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  • 1
    Electronic Resource
    Electronic Resource
    Intrinsic inter- and intralaminar connections and their relationship to the tonotopic map in cat primary auditory cortex (1991)
    Springer
    Experimental brain research 86 (1991), S. 527-544 
    Details
    ISSN: 1432-1106
    Keywords: Auditory cortex ; Interlaminar connections ; Isofrequency bands ; Corticocortical connections ; Biotinylated PHA-L ; Anterograde tracing ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Small iontophoretic injections of the lectin, Phaseolus vulgaris leucoagglutinin (PHA-L), were made into different layers of the primary auditory cortex (AI) of cats. Injections in layer I labeled two types of morphologically distinct fibers in layer I as well as a smaller number of axons in layers II and III. Layer II injections labeled descending axons that produced a dense plexus of terminal fibers in layers I–III of both AI and adjacent auditory fields. Injections in layer III also labeled a dense plexus of axon collaterals at the junction of layers V and VI and labeled patches of terminal fibers in both AI and adjacent auditory fields. These were densest in layers I–III but usually extended into layers IV and V as well. The patches were partly formed by axon collaterals of layer III pyramidal cells that traveled for over 4 mm in the gray matter. Injections confined to layer IV labeled axons in all layers of the cortex but none of these axons appeared to reach the white matter. The axons spread laterally in layer IV and up into the superficial layers and ramified especially layer I. Injections in layers V and VI labeled axons in all layers of the cortex but these were densest in the deep layers where labeling was fairly homogeneous. In the upper layers the labeling was arranged in semi-discrete patches. Large injections involving layers I–III were studied in tangential sections. Between 3 and 8 patches of terminal labeling were observed in AI and these were mainly arranged in a band with its long axis aligned approximately in the dorsoventral direction. However dense patches of terminal labeling also occurred both anterior and posterior to the injection site. In selected experiments portions of the tonotopic map in AI were mapped by single unit recording and subsequently the map was related to patches of anterogradely labeled fibers that surrounded injections of PHA-L. Rows of dorsoventrally oriented patches were among cells with a similar best frequency to those in the injection site. However patches located anterior or posterior to the injection site were among cells with higher or lower best frequencies. Two injections of PHA-L close together produce different patterns of labeling. One of the injections usually produces one or more patches that has no correlate among the patches of fibers labeled by the adjacent injection. This is clearest when one of the injections is made with biotinylated PHA-L that can be visualized directly without the use of primary antibodies. Thus the intrinsic connections of AI arising from nearby cylinders of neurons are not homogenous and clusters of cells can be identified by their unique pattern of connections within AI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230526
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Chemoarchitectonic organization of the cat primary auditory cortex (1991)
    Springer
    Experimental brain research 86 (1991), S. 518-526 
    Details
    ISSN: 1432-1106
    Keywords: Architectonic organization ; Acetylcholines ; terase ; CAT 301 ; Calbindin ; Parvalbumin ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Acetylcholinesterase (AChE) activity, demonstrated histochemically, defines an area of cortex on the middle ectosylvian gyrus that appears to correspond to the cytoarchitectonically defined area 41 and the physiologically defined primary auditory area (AI). In this area there are high levels of AChE in layers III, IV and VI while in the surrounding areas there are comparatively low levels of enzyme in these layers. The monoclonal antibody CAT 301, which was raised against a cell surface proteoglycan, also defines this area. There are high levels of CAT 301 immunoreactivity in cell bodies and the neuropil of layer III and an absence of very large immunoreactive neurons in layer V. Furthermore there are higher levels of the calcium binding protein, parvalbumin and the metabolic enzyme, cytochrome oxidase, in layers III and IV of AI, than in most of the surrounding cortex. By contrast the distribution of the calcium binding protein, calbindin and the distribution of myelinated fibers are similar in area 41 and the surrounding areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230525
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Deoxyglucose uptake in the ferret auditory cortex (1997)
    Springer
    Experimental brain research 117 (1997), S. 488-500 
    Details
    ISSN: 1432-1106
    Keywords: Key words Auditory system ; Neocortex ; 2-Deoxyglucose autoradiography ; Deafness ; Chemoarchitectonic areas ; Ferret
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Histological methods and 2-deoxyglucose autoradiography were used in an attempt at finding distinguishing characteristics that would permit the clear definition of different auditory areas on the ectosylvian gyrus. This region was studied in both coronal and flattened tangential sections. In tangential sections a crescent-shaped region of high deoxyglucose uptake was identified. The centre of this crescent was in the position of the primary auditory area on the middle ectosylvian gyrus. The ventro-anterior arm of the crescent was on the surface of the anterior ectosylvian gyrus and the ventro-posterior arm on the posterior ectosylvian gyrus. All three parts of the crescent appear to have an auditory function, because ablating the inferior colliculus or inserting a contralateral earplug reduced their deoxyglucose uptake. This was shown by using two separately distinguishable forms of 2-deoxyglucose, incorporating the 18F and 14C isotopes. In addition, another area of high deoxyglucose activity was identified in the ventral wall of the suprasylvian sulcus, which seems to correspond to the anterior auditory field. These four areas with high deoxyglucose uptake also have high levels of succinate dehydrogenase activity and moderately high densities of myelinated fibres. Succinate dehydrogenase histochemistry provides a simple method for identifying auditory cortical areas and should be of use in future physiological studies. These results provide evidence that the ferret has four separate auditory areas with relatively high metabolic and functional activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050245
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    Paper (German National Licenses)
    Fulltext
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