关于举行复旦大学于玉国研究员学术报告的通知

报告题目1：神经元动作电位Hodgkin-Huxley经典理论模型的普适性

报告题目2： Sparse Coding and Lateral Inhibition Arising from Balanced and Unbalanced Dendrodendritic Excitation and Inhibition

报 告 人：于玉国  研究员

 (复旦大学计算生物学中心，医学神经生物学国家重点实验室)

时    间：2014年12月14日(周日)上午9:00-12:00

地    点：4号楼 4318室。                                                  

欢迎广大师生参加。

                                 数学学院

                             2014年12月9日

附：

报告1摘要：自1952年基于冷血动物枪乌贼鱼巨轴突的描述神经元动作电位的理论Hodgkin-Huxley（HH）模型建立以来，被广泛应用于描述不同动物种类的不同类型的神经元动作电位的产生和传输的实验现象。但基于低等动物的HH理论模型是否也适用于温血动物皮层神经元动作电位的产生过程一直作为一个质疑，不断受到实验现象的挑战。在最近几年有两个来自实验现象的有力挑战，均倾向认为进化可能优化了高等动物的动作电位产生机制。我们也对这些实验现象进行了详尽的检验，并研究了HH模型在什么情况下能够解释实验现象。我们成功发现在考虑到温血动物和冷血动物的温度因素以及动作电位的空间传播等特性的情况下，经典HH理论对高等动物神经元的动作电位产生机制仍然成立，这从另一方面也说明了神经元动作电位产生机制对于所有动物的普适性。

报告2摘要：The precise mechanism by which synaptic excitation and inhibition interact with each other in odor coding through the unique dendrodendritic synaptic microcircuits present in olfactory bulb is unknown. In the olfactory bulb, lateral inhibition mediated by granule cells has been suggested to modulate the timing of mitral cell firing, thereby shaping the representation of input odorants. Current experimental techniques, however, do not enable a clear study of how the mitral-granule cell network sculpts odor inputs to represent odor information spatially and temporally. To address this critical step in the neural basis of odor recognition, we built a large scale biophysical network circuit model of olfactory bulb with over 500 mitral and 10000 granule cells, corresponding to 1/100th of the real system in the rat, and used direct experimental imaging data of glomeruli activated by various odors. The model allows the systematic investigation of dendrodendritic processing of experimentally determined odor patterns. We found that the interaction between excitation and inhibition is responsible for two fundamental computational mechanisms: (1) a balanced excitation/inhibition in strongly activated mitral cells, leading to a sparse representation of odorant input, and (2) an unbalanced excitation/inhibition (inhibition dominated) in surrounding weakly activated mitral cells, leading to lateral inhibition. These results suggest how both mechanisms can carry information about the input patterns, with optimal level of synaptic excitation and inhibition producing the highest level of sparseness and decorrelation in the network response. The results suggesthowthe learning process, through the emergent development of these mechanisms, can enhance odor representation of olfactory bulb.