摘要:

AbstractA specific antibody raised against 5‐hydroxytryptamine (5‐HT) conjugated to bovine serum albumin was used to study the serotoninergic innervation of the basal ganglia in the squirrel monkey (Saimiri sciureus). At midbrain level, numerous fine 5‐HT‐immunoreactive axons were seen to arise from the immunopositive neurons of the dorsal raphe nucleus and less abundantly from those of the nucleus centralis superior. The bulk of these axons formed a rather loosely arranged bundle that arched ventrorostrally through the central portion of the midbrain tegmentum and ascended toward the ventral tegmental area. Several fascicles detached themselves from this bundle to reach the substantia nigra where they arborized into a multitude of heterogeneously distributed 5‐HT terminals. The 5‐HT innervation was particularly dense in the pars reticulata but much less so in the pars compacta of the substantia nigra. More rostrally other 5‐HT fibers swept dorsolaterally and formed a remarkably dense network of varicose fibers within the subthalamic nucleus. A multitude of 5‐HT axons continued their ascending course within the lateral hypothalamic area, and many of them swept laterally to invade the lenticular nucleus. At pallidal levels, the 5‐HT axons arborized much less profusely in the external segment than in the internal segment, which contained numerous 5‐HT varicose fibers and terminals arranged in a typical bandlike pattern. At striatal levels, the 5‐HT terminals were particularly abundant in the ventral striatum, including the nucleus accumbens and deep layers of the olfactory tubercle. They also abounded in the ventrolateral region of the putamen and the ventromedial aspect of the caudate nucleus. Overall, the number of 5‐HT fibers and terminals decreased progressively along the rostrocaudal axis of the striatum and several large and elongated zones rather devoid of 5‐HT immunoreactivity were visualized, particularly in the caudate nucleus and the dorsal putamen. These zones of poor 5‐HT immunoreactivity were in register with similar areas devoid of tyrosine hydroxylase immunoreactivity as seen on contiguous sections. These findings reveal that all the core structures of the basal ganglia in primates receive a significant serotoninergic input, but that the densities and patterns of innervation vary markedly from

ISSN:0092-7317    

DOI:10.1002/cne.902990102

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe used several fluorescent dyes (Fast Blue, Diamidino Yellow, Rhodamine Latex Microspheres, Evans Blue, and Fluoro‐Gold) in each of eight macaques, to examine the patterns of thalamic input to the sensorimotor cortex of macaques 12 months or older. Inputs to different zones of motor, premotor, and postarcuate cortex, supplementary motor area, and areas 3b/1 and 2/5 in the postcentral cortex, were examined. Coincident labeling of thalamocortical neuron populations with different dyes (1) increased the precision with which their soma distributions could be related within thalamic space, and (2) enabled the detection by double labeling, of individual thalamic neurons that were common to the thalamic soma distributions projecting to separate, dye‐injected cortical zones.Double‐labeled thalamic neurons projecting to sensorimotor cortex were rarely seen in mature macaques, even when the injection sites were only 1–1.5 mm apart, implying that their terminal arborizations were quite restricted horizontally. By contrast, separate neuron populations in each thalamic nucleus with input to sensorimotor cortex projected to more than one cytoarchitecturally distinct cortical area. In ventral posterior lateral (oral) (VPLo), for example, separate populations of cells sent axons to precentral medial, and lateral area 4, medial premotor, and postarcuate cortex, as well as to supplementary motor area.Extensive convergence of thalamic input even to the smallest zones of dye uptake in the cortex (≈0.5 mm3) characterized the sensorimotor cortex. The complex forms of these projection territories were explored using 3‐dimensional reconstructions from coronal maps. These projection territories, while highly ordered, were not contained by the cytoarchitectonic boundaries of individual thalamic nuclei. Their organization suggests that the integration of the diverse information from spinal cord, cerebellum, and basal ganglia that is needed in the execution of complex sensorimotor tasks begins in t

ISSN:0092-7317    

DOI:10.1002/cne.902990103

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn the present experiments thalamocortical projections to different functional areas of the newborn (or prematurely delivered) macaque's sensorimotor cortex were labeled using retrogradely transported fluorescent dyes. Several dyes were used in each animal to (1) enable the direct comparison of the soma distributions of different thalamocortical projections within thalamic space, and (2) identify by double labeling neurons shared between these distributions. The projection patterns in the newborn macaque were compared with those of the mature animal reported by Darian‐Smith et al. (J. Comp. Neurol. 1990;298:000–000).The main observations were (1) all thalamocortical projections to the sensorimotor cortex of the mature macaque are well established by embryonic days 146–150, as was shown by labeling these pathways in infants delivered by cesarian section, (2) a significant number of thalamocortical neurons in the newborn were double‐labeled following dye injections into different pre‐ or postcentral areas, and where the margins of the dye uptake zones were separated by 3–8 mm, and (3) extensive projections from the anterior pulvinar nucleus to the motor and premotor cortex, and to the supplementary motor cortex were labeled in the newborn macaque. Both the exuberant terminal arborizations, and the precentral pulvinar projections were diminished by the 6th postnatal month, and absent in the mature macaque. The role of epigenetic determinants of these postnatal events is briefly

