摘要:

AbstractThe total numbers of neurons in five subdivisions of human hippocampi were estimated using unbiased Stereological principles and systematic sampling techniques. The method addresses the problems associated with the results and conclusions of previous quantitative studies, virtually all of which have been based on biased estimates of neuron densities. For each subdivision, the total number of neurons was calculated as the product of the estimate of the volume of the neuron‐containing layers and the estimate of the numerical density of neurons in the layers.Each hippocampus was cut into 3‐mm‐thick slabs, transverse to the rostrocaudal axis. One 70‐μUm‐thick section from each slab was used in the analysis. The volumes of the layers containing neurons in five major subdivisions of the hippocampus (granule cell layer, hilus, CA3–2, CA1, and subiculum) were estimated with point‐counting techniques after delineation of the layers on each section. The numerical densities of neurons in each subdivision were estimated on the same sections with optical directors. The sampling used in both estimates was performed systematically in all three dimensions.In an example of five hippocampi, the mean numbers of neurons (CV=SD/mean) in the different subdivisions were as follows: granule cells 15 × 106(0.28), hilus 2.0 × 106(0.16), CA3‐2 2.7 × 106(0.22), CA1 16 × 106(0.32), subiculum 4.5 × 106(0.19). The stereological measurements contributed approximately 25% of the observed variance. Among the five subjects there was a significant inverse relationship between age (which ranged from 47 to 85 years) and the total number of neurons in CA1 (which ranged from 24 to 11 × 106).An optimized sampling scheme for studies of the number of neurons in the human hippocampus has been designed on the basis of an analysis of variance of the estimates at different levels of the sampling scheme. Counting neurons in the five subdivisions of the human hippocampus with the optimized sampling scheme t

ISSN:0092-7317    

DOI:10.1002/cne.902960102

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

年代:1990

数据来源: WILEY

摘要:

AbstractCapsaicin, administered on the day of birth, was found to alter laminar distribution, but not the receptive field properties or the morphology of the collateral arborizations of hair follicle afferents (HFAs) intra‐axonally injected with horseradish peroxidase (HRP). Of the 65 HFA terminal arbors in capsaicin treated rats, 46 (71 %) were found to enter the substantia gelatinosa (in control rats, 44/165, 27%). All of the collaterals projected to somatotopically normal areas of cord. Dorsal horn shrinkage (21%), as estimated by planimetric measurements of Nissl and acetylcholinesterase‐stained material, was only a partial explanation of this result. This idea was supported by the statistically significant increase (27%,P<0.05) in the absolute dorsoventral length of collaterals.The results show that the destruction of unmyelinated fibres during the early postnatal period by capsaicin induces HFA invasion into the area that C fibres normally occupy. This invasion suggests that the laminar termination sites for different primary afferent fibres are not altogether specified and that intact neonatal primary afferents have the capacity to sprout into denervated regions of spinal c

ISSN:0092-7317    

DOI:10.1002/cne.902960103

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

年代:1990

数据来源: WILEY

摘要:

AbstractCholine acetyltransferase, the biosynthetic enzyme for acetylcholine, is thought to be a marker for cholinergic neurons. This report presents an analysis of the pattern of choline acetyltransferase‐like immunoreactivity in the superior colliculus of the cat, A dense network of highly varicose immunoreactive fibers pervaded the superficial gray and optical layer. The density of the fiber network in the superficial layers was heterogeneous, forming a mosaic pattern with a period of about 400 μm. The antigen was also located in numerous small perikarya embedded in this network. This neuronal population reached a density of 2,000 cells/mm3of the superficial gray layer and suggested the presence of a substantial cholinergic system originating in the superior colliculus. A detailed comparison was made between the pattern of choline acetyltransferase‐like immunoreactivity and the distribution of acetylcholinesterase activity. By comparisons of adjacent sections, both staining patterns were found to be similar in all collicular layers. In particular, the compartmental distribution of immunoreactivity in the intermediate collicular layers seemed to mimic the pattern of acetylcholinesterase staining. A double‐staining technique demonstrated a near‐perfect correlation between the two patterns. In conclusion, there was no indication of heightened acetylcholinesterase activity without an associated elevation in choline acetyltransferase‐like immunoreactivity throughout the superior colliculus. In this part of the brain, the presence of the putative cholinergic terminals could fully account for the distribution of acetylcholinesteras

