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fMRI adaptation to anomalous motion in the a??Rotating Snakesa?? patterns

机译：fMRI对“旋转蛇形”中异常运动的适应模式

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Stationary patterns with a specially designed repetitive pattern, such as the a??Rotating Snakesa?? (Kitaoka & Ashida, 2003), can elicit illusory perception of motion. By using a conventional fMRI contrast, we have shown that the a??Rotating Snakesa?? figure activates human MT+ (Kuriki et al, 2008). Activity in V1 was not evident, which can be either because motion signals arise within MT+ (Thiele et al, 2004), or because our motionless control stimulus (for comparison of BOLD signals) that consisted of the same local patterns might have elicited local motion signals (while globally cancelled out). In this study, we used an fMRI adaptation paradigm that does not require an explicit control stimulus, in order to assess direction-selective responses in the visual areas to the a??Rotating Snakesa?? pattern. Four disks that comprised repetitive patterns of white-yellow-black-blue were used. They appeared as rotating in this direction when viewed naturally. After an adapting stimulus (S1) followed by a blank interval, a probe stimulus (S2) of either the same or the reversed color order (hence eliciting illusory motion in the same or the opposite direction) was presented. The spatial phase was altered between S1 and S2 to avoid local coincidence. The fixation mark was blurred to relax fixation to some extent because hard fixation can abolish illusory motion. Attention was controlled by a fixation task. Regions of interest were defined for each participant by separate localizer runs. A 3-T scanner (Siemens Trio Tim) was used. Event-related averages of time-courses revealed larger BOLD responses for reversed S2 than for the same S2 in MT+, indicating direction-specific adaptation. The difference was smaller but evident in V1-V4 and V3A. The overall results suggest that local motion sensors in V1 are indeed activated by the illusion figure, which is in line with most of currently proposed models.
机译：具有特别设计的重复图案的固定图案，例如“旋转蛇”。 （Kitaoka和Ashida，2003年）可以引起运动的幻觉。通过使用常规的fMRI对比，我们显示出“旋转的Snakesa”该图激活了人类的MT +（Kuriki等，2008）。 V1中的活动并不明显，这可能是因为运动信号出现在MT +内（Thiele等，2004），或者是因为我们的由相同局部模式组成的静止控制刺激（用于比较BOLD信号）可能引起了局部运动信号（同时全局取消）。在这项研究中，我们使用了不需要显式控制刺激的fMRI适应范式，以评估视觉区域对“旋转蛇”的方向选择响应。模式。使用了四个包含白色，黄色，黑色，蓝色的重复图案的磁盘。从自然角度看，它们似乎朝这个方向旋转。在适应性刺激（S1）之后是空白间隔之后，出现了相同或相反颜色顺序的探针刺激（S2）（因此引起相同或相反方向的幻觉运动）。为了避免局部重合，在S1和S2之间更改了空间相位。固定标记模糊不清，可以在某种程度上放松固定，因为硬固定可以消除幻觉。注意是由固定任务控制的。通过单独的本地化运行为每个参与者定义了感兴趣的区域。使用了3-T扫描仪（Siemens Trio Tim）。时间相关事件的平均值显示，与MT +中相同的S2相比，反向S2的BOLD响应更大，表明方向特定的适应性。差异较小，但在V1-V4和V3A中明显。总体结果表明，V1中的局部运动传感器确实已被幻觉图形激活，这与当前提出的大多数模型一致。

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