摘要:

AbstractThe general distribution and morphology of vasoactive intestinal polypeptide‐like immunoreactive (VIP‐LI) neurons in the area dentata (AD) have been studied using immunohistochemical methods on thick (70–120 μm) sections from the rat brain. The long (≥ 72 hours) incubation of free‐floating sections in combination with a sensitive immunoperoxidase method resulted in extensive labeling of VIP‐positive cell bodies, along with their dendritic and axonal processes in the hippocampal formation, including the area dentata. The VIP‐positive cells are found in all parts of the area dentata, and plots of the distribution of individual cells showed that there is a preferential clustering of these neurons within, or in close proximity to, the granule cell layer, while the deep zones in the hilus are almost completely devoid of VIP‐LI immunoreactive neurons. Throughout the long axis of the AD the number and relative position of the VIP‐LI neurons remains rather constant. Analysis of the size and shape of the VIP‐positive neurons in the AD shows a remarkable morphological heterogeneity, with the soma ranging from small (long axis: ˜ 10 μm) ovoid or round, to large (long axis: ˜ 25 μm) stellate or multipolar; of these the small to medium sized cells predominate.Comparisons between the morphology of neurons visualized with the VIP antibody and sections stained by the rapid Golgi method allow a rather conclusive classification of some of the VIP‐stained neurons, while the classification of a majority of the VIP nerons remains tentative, perhaps because of the selective visualization by the rapid Golgi method of only certain cell types in the AD. On the basis of this comparison, several displaced granule cells in the molecular layer, as well as granule cells, small ovoid cells, and pyramidal basket cells in the granule cell layer have been identified as VIP‐positive as determined by their somatic shape, dendritic branching pattern, and axonal projections. In addition, several VIP‐positive neurons have been identified with less certainty. These include the dentate basket cell of Cajal, certain small cells in the molecular layer, and fusiform cells in the polymorph layer. Taken together the present results demonstrate the usefulness of “Golgi‐like” immunoperoxidase staining for detailed classification of chemically defined neurons. Furthermore, these studies provide evidence for a morphological heterogeneity of VIP cells in the area dentata, and suggest that although some of the VIP cells may project out of the AD (the granule cells) a majority of the VIP neurons are interneu

ISSN:0092-7317    

DOI:10.1002/cne.902210302

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

年代:1983

数据来源: WILEY

摘要:

AbstractGlutamate decarboxylase (GAD)‐immunoreactive varicosities were found around cell bodies of nonimmunoreactive and immunoreactive neurons in the cat's visual cortex; they also occurred along apical dendrites and axon initial segments of pyramidal neurons. By examination in the electron microscope of structures first identified in the light microscope, it was established that the GAD‐immunoreactive varicosities were boutons in symmetrical synaptic contact with pyramidal cells in layers II‐IV. More than 90% of 142 boutons surrounding the cell bodies of 20 pyramidal neurons were immunoreactive for GAD. Since such a high proportion of the axosomatic boutons are GAD‐immunoreactive, it is likely that the terminals of basket cells are included in this population and so the basket cell probably uses γ‐aminobutyrate as a transmitter, as suggested by previous authors.Almost all the 68 boutons in symmetrical contact with the axon initial segments of six pyramidal neurons could be shown to be GAD‐immunoreactive, which makes it very likely that the boutons of axoaxonic cells contain GAD‐immunoreactivity. This was established unequivocally for an individual Golgi‐impregnated axoaxonic cell by combining Golgi impregnation and immunocytochemistry in the same sections: A Golgi‐impregnated axoaxonic cell whose cell body was in layer II gave rise to numerous terminal segments, some of which were examined in the electron microscope after gold‐toning. These boutons were in synaptic contact with axon initial segments and not only contained the Golgi precipitate but were also immunoreactive for GAD. It is concluded that the axoaxonic cell in the visual cortex uses γ‐aminobutyrate as a transmitter.An individual axoaxonic cell in layer II/III was filled with horseradish peroxidase by intracellular iontophoresis. The very extensive local axonal field was composed of 330 terminal bouton rows in layer II/III and a sparse descending collateral projection to infragranular layers. A computer‐assisted reconstruction of the axonal field in three dimensions revealed the following: The main output of the cell is to pyramidal neurons that lie deeper than the soma; the axonal arborization occupies an area of 400 μm in the anteroposterior axis and extends 200 μm along the mediolateral axis; the terminal bouton rows in layer II/III form clusters about 50 μm wide running approximately at right angles to the border between areas 17 and 18, with an intercluster interval of about 100 μm. These findings suggest that the terminals of an individual axoaxonic cell could be contained within one ocular dominance column but that there may be inhomogeneities in the weighting of the axoaxonic input to pyramidal cells in the supragranular layers.The possible functions of GABAergic axoaxonic cells are discussed, including the ideas that they may be involved in controlling the output of pyramidal neurons in superficial layers not only to contralateral cortical areas but also to deeper layers of the ipsilateral cortex, and that they may be involved in imposing a functionally significant spatial pattern o

