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81.
82.
Integration of local inputs in visual cortex 总被引:1,自引:0,他引:1
In mammalian visual cortex, local connections are ubiquitous, extensively
linking adjacent neurons of all types. In this study, optical maps of
intrinsic signals and responses from single neurons were obtained from the
same region of cat visual cortex while the effectiveness of the local
cortical circuitry was altered by focally disinhibiting neurons within a
column of known orientation preference. Maps of intrinsic signals indicated
that local connections provide strong and functional subthreshold inputs to
neighboring columns of other orientation preferences, altering the observed
orientation preference to that of the disinhibited column. However,
measuring the suprathreshold response using single-cell recordings revealed
only mild changes of preferred orientation over the affected region.
Because strongly tuned subthreshold inputs from cortex only marginally
affect the tuning of a cortical cell's output, it is concluded that local
cortical inputs are integrated weakly compared to geniculate inputs. Such
circuitry potentially allows for the normalization of responses across a
wide range of input activity through local averaging.
相似文献
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蓣知子皂甙IV的结构 总被引:6,自引:1,他引:5
从木通科木通属植物白木通[Akebia trifoliata(Thunb.)Koidz.var.australis(Diels)Rehd]种子的乙醇提取物中以硅胶层析等方法得四种三萜皂甙。其中甙IV是新天然产物,命名为蓣知子皂甙IV(yuzhiziosideIV)。根据化学和光谱分析,确定甙IV的结构为3-O-β-D-吡喃木糖基-(1→2)-a-L-吡喃阿拉伯糖齐墩果酸-28-O-β-D-吡喃葡萄糖基-(1→6)-β-D-吡喃葡萄糖酯甙。另外皂甙B(I)、皂甙C(II)和皂甙D(III)为已知物。这些化合物在白木通种子中均是首次得到。 相似文献
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Kenneth MC Cheung Jing-ping Wu Qing-he Cheng Bonnie SC Ma Ji-chang Gao Keith DK Luk 《Journal of orthopaedic surgery and research》2007,2(1):16-5
Background
Thoracoscopic anterior release has been shown that it can effectively improve spinal flexibility in animal and human cadaveric studies, and has been advocated for use in patients with scoliosis. This prospective case series aims to investigate the improvement of the spinal flexibility and the effectiveness in deformity correction by anterior thoracoscopic release and posterior spinal fusion. 相似文献89.
Rudy W; Guckel B; Siebels M; Lindauer M; Meuer SC; Moebius U 《International immunology》1997,9(6):853-860
Introduction of co-stimulatory molecules like CD80 and CD86 represents a
means to augment the immunogenicity of tumor cells and to induce immune
responses directed at tumor antigens. Here we compared CD80- and
CD86-transfected human melanoma cells to induce primary immune responses by
their capacity to promote proliferation of human allogeneic resting T
lymphocytes. CD80- and CD86-transfected SkMel63 melanoma cells induced T
cell activation to a comparable degree, which was found to be independent
of the cell surface density of these co- stimulatory molecules.
Co-expression of CD80 and CD86 did not result in a synergistic increase in
T cell proliferation. Both CD80 and CD86 transfectants induced the
proliferation of isolated CD4+ or CD8+ T cells. Exogenous IL-2, IL-4 and
tumor necrosis factor-alpha respectively enhanced primary T cell
proliferation independent of CD80 or CD86 expression. Interestingly,
differential activities of CD80 and CD86 were observed following
stimulation of resting T cells in the presence of IL-12. Whereas IL-12
increased T cell proliferation in the presence of CD86-transfected melanoma
cells, it exhibited an inhibitory function in the presence of
CD80-expressing SkMel63 cells. Experimental evidence indicates that this
inhibitory effect was mediated by IFN- gamma since (I) IFN-gamma secretion
of stimulated T cells was augmented by IL-12, (II) exogenous IFN-gamma also
inhibited T cell proliferation induced by CD80- but not CD86-transfected
SkMel63 cells and (III) the inhibitory effect of IL-12 was blocked by an
anti-IFN-gamma mAb.
相似文献
90.