摘要:

AbstractThe subdivisions of the medial geniculate body inTupaiarecognized in previous connectional and cytoarchitectural studies are identified in Golgi‐impregnated material. They may be distinguished by the organization of the neuropil, especially the dendrites, and, in many cases, by differences in the neurons. The ventral nucleus contains tufted cells with disc‐shaped dendritic fields which are aligned to form laminae. The caudomarginal and deep dorsal nuclei have less tufted, less precisely arranged cells with longer, thin appendages. Neurons in the suprageniculate and dorsal nuclei are similar except that they apparently are arranged more randomly and tend to have more spherically shaped dendritic fields. The medial division is characterized rostrally by the presence of stellate cells and caudally by large cells which appear to be the neurons, observed in previous studies to have widespread connections.The results of this Golgi study suggest that the subdivisions of the medial geniculate body might be grouped differently than in previous reports. When combined with data from previous studies of connections, the results show that the medial geniculate body of even distantly related species may follow a common plan. The ventral nucleus is the medial geniculate component of the central pathway which extends from the central nucleus of the inferior colliculus to the primary auditory cortex. Most of the other medial geniculate subdivisions participate in either pericentral pathways originating in the cortex and other nuclei which surround the central nucleus of the inferior colliculus or in the pathways of the lateral midbrain tegmentum. Pericentral and lateral tegmental pathways terminate in nonprimary auditory cortex. The widespread pathway involves only the caudal nucleus of the medial division. It receives afferents from most, if not all, of the midbrain regions that give rise to the other pathways and distributes to all parts of the auditory cortex where it terminates in layers other than layer III

ISSN:0092-7317    

DOI:10.1002/cne.902090102

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe dimensions of the somata and stem dendrites of 57 α‐ and three γ‐ motoneurons, identified as to motor unit type and labeled by intracelluar injection of horseradish peroxidase, were measured in the triceps surae and plantaris motor pools. The somata of type S motoneurons tended to be smaller (mean diameter 47.9 μm) than those of FF and FR units (52.5 and 53.1 μm, respectively) but these mean values were not significantly different and the data distributions showed considerable overlap between the unit types. The mean numbers and diameters of stem dendrites of stem dendrites exhibited somewhat larger differences related to motor unit type and some of these were statistically significant. The total membrane area (AN) of each cell was estimated from measurements of the soma and stem dendrites, by using recent data of Ulfhake and Kellerth ('81) to calculate the membrane area of a dendritic tree from stem dendrite diameter. Mean ANvaried with motor unit type in the sequence FF>FR>S (average values: 369 × 1003μm2, 323 × 1003μm2, and 250 × 1003μm2, respectively). There was covariation between ANand the conduction velocity of the motor axon, as well as with the force output from the muscle unit. Comparison of ANand motoneuron input resistance (RN) in 19 α‐motoneurons suggested that the specific resistivity of the cell membrane in type S motoneurons was systematically higher than that characteristic of type FF o

ISSN:0092-7317    

DOI:10.1002/cne.902090103

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn 17 adult squirrel monkeys(Saimiri), horseradish peroxidase was used as a retrograde tracer substance to reveal the subcortical structures (other than the lateral geniculate nucleus and pulvinar) which project to the occipital lobe, and, in particular, to the central visual field representation in areas 17, 18, 19, and MT. Evidence is provided that each of areas 17, 18, and MT receives a projection from locus coeruleus, nucleus dorsalis raphae, nucleus annularis, nucleus centralis superior, formatio reticularis pontis oralis, nucleus basalis of Meynert, lateral hypothalamus, claustrum, and nuclei paracentralis and centralis medialis thalami. Area 19 receives a projection from all these structures except from the nucleus annularis. Only area MT was determined to be a target of a projection from the nucleus linearis. For technical reasons, only area MT was determined to receive afferent fibers from the nucleus basalis lateralis amygdalae. The results indicate that there is no topographical organization of subcortical inputs to the central visual field representation in individual cortical areas.

