Rio Daniel E, Rawlings Robert R, Woltz Lawrence A, Salloum Jasmin B, Hommer Daniel W
Section of Brain Electrophysiology and Imaging, Laboratory of Clinical Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-1540, USA.
Comput Methods Programs Biomed. 2006 Apr;82(1):10-9. doi: 10.1016/j.cmpb.2005.12.003. Epub 2006 Mar 13.
A linear time invariant model is applied to functional fMRI blood flow data. Based on traditional time series analysis, this model assumes that the fMRI stochastic output sequence can be determined by a constant plus a linear filter (hemodynamic response function) of several fixed deterministic inputs and an error term assumed stationary with zero mean. The input function consists of multiple exponential distributed (time delay between images) visual stimuli consisting of negative and erotic images. No a priori assumptions are made about the hemodynamic response function that, in essence, is calculated at each spatial position from the data. The sampling rate for the experiment is 400 ms in order to allow for filtering out higher frequencies associated with the cardiac rate. Since the statistical analysis is carried out in the Fourier domain, temporal correlation problems associated with inference in the time domain are avoided. This formal model easily lends itself to further development based on previously developed statistical techniques.
线性时不变模型应用于功能磁共振成像血流数据。基于传统时间序列分析，该模型假定功能磁共振成像的随机输出序列可由一个常数加上几个固定确定性输入的线性滤波器（血液动力学响应函数）以及一个假定均值为零的平稳误差项来确定。输入函数由多个呈指数分布（图像间的时间延迟）的视觉刺激组成，这些视觉刺激包括负面和色情图像。对于血液动力学响应函数未作先验假设，本质上是根据数据在每个空间位置进行计算的。实验的采样率为400毫秒，以便滤除与心率相关的较高频率。由于统计分析是在傅里叶域中进行的，因此避免了与时域推断相关的时间相关性问题。基于先前开发的统计技术，这个形式模型很容易进行进一步开发。