ISSN:0092-7317    

DOI:10.1002/cne.902960104

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

年代:1990

数据来源: WILEY

摘要:

AbstractOne of the major pathways of information flow through the basal ganglia is the pallidonigrofugal system. In order to better understand this system in the rat, experiments have been performed to study the topography, synaptic organization, and neurotransmitter content of the pallidonigral projection and to determine whether the pallidonigral neurones make direct synaptic contacts with nigrofugal cells. This was achieved by combining the anterograde transport of the lectinPhaseolus vulgaris‐leucoagglutinin (PHA‐L) with the retrograde transport of lectin‐conjugated horseradish peroxidase (WGA‐HRP), postembedding immunocytochemistry for gamma‐aminobutyric acid (GABA), and pre‐embedding immunocytochemistry for tyrosine hydroxylase (TH). Following injections of PHA‐L in different regions of the lateral part of the globus pallidus, a substantial number of immunoreactive fibres and terminals occurred in the ipsilateral substantia nigra reticulata (SNr). The immunoreactive elements were distributed according to a rostral to medial and caudal to lateral topography. Injections that were restricted to the medial tip of the globus pallidus led to the anterograde labeling of a small number of fibres that were sparsely distributed in the SNr. The most characteristic feature of the pallidonigral fibres was the presence of large varicosities that were often grouped to form pericellular baskets. Injections of WGA‐HRP in the ventromedial thalamic nucleus, superior colliculus, or midbrain tegmentum, including the pedunculopontine nucleus, showed that the perikarya and primary dendrites of the output cells of the SNr were often surrounded by the large pallidonigral varicosities. The number of varicosities surrounding a single cell varied from 2–12. Electron microscopic analysis showed that the varicosities contained round or slightly pleomorphic vesicles and numerous mitochondria and that they established symmetrical synaptic contacts. Quantitative measurements revealed that the varicosities had a maximum diameter varying from 0.5 to 2.5 μm and a mean cross‐sectional area of 0.76 ± 0.25 μm2(N = 237, mean ± S.D.). The postsynaptic structures of the pallidonigral varicosities included perikarya (48%), large dendrites (38%), and small dendrites (14%). A large proportion of these postsynaptic targets were retrogradely labeled after injection of WGA‐HRP in the ventromedial thalamic nucleus, superior colliculus, or midbrain tegmentum. Postembedding immunocytochemistry was used to show that the pallidonigral axons and terminals in contact with nigrofugal neurones displayed GABA immunoreactivity. The use of a double immunocytochemical method revealed, that in addition to the nondopaminergic SNr output neurones, the dendrites and perikarya of the dopaminergic cells of the substantia nigra pars compacta (SNc) receive an input from the globus pallidus. However, this input is very much sparser than that to the cells of the SNr.In conclusion, the results of our study (1) demonstrate that the pallidonigral projection arises predominantly from cells in the lateral third of the globus pallidus and arborizes in the SNr according to a rostral to medial and caudal to lateral topography, (2) suggest that the pallidonigral neurones exert a powerful control over the output neurones of the SNr, (3) reveal that the pallidonigral projection is a major source of GABA in the rat substantia nigra, and (4) show that the perikarya and dendrites of the dopaminergic cells in the SNc receive an input albeit sparse

