Janz C, Schmitt C, Speck O, Hennig J
Section of Medical Physics, University Clinic Freiburg, 79106 Freiburg, Germany.
J Magn Reson Imaging. 2000 Nov;12(5):708-14. doi: 10.1002/1522-2586(200011)12:5<708::aid-jmri7>3.0.co;2-g.
Experiments with three different types of basic visual stimulation were performed to compare cortical activation in single-event and block trials. Independent of the stimulation paradigm, the single-event presentation leads to highly consistent signal responses regarding both the activated cortical areas and the dynamics of the signal time course. In contrast, signal time courses during block paradigms depend on the stimulus applied and are a complex and nonlinear function of the single-event responses. Additionally, the initial dip during the first 2 seconds after stimulus onset is consistently observed. However, the small amplitude change (-0.1% to -0.3%) requires signal averaging to establish statistical significance of the effect. Furthermore, different patterns of activation were observed within the primary visual cortex. In an anterior part of the primary visual cortex, activation was only observed at the onset and at the cessation of stimulation involving luminance changes.
进行了三种不同类型的基本视觉刺激实验，以比较单事件试验和组块试验中的皮层激活情况。与刺激范式无关，单事件呈现导致在激活的皮层区域和信号时间进程动态方面高度一致的信号反应。相比之下，组块范式期间的信号时间进程取决于所施加的刺激，并且是单事件反应的复杂非线性函数。此外，在刺激开始后的前2秒内始终观察到初始负向偏转。然而，小幅度的变化（-0.1%至-0.3%）需要信号平均来确定该效应的统计学显著性。此外，在初级视觉皮层内观察到了不同的激活模式。在初级视觉皮层的前部，仅在涉及亮度变化的刺激开始和停止时观察到激活。