ISSN:0092-7317    

DOI:10.1002/cne.902210303

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

年代:1983

数据来源: WILEY

摘要:

AbstractRetinal ganglion cells of the cat have been classified physiologically into X‐, Y,‐ and W‐cells, on the basis of the receptive field properties, and morphologically into α‐, β‐, and γ‐cells.In order to study directly the correspondence between these classifications, intracellular recordings from the ganglion cells in supervised eye‐cup preparations were made with the aid of microelectrodes filled with Lucifer yellow CH. The cells were stained after their photic responses were studied under mesopic adaptation.X‐cells, showing sustained depolarization (on‐center cells) or hyperpolarization (off‐center cells) in response to a spot of light had medium‐sized round somata and spread bushy dendrites within a narrow retinal area. On the other hand, on‐center and off‐center Y‐cells, showing transient responses to the spot stimulus, had large somata and widely expanded thick dendrites which were sparsely branched. W‐cells which showed weak sustained responses had widely extended thin and winding dendrites, despite a small somal size. These morphological features of Y‐, X‐, and sustained W‐cells correspond well to those of α‐, b̃‐, and δ‐cells (a subtype of γ‐cells), respectively. The hypothesis of “m

ISSN:0092-7317    

DOI:10.1002/cne.902210304

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe number and distribution of corticopontine neurons within area 17 of the cat were studied quantitatively with the use of retrograde transport of horseradish peroxidase‐wheat germ agglutinin. Eight cats received stereotactic injections in the pontine nuclei; in three of these complete staining of the parts of the pontine nuclei receiving fibers from the visual cortex was achieved. Labeled cells were counted in frontal sections through the hemisphere, spaced at 0.5 mm.The borders of area 17 were determined cyto‐ and myeloarchitectonically and a flat map was produced for each animal. A map of the representation of the visual field in 10° × 10° blocks in the first visual area (Tusa et al., '78, '81) was transferred to our maps of area 17. The density and number of labeled corticopontine cells could then be determined within blocks of the cortex representing 10° × 10° of the visual field.Thecell density(number of labeled cells per mm2cortex) was found in general to be highest in parts of the cortex representing peripheral parts of the visual field. The cell density is low in cortex representing the central visual field, but the lowest density was found in the representation of a paracentral region in the upper visual field. Furthermore, cortical regions representing the lower part of the visual field have a higher cell density than those representing the upper part; in four cases, 68–86% of all labeled cells were found in parts of area 17 representing the visual field below the horizontal meridian.Since there is an enlarged cortical representation of central vision, the much lower cell densities in ‘central’ parts of area 17 than in “peripheral” parts may mean that all parts of the visual field are represented with equal numbers of corticopontine neurons (“linear” representation). This is not the case, however, since thenumber of labeled cellsper 10° × 10° is considerably higher in the cortex representing the central 10° and medial parts of the lower visual field than in the rest of area 17. Assuming that the corticopontine cells in the visual cortex transmit spatially relevant information, we conclude that there is an overrepresentation of central vision and the medial parts of the lower visual field in the corticopont

ISSN:0092-7317    

DOI:10.1002/cne.902210305

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe central projections of muscle and cutaneous sensory neurons in the bullfrog were labeled by filling their peripheral axons in the forelimb with horseradish peroxidase (HRP). Muscle afferent fibers were found to project exclusively to the ventral neuropil of the brachial spinal cord in the intermediate gray zone. Cutaneous afferent axons had their arbors limited to the dorsal neuropil. There is therefore a topography in the central representation of two classes ofsensorymodalities.

ISSN:0092-7317    

DOI:10.1002/cne.902210306

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe physiological properties of neurones in the superficial laminae of the dorsal horn of the fourth and fifth lumbar segments of the rat spinal cord have been investigated in decerebrate spinal animals. Both extracellular recordings with platinum‐plated tungsten microelectrodes (n = 72) and intracellular recordings with glass microelectrodes (N = 79) were made. Attempts were made to fill cells intracellularly with horseradish peroxidase or Lucifer Yellow. Thirty‐seven percent of the intracellularly injected neurones were recovered after histological processing and their cell bodies found to be in lamina 1 or 2 and in the dorsal white matter overlying lamina 1. The dendritic spread of the stained neurones was maximal in the rostrocaudal plane with a restricted mediolateral spread. The physiological properties of the extracellularly recorded units, the intracellularly unidentified units, and the intracellularly stained units were the same. The neurones were characterized by low background activity and all had excitatory receptive fields on the lower limb. Some neurones responded only to low‐threshold mechanical stimulation of the skin or only to noxious skin stimulation but the majority of units (58%) were wide‐dynamic‐range cells responding to both types of stimuli. Receptive field classification was made questionable, however, by the existence of cells (9%) that exhibited a spontaneous shift in the size of their receptive fields and in the type of stimulus that elicited a response. The neurones in the superficial dorsal horn commonly showed a marked inhibition to repeated cutaneous stimuli (27%) or a prolonged afterdischarge followed a single stimulus (20%). Afferent input from the sural nerve was found to be from A and C fibres in both extra‐ and intracellular recordings. Aδ‐ and C‐mediated excitations were most common although convergent inputs from Ab̃‐fibres occurred in 40% of units.No correlation was found between cell structure or distribution of dendritic fields and physiological properties in our small sample of intracellularly stained cells. The morphology of the cells was highly diverse, as were the different receptive fields. There was, however, some correlation between the location of cell bodies and their responses. Neurones responding only to low‐threshold stimuli were distributed either in the dorsal white matter or in inner lamina 2. Wide‐dynamic‐range cells were distributed throughout the superficial dorsal horn. These results suggest that neurones of different shapes and positions may subserve the same function and, conversely, that neurones of the same shape and position may sub

