摘要:

AbstractThis study was undertaken to determine the origin of projections from the basilar pontine nuclei (BPN) and nucleus reticularis tegmentis pontis (NRTP) to the posterior vermal lobules VI‐IX of the rat cerebellum. We describe the topographical organization of this component of the pontocerebellar projection, and the congruence of the cells of origin in the basilar pons with some of the major pontine afferent systems including the corticopontine and tectopontine projections. Horseradish peroxidase (HRP) was injected into the midline cerebellar vermal zones of Long‐Evans hooded rats. The more sensitive chromogens, tetramethyl benzidine and benzidine dihydrochloride, were used to reveal the location of labeled neurons.With injections located near the midline, groups of labeled cells were observed bilaterally within the BPN. The basic trend of the projections noted was: lobule VIa receives a nonfocal projection from nearly all subdivisions of the BPN throughout its rostrocaudal extent, as well as a substantial input from NRTP. Lobules VIb‐c receive input from NRTP, the rostral pons, and from the ventral, lateral, and medial groups of the middle BPN. A combination of lateral, medial, and dorsolateral groups of cells in the middle BPN project to lobule VII, in addition to projections from limited groups of cells in the rostral BPN. Lobule VIII receives afferents from the caudal aspect of the pontine gray. Lobules IXa‐b receive afferents from the medial and peduncular groups in the middle BPN, whereas lobule IXc receives inputs from a medial group and a small lateral cluster of cells in the caudal aspect of the BPN.Pontine neurons projecting to the posterior vermis originate from areas which appear to receive descending inputs from visual, auditory, and somatosensory regions of the cerebral cortex. However, a large number of pontine and NRTP neurons projecting to lobules VI and VII are located within the terminal fields of tectal neurons, perhaps indicating a stronger input from the tectum rather than visual and auditory cerebral cortical

ISSN:0092-7317    

DOI:10.1002/cne.901970402

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe projection of basilar pontine neurons to the cerebellar hemispheres was studied in pigmented rats by means of the retrograde transport of horseradish peroxidase. Injections of horseradish peroxidase were restricted to the lateral aspects of the lobulus simplex (11 cases), crus I (26 cases), crus II (23 cases), and paramedian lobule (18 cases). The main focus of labeled neurons following lobulus simplex injections of horseradish peroxidase was located in the ventral pons, at rostral levels. Interestingly, the majority of labeled cells were distributed ipsilateral to the injection site. After crus I injections, however, labeled neurons were most evident contralaterally, although labeled ipsilteral cells were conspicuous rostrally. The majority of labeled cells were characteristically distributed along the medial, ventral, and lateral perimeters of the pontine gray. This pattern of labeling contrasts with that in cases of crus II injections, in which the main focus of labeled somata occupied more central regions of medial and ventral portions of the pons. Similarly, the pattern of labeling following injections into the paramedian lobule largely avoided the medial and lateral perimeters of the pontine gray, while numerous labeled somata occupied the central region of the pons. In addition to the pontine regions described above, labeled cells were observed in various cases in the dorsal peduncular region, the lateral and dorsolateral areas, and the nuclear reticularis tegmenti pontis (NRTP) where three separate zones of labeling could be discerned in various cases.Several general organizational features were derived from these studies. Although specific quantitation procedures were not applied, the number of ipsilaterally labeled neurons was impressive in some cases, as was the mirror‐image location of certain ipsi‐ and contra‐lateral cell clusters. It was also noted that certain, similarly located clusters of labeled pontine neurons were present in cases in which injections were made into different cerebellar lobules, at least raising the possibility that some pontine neurons might give rise to divergent projections to multiple cerebellar locations. Moreover, it was evident that the location of certain clusters of labeled neurons was congruent with terminal zones of various pontine afferent systems, particularly those of the sensorimotor cortex. Combining the latter finding with the preceeding notion regarding pontocerebellar divergence suggests a mechanism by which sensorimotor information might be transmitted to several different cerebellar loca

ISSN:0092-7317    

DOI:10.1002/cne.901970403

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

年代:1981

数据来源: WILEY

摘要:

AbstractAttempts were made to determine the topographic organization of subthalamopallidal and pallidosubthalamic projections in order to evaluate interconnections between the subthalamic nucleus (STN) and the globus pallidus (GP). In a series of monkeys retrograde and anterograde axoplasmic transport technics were used to explore these interconnections. Small volumes of horseradish peroxidase (HRP) were injected selectively into: (1) the medial pallidal segment (MPS), (2) the rostral division of the lateral pallidal segment (LPS, rostral to the medial medullary lamina of the GP), and (3) the central division of the LPS (lateral to the medial medullary lamina of GP). Retrograde transport of the enzyme to cells in the STN indicated that: (1) cells in the medial and caudal third of the nucleus project predominantly to the MPS, (2) cells in medial portions of the middle third of the nucleus project predominantly to the rostral division of the LPS, and (3) cells in central portions of the rostral two‐thirds of the nucleus project to the central division of the LPS, with the largest contribution derived from rostral regions of the nucleus. An inverse dorsoventral topographical relationship appears to exist between cells in the STN and axonal terminations in the LPS, in that cells in dorsal regions of the STN project to ventral regions of the LPS, while cells in ventral regions of the STN project to dorsal regions of the LPS. No similar relationship could be established between the STN and the MPS because of its smaller size. Cells in the lateral third of the STN do not project terminals to the MPS or the rostral or central divisions of the LPS. It is suggested that cells in the lateral third of the STN project to the caudal division (caudal to the medial medullary lamina of the GP) of the LPS. A small number of cells in the pedunculopontine nucleus project to the MPS.Pallidosubthalamic projections were determined from autoradiographs based upon injections of [3H] amino acids into the MPS, the LPS, and both segments of the GP. Selective labeling of cells in the MPS resulted in no transport of isotope to any part of the STN. Labeling of cells in the rostral division of the LPS resulted in transport of isotope to: (1) the medial two‐thirds of the rostral part of the STN and (2) the central region of the middle third of the nucleus. Cells in the central division of the LPS projected fibers to the lateral third of the STN throughout most of its rostrocaudal extent.Even though the STN is a relatively small nucleus, it appears organized into afferent and efferent portions with respect to the GP. Subthalamopallidal fibers originate mainly from the medial two‐thirds of the STN and are topographically organized; cells in specific and separate locations within the STN project to wellcircumsumscribed terminations within either the MPS or the LPS. These data do not support the thesis that major axonal collaterals of STN neurons supply both pallidal segments, although this possibility cannot be excluded. Subthalamic neurons projecting to the MPS arise from cells in medial and caudal parts of the nucleus that do not receive projections from any part of the GP or from the cerebral cortex.Pallidosubthalamic projections derived from the rostral and central divisions of the LPS terminate in distinctive loci within the STN. Comparisonsof these regions of termination with those that give rise to subthalamopallidal projections suggest that direct reciprocal connections between the STNand the LPS must be partial. If functional reciprocal connections exist between STN and the two major segments of the GP, these are not on a point forpoint basis and local interneurons must be inv

ISSN:0092-7317    

DOI:10.1002/cne.901970404

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

年代:1981

数据来源: WILEY

摘要:

AbstractWe have examined callosal‐axon neurons giving rise to homotopic and heterotopic callosal projections to caudal inferior parietal lobule (area PG) inMacaca mulatta, identifying these neurons by means of retrograde axonal transport of horseradish peroxidase. The labeled neurons in the homotopic region occur predominantly in layers IIIB and V. A moderate number are seen also in layer VI, a smaller number in layer IV, and rare cells occur in layer II. These neurons occupy a region very similar in outline to the injection area, and though variable in density in the horizontal plane are continuously distributed in this plane.The heterotopic neurons are seen in the contralateral cingulate gyrus, continuing caudally into medial parietal cortex, in the cortex of the superior temporal and occipitotemporal sulci, in the caudal superior temporal gyrus, and in the caudal inferior parietal lobule, behind the homotopic area. These same regions on the ipsilateral side contain labeled neurons of origin of ipsilateral association projections to area PG. For other ipsilateral association regions (e.g., frontal lobe), no corresponding contralateral heterotopic labeling was found. A review of the literature on heterotopic callosal connections allows tentative generalization of this conclusion: The callosal heterotopic connections of a particular cortical area are made with regions which on the ipsilateral side have association connections with that area, though usually not with all of such region

ISSN:0092-7317    

DOI:10.1002/cne.901970405

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe cochlear nucleus of the young adult rabbit was studied using both anatomical and electrophysiological techniques. The cytoarchitecture of the cochlear nucleus, as revealed by Nissl‐staining and Bodian's Protargol method, was quite similar to that of the cat. The cell types observed by the Golgi‐Cox method were very similar to those observed in the cat cochlear nucleus. Bushy and stellate cells were predominant in the anterior ventral cochlear nucleus, and multipolar and globular cells were observed throughout the posterior ventral cochlear nucleus, surrounding a region containing mainly octopus cells. The dorsal cochlear nucleus was revealed as a laminated structure with a prominent band of fusiform cells. The polymorphic layers contained varieties of giant neurons similar to those observed in the cat. Units in the cochlear nucleus were classified electrophysiologically, in terms of their discharge pattern, and located histologically. The ventral cochlear nucleus contained mainly “primarylike,” “chopper” and “onset” units, but the dorsal cochlear nucleus contained a greater variety of response patterns. “Buildup,” “pauser” and “chopper” response patterns were predominant, and the dorsal cochlear nucleus also contained more inhibitory units than the ventral cochlear nucleus.Both the types of units observed and their location in each nucleus were very similar to those reported for the cat. Both divisions of the ventral cochlear nucleus and the dorsal cochlear nucleus were found to be tonotopically organized in a dorsal (high frequency) to ventral (low frequency) direction. A trend for an organization in a medial to lateral direction was also apparent, particularly in

ISSN:0092-7317    

DOI:10.1002/cne.901970406

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

年代:1981

数据来源: WILEY

摘要:

AbstractAn increased retinal projection to the pulvinar occurred in cats following neonatal ablation of visual cortical areas 17, 18, and 19. After unilateral lesions, the retinopulvinar projection visualized with autoradiography was larger and denser on the lesioned side than on the intact side. This increased projection was first recognized when the lesioned kittens were 1 week old, when increased labeling in the pulvinar was first detected. The retinopulvinar projection on the intact side of the brain decreased in size with age over the first 3 months of life. This decrease in size was not observed on the lesioned side of the brain. The absence of this decrease on the lesioned side may represent a failure of retraction of exuberant connections, but because of the active invasion by retinal fibers immediately after the lesion, observations of the normal retraction may simply be obscured. Severe cellular degeneration in the dorsal lateral geniculate occurred a few days before the changes in the retinopulvinar projection began; this loss of a postsynaptic target for many retinal axons may trigger the reorganization of input to the pulvinar retino‐recipient zone (pulvinar‐RRZ).After adult visual cortex lesions, no reorganization of the retinopulvinar projection took place. The modification of the projection from the retina to the pulvinar that occurs after ablation of visual cortex in the newborn cat may contribute to the sparing of visual abilities seen after these lesi

ISSN:0092-7317    

DOI:10.1002/cne.901970407

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

年代:1981

数据来源: WILEY

摘要:

AbstractA bipolar cell type forming invaginating contacts with many cones was found by light and electron microscopy of Golgi preparations of the rhesus monkey retina. This diffuse, invaginating cone bipolar cell resembles, superficially, rod (“mop”) bipolars, and so may correspond to Polyak's “brush” bipolar. However, it differs from rod bipolars in that its dendrites are finer and they end in a single stratum containing cone pedicles in the outer plexiform layer (OPL). In the inner plexiform layer (IPL) its axon terminal is located sclerad (S4) to those of rod bipolars (S5), is thinner, and also more branched, and wider in span than rod bipolar axon terminals. Resectioning of Golgi‐impregnated diffuse, invaginating cone bipolars to study their connections in the OPL shows that their dendrites invaginate as many as seven cone pedicles, and terminate as central elements at the ribbon synaptic complex. Thus, the primate retina has multiple (diffuse) and single (midget) cone‐contacting bipolar cell pathways in both invaginating as well as fla

ISSN:0092-7317    

DOI:10.1002/cne.901970408

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

年代:1981

数据来源: WILEY

摘要:

AbstractAfferents from the hindbrain auditory system to the nuclei of the lateral lemniscus were analyzed by the use of orthograde and retrograde axontracing techniques. Three divisions of the nuclei of the lateral lemniscus, a dorsal, an intermediate, and a ventral division are discussed. The dorsal nucleus of the lateral lemniscus is a recipient of afferents from cells located mainly in the superior olivary complex and the contralateral dorsal nucleus of the lateral lemniscus. It receives direct afferents from only a few cells in the cochlear nuclei. In sharp contrast, the ventral nucleus of the lateral lemniscus is the recipient of afferents from many cells in the contralateral ventral cochlear nucleus and from only a few cells in the superior olivary complex. Further, it receives no afferents from cells in the contralateral nuclei of the lateral lemniscus. The intermediate nucleus of the lateral lemniscus receives afferents from some cells in the cochlear nucleus and the superior olivary complex. It is unique among the three nuclei of the lateral lemniscus in that it receives a substantial projection from the medial nucleus of the trapezoid body.

ISSN:0092-7317    

DOI:10.1002/cne.901970409

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe ascending auditory projections to central nucleus of inferior colliculus its ventrolateral and dorsomedial subdivisions (ICVI, and ICDM) have been studied in cat using both pressure and electrophoretic injections of horseradish peroxidase (HRP). The results indicate that the predominant ascending projections to inferior colliculus orginate in (1) contralateral cochlear nucleus, (2) contralateral and ipsilateral lateral superior olive, (3) ipsilateral medial superior olive, (4) ipsilateral ventral nucleus of the lateral lemniscus, (5) ipsilateral and contralateral dorsal nucleus of the lateral lemniscus, and (6) contralateral inferior colliculus. In addition, ipsilateral cochlear nucleus, ipsilateral and contralateral intermediate nucleus of the lateral lemniscus, ipsilateral, and to a lesser extent contralateral, periolivary nuclei project to inferior colliculus. Of these nuclei, the lateral superior olive projects exclusively to ICVLand ipsilateral cochlear nucleus and contralateral inferior colliculus project mostly, if not exclusively, to ICDM. Many of these projections demonstrate a cochleotopic organization and frequently a nucleotopic organization as well. A cochleotopic organization of the projections is apparent for cochlear nucleus and superior olivary complex. A nucleotopic organization suggests that the heaviest terminations of contralateral inferior colliculus are medial and dorsal in inferior colliculus, of medial superior olive are dorsal and lateral, of superior olivary complex are rostral, of cochlear nucleus are caudal, and of ventral nucleus of the lateral leminiscus are caudal.

ISSN:0092-7317    

DOI:10.1002/cne.901970410

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.901970401

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

年代:1981

数据来源: WILEY