摘要:

AbstractThe cell bodies and central projections of neurons innervating the vibrissae follicles and adjacent skin in the rat were investigated by retrograde and transganglionic transport of HRP. The cell bodies of neurons innervating the vibrissa follicle via the deep vibrissa nerve (DVN) were the largest, followed by those innervating the follicle via the superficial vibrissa nerve (SVN). The smallest cell bodies were those innervating the intervibrissal skin. The DVN neurons terminated centrally as an almost uninterrupted column through the trigeminal sensory nuclear complex. The DVN projections to nucleus caudalis and C1 dorsal horn were entirely restricted to laminae III, IV, and V. Besides the projections to lamina V, the DVN projections were strictly localized somatotopically at all levels replicating the peripheral organization of the vibrissae. The SVNs projected sparsely to midlevels of the main sensory nucleus but not to nuclei oralis and interpolaris. The main SVN projections appeared in laminae I‐III of nucleus caudalis. In addition, a small projection to lamina V was observed. The projections to laminae II and III were organized mediolaterally in a similar way as the DVN projections; those to laminae I and V were less restricted. The intervibrissal skin neurons projected sparsely to the caudal main sensory nucleus and to the border between nuclei oralis and interpolaris. The projections to nucleus caudalis were restricted to laminae I‐III and V and were organized in a similar way as the SVN projecti

ISSN:0092-7317    

DOI:10.1002/cne.903090102

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

年代:1991

数据来源: WILEY

摘要:

AbstractAn antibody directed against the αosubunit of bovine brain Go(R4) was used to identify aDrosophilaretinal protein which may be the analogue of vertebrate transducin. The immunoreactivity appears predominantly in the retinal and occellar rhabdomeres. On a Western blot, the antibody recognizes a 41 kDa protein that is present in the heads ofyellow whiteflies, but not in the heads of eyeless mutant flies,eyes absent.This protein is not recognized by an antibody raised againstDrosophilaαo.Antibody R4 intensely stains rhabdomeres and, to a lesser extent, the neuropil of the central nervous system in tissue sections of adult flies. Antibody toDrosophilaαostains the neuropil of the central nervous system, but does not stain rhabdomeres. In developing flies, faint immunoreactivity appears in the retinal rhabdomeres at about 70% of the time through pupal development and increases to its apparent adult maximal level about 1 day after eclosion. Tissue sections from a phototransduction mutant,norp A, have retinal immunoreactivity at normal levels up to about 1 week after eclosion, but by 2 weeks, immunoreactivity has largely disappeared. This disappearance parallels the degeneration of the retina innorp Amutants.InDrosophilaand other invertebrates, light activates a phospholipase C in the retina. The identification of a protein inDrosophilarhabdomeres with an antibody raised against a mammalian G protein α subunit thought to be involved in phospholipase C activation suggests that there may be common structural features between the putativeDrosophilatransducin and α0, The identification of regions common to mammalian α0andDrosophilatransducin may then provide clues to the structural requirements for PLC activ

ISSN:0092-7317    

DOI:10.1002/cne.903090103

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe effectiveness of basic fibroblast growth factor and nerve growth factor in preventing the lesion‐induced disappearance of septal cholinergic neurons was compared by using a computerized data‐acquisition system and a digital brain atlas that yielded quantitative and distributional information. Adult rats were given unilateral partial transections of the fimbria and then received daily intraventricular injection of one of the growth factors for 15 days. Given the high degree of co‐localization of nerve growth factor receptors with choline acetyltransferase in these areas, cholinergic neurons were identified by nerve growth factor receptor immunoreactivity. Their locations were plotted in the context of a three‐dimensional brain atlas permitting the analysis of relative distributions of cholinergic neurons in control brains and those of animals treated with each growth factor. The cholinergic cell disappearance induced by the partial fimbrial transection was restricted to the medial septal nucleus and the vertical limb of the diagonal band of Broca. Within the affected areas cholinergic cell disappearance increased gradually in severity from anterior to posterior levels of the septal nucleus. Both growth factors prevented the disappearance of cholinergic cell bodies in medial septal nucleus and vertical limb of the diagonal band. In lesioned control animals the unilateral cell disappearance amounted to 53.5% of the number of cholinergic neurons of the unlesioned side. Nerve growth factor and basic fibroblast growth factor reduced this disappearance to 13% and 28%, respectively. The distribution of cholinergic cells was the same in animals treated with each growth factor, suggesting that the two growth factors protect the same population of cholinergic

