Gaab Nadine, Gabrieli John D E, Glover Gary H
Department of Psychology, Stanford University, Stanford, California, USA.
Hum Brain Mapp. 2007 Aug;28(8):703-20. doi: 10.1002/hbm.20298.
We compared two experimental designs aimed at minimizing the influence of scanner background noise (SBN) on functional MRI (fMRI) of auditory processes with one conventional fMRI design. Ten subjects listened to a series of four one-syllable words and had to decide whether two of the words were identical. This was contrasted with a no-stimulus control condition. All three experimental designs had a duration of approximately 17 min: 1) a behavior interleaved gradients (BIG; Eden et al. [1999] J Magn Reson Imaging 41:13-20) design (repetition time, TR, = 6 s), where stimuli were presented during the SBN-free periods between clustered volume acquisitions (CVA); 2) a sparse temporal sampling technique (STsamp; e.g., Gaab et al., [2003] Neuroimage 19:1417-1426) acquiring only one set of slices following each of the stimulations with a 16-s TR and jittered delay times between stimulus offset and image acquisition; and 3) an event-related design with continuous scanning (ERcont) using the stimulation design of STsamp but with a 2-s TR. The results demonstrated increased signal within Heschl's gyrus for the STsamp and BIG-CVA design in comparison to ERcont as well as differences in the overall functional anatomy among the designs. The possibility to obtain a time course of activation as well as the full recovery of the stimulus- and SBN-induced hemodynamic response function signal and lack of signal suppression from SBN during the STsamp design makes this technique a powerful approach for conducting auditory experiments using fMRI. Practical strengths and limitations of the three auditory acquisition paradigms are discussed.
我们将旨在最小化扫描仪背景噪声（SBN）对听觉过程功能磁共振成像（fMRI）影响的两种实验设计与一种传统fMRI设计进行了比较。10名受试者聆听了一系列四个单音节单词，并必须判断其中两个单词是否相同。这与无刺激对照条件形成对比。所有三种实验设计的持续时间约为17分钟：1）行为交错梯度（BIG；伊登等人，[1999]《磁共振成像杂志》41:13 - 20）设计（重复时间，TR，= 6秒），其中刺激在聚类容积采集（CVA）之间的无SBN时间段内呈现；2）一种稀疏时间采样技术（STsamp；例如，加布等人，[2003]《神经影像学》19:1417 - 1426），在每次刺激后仅采集一组切片，TR为16秒，刺激偏移与图像采集之间有抖动延迟时间；3）一种使用STsamp刺激设计但TR为2秒的连续扫描事件相关设计（ERcont）。结果表明，与ERcont相比，STsamp和BIG - CVA设计在Heschl回内的信号增强，并且各设计之间的整体功能解剖结构存在差异。在STsamp设计中能够获得激活的时间进程以及刺激和SBN诱导的血流动力学反应函数信号的完全恢复，且无SBN引起的信号抑制，这使得该技术成为使用fMRI进行听觉实验的有力方法。讨论了三种听觉采集范式的实际优势和局限性。