ISSN:0092-7317    

DOI:10.1002/cne.902090104

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe intrinsic connectivity of striate cortex was investigated by injecting horseradish peroxidase (HRP) into this area in tree shrews. Such HRP injections demonstrated periodically organized, stripelike connections within area 17. These stripes occur in layers I–IIIA and consist of a small number of retrogradely filled neurons, some clearly pyramidal, together with HRP‐labeled axon terminals. HRP‐filled axon trunks run between labeled stripes, interconnecting adjacent and distant regions of the stripe pattern. Correlation with Golgi‐stained tissue suggests that these stripes are horizontally interconnected by pyramidal neurons with long intracortical axon collaterals (followed for distances over 1 mm form the soma). The HRP‐labeled stripes measure about 230 μm in width, with a center‐to‐center repeat distance of 450–500 μm. They have been mapped over an 8 mm2area of striate cortex and would thus seem capable of effecting lateral interactions over considerable portions of the retinotopic map. In their dimensions and overall pattern, these anatomical stripes resemble the 2‐deoxyglucose (2‐DG) bands resulting from visual stimulation of tree shrews with stripes of a single orientation. While the functional role of the HRP‐labeled stripes is unclear, their similarities with the 2‐DG pattern raise the intriguing possibility that they may be related to orientation selectivity. The striking regularity of these extensive lateral interconnections emphasizes the importance of horizontal intralaminar conn

ISSN:0092-7317    

DOI:10.1002/cne.902090105

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

年代:1982

数据来源: WILEY

摘要:

AbstractFour separate neuronal groups, termed the anterior, dorsal, vental, and posterior nuclei of the juxtamamillary complex, were labeled retrogradely form the thalamic lateral posterior nucleus with horseradish peroxidase. The retrograde labeling was predominantly ipsilateral in the anterior, dorsal, and ventral nuclei, while it was predominantly contralateral in the posterior nucleus. The anterior, dorsal, and posterior nuclei could be detected clearly in Nissl sections; the ventral nucleus was only identified by horseradish peroxidase transport. The distribution of afferents to the juxtamamillary nuclei was investigated with the Fink‐Heimer technique. Following lesions of the olfactory tubercle and underlying structures, degenerating fibers in the medial forebrain bundle terminated discretely in the juxtamamillary nuclei. The dense terminal pattern conformed to the borders of the nuclei and was sometimes visible macroscopically. This pattern resembles that of medial forebrain bundle afferents to nuclei gemini in the rabbit and rat. Since the anatomical portions of these nuclei are also similar, it was concluded that the nuclei of the cat are comparable with the nuclei gemini in the rabbit and ra

ISSN:0092-7317    

DOI:10.1002/cne.902090106

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

年代:1982

数据来源: WILEY

摘要:

AbstractRetrograde tracing experiments were performed to clarify the topographic projection from medial (area 28m) and intermediate (area 28i) divisions of the entorhinal cortex to the dentate gyrus. Pipets filled with horseradish peroxidase (HRP) were positioned by electrophysiologic guidance at one of several septotemporal (S‐T) levels in the dentate molecular layer of anesthetized rats; the tracer was expelled iontophoretically to minimize its spread. Retrograde labeling of neurons within areas 28m and 28i was analyzed in relation to cytoarchitectonic as well as spatial features of the region (obtained by histologic reconstruction).Regardless of the S‐T level, ejections of HRP which were confined to the dentate gyrus labeled only layer II neurons of each area. Following septal pole ejections, labeled neurons were located in the posterolateral, extreme posterior, and postermedial parts of both areas 28m and 28i. Mid S‐T ejections produced not only a ventral, but also an anteromedial, shift in the location of entorhinal projection cells; no cells were labeled posterolaterally. After temporal dentate ejections labeled neurons occupied the most anteromedial part of these entorhinal areas. For both areas, but especially for area 28i, convergence of entorhinal efferents upon a single S‐T level in the dentate gyrus occurred from neurons which lay in a dorsoventral (i. e., frontal), and to a lesser extent a rostrocaudal, plane.The efferent axes of both areas 28m and 28i thus appear to be curved and are therefore best described in three dimensions. The entorhinal axes begin in a posterodorsolateral location, wrap around the posterior cortical convexity, and end in an anteroventromedial position. The results provide a useful map for in situ exploration of entrohinodentate connections in the rat, emphasize the parallel innervation of the dentate gyrus by distinct entorhinal fiber systems, and reflect the importance of the S‐T axis as a framework for interpreting hippocampal org

