Janz C, Heinrich S P, Kornmayer J, Bach M, Hennig J
Section of Medical Physics, University Medical Center, Freiburg, Germany.
Magn Reson Med. 2001 Sep;46(3):482-6. doi: 10.1002/mrm.1217.
Functional magnetic resonance imaging (fMRI) measures the correlation between the fMRI response and stimulus properties. A linear relationship between neural activity and fMRI response is commonly assumed. However, the response to repetitive stimulation cannot be explained by a simple superposition of single-event responses. This might be due to neural adaptation or the hemodynamic changes underlying the fMRI BOLD response. To assess the influence of adaptation, the BOLD responses and visual evoked potentials (VEPs) to identical stimuli were recorded. To achieve different adaptation levels, 2-s stimulus epochs alternated with different interstimulus intervals (ISI = 0.0, 0.4, 0.8, 2.0, and 12 s) were presented. Neural adaptation during the checkerboard reversal paradigm used for fMRI measurements is demonstrated. Even if the measured VEP amplitude is used as the weighting function for a linear model, the measured BOLD fMRI signal time-course is not adequately predicted.
功能磁共振成像（fMRI）测量fMRI反应与刺激特性之间的相关性。通常假定神经活动与fMRI反应之间存在线性关系。然而，对重复刺激的反应无法通过单事件反应的简单叠加来解释。这可能是由于神经适应性或fMRI血氧水平依赖（BOLD）反应背后的血液动力学变化。为了评估适应性的影响，记录了对相同刺激的BOLD反应和视觉诱发电位（VEP）。为了实现不同的适应水平，呈现了2秒的刺激时段，并交替使用不同的刺激间隔（ISI = 0.0、0.4、0.8、2.0和12秒）。结果表明，在用于fMRI测量的棋盘格反转范式中存在神经适应性。即使将测得的VEP幅度用作线性模型的加权函数，也无法充分预测测得的BOLD fMRI信号时间进程。
