CAREER: Dendritic Subunits in Cortical Visual Processing and Development

IBN 97-34350 Mel神经元是大脑的计算细胞，通常具有广泛的、高度分枝的树状结构，称为树突，在树突上形成了数以万计的其他神经元的输入连接。与大脑的计算能力主要存在于“神经网络”，即紧密相连的神经细胞网络的经典概念不同，在过去40年里，人们的理解不断发展，包括梅尔博士的实验室和其他几个实验室的建模工作，确立了在单个神经元的树状结构树内进行的计算可以在很大程度上促进神经组织的计算功能。从这项建模工作中得出的一个重要原则是，不同的计算可以在树状结构树的不同“亚单位”中同时进行，这可以极大地提高单个神经细胞的计算能力。第二个原理是，学习和记忆可能不仅涉及细胞间连接的绝对效力的变化，也可能涉及单个神经元树突上输入连接的空间排列的变化。并行子单位计算是否真的发生在真实神经元的树突内仍有待确定。然而，回答这些问题的实验设计是复杂的，因为测量到的神经元的生理反应可能是由于单个细胞的内部操作，也可能是细胞网络的综合影响。在这项工作中，梅尔博士和他的同事们将对单个神经元计算以及由相互连接的神经元组成的嵌入式网络进行的计算的作用和相互作用进行建模，以指导与神经处理的关键问题相关的实验方法。

IBN 97-34350 MEL Neurons, the computing cells of the brain, typically possess extensive, highly branched tree-like structures called dendrites onto which tens of thousands of input connections from other neurons are formed. In contrast to the classical conception that the brain's computation power lies primarily in the "neural network", i.e. in the richly interconnected network of nerve cells, evolving understanding over the last 40 years and including modeling work in Dr. Mel's laboratory, among several others, has established that computations carried out within the dendritic trees of individual neurons can contribute in significant ways to the computing functions of neural tissue. One of the important principles to emerge from this modeling work is that different computations may be carried out simultaneously in different "subunits" of the dendritic tree, which could dramatically increase the computational capacities of individual nerve cells. A second principle is that the learning and memory may involve changes not only in the absolute potency of cell-to-cell connectivity but in the spatial arrangements of input connections onto the dendrites of individual neurons as well. Whether parallel subunit computations actually occur within the dendrites of real neurons remains to be determined. However, the design of experiments to answer these questions is complicated by the fact that the measured physiological responses of neurons can be due to either to internal operations of individual cells or the combined effects of networks of cells. In this work, Dr. Mel and his colleagues will model the roles and interaction of single- neuron computations and those carried out by the embedded network of interconnected neurons, in order to guide experimental approaches relating to critical questions of neural processing.