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  • 1
    Electronic Resource
    Electronic Resource
    High-Resolution Light and Electron Microscopic Immunocytochemistry of Colocalized GABA and Calbindin D-28k in Somata and Double Bouquet Cell Axons of Monkey Somatosensory Cortex (1992)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 4 (1992), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A simple method for high-resolution immunocytochemical colocalization of different antigens in semithin sections 1 - 3 μm thick was used to study the colocalization of the calcium binding protein calbindin D-28k (calbindin) with γ-aminobutyric acid (GABA) in double bouquet cells of monkey (Macaca fuscata) somatosensory cortex. Double bouquet cells were first visualized in vibratome sections by pre-embedding immunocytochemical staining for calbindin. Sections containing calbindin-immunoreactive somata and double bouquet cell axons were then osmicated, embedded in Araldite, resectioned at 1–3μm and stained for GABA by postembedding immunocytochemistry after elution of the bound anti-calbindin antibodies. Other semithin sections adjacent to those eluted and still containing calbindin immunoreactive somata and processes were resectioned at 60–70 nm for electron microscopy and stained immunocytochemically for GABA by the postembedding immunogold procedure. Calbindin-positive cells are most numerous in layer II and upper layer III, where they outnumber those in all other layers combined. In layers II and upper III, -30% of the stained cells are pyramidal and do not colocalize GABA. Only approximately two-thirds of the calbindin-stained nonpyramidal cells in these layers colocalize GABA, but among these virtually all the calbindin-positive double bouquet cells and their axons are GABA-immunoreactive. In deeper layers all calbindin-positive cells are nonpyramidal and all colocalize GABA. At the electron microscopic level, however, significant numbers of calbindin-positive axon terminals making symmetrical synapses are not GABA-immunoreactive. These results suggest the calbindin cells of monkey somatosensory cortex are a heterogeneous population that includes GABAergic and non-GABAergic cell types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1992.tb00108.x
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  • 2
    Electronic Resource
    Electronic Resource
    Synaptology of the proximal segment of pyramidal cell basal dendrites (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pyramidal neurons are covered with dendritic spines, the main postsynaptic targets of excitatory (asymmetrical) synapses. However, the proximal portion of both the apical and basal dendrites is devoid of spines, suggesting a lack of excitatory inputs to this region. In the present study we used electron microscopy to analyse the proximal region of the basal dendrites of supra- and infragranular pyramidal cells to determine if this is the case. The proximal region of 80 basal dendrites sampled from the rat hindlimb representation in the primary somatosensory cortex was studied by electron microscopy. A total of 317 synapses were found within this region of the dendrites, all of which were of the symmetrical type. These results suggest that glutamate receptors, although present in the cytoplasm, are not involved in synaptic junctions in the proximal portion of the dendrites. These data further support the idea that inhibitory terminals exclusively innervate the proximal region of basal dendrites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0953-816X.2003.03166.x
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  • 3
    Electronic Resource
    Electronic Resource
    Altered synaptic circuitry in the human temporal neocortex removed from epileptic patients (1997)
    Springer
    Experimental brain research 114 (1997), S. 1-10 
    Details
    ISSN: 1432-1106
    Keywords: Key words Epilepsy ; Synapse ; Quantification ; Synaptic density ; Sprouting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Quantitative electron microscopic methods were used to study possible alterations in presumptive excitatory and inhibitory synaptic circuits in human neocortex removed from patients with intractable temporal lobe epilepsy. Synaptic density was compared between normal and abnormal regions as identified by Nissl staining and immunocytochemistry for the Ca2+-binding protein parvalbumin (PV). The normal regions showed a normal cytoarchitecture and normal pattern of staining for PV, whereas the abnormal regions displayed focal neuronal cell loss and a decrease in immunostaining for PV. In the abnormal regions the overall synaptic density (per 100 μm2 and per mm3) was approximately 30% higher than in normal regions, which corresponded to an increase of approximately 300 million synapses per mm3. The number of excitatory and inhibitory synapses was significantly higher and lower, respectively, than in normal regions. We suggest that these changes are a result of a focal sprouting of excitatory axon terminals and loss of inhibitory terminals which leads to hyperexcitatory synaptic circuits. These circuits may represent a neural substrate for the initiation or propagation of seizure activity in human epileptogenic neocortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005608
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  • 4
    Electronic Resource
    Electronic Resource
