Neural mechanism for critical period of the auditory cortex

本研究将干细胞植入实验动物的听道，以探索操纵听皮层关键期的可能性。我们将自体骨髓基质细胞（MSC）注射到氨基糖苷类药物损伤的耳蜗蜗轴中，观察到大量MSC存活，其中一些分化为神经元细胞。将小鼠胚胎干细胞（ES细胞）培养于颅骨骨髓细胞层上，与耳蜗感觉上皮细胞共培养，可使ES细胞的神经突大量伸长并附着于毛细胞上。突触素的表达观察到的ES细胞衍生的神经元的轴突邻近的基底或基底外侧部分的毛细胞。这些发现表明ES细胞分化为听道神经元的潜力很高。我们还使用SDIA处理后的小鼠ES细胞作为移植物。用卡那霉素和依他尼酸致敏的Hartley豚鼠， ...更多信息 艾德作为受体动物。将ES细胞导入耳蜗蜗轴。耳蜗移植后的eABR阈值明显低于未手术组，提示SDIA处理的ES细胞移植可能有助于听觉功能的恢复。这些结果表明，未来的潜力，使用干细胞植入，以克服听觉神经系统的关键期。至于脑功能成像的研究，我们对听力正常的志愿者使用18F-FDG，让他们观看说话者面部的无声视频。正电子发射断层扫描（PET）显示，他们的大脑视觉皮层，顶叶和上级颞回（STG）在左半球的后部显着激活。如果左侧STG的这种唇读阅读激活在先天性耳聋受试者中占据主导地位，那么语言视觉方面的处理可能在颞叶皮质中占主导地位，这有望成为口语习得关键期的指标之一。少

We studied on stem cell implantation in the auditory tract of experimental animals in search for possibilities of manipulating the critical period of the auditory cortex. We injected autologous bone marrow stromal cells (MSC) into the modiolus of the cochlea damaged by aminoglycoside, and observed massive survival of MSCs, some of which differentiated into neuronal cells. Mouse embryonic stem cells (ES cells) cultured on skull bone marrow cell layer were co-cultured with cochlear sensory epithelium, which resulted in massive elongation of neurites from ES cells and attachment of the neurites to hair cells. Expression of synaptophysin was observed in the neurites of ES cell-derived neurons adjacent to the basal or basolateral portion of hair cells. These findings indicate a high potential of ES cells to differentiate into auditory tract neurons. We also used mouse ES cells after treatment with the SDIA as transplants. Hartley guinea pigs deafened by kanamycin and ethacrynic acid were us … More ed as recipient animals. ES cells were introduced into the cochlear modiolus. Transplanted cochleae exhibited significantly lower eABR thresholds in comparison with those of non-operated ones, which suggests possible contribution of SDIA-treated ES cell implantation to retrieval of auditory function. These results suggest future potential of using stem cell implantation to overcome critical period of the auditory nervous system. As for studies by functional brain imaging, we used 18F-FDG in normal hearing volunteers and let them watch silent video of a speaker's face. Positron emission tomography (PET) scan of their brain revealed significant activation of visual cortex, parietal lobe and the posterior portion of the superior temporal gyrus(STG) in the left hemisphere. If this lip reading activation of the left STG become dominant in congenitally deafened subjects, processing of visual aspects of language may be prevailing in the temporal cortex, which is expected to become one of the indicators for critical period of spoken language acquisition. Less