摘要:

AbstractThis paper presents evidence on the retinal distribution and certral projections of retinal ganglion cells of various cell body sizes in the adul macaque monkey. The ganglion cell sizes have been determined by computer assisted measurement of camera lucida drawings at various eccentricities of both flat mounted and sectioned retinae. The pattern of projections of individual ganglion cells to the dorsal lateral geniculate nucleus and superior colliculus has been studied using retrograde axonal transport of horseradish peroxidase. Following peroxidase injections into the parvocellular laminae of the geniculate, virtually every ganglion cell was labeled within a circumscribed zone of the retina known to project to the region of the geniculate immediately surrounding the injection needle tip. After magnocellular injections, only the largest cells of the peripheral retina and approximately 26% of the ganglion cells of the parafovea were labeled. Peroxidase injections into the superior colliculus produced labeling of scattered ganglion cells of all sizes in the retina, although no labeled cells were found within the centralmost 10° eccentricity. From these observations it is concluded that all ganglion cells of the macaque retina project to the parvocellular layers of the dorsal lateral geniculate, but that only the largest ganglion cells of the more peripheral retina and not all cells of the parafovea project to the magnocellular laminae. In contrast, only scattered ganglion cells, although these are of all sizes, appear to project to the superior colliculus.Two major problems with the peroxidase tracing technique are described:The extent of stainable peroxidase activity around the injection site appears to be larger than the area of injected tracer actually available for uptake by axons to produce labeled cells.Cut or damaged axons appear to incorporate peroxidase sufficiently to produce labeling of the cell body

ISSN:0092-7317    

DOI:10.1002/cne.901640302

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe retrograde transport of horseradish peroxidase has been used to identify efferent cells in area 17 of the macaque. Cells projecting to the lateral geniculate nucleus are small to medium sized pyramidal neurons with somata in lamina 6 and the adjacent white matter. The projection to the parvocellular division arises preferentially from the upper half of lamina 6, while that to the magnocellular division arises preferentially from the lower part of the lamina. The projection to both superior colliculus and inferior pulvinar arises from all sizes of pyramidal neurons lying in lamina 5B (Lund and Boothe, '75); at least the largest pyramidal neurons of lamina 5B send collateral axon branches to both destinations. Injections with extensive spread of horseradish peroxidase show that many cells of lamina 4B and the large pyramidal neurons of upper lamina 6 also project extrinsically but their terminal sites have not been identified.Other studies have indicated that cells of laminae 2 and 3 project to areas 18 and 19. Therefore every lamina of the visual cortex, with the exception of those receiving a direct thalamic input, contains cells projecting extrinsically. Further, each lamina projects to a different destination and from Golgi studies can be shown to contain cells with specific patterns of dendritic branching which relate to the distribution of thalamic afferents and to the patterns of intracortical connections. These findings emphasise the significance of the horizontal organisation of the cortex with relation to the flow of information through it and contrast with the current concept of columnar organisation shown in physiological studies.

ISSN:0092-7317    

DOI:10.1002/cne.901640303

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe GABA synthesizing enzyme, glutamate decarboxylase (GAD), has been localized by light and electron microscopy in the rat lumbosacral spinal cord using a peroxidase‐labeling antibody technique. The light microscopic localization shows heavy, punctate reaction product for GAD in the dorsal horn laminae I–III. Moderately heavy reaction product is also seen in the deeper dorsal horn laminae IV–VI, the medial aspect of the intermediate gray (lamina VII) and the region around the central canal (lamina X). A moderately light concentration of GAD reaction product is observed in the ventral horn, and punctate deposits of reaction product also are seen on motoneuron cell bodies.The punctate distribution of reaction product for GAD in both ventral and dorsal horns, as visualized by light microscopy, corresponds to GAD‐containing synaptic terminals seen by electron microscopy in comparable regions of the spinal gray. Many more GAD‐positive terminals are observed in dorsal horn laminae I–III than in deeper laminae IV–VI. GAD‐containing terminals in the dorsal horn are presynaptic to dendrites and cell bodies. GAD‐containing terminals presynaptic to other axon terminals are observed also, and they are more numerous in laminae II and III. In the ventral horn motor nuclei, GAD‐positive knobs are presynaptic to large and small dendrites and motoneuron cell bodies. In addition, small GAD‐containing terminals also are presynaptic to larger axonal terminals which are in turn presynaptic to motoneuron somata.The observation of GAD‐containing terminals presynaptic to dendrites and cell bodies in both dorsal and ventral horns is compatible with the evidence suggesting that GABA terminals may mediate postsynaptic inhibition of spinal interneurons and motoneurons. The additional finding of GAD‐positive terminals presynaptic to other axonal terminals in the dorsal horn and motor nuclei is consistent with the growing evidence that GABA also may be the transmitter mediating presynaptic inhibition via axo‐axonal