    Local changes in GTP-binding protein immunoreactivities in human epileptogenic neocortex (1998)
    Springer
    Experimental brain research 119 (1998), S. 153-158 
    Details
    ISSN: 1432-1106
    Keywords: Key words G proteins ; Intractable epilepsy ; Immunoelectrophoresis ; Cytoarchitecture ; Gliosis ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The relative levels of guanine nucleotide-binding protein α-subunits Gi1α, Gi2α, Gi3α, Goα, Gsα, and Gx/zα were measured in neocortex removed at surgery from patients with intractable temporal lobe epilepsy. Immunoreactivity was quantified using specific polyclonal antisera against the Gα-subunits according to the Laurell “rocket” immunoelectrophoresis technique. We compared the G protein contents of spiking (active) and nonspiking (nonactive) cortical regions, based on intraoperative electrocorticography, within the same and different patients. There were no clear trends for lower or higher levels of G-protein subtypes to be found in the samples of protein extracts from nonspiking regions as compared to spiking regions. However, comparison of paired samples of spiking and nonspiking cortex within the same patient demonstrated that levels of certain G-protein subtypes were either increased or decreased in all patients. This indicates that cortical regions with enhanced neuronal activity may produce microzonal alterations in the levels of G proteins. Moreover, our results suggest that high levels of Gi1α and low levels of the other G-protein subtypes appear to be associated with a greater susceptibility to maintaining spiking activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050328
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  • 5
    Electronic Resource
    Electronic Resource
    Local connections in transplanted and normal cerebral cortex of rats (1988)
    Springer
    Experimental brain research 69 (1988), S. 387-398 
    Details
    ISSN: 1432-1106
    Keywords: Neocortical transplants ; Fluorescent retrograde labeling ; Intracortical connectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Injections of the fluorescent tracer Fluoro-Gold were made in transplanted and normal cerebral cortex of rats in order to investigate and compare the local connectivities of both. In the normal somatosensory cortex, small injections in superficial layers (I to III) produced retrograde cell labeling below the injection site in two bands: in layer V and in the deep part of layer VI. Pieces of embryonic rat neocortical tissue were transplanted into a cavity made in the somatosensory cortex of young adult rats. After a survival period of 2–3 months, small injections of Fluoro-Gold were made in the superficial part of the grafts. These injections revealed multiple clusters of intratransplant-projecting cells. No callosal or thalamic neurons were labeled in these experiments. On occasion, a bilaminated pattern of retrograde cell labeling was observed inside the transplants. In both transplanted and normal cortices, pyramidal and non-pyramidal cells were retrograde-labeled. We conclude that in the neocortical transplants there is a pattern of local connectivity that is reminiscent of the pattern of intracortical connectivity in the normal neocortex in at least two aspects: first, the retrograde-labeled cells tended to form clusters or bands; second, both pyramidal and non-pyramidal cells were labeled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247584
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  • 6
    Electronic Resource
    Electronic Resource
    A light and electron microscopic study of serotonin-immunoreactive fibers and terminals in the monkey sensory-motor cortex (1988)
    Springer
    Experimental brain research 71 (1988), S. 171-182 
    Details
    ISSN: 1432-1106
    Keywords: Serotonin synapses ; Sensory-motor cortex ; Monkey ; Electron microscopic immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunocytochemical methods were used to study the distribution and ultrastructure of serotonin (5-hydroxytryptamine; 5-HT) immunoreactive fibers innervating the monkey sensory-motor cortex. Beaded 5-HT positive fibers were found in all cortical layers of both areas but with relatively fewer in middle cortical layers. Examination of 2 μm-thick plastic sections at the light microscope level, revealed that the vast majority of the bouton-like structures on the fibers lay in the neuropil and not adjacent to neuronal somata. A few beaded immunoreactive fibers were seen around certain pyramidal and nonpyramidal cell somata, very occasionally forming modest pericellular ramifications. Serial reconstructions made from electron micrographs after resectioning the 2 μm-thick sections, revealed that the dilatations of the fibers are 5-HT positive boutons but the boutons examined rarely formed morphologically identifiable synaptic contacts. Of 191 reconstructed boutons only 5 made contacts with obvious membrane specializations, all of which were of the asymmetrical type. No immunoreactive synaptic contacts were seen on pyramidal cell somata in the cortex, nor on dendrites or somata in the white matter underlying the cortex, although 5-HT positive boutons commonly lay closely adjacent to neuronal profiles in both sites. 5-HT fibers in the cortex and white matter have a similar morphological appearance and both myelinated and unmyelinated types are seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247532
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