ISSN:0092-7317    

DOI:10.1002/cne.903090104

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe synaptic organization of starburst amacrine cells was studied by electron microscopy of individual or overlapping pairs of Golgi‐impregnated cells. Both type a and type b cells were analyzed, the former with normally placed somata and dendritic branching in sublamina a and the latter with somata displaced to the ganglion cell layer and branching in sublamina b. Starburst amacrine cells were thin‐sectioned horizontally, tangential to the retinal surface, and electron micrographs of each section in a series were taken en montage. Cell bodies and dendritic trees were reconstructed graphically from sets of photographic montages representing the serial sections.Synaptic inputs from cone bipolar cells and amacrine cells are distributed sparsely and irregularly all along the dendritic tree. Sites of termination include the synaptic boutons of starburst amacrine cells, which lie at the perimeter of the dendritic tree in the “distal dendritic zone” In central retina, bipolar cell input is associated with very small dendritic spines near the cell body in the “proximal dendritic zone.” The proximal dendrites of type a and type b cells generally lie in planes or “strata” of the inner plexiform layer (IPL), near the margins of the IPL. The boutons and varicosities of starburst amacrine cells, distributed in the distal dendritic zone, lie in the “starburst substrata” which occupy a narrow middle region in each of the two sublaminae, a and b, in rabbit retina. As a consequence of differences in stratification, proximal and distal dendritic zones are potentially subject to different types of input. Type b starburst amacrines do not receive inputs from rod bipolar terminals, which lie mainly in the inner marginal zone of the IPL (stratum 5), but type a cells receive some input from the lobular presynaptic appendages of rod amacrine cells in sublamina a, at the border of strata 1 and 2.There is good correspondence between boutons or varicosities and synaptic outputs of starburst amacrine cells, but not all boutons gave ultrastructural evidence of presynaptic junctions. The boutons and varicosities may be both pre‐ and postsynaptic. They are postsynaptic to cone bipolar cell and amacrine cell terminals, and presynaptic primarily to ganglion cell dendrites. In two pairs of type b starburst amacrine cells with overlapping dendritic fields, close apposition of synaptic boutons was observed, raising the possibility of synaptic contact between them. The density of the Golgi‐impregnation and other technical factors prevented definite resolution of this question. No unimpregnated profiles, obviously amacrine in origin, were found postsynaptic to the impregnated starburst boutons. Nevertheless, synapses were occasionally formed between unimpregnated boutons that resembled neighboring impregnated boutons of starburst amacrine cells.The synaptic outputs of starburst amacrine cells commonly occur in clusters, with some participation of other amacrine cell input (presumably including GABAergic and glycinergic input) and cone bipolar cell input. Through these clusters, arrayed in a flanking gantlet, run fascicles of two to four ganglion cell dendrites joined by puncta adherentia. The major portion of these ganglion cell dendrites is thought to belong to type 1 bistratified, or ON‐OFF directionally selective ganglion cells, and in sublamina b, also to ON directionally selective ganglion cells.The ultrastructural evidence and the synaptic organization of starburst amacrine cells is considered together with histochemical and pharmacological evidence in regard to the role of starburst amacrine cells in the mechanism of directional selectivity. The evidence appears to favor the proposal, formerly advanced, that starburst amacrine cells potentiate the excitatory drive to directionally selective and other types

ISSN:0092-7317    

DOI:10.1002/cne.903090105

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe development of neurons in the dorsal lateral geniculate nucleus (dLGN) of pigmented ferrets was studied by using the Golgi‐Hortega technique. In adult ferrets, four dLGN cell classes were defined on the basis of somatic and dendritic morphology. Classes 1 and 2 were divided into stellate and oriented subtypes. Class 1 and 4 cells are characterized by filiform appendages, class 2 cells by club‐like appendages, and class 3 cells by stalked appendages. At birth, dLGN neurons have simple dendritic arbors. During the first postnatal week, dendritic length and proximal branching density increase markedly. By postnatal day 21 (P21), dendritic morphology begins to take on mature characteristics and by the time of eye opening (P30‐P35), most neurons can be classified. Also by that time, dLGN cells are covered with abundant filiform appendages. Developmental changes in appendage density were quantified for class 1 stellate cells. These data reveal that appendage density reaches a peak at P56, decreases sharply until P90, and then gradually declines to mature levels by P180. Elaboration and elimination of transient appendages occurs centrifugally; at maturity appendage density remains greater dis

ISSN:0092-7317    

DOI:10.1002/cne.903090106

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

年代:1991

数据来源: WILEY

摘要:

AbstractTime of cell origin in the retina of the rhesus monkey (Macaca mulatto) was studied by plotting the number of heavily radiolabeled nuclei in autoradiograms prepared from 2‐ to 6‐month‐old animals, each of which was exposed to a pulse of3H‐thymidine (3H‐TdR) on a single embryonic (E) or postnatal (P) day. Cell birth in the monkey retina begins just after E27, and approximately 96% of cells are generated by E120. The remaining cells are produced during the last (∼ 45) prenatal days and into the first several weeks after birth. Cell genesis begins near the fovea, and proceeds towards the periphery. Cell division largely ceases in the foveal and perifoveal regions by E56.Despite extensive overlap, a class‐specific sequence of cell birth was observed. Ganglion and horizontal cells, which are born first, have largely congruent periods of cell genesis with the peak between E38 and E43, and termination around E70. The first labeled cones were apparent by E33, and their highest density was achieved between E43 and E56, tapering to low values at E70, although some cones are generated in the far periphery as late as E110. Amacrine cells are next in the cell birth sequence and begin genesis at E43, reach a peak production between E56 and E85, and cease by E110. Bipolar cell birth begins at the same time as amacrines, but appears to be separate from them temporally since their production reaches a peak between E56 and E102, and persists beyond the day of birth. Müller cells and rod photoreceptors, which begin to be generated at E45, achieve a peak, and decrease in density at the same time as bipolar cells, but continue genesis at low density on the day of birth. Thus, bipolar, Müller, and rod cells have a similar time of origin. The maximal temporal separation of cell birth is between cones and amacrine cells so that cell generation exhibits two relatively distinct phases: the first phase gives rise to ganglion, horizontal, and cone cells, and the second phase to amacrine, bipolar, rod, and Müller cells. In addition, cells of the first phase are generated faster than the second phase cells, and there are differences in the topography of spread of labeled cells between the two phases.Each cell class displays a central‐to‐peripheral gradient in genesis, although the spatiotemporal characteristics of the gradients differ between the classes. Heavily labeled ganglion cells, horizontal cells, and cone photoreceptors (phase 1) are found near the retinal margin much sooner than amacrine, bipolar, Müller, and rod photoreceptor cells (phase 2). As a consequence, genesis of phase 1 cells generally occurs over a more extensive retinal area, extending to the retinal margin, while phase 2 cell genesis ceases centrally by the time cell birth begins near the margin. The site of initial cessation of cell division is more variable than it is for the beginning of cytogenesis, although for all cell classes it is roughly

ISSN:0092-7317    

DOI:10.1002/cne.903090107

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

年代:1991

数据来源: WILEY

摘要:

AbstractA quantitative study has been made from Golgi impregnations of the maturation of dendrites and their spines on spiny stellate neurons in the macaque monkey primary visual cortex. The neurons studied lay within either the alpha or the beta division of lamina 4C; previous workers have shown the alpha division neurons to be contacted by thalamic axon terminals arising from the magnocellular division of the lateral geniculate nucleus (LGN) of the thalamus and the beta division neurons to be contacted by parvocellular LGN inputs. Most thalamic terminals and perhaps the majority of other, type 1 (Colonnier, '81), presumed excitatory, inputs to these cells make synaptic contacts on the tips of their dendritic spines. Measurement was made of relative changes in the total number of spines on these alpha and beta spiny neurons over age by measuring both spine density along the dendrites and dendritic arbor size in single 90‐m̈m sections from Golgi rapid preparations. Our previous work (Lund et al., '77; Boothe et al., '79) showed a marked proliferation and attrition of spines and dendritic branches to occur in the early postnatal weeks; Rakic et al. ('86) have since proposed that there is a cortexwide synchrony of synapse acquisition and loss during this same period. However, different visual capacities channelled via the magnocellular and parvicellular geniculate relays show different maturational rates (Harwerth et al., '86). This study indicates that the anatomical maturation of spines on the alpha and beta neurons is not temporally coincident from birth to 30 weeks. During this period, phases of spine acquisition and loss on alpha neurons precedes similar phases on beta neurons. The alpha neurons carry a peak spine population at 5–8 weeks postnatal, whereas the beta neurons carry their peak spine populations between 8 and 24 weeks postnatal.At all ages prior to 30 weeks, the two sets of neurons carry quite different total spine populations. Close to 30 weeks of age, the total spine coverage has fallen on both sets of neurons and becomes identical between the alpha and beta neurons. In animals aged 30 weeks to adult, spine coverage per neuron is maintained at a common figure for the alpha and beta neurons despite further growth and disparate dendritic arbor sizes and different local spine densities in the two groups; this suggests that some common sampling paradigm between pre‐ and postsynaptic elements is adopted by the alpha and beta neurons and also suggests the development of a close functional correlation between the two sets of n

