Siegel M, Körding K P, König P
Institute of Neuroinformatics, ETH/University Zürich.
J Comput Neurosci. 2000 Mar-Apr;8(2):161-73. doi: 10.1023/a:1008973215925.
The classical view of cortical information processing is that of a bottom-up process in a feedforward hierarchy. However, psychophysical, anatomical, and physiological evidence suggests that top-down effects play a crucial role in the processing of input stimuli. Not much is known about the neural mechanisms underlying these effects. Here we investigate a physiologically inspired model of two reciprocally connected cortical areas. Each area receives bottom-up as well as top-down information. This information is integrated by a mechanism that exploits recent findings on somato-dendritic interactions. (1) This results in a burst signal that is robust in the context of noise in bottom-up signals. (2) Investigating the influence of additional top-down information, priming-like effects on the processing of bottom-up input can be demonstrated. (3) In accordance with recent physiological findings, interareal coupling in low-frequency ranges is characteristically enhanced by top-down mechanisms. The proposed scheme combines a qualitative influence of top-down directed signals on the temporal dynamics of neuronal activity with a limited effect on the mean firing rate of the targeted neurons. As it gives an account of the system properties on the cellular level, it is possible to derive several experimentally testable predictions.
经典的皮质信息处理观点认为，这是一个前馈层级中的自下而上的过程。然而，心理物理学、解剖学和生理学证据表明，自上而下的效应在输入刺激的处理中起着关键作用。对于这些效应背后的神经机制，人们了解得并不多。在这里，我们研究了一个受生理学启发的、由两个相互连接的皮质区域组成的模型。每个区域都接收自下而上以及自上而下的信息。这些信息通过一种利用了近期关于体树突相互作用研究结果的机制进行整合。（1）这会产生一个突发信号，该信号在自下而上信号存在噪声的情况下依然稳健。（2）通过研究额外的自上而下信息的影响，可以证明类似启动效应的现象对自下而上输入的处理过程产生作用。（3）与近期的生理学研究结果一致，自上而下的机制会显著增强低频范围内的区域间耦合。所提出的方案将自上而下定向信号对神经元活动时间动态的定性影响与对目标神经元平均放电率的有限影响结合起来。由于它阐述了细胞水平上的系统特性，所以有可能得出一些可通过实验验证的预测。