ISSN:0092-7317    

DOI:10.1002/cne.902960105

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe anatomical and functional organization of the inferior parietal lobule was investigated in macaque monkeys by using anterograde and retrograde anatomical tracing techniques and single cell recording techniques in awake, behaving monkeys. The connections of areas 7a and 7b, and of two previously unexplored areas, the lateral intraparietal area (LIP) and the dorsal prelunate area (DP), were examined in detail. Functional mapping experiments were performed in all four areas.Prior to this study the pathways for visual input to area 7a were unclear. In these experiments we found several direct projections from extrastriate visual areas, including the lateral intraparietal (LIP), dorsal prelunate (DP), parieto‐occipital (PO), and medial superior temporal (MST) areas into area 7a. Using the observed laminar patterns of connections between areas 7a, LIP, and DP and other extrastriate cortical areas, we were able to construct a hypothetical flow of visual information processing from striate cortex to area 7a. A broader hierarchy was also produced, which relates the positions of areas 7a, 7b, LIP, and DP to various cortical fields in the parietal, temporal, and frontal lobes.By combining single cell recording techniques in trained monkeys with anatomical tracing techniques, we have parcelled the inferior parietal lobule into several subdivisions on the basis of both anatomical and physiological grounds. A clear segregation of visual and somatosensory responses was found in the inferior parietal lobule with areas 7a, LIP, and DP being visual and visual‐motor and area 7b being primarily somatosensory. A similar segregation was found anatomically with areas 7a LIP, and DP being interconnected primarily with other visual cortical areas and area 7b being connected with several somatosensory areas. Area 7b was also found to connect to a few visual cortical areas, and these connections likely account for the small but consistent number of visually responsive cells that are found in this region. Areas LIP, DP, and 7a differed in receptive field and saccade‐related properties. Area 7a visual receptive fields were very large and usually bilateral with a small but significant number of them having receptive field centers in the ipsilateral visual field. Area DP and LIP receptive fields were smaller and the receptive field peaks were almost always confined to the contralateral visual field. Areas 7a, DP, and LIP all contained cells with saccade‐related responses; however, in area 7a there were fewer saccade cells than area LIP, and presaccadic responses were only observed in area LIP. Consistent with its functional specialization for saccades, area LIP was found to be strongly interconnected with areas involved in saccadic eye movements, including the frontal eye fields and intermediate layers of the superior colliculus, whereas area 7a had only weak connections to the frontal eye fields and had no detectable projection to the superior colliculus. Areas LIP, 7a, and DP neurons were found to have eye‐position‐related activity. Extensive quantitative experiments showed the distributions of the slopes and directions of the gaze fields were similar in areas 7a and LIP, but the intercepts were larger for area LIP.Area 7a was found to be connected to at least 22 cortical areas, including MST, superior temporal polysensory (STP), fundus superior temporal (FST), inferotemporal (IT), lateral and medial T F (TF1, TFm) areas, and TEO in the temporal lobe; LIP, DP, PO, medial intraparietal (MIP), posterior intraparietal (PIP), medial dorsal parietal (MDP), medial PG (PGm), and 7b areas in the parieto‐occipital cortex; areas Ba, 46,45,11, and supplementary eye fields (SEF) in the frontal lobe; and areas LC and LA in the cingulate gyrus. Area 7b was found to be connected to area 5; the granular insula (IG), PGm, LC, LA, MDP, MST, PO, STP, and IT areas, and areas 45, 6, and 12. Area LIP had corticocortical connections with the PO, DP, 7a, MST, middle temporal (MT), V4, dorsal and ventral V3 (V3d, V ∼ V ), V3A, TEO, TF, 8a, and 46 areas. Area DP was connected to V3A, LIP, 7a, V4, MST, PO, 46, and 8a. All corticocortical connections were reciprocal.The view that emerges from this study is of a densely interconnected network of connections between large numbers of brain regions with each cortical area, including areas 7a, 7b, LIP, and DP, being a single node in this highly distributed and interactive network. An important goal is to determine what different computations are being performed at each node

ISSN:0092-7317    

DOI:10.1002/cne.902960106

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

年代:1990

数据来源: WILEY

摘要:

AbstractTo gain some insight into possible functions of nerve growth factor (NGF), we suppressed the endogenous levels of NGF in newborn rats by subcutaneous injections (3 μl/g body weight) of rabbit antibodies to purified mouse β‐NGF (ANTI‐NGF). Fiber and axonal areas and perimeters were measured for unmyelinated and myelinated sensory fibers in T9 dorsal roots (DR) in three groups of animals: (1) ANTI‐NGF treated littermates, (2) preimmune sera treated littermates (PREIMM), and (3) untreated littermates (UNTR). In some rats, fibers in ventral roots (VR) were measured and, in other rats, sensory processes in peripheral nerves (PN) were measured following radical ventral rhizotomy. The only outer area and perimeter measurements that were statistically different were those in the ventral root (P<0.013 and P<0.043, respectively). However, myelin thickness was significantly thinner in the dorsal roots of the ANTI‐NGF group than in the dorsal roots of the UNTR and PREIMM groups (P<0.000009 and P<10−6, respectively). Myelin thickness in the ventral roots of the ANTI‐NGF group was also statistically thinner than that in the UNTR group (P<0.001). There were no statistically significant differences when comparing the UNTR group to the PREIMM group. In the peripheral nerves studied, there was no significant change in the myelin thicknesses between the ANTI‐NGF and UNTR groups of animals. These results indicate that Schwann cell‐neuronal interactions are altered by the inactivation of NGF, and that (1) the central processes of sensory fibers are affected and not the peripheral processes and (2) motor fiber myelination is altered. Therefore, we propose that NGF is not only a neurotrophic and neurotropic molecule but is also an important instructive molecule for the initiation and progress of n

