly manner than those in the first.All salamanders studied possess a spinal accessory nerve whose motor neurons are located in the cervical spinal cord; the axons leave the brainstem with fibers of the vagus nerve. The rostrocaudal extent of this nucleus differs markedly among species. In bolitoglossines the nucleus is more or less restricted to the region of the nucleus of the second spinal nerve. In all other species studied, the accessory nucleus extends from the obex to the caudal end of the nucleus of the third spinal nerve. In the tribe Plethodontini the cytoarchitecture of the accessory nucleus is similar to that of the second spinal. In desmognathine and hemidactyliine plethodontids as well as in all nonplethodontid species studied the nucleus consists of pear‐shaped and cone‐shaped cells. No separate lateral motor column is present and the cone‐shaped cells are found at various positions inside and slightly outside the gray matter. In bolitoglossines both pear‐shaped and polygonal cells are found in the gray matter; again, no lateral motor column is present.A developmental‐evolutionary hypothesis is presented to account for the unique pattern of cellular organization in the bolitoglossines, and functional and phylogenetic implications of our findin

ISSN:0092-7317    

DOI:10.1002/cne.902780204

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe cat cochlear nuclear complex (CNC) is divided into three major subdivisions: the anteroventral, the posteroventral, and the dorsal cochlear nuclei (AVCN, PVCN, and DCN, respectively). Each of these subdivisions receives a topographic projection from the cochlea and each consists of a number of different cell types. The interconnections between these subdivisions and the cell types which give rise to them were studied by means of small injections of horseradish peroxidase (HRP) made at physiologically identified locations. DCN injections resulted in few labeled cells in the DCN, suggesting that its internal connections are very limited. In contrast, these same DCN injections resulted in numerous labeled cells in the PVCN and AVCN. Labeled PVCN cells, consisting of multipolar, octopus, and small spindle‐shaped cells, were located in spatially restricted laminae stretching the entire rostrocaudal length of the nucleus, while labeled AVCN cells consisting of multipolar, globular, small spindle‐shaped and small spherical cells were broadly distributed over the posterior half of the nucleus. Similar injections placed in the PVCN resulted in numerous labeled cells in all three subdivisions. The PVCN and AVCN cells labeled after PVCN injections were widely distributed across the isofrequency representations in both nuclei, while the labeled DCN cells were restricted to locations over the injection sites. Injections placed in the posterior half of the AVCN resulted in only very few labeled cells in the DCN. No cells were labeled following injections in the rostral A

ISSN:0092-7317    

DOI:10.1002/cne.902780205

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe sandlance or tommy fishLimnichthyes fasciatus(Creeiidae, Perciformes) is a tiny species that lives beneath the sand with only its eyes protruding and is found throughout the Indopacific region.The retina of the sandlance possesses a deep convexiclivate fovea in the central fundus of its minute eye (1.04 mm in diameter). A Nissl‐stained retinal whole mount in which the pigment epithelium had been removed by osmotic shock was used to examine the retinal topography of the ganglion cell layer. There was a foveal density of between 13.0 × 104cells per mm2(S.D. ± 1.8 × 104cells per mm2), counted in the retinal whole mount, and 15.0 × 104cells per mm2, counted in transverse sections, which diminished to a peripheral density of 4.5 × 104cells per mm2(S. D. ± 0.8 × 104cells per mm2). The total population of axons within the optic nerve was assessed by electron microscopy. Optic axon densities ranged from 2 × 106axons per mm2in the caudal apex to over 16 × 106axons per mm2within a specialized region of unmyelinated axons in the rostral apex. The topography of the proportion of unmyelinated axon population (26%) follows closely that of the total population of optic nerve axons. There was a total of 104,452 axons within the optic nerve compared with 102,918 cells within the retinal ganglion cell layer. A close relationship is revealed between ganglion cell soma areas and axon areas where the organization in the optic nerve and retina may reflect some functional reti

ISSN:0092-7317    

DOI:10.1002/cne.902780206

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn these experiments we have asked whether the projection from the rat's primary visual cortex, area 17, to the extrastriate visual cortical area 18a is formed in a sequence and whether that sequence resembles the pattern of inside‐out cortical neurogenesis. For this purpose fluorescent retrograde tracers were injected into area 18a at different postnatal ages (P1, P5, adult). Animals survived until 3–4 weeks of age, after migration is complete and neurons have arrived at their final laminar location. In the ipsilateral cortex, P1 injections retrogradely labeled cells in layers 5 and 6 of area 17. Labeling after P5 injections extended into more superfical layers and included the bottom of layer 2/3 and layers 4–6. After P5, more labeled cells were found at the top of layer 2/3, producing the adult laminar pattern, where the projection originates predominantly from layer 2/3. A similar sequence of laminar labeling was observed in the transcallosal connection of area 18a. This sequence of labeling, deep layers before superficial, resembles the pattern in which cortical neurons are born and indicates that axons arrive at their cortical targets in the order the cells were gene