ISSN:0092-7317    

DOI:10.1002/cne.902090107

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe neurotoxic and gliotoxic effects of glutamate and several glutamate analogues were studied in isolated chick embryo retinas. To facilitate examination of initial pathological events, a short‐term incubation system was developed and used for light microscopic and autoradiographic investigation. Low‐dose, short‐term glutamate treatment of 12‐day retinas resulted in a glial‐specific lesion in the Müller cells, characterized by extensive cellular edema; at higher concentrations and/or longer treatment times, neurotoxic as well as gliotoxic effects were seen. The early glial damage was identical in appearance to that seen after incubation with DL‐α‐aminoadipate and other reported gliotoxins. No evidence of a similar glialspecific action was seen after administration of kainic acid, although extensive neuronal degeneration did result.Incubation of retinas with tritiated glutamate (3H‐glu) revealed a selective uptake of the label by Müller cells. Autoradiographic grains were localized over Müller foot processes at the inner limiting membrane, and by 30 minutes labeled the entire glial system. Prior treatment with neurotoxic levels of glutamate did not alter the autoradiographic localization to glial cells.Possible glial‐neuronal interactions and their effect on cytotoxic p

ISSN:0092-7317    

DOI:10.1002/cne.902090108

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe distribution of 5‐hydroxytryptamine (serotonin, 5‐HT)‐containing nerve fibers and terminals in the septal area of the rat was studied by using immunohistochemistry with specific antibodies to 5‐HT in combination with fluorescent retrograde tracing methods. The 5‐HT innervation of the septum is heterogeneous with regard to both the morphology of individual processes and the density of distribution in different parts of the septum. Three major classes of 5‐HT like immunoreactive processes can be distinguished: (1) thin, convoluted fibers with small, round or elongated varicosities; (2) thick and relatively straight fibers with few varicosities; and (3) pericellular plexuses with large varicosities in close association with perikarya in the lateral septum. Three areas of the septum receive a prominent innervation by 5‐HT processes: the diagonal band of Broca, the ventral part of the lateral septum, and and area bordering the medial edge fo the islands of Calleja (insula magna). Whereas the two latter areas contain dense terminal networks, the diagonal band of Broca is occupied primarily by 5‐HT fibers en route to other parts of the septum. Intraseptal injections of HRP or fluorescent dyes (granular blue, propidium iodide) resulted in retrograde labeling of neuronal cell bodies in several nuclei of the brainstem which are known to contain 5‐HT neurons: the dorsal raphe, the median raphe, the nucleus reticularis tegmenti pontis, the raphe pontis, and the raphe magnus. Where fluorescent retrograde tracing was performed with 5‐HT immunohistochemistry on the same tissue section, a prominent 5‐HT containing pathway and a non‐5‐HT‐containing pathway from the raphe nuclei to the septum were revealed. Finally, double retrograde fluorescent labeling after injections of granular blue or propidium iodide into the septum and entorhinal area respectively of the same rat revealed extensive branching of the raphe efferents. Thus, individual raphe neurons may simultaneously connect with septum and the entorhinal area, two structures essential for

ISSN:0092-7317    

DOI:10.1002/cne.902090109

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

年代:1982

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.902090101

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

年代:1982

数据来源: WILEY