ISSN:0092-7317    

DOI:10.1002/cne.902990104

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe lateral magnocellular nucleus (LM) contains the largest neurons in the rabbit thalamus, yet its cortical connections have not been described. This study evaluates the architecture, cingulate cortical connections, and spontaneous rate of neuronal discharges in LM. At its maximal mediolateral extent in coronal sections, LM underlies the laterodorsal and lateroposterior nuclei. It has a short medial and long lateral limb, both of which have high levels of cytochrome oxidase activity. On the basis of horseradish peroxidase and fluorescent dye injections, LM projects primarily to area 29 and posterior area 24. Projections to area 29d are topographically organized so that the medial limb of LM projects to rostral area 29d, mid levels of LM where the limbs join project to midlevels of area 29d and lateral parts of the lateral limb project to posterior area 29d. It is mainly the midportion of the lateral and medial limbs that projects to areas 29b and 29c. The anterior parts of these areas receive input from dorsal parts of LM, whereas posterior levels of these areas receive input from ventral LM. The midregion of LM also projects to caudal area 24. Injections of3H‐amino acids into area 29d anterogradely label neuronal processes in LM. Finally, single unit electrophysiological recordings from LM in halothane‐anesthetized rabbits showed a unique pattern of spontaneous discharges. Over 70% of the LM neurons cycled through a number of different phases with a mean ± S.E.M. peak discharge rate of 31 ± 4.7 Hz. This high rate contrasts with the 17.6 ± 3.2 Hz rate for neurons that maintained a constant rate of discharge and the 7.5 ± 1.3 Hz rate of discharges for neurons in nuclei dorsal and ventral to LM.LM neurons are large, have high levels of cytochrome oxidase and spontaneous activity, and project extensively to the posterior cingulate cortex. These features suggest that LM neurons are highly active metabolically and may be fast conducting efferents to cingulate

ISSN:0092-7317    

DOI:10.1002/cne.902990105

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe prenatal development of the rabbit's retinal projections to the dorsal lateral geniculate nucleus (dLGN) was studied by using anterograde axonal transport of HRP injected intraocularly. Further, the ontogenesis of the dLGN's α and β sectors was studied. Fetuses aged embryonic day 18 (E18) to E29 were examined. Gestation in the rabbit is 30–31 days.On E18 the future dorsal lateral and medial geniculate nuclei appear as a continuous strip of cells along the lateral margin of the dorsal thalamus. On E21 labelled retinal fibers are invading the lateral margin of the dLGN contralateral, but not ipsilateral, to an injected eye. At this age the dorsal lateral and medial geniculate nuclei are separating. By E23 contralateral fibers occupy the entire presumptive α sector, while ipsilateral fibers are invading the caudal half of the sector, overlapping the contralateral fibers. At this age the α and β sectors begin to differentiate. On E25 contralateral fibers are more densely distributed throughout the α sector and the ipsilateral fibers are concentrated dorsally within the caudal three‐quarters of the sector. By E27 contralateral fibers begin to withdraw from a medial zone of the α sector, while ipsilateral fibers remain densest in this zone and begin to withdraw from more lateral and caudal aspects of the sector; contralateral fibers, but not ipsilateral fibers, invade the β sector. At this age the α and β sectors acquire an adult‐like appearance. By E29 the contralateral fibers vacate the β sector and the medial zone of the dLGN and the ipsilateral fibers are restricted to this zone. Thus, 1 or 2 days before birth, the locations of the ipsilateral and contralateral retinal projections to the dLGN resemble those seen in the adult.The early overlapping projections of ipsilateral and contralateral retinal fibers within the dLGN and their eventual segregation in the fetal rabbit are consistent with the development of these projections in other mammalian orders. Further, the brief invasion of the β sector by the contralateral fibers resembles the transient occupation of the carnivores' perigeniculate nucleus by developing retinal fibers. In addition, direct comparisons of temporal and spatial events during retinal innervation of the dLGN and the superior colliculus indicate several developmental differences betwe

