Regulation of rCBF by diffusible signals: An analysis of constraints on diffusion and elimination
Regulation of rCBF by diffusible signals: An analysis of constraints on diffusion and elimination
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DOI：
10.1002/hbm.460030106
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发表时间：
1995-01-01
影响因子：
4.8
通讯作者：
Friston, KJ
中科院分区：
文献类型：
--
作者：
Friston, KJ
脑血流动力学的局部变化在神经活动变化的几百毫秒内被观察到。如果血流动力学反应是由空间信号的被动扩散（从神经活动部位到微血管）介导的，则反应的动力学表明信号的表观扩散和消除的下限。这项工作的目的是估计这些限制和缩小可能的候选物质的领域。一个简单的生物物理模拟被用来检查如何的时间过程中的浓度变化的空间信号，在作用部位（微血管），取决于关键的扩散参数（源的几何形状，表观扩散和消除半衰期）。模拟表明：1）信号浓度的上升主要是源几何形状和扩散的函数。相反，浓度的福尔斯下降取决于消除，2）即使来源分布非常稀疏，一氧化氮也会有足够快的扩散和消除，通过被动扩散发出活性依赖性血液动力学反应早期成分的信号。(C)1995 Wiley-Liss，Inc.
Local changes in cerebral hemodynamics are observed within a few hundred milliseconds of changes in neural activity. If hemodynamic responses are mediated by passive diffusion of a spatial signal (from the site of neural activity to the microvessels) then the dynamics of the response suggest a lower limit on the signal's apparent diffusion and elimination. The aim of this work was to estimate these limits and narrow the field of possible candidate substances.A simple biophysical simulation was used to examine how the time course of concentration changes in a spatial signal, at the site of action (microvessels), depends on key diffusion parameters (source geometry, apparent diffusion and elimination half-life). The simulations suggested 1) that the rise in signal concentration is mostly a function of source geometry and diffusion. Conversely falls in concentration depend on elimination and 2) even when sources are very sparsely distributed Nitric Oxide would have a sufficiently fast diffusion and elimination to signal the early components of activity-dependent hemodynamic response by passive diffusion. (C) 1995 Wiley-Liss, Inc.