ISSN:0092-7317    

DOI:10.1002/cne.901640304

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

年代:1975

数据来源: WILEY

摘要:

AbstractNucleus rotundus receives a major input from the optic tectum in crocodiles,Caiman crocodilus. Telencephalic projections of nucleus rotundu were studied inCaimanby means of the Fink‐Heimer procedure after anodal, stereotaxic lesions. Efferent axons of nucleus rotundus assemble on the ventrmedial aspect of this nucleus and swing ventrolaterally to enter the dorsal peduncle of the lateral forebrain bundle. These ascending fibers continue rostrally in the dorsal peduncle of the lateral forebrain bundle to enter the telencephalon where they remain restricted to a lateral portion of the lateral forebrain bundle. At more anterior levels, these fascicles turn dorsally, pass through the ventrolateral area, and terminate massively in a lateral part of the rostral dorsolateral area.The results of this experiment are compared with similar studies on thalamotelencephalic connections of diencephalic visual areas in other amniotes. Parallels in fiber connections of thalamic auditory and visual areas and the segregation these modalities in the telencephalon ofCaimanare discussed. These similarities in neural circuitry and synaptic elements of auditory and visual systems that synapse in the midbrain ofCaimanform the basis for a different interpretation of sensory system organization in amniote

ISSN:0092-7317    

DOI:10.1002/cne.901640305

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

年代:1975

数据来源: WILEY

摘要:

AbstractCatecholamine distribution was examined in cat hypothalamus using the histochemical fluorescence technique of Falck and Hillarp. The heaviest accumulations of catecholamine‐containing varicosities were seen within the: anterior periventricular nucleus; dorsal hypothalamic area; bed nucleus of the inferior thalamic peduncle; dorsal component of the paraventricular nucleus; dorsomedial nucleus; infundibular nucleus; bed nucleus of the stria terminalis‐medial division; and supraoptic nucleus. Catecholaminergic perikarya were observed within periventricular, dorsal, and caudal hypothalamic areas as well as within the supramamillary nucleus and caudal diencephalon. Catecholamine distribution in cat hypothalamus possesses both similarities and dissimilarities in relation to distributions reported in other mamm

ISSN:0092-7317    

DOI:10.1002/cne.901640306

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

年代:1975

数据来源: WILEY

摘要:

AbstractCommissural, cortico‐cortical and cortico‐caudate neurons have been investigated in the primary sensorimotor cortex of the cat, using antidromic stimulation techniques, and histological identification of recording sites. These neurons are to be found in all cortical laminae except the first; commissural and cortico‐cortical neurons were found to be commonest in laminae III and VI, whilst cortico‐caudate neurons were most abundant on the border between laminae III and V, in motor areas. In sensory areas topographically identified as representing distal parts of limbs, commissural neurons are very rare, confirming neuroanatomical studies on the origin and termination of callosal fibres.The intracerebral neuronal projections investigated in this study had slow conduction velocities (less than 1 m/sec, up to about 10 m/sec). It was found that projections from area 6, whether commissural, cortico‐caudate, or corticopeduncular have slower conduction velocities than their counterparts from area 4. It is suggested that this is related to the type of motor control in which these two areas are involved (slowly‐responding postural movements, as opposed to more rapid distal limb movements). No neurons were found which had both commissural (or cortico‐cortical), and cortico‐fu

ISSN:0092-7317    

DOI:10.1002/cne.901640307

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe projections of the cerebral cortex upon the septum in water snakes (Natrix sipedon) and garter snakes (Thamnophis sirtalis) were studied with the Fink‐Heimer degeneration techniques. Two cortical areas send major projections to the septum. Medial cortex projects bilaterally to the dorsal portion of the precommissural septum along its full rostrocaudal extent. The ipsilateral projection is more massive than the contralateral one. Dorsal cortex projects ipsilaterally to a column within the septum which is present dorsally, caudal to the level of the anterior commissure, but shifts ventrally as the septum is followed rostrally. Lateral cortex may send a sparse projection to the ipsilateral ventral septu

ISSN:0092-7317    

DOI:10.1002/cne.901640308

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

年代:1975

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901640301

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

年代:1975

数据来源: WILEY