ISSN:0092-7317    

DOI:10.1002/cne.902780207

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe distribution of substance P (SP) and vasoactive intestinal polypeptide (VIP) was investigated by immunohistochemistry in the adult chicken spinal cord. By using colchicine treatment, populations of neurons containing either SP or VIP was observed in several regions of the spinal cord. SP neurons were found dorsal to the central canal (CC) and in lamina IV throughout the cord. However, at the thoracic level, numerous relatively larger SP perikarya were located ventral to the CC and aligned on either side of the midline. The distribution of SP fibers is very similar to that reported previously in mammals: they were mostly observed in laminae I and II, in Lissauer's tract, in the dorsolateral funiculus, and dorsal to the CC. In addition, two dense plexuses of SP fibers were noticed in lamina IV. VIP neurons were located mainly in lamina I, in the nucleus of the dorsolateral funiculus, and in the lateral portion of the neck of the dorsal horn throughout the spinal cord. At the thoracic level, many also were located lateral to the CC. Occasionally, single VIP neurons also were encountered dorsal to the CC, in laminae II–IV, and in the intermediate zone. VIP fibers were observed in similar numbers at all spinal levels, occurring mainly in laminae II (probably I) and III, dorsal to the CC, and in the intermediate zone. In addition, examination of the developing chick spinal cords showed similar results as in adult chicken

ISSN:0092-7317    

DOI:10.1002/cne.902780208

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe regional distributions of muscarinic receptor subtypes (M1 and M2) in the macaque brain were investigated by in vitro receptor autoradiography. Putative muscarinic receptor subtypes were distinguished by their differential affinities for pirenzepine and carbachol in competition with [3H]‐quinuclidinyl benzilate. Autoradiographic visualization of muscarinic receptor subtypes demonstrated marked regional and laminar variations that respected architectonic boundaries.The M1 receptor subtype was widely distributed throughout most cortical areas and was most intense over the superficial layers. Almost all limbic and paralimbic regions including the amygdala, hippocampus, orbitofrontal, temporopolar, parahippocampal, cingulate, and parolfactory areas displayed peak densities of the M1 receptor subtype. The M2 receptor subtype was selectively elevated in the primary sensory areas of all five sensory modalities, including the visual (area 17, V1), auditory (A1), and somatosensory (3b,S1) koniocortices, the anterior olfactory nucleus, and the gustatory area. The primary motor area also displayed a relative peak of M2 receptor subtype labeling.In the hippocampal formation, M1, M2, and nicotine receptors were distributed differentially, with each subdivision having a specific complement of cholinergic receptor subtype. The M1 receptor subtype was prevalent in the dentate gyrus, the CA4‐CA3 region, and the CA1 ammonic sector. The M2 receptor subtype was concentrated in the CA2 sector, the subiculum, the rhinal cortices, and the parasubiculum. Putative neural nicotinic receptors, tagged with L‐[3H]‐nicotine, were most concentrated within the presu

ISSN:0092-7317    

DOI:10.1002/cne.902780209

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe anterograde transport of both wheat germ agglutinin conjugated to horseradish peroxidase and the kidney bean lectinPhaseolus vulgarisleucoagglutinin was utilized to investigate the projection of primary sensorimotor corticospinal tract axons to the superficial laminae of the spinal dorsal horn in the rat. Both methods yielded qualitatively similar patterns of connectivity. Corticospinal tract axons were found to terminate within all laminae on the side contralateral to the injection site. Labeling was most dense within laminae III and IV and medial portions of laminae I, II, and V in the cervical and lumbar enlargements. Labeling in the ventral horn, though present, was relatively less dense.P. vulgarisleucoagglutinin—labeled axons within laminae I and II exhibited boutonsen passantandterminaux; many of these axons also terminated or were collaterals of axons that terminated in deeper dorsal horn laminae. Results are discussed with reference to the somatotopic organization of the spinal cord and to a possible role for the cortex in the modulation of nociception within the spinal cor

ISSN:0092-7317    

DOI:10.1002/cne.902780210

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe postnatal maturation of the projection from the lateral geniculate nucleus to the posteromedial lateral suprasylvian visual cortex (PMLS) was studied with injections of fluorescent dyes into the PMLS at various postnatal ages. Labeled neurons projecting to the PMLS were present in all laminae of the ipsilateral lateral geniculate on the day of birth. However, there was a conspicuous change in the distribution of labeled geniculo‐PMLS neurons by 11 days of age: now very few labeled neurons were present in lamina A, indicating a loss of geniculo‐PMLS connections. The loss of connections began at the peripheral margins of lamina A and proceeded through other laminae toward laminae C1‐3. By adulthood, labeled geniculo‐PMLS neurons were largely confined to laminae C1‐3; they were never observed in lamina A or A1 and were rarely observed in lamina C.To determine whether the lateral geniculate neurons survived after their projections to PMLS were lost, injections of fast blue were made at 1 or 2 days postnatally and the animals were allowed long postinjection survival times. Labeled neurons were found in all lateral geniculate laminae, thereby indicating that for many neurons the loss of connections could be attributed to a loss of their axon collaterals rather than to the death of the neurons themselves.After injections of fast blue into the PMLS and diamidino yellow dihydrochloride into area 17 shortly after birth, many double‐labeled neurons were present in all laminae, indicating that they have collaterals to both targets. Thus, the survival of many of the geniculo‐PMLS neurons contributing to the transient geniculo‐PMLS projection seems to be due to sustaining collateral projections to area 17 or other c

ISSN:0092-7317    

DOI:10.1002/cne.902780211

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

年代:1988

数据来源: WILEY