ISSN:0092-7317    

DOI:10.1002/cne.902210307

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe topographical distributions of photoreceptors and ganglion cells of the California ground squirrel (Spermophilus beecheyi) were quantified in a light microscopic study. The central retina contains broad, horizontal streaks of high photoreceptor density (40–44,000/mm2) and high ganglion cell density (20–24,000/mm2). The isodensity contours of both cell types are elliptical and oriented along the nasal‐temporal axis. There are roughtly fivefold decreases in both photoreceptor and ganglion cell densities with increasing eccentricity, the lowest densities being found in the superior retina. Large transitions in cell density and retinal thickness occur across the linear optic nerve head. Rod frequency increases with increasing eccentricity, from 5 to 7% in the central retina to 15 to 20% in the periphery. Roughly 10% of the cones possess wide, dark‐staining ellipsoids. These cones are uniformly distributed across the retina which suggests that they may belong to a separate cone class, possibly blue‐sensitive cones. The ganglion cell soma size distribution is unimodal, with the majority of somata being 25–50 μm2. Large ganglion cells (somata>100 μm2) are rare in the central retina, but their frequency increases with increasing eccentricity. No evidence for separate size classes of ganglion cells was found. The gradual decrement of photoreceptor density across the ground squirrel retina suggests that there are only relatively small changes in acuity across much of the animal's visual space compared with species possessing either a narrow visual streak or fovea or a

ISSN:0092-7317    

DOI:10.1002/cne.902210308

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe [3H]thymidine autoradiographic method was used to determine the birth dates of neurons in the cat parahippocampal gyrus. Cat fetuses were exposed to a single pulse of the radioactive marker between the 20th and 55th embryonic days. All animals were delivered normally and allowed to survive for 2–6 months postnatal. The resulting autoradiographs demonstrate three spatiotemporal gradients of cell birth in the entorhinal and subicular cortices. First, an inside‐out gradient is apparent; i.e., neurons in the deeper layers are born earlier than those in the more superficial layers. Second, a rhino to dentate gradient exists. Accordingly, cells closer to the lateral entorhinal region tend to be generated earlier than those further away. Third, a temporal to septal gradient is present. Neurons close to the anterior pole of the temporal lobe are born earlier than those more caudally located. Whereas the first two gradients have been observed in other species, the latter gradient has not been reported consistently. Three exceptions to these overall gradients exist. First, neurons near the layer I/II border are born earlier than the majority of the layer II neurons. Second, neurons near the transition zone between two adjacent regions are born earlier than neurons located in the middle of each region. Third, the prosubiculum and subiculum do not exhibit a clear inside‐out or temporal to septal gra

ISSN:0092-7317    

DOI:10.1002/cne.902210309

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

年代:1983

数据来源: WILEY

摘要:

AbstractAn anterograde tracer (35S‐methionine) was injected unilaterally in the superior olivary complex (SOC) at regions previously demonstrated by retrograde labeling to contain olivocochlear (OC) cell bodies. Quantitative analysis of cochlear autoradiographs from these cats demonstrates that there are two OC systems. ThelateralOC system has cell bodies lateral to the medial superior olivary nucleus (MSO) and projects to the inner hair cell (IHC) region bilaterally (mostly ipsilaterally). ThemedialOC system has cell bodies medial, ventral, and anterior to the MSO and projects to the outer hair cell (OHC) region bilaterally (mostly contralaterally). A single medial OC neuron innervates many small patches of OHCs with substantial gaps between the patches. Medial OC neurons also appear to project to the IHC region to a small extent. A review of the literature with the medial‐lateral division of OC efferents in mind reveals many differences between these two systems. In particular, lateral OC axons are unmyelinated and innervate the dendrites of radial afferent fibers under IHCs, whereas medial OC axons are myelinated and directly innervate OHCs. Although both systems appear to be cholinergic, the lateral OC system also shows met‐enkephalin‐like immunoreactivity. The synapses of the medial OC system are formed in development before those of the lateral OC system and they degenerate more slowly after the OC axons are cut. The many differences between these two OC systems suggest that they are functionally separate

ISSN:0092-7317    

DOI:10.1002/cne.902210310

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

年代:1983

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902210301

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

年代:1983

数据来源: WILEY