ISSN:0092-7317    

DOI:10.1002/cne.903090108

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis study uses Golgi‐impregnated material to examine the effects of altering the nature of afferent driving on the maturation of spines and dendrites on thalamic recipient spiny stellate neurons in layers 4C alpha and beta of the monkey striate cortex. These two laminae receive input from different sets of thalamic afferents with different functional properties. The development of dendritic spine and dendritic branch populations on these neurons in experimental animals is compared to the same features on similar groups of neurons in a series of normal animals described in the preceding study (Lund and Holbach, '91). Three conditions of rearing were used to alter afferent driving from normal: complete darkness (with in some cases return to normal diurnal light‐dark cycle), bilateral eye lid suture, and monocular eye lid suture. Some of the normal and dark‐reared infant monkeys were examined behaviorally for visual capacity in an earlier study (Regal et al., '76). All conditions of abnormal afferent driving caused changes from the normal developmental patterns of spine and dendritic arbor growth in these first‐order neurons of the cortex and each condition differed in the nature of change produced. Major findings of this study are:1Vigorous spine acquisition and dendritic growth occurs under all conditions of visual deprivation on alpha and beta neurons. Eventual spine and dendritic attrition occurs under at least conditions of bilateral or monocular lid suture to produce a rather constant adult morphology. We assume, therefore, that visually driven activity is a modulator or shaper of the developmental process for thalamic recipient neurons of visual cortex, rather than being an initiator, terminator, or driving force for their maturation.2An innate “clock” whose nature is unknown but is apparently not driven by visual input, initiates and terminates a period of growth of the thalamic recipient neurons between birth and 30–32 weeks of age.3Factors controlling dendritic arbor growth and retraction are different from those controlling spine synapse addition or attrition.4Whereas the alpha and beta neurons normally show quite different early growth patterns between birth and 30 weeks of age, when both eyes are simultaneously deprived of vision, an early temporal and numerical convergence occurs in patterns of spine population development on the two groups of neurons. This convergent pattern assumes a different form in dark‐reared and lid‐sutured animals. This suggests that the different patterns of development normally seen in the alpha and beta neurons depend on receiving different patterns of afferent driving, not on innate differences between alpha and beta neurons or links to different afferent axon populations independent of activity patterns.5Monocular suture was found to affect aspects of spine acquisition and dendritic growth of layer 4C neurons after 30 weeks of age. This may be due to a lack of development of layer 4C synaptic connections normally supporting binocular interactions in more s

ISSN:0092-7317    

DOI:10.1002/cne.903090109

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe development of type 2 (Colonnier,1981) synapses on the cell bodies of thalamic recipient spiny stellate neurons in layers 4C alpha and 4C beta of primary visual cortex neurons was examined over the first 36 postnatal weeks and in the adult monkey. The type 2 synapses, known to be GABAergic (Ribak, 1978) and therefore presumed to be inhibitory, developed faster on the alpha neurons than the beta neurons. Both neuron groups show a marked increase and then decline in the percentage of the somatic membrane covered by type 2 synaptic appositions during this 36‐week time period. The time course of the type 2 synapses development is compared to that of the spine synapse development described in previous studies (Lund and Holbach, 1991; Lund et al., 1991), and it is clear that on both neuron groups this inhibitory synapse population is put in place and refined later than the spine synapses. These findings suggest that each cortical neural circuit has a unique time course for its early development within an overall time window (Rakic et al., 1986), or sensitive period (Hubel and Wiesel, 1970). Visual deprivation, although causing the alpha and beta neurons to adopt a more similar temporal and numerical developmental pattern than normal, did not prevent acquisition and loss phases of type 2 synapses or the assumption of a normal numerical loading by 36 weeks of ag

ISSN:0092-7317    

DOI:10.1002/cne.903090110

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

年代:1991

数据来源: WILEY

摘要:

AbstractSubcortical Lewy bodies are the pathological hallmark of idiopathic Parkinson's disease. This study sought to determine the extent to which each neurofilament subunit [low (NF‐L), mid (NF‐M), or high (NF‐H)] was present in Lewy bodies by using light, confocal, and electron microscopy. A battery of 37 antineurofilament antibodies, characterized as to subunit specificity, epitope domain, and phosphorylation status, was employed to probe substantia nigra Lewy bodies from 15 Parkinson's disease cases. All 37 antibodies labelled Lewy bodies. The epitopes recognized by these antibodies included those in the NF‐L rod and tail domains; the NF‐M head, rod, and tail domains, as well as epitopes within, and flanking, the multiphosphorylation repeat site; and the NF‐H rod domain and multiphosphorylation repeat sites. With these probes, nearly the entire length of each subunit could be demonstrated in Lewy bodies. However, the staining pattern of the Lewy bodies suggested that the tail domains of NF‐M and NF‐H were present in the periphery of the Lewy body core and in the Lewy body corona, but they appeared to be altered or missing in the center of the Lewy body core. In contrast, the head domain of NF‐M, the tail domain of NF‐L, and the rod domains of all three subunits are present throughout the Lewy body. These results strongly suggest that the entire extent of each neurofilament subunit is found in Lewy bodies but that the neurofilament subunits may be altered during the processing of these filamen

ISSN:0092-7317    

DOI:10.1002/cne.903090111

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

年代:1991

数据来源: WILEY