ISSN:0092-7317    

DOI:10.1002/cne.902960107

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

年代:1990

数据来源: WILEY

摘要:

AbstractRetinoic acid (RA) and its specific binding protein, cellular RA binding protein (CRABP), are found in relative abundance in bovine and rat retinas. Since RA does not participate in the visual cycle, the presence of RA and its binding protein in retina suggests that they may be involved in other aspects of retinoid action. As an initial step in identifying the role of RA and its binding protein in retina, monoclonal antibodies were prepared against CRABP purified from bovine retina and used to localize this antigen by immunocytochemistry in retinas of different species. Human and monkey retinas showed specific cytoplasmic labeling of Müller cells. Cat, bovine, rabbit, rat, turtle, and chick retinas showed specific cytoplasmic labeling of some somata in the inner nuclear and ganglion cell layers and characteristic strata in the inner plexiform layer. Cat and bovine retinas also showed cytoplasmic labeling of Müller cells. Immunoreactivity in these species was absent with nonimmune serum or abolished when the antibodies were preabsorbed with purified antigen. Chameleon, goldfish, and frog retinas were nonreactive.We used double‐labeling immunofluorescence experiments to determine if the CRABP‐positive cells were also positive for known neurotransmitters or associated enzymes. CRABP‐positive amacrine cells of cat, cow, rabbit, rat, and chick represented a subset of the more numerous γ‐aminobutyric acid (GABA)‐positive amacrine cells. However, turtle CRABP‐positive amacrine cells were negative for GABA despite the fact that turtle retina contains many GABA positive cells. CRABP‐positive amacrine cells in rat retinas were not immunoreactive for glycine, choline acetyltransferase, somatostatin, or tyrosine hydroxylase.To test whether CRABP‐positive somata in the ganglion cell layer were ganglion cells, we retrogradely labeled the ganglion cells of rat retinas with rhodamine dextran. No rhodamine labeled ganglion cells were positive with anti‐CRABP, indicating that the CRABP‐positive cells in the ganglion cell layer are probably amacrine cells.Other retinoid binding proteins thought to be involved in the visual cycle have been localized to Müller and retinal pigment epithelium cells. This study reveals that CRABP immunoreactivity is present in Müller and/or amacrine cells, depending on the species. CRABP immunoreactivity in amacrine cells of certain species was an unanticipated and provocative result. Its significance

ISSN:0092-7317    

DOI:10.1002/cne.902960108

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

年代:1990

数据来源: WILEY

摘要:

AbstractCharacterization of the distribution of the peptide‐degrading enzyme neutral endopeptidase‐24.11 (E.G. 3.4.24.11; NEP; enkephalinase) in the rat brainstem was examined by means of a unique fluorescent histochemical method. Enzyme staining was completely blocked by three potent NEP inhibitors (thiorphan, phosphoramidon, and JHF‐26) at a concentration of 50 nM, supporting the specificity of this method to visualize sites of NEP activity selectively.At all levels of the brainstem, NEP was localized to cell bodies, cell processes, or terminal‐like fields and was localized to more than 90 distinct nuclei or subnuclei. In the mesencephalon these included the central gray, cuneiform n., dorsal and lateral tegmental n., inferior colliculus, interpeduncular n., lateral and medial geniculate n., central linear raphe n., mesencephalic n. of the trigeminal nerve, mammillary nuclei, Occulomotor n., red n., superior colliculus, ventral n. of the lateral lemniscus, substantia nigra‐ventral tegmental area, and the zona incerta.In the pons, NEP staining was restricted to fewer regions or nuclei, including the dorsal and ventral cochlear n., facial n., motor trigeminal n., principal sensory trigeminal n., parabrachial nuclei, pontine n., the oral and caudal pontine reticular n., pontine olivary nuclei, several pontine tegmental nuclei, pontine raphe nuclei, and the trapezoid n. In the cerebellum, staining was localized largely to the granule cell layer of the cerebellar cortex. Scattered staining was observed in the molecular cell layer.The medulla contained extensive NEP staining localized to nuclei that included the ambiguus n., dorsal motor n. of the vagus, hypoglossal n., inferior olivary n., prepositus hypoglossus n., solitary tract n., nuclei of the spinal tract of the trigeminal n., and the lateral, medial, and superior vestibular nuclei. Nuclei of the medullary reticular formation that were also richly stained for NEP included the raphe magnus n., raphe obscurus n., raphe pallidus n., dorsal, lateral, and ventral reticular nuclei of the medulla, and the gigantocellular, lateral paragigantocellular, linear, paramedian and parvicellular reticular nuclei.The widespread distribution of NEP in the brainstem suggests the existence of a number of functional systems, including the pathways involved in the mechanisms of pain and analgesia, which are potential targets of NEP inhibitors. In most regions, the distribution of NEP closely overlapped with that reported for the enkephalins, and showed a more restricted overlap with the reported distribution of su

ISSN:0092-7317    

DOI:10.1002/cne.902960109

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe primate neocortex possesses an extraordinary degree of regional specialization. Virtually all cortical functions are dependent upon a complex system of reciprocal connections between related cortical regions that allow for distributed information processing. Although some aspects of the organization of these corticocortical projections are understood, little is known about the morphology and afferents to the cells of origin of long corticocortical projections in primates. We combined intracellular injection of Lucifer Yellow (LY) in fixed tissue with in vivo retrograde transport of fast blue to study the dendritic morphology of neurons within the inferior temporal gyrus (ITG) and the superior temporal sulcus (STS) that furnish corticocortical projections to the prefrontal cortex. The fast blue retrogradely labeled cells formed two clearly defined bands within the inferior temporal cortex: a supragranular band that corresponded to layer III, and an infragranular band that corresponded to layers V and VI. After Lucifer Yellow intracellular filling, these retrogradely labeled cells projecting to the prefrontal cortex were found to be morphologically very heterogeneous. Although all filled cells had spiny dendrites, they presented a wide range of cell body sizes and dendritic tree morphologies. In layer III, the majority of cells were typical pyramids of various sizes. In layers V–VI, numerous typical pyramidal cells were present. In addition, significant numbers of modified pyramidal forms were found, including vertical and horizontal fusiform cells, asymmetrical pyramids and multipolar cells. The entire dendritic arbor of individual subtypes in layers III, V, and VI was restricted to a few cortical layers, but as a group these cells had dendrites spanning the whole cortical depth. We suggest that corticocortically projecting cells are distinct from subcortically projecting cells and consist of a defined set of morphological and functional subgroups, each of which is driven by a distinct set of afferents and likely possesses different response propertie

ISSN:0092-7317    

DOI:10.1002/cne.902960110

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

年代:1990

数据来源: WILEY

摘要:

AbstractColocalization of GABA‐ and tyrosine hydroxylase‐like immunoreactivity was studied in the retinae of various vertebrate species in order to ascertain whether the presumed coexistence of GABA and dopamine, reported earlier for mammals (Kosaka et al.:Exp. Brain Res. 66:191–210, '87; Wässle and Chun:J. Neurosci. 8:3383–3394, '88) is a common phenomenon. GABA‐immunopositive cells constituted a separate population from tyrosine hydroxylase‐positive cells in fish and amphibians, whilst in higher–i.e., amniote–vertebrates, such as reptiles, birds, and mammals, all dopaminergic cells contained GABA‐like immunoreactivity. No clear correlation was found between the type of dopaminergic cell (amacrine/interplexiform) and the presence or absence

ISSN:0092-7317    

DOI:10.1002/cne.902960111

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

年代:1990

数据来源: WILEY