Visual quality determines the direction of neural repetition effects.
Visual quality determines the direction of neural repetition effects.
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视觉质量决定了神经重复效应的方向。
DOI：
10.1093/cercor/bhj159
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Chun,MM
中科院分区：
文献类型：
--
作者：
Turk-Browne,NB;Yi,D-J;Leber,AB;Chun,MM
功能磁共振成像研究中普遍存在的一项发现是，重复刺激引起的反应低于新刺激。明显矛盾的是，一些研究报告了在许多相同的大脑区域中出现完全相反的效果——对重复刺激的反应比对新刺激的反应更大。有趣的是，后者的增强效果通常是在刺激减弱时获得的。为了探索这一观察结果，本研究检查了视觉质量在刺激选择性腹侧视觉区域介导重复效应的程度。向受试者展示接近或远高于视觉阈值的场景灰度照片，这是通过根据行为表现校准图像对比度来确定的。与呈现 2 个不同的高对比度场景（重复衰减）相比，呈现 2 个相同的高对比度场景引发的血氧水平依赖性 (BOLD) 反应较低。相反，呈现 2 个相同的低对比度场景比呈现 2 个不同的低对比度场景（重复增强）引起更大的 BOLD 反应。神经生理学研究表明，腹侧视觉区域的重复衰减可能反映了由于先前经验而变得稀疏和选择性的知觉表征的重新激活，而重复增强可能反映了由于严重退化的输入而对现有表征的访问得以保留。
One ubiquitous finding in functional magnetic resonance imaging studies is that repeated stimuli elicit lower responses than novel stimuli. In apparent contradiction, some studies have reported the exact opposite effect—greater responses to repeated than novel stimuli—in many of the same brain regions. Interestingly, these latter enhancement effects are typically obtained when stimuli have been degraded. To explore this observation, the present study examines the degree to which visual quality mediates repetition effects in a stimulus-selective ventral visual area. Subjects were presented with grayscale photographs of scenes that were either near or substantially above visual threshold, as determined by calibrating image contrast to behavioral performance. The presentation of 2 identical high-contrast scenes elicited lower blood oxygen level–dependent (BOLD) responses than the presentation of 2 different high-contrast scenes (repetition attenuation). Conversely, the presentation of 2 identical low-contrast scenes elicited greater BOLD responses than the presentation of 2 different low-contrast scenes (repetition enhancement). Neurophysiological studies suggest that repetition attenuation in ventral visual areas may reflect the reactivation of perceptual representations that have become sparse and selective as a result of prior experience, whereas repetition enhancement may reflect spared access to existing representations by severely degraded input.