ISSN:0092-7317    

DOI:10.1002/cne.902990106

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe three‐dimensional structural organization of layer I of the developing and adult human cerebral cortex has been investigated by using sagittal, transverse, and tangential rapid Golgi and Klüver‐Barrera preparations. The actual morphology of its fundamental neuron—the Cajal‐Retzius cell (C‐R)—is established. These large and solitary cells arehorizontal multipolarneurons characterized by: (1) long horizontal dendrites thatradiate in all directionswithin a tangential plane parallel to the pial surface, (2) long horizontal axonic collaterals thatradiate in all directionswithin layer I middle level, and (3) a descending axonic process that reaches the lower level, becomes a long tangential fiber—and eventually a myelinated one—andprojects in any directionwithin this level. In cortical ontogenesis, its dendrites, axonic collaterals and terminal axon undergo a progressive multipolar “horizontalization” extending throughout the surface of the expanding cerebral cortex. The neuron's body and main dendrites will be found only in some areas, whereas its axonic collaterals and terminal tangential axon should be found throughout the cerebral cortex. This developmental feature explains the presence of two—middle and lower—plexuses in layer I, composed of the axonic collaterals and the terminal tangential axons of C‐R cells, respectively. It is emphasized that the basic morphology of the C‐R cell remains essentially unchanged in the course of cortical ontogenesis and that the neuron persists in the adult cerebral cortex. Whereas the C‐R cell is the basic neuron of layer I, the pyramidal cells dendritic bouquets represent its larger and main receptive surface (the only one early in development). By the 30th week of gestation, a C‐R cell could establish: (1) proximal contacts, through its axonic collaterals, with all dendritic bouquets within a ∼ 350 μm radius, and (2) distant contacts, through its tangential axon, with dendritic bouquets within a narrow sagittal, transverse, or diagonal territory several mm long. In cortical ontogenesis, the C‐R cells' functional territories continue to expand throughout the surface of the cerebral cortex and possibly overlap with each other, It is proposed that the C‐R cell receives inputs from primitive (mesencephalic?) corticipetal fibers and that it transmits the same kind of information (perhaps a basal tone?) to the dendritic bouquets of all pyramidal neurons throughout the cerebral cortex regardless of their locat

ISSN:0092-7317    

DOI:10.1002/cne.902990107

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to identify the basic pattern of interconnections between the cerebellar nuclei and hypothalamus inMacaca fascicularis.The distribution of retrogradely labeled cells and anterogradely filled cerebellofugal axons in the hypothalamus ofM. fasciculariswas investigated after pressure injections of a horseradish peroxidase mixture (HRP + WGA‐HRP) in the cerebellar nuclei. Following injections in the lateral, anterior, and posterior interposed cerebellar nuclei retrogradely labeled cells were present in the following areas (greatest to least concentration): lateral and dorsal hypothalamic areas, dorsomedial nucleus, griseum periventriculare hypothalami, supramammillary and tuberomammillary nuclei, posterior hypothalamic area, ventromedial nucleus and periventricular hypothalamus, around the medial mammillary nucleus, lateral mammillary nucleus, and infundibular nucleus. Cell labeling was bilateral with an ipsilateral preponderance. In these same experiments anterogradely labeled cerebellar efferent fibers terminated in the contralateral posterior, dorsal and lateral hypothalamic areas, and the dorsomedial nucleus. In these regions retrogradely labeled hypothalamic cells were occasionally found in areas that also contained anterogradely filled cerebellar axons. This suggests a partial reciprocity in this system. In addition, sparse numbers of labeled cerebellar fibers recross in the hypothalamus to distribute to homologous areas ipsilateral to the injection site. Subsequent to an injection in the medial cerebellar nucleus (NM), cell labeling was present in more rostral hypothalamic levels including the lateral and dorsal hypothalamic areas, the dorsomedial nucleus, around or in fascicles of the column of the fornix, and in the periventricular hypothalamic area. Although no fastigiohypothalamic fibers were seen in this study, on the basis of information available from the literature it is likely that such a connection exists in primates. In summary, hypothalamic projections to NM originated mainly from rostral to midhypothalamic levels, whereas those projections to the lateral three cerebellar nuclei came from mid and more caudal levels.The existence of direct hypothalamic projections to cerebellar nuclei inM. fascicularisand of cerebellofugal projection to some hypothalamic centers indicates that circuitry is present through which the cerebellum may influence visceral functions. Furthermore, the fact that projections to NM versus the other cerebellar nuclei originate from somewhat different regions of the hypothalamus would suggest that the visceral functions modulated by each pathway is not the sam

ISSN:0092-7317    

DOI:10.1002/cne.902990108

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

年代:1990

数据来源: WILEY

摘要:

AbstractCell migration and axon growth during neural development rely upon cell‐cell and cell‐matrix interactions mediated by surface glycoproteins. The surface glycoprotein recognized on leech neurons by monoclonal antibody Lan3‐2 has previously been implicated in the process of axon fasciculation during regeneration in adults. In adult leeches, Lan3‐2 binds to a carbohydrate epitope of a 130 kD protein. The present study demonstrates that in embryos the antibody binds to the same carbohydrate epitope of glycoproteins with molecular weights of 130 kD and higher. As a first step in evaluating a possible role of the Lan3‐2 glycoprotein or the cells that express it during neural development, we determined its distribution in the developing nervous system of the leechHirudo medicinalis.In embryos, Lan3‐2 epitope is expressed on fasciculated sensory afferents and it appears on the cell bodies before neurite outgrowth. The sensory fibers appear rostrally by embryonic day 10, less than halfway through development. Earlier, by 7 days of development at 20°C, Lan3‐2 binds to previously undocumented cell types: (1) cells appearing along the embryonic midline and (2) a cluster of cells located at the rostral edge of the germinal plate. These cells only transiently express this antigen and are present at critical left‐right and rostrocaudal boundaries during a period of cell proliferation, movement, and migration that produces the nervous system. Thus the Lan3‐2 surface glycoprotein or the cells expressing it are candidates for involvement in axon fasciculation, cell migration, and dire

ISSN:0092-7317    

DOI:10.1002/cne.902990109

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

年代:1990

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902990101

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

年代:1990

数据来源: WILEY