Dendrite growth increased by visual activity requires NMDA receptor and Rho GTPases

Previous studies suggest that neuronal activity may guide the development of synaptic connections in the central nervous system through mechanisms involving glutamate receptors and GTPase-dependent modulation of the actin cytoskeleton. Here we demonstrate by in vivo time-lapse imaging of optic tectal cells in Xenopus laevis tadpoles that enhanced visual activity driven by a light stimulus promotes dendritic arbor growth. The stimulus-induced dendritic arbor growth requires glutamate-receptor-mediated synaptic transmission, decreased RhoA activity and increased Rac and Cdc42 activity. The results delineate a role for Rho GTPases in the structural plasticity driven by visual stimulation in vivo.     

管状曲面的奇点

研究管状曲面和它的平行曲面的奇点问题.所谓管状曲面,是沿着E3里一条曲线的双参数空间运动产生的.选定曲线的Frenet向量T作为旋转轴,用不同的方法得到了运动管状曲面的特征.然后,给出管状曲面奇点的一些定理和结果.