Automatic gain control contrast mechanisms are modulated by attention in humans: evidence from visual evoked potentials
Automatic gain control contrast mechanisms are modulated by attention in humans: evidence from visual evoked potentials
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DOI：
10.1016/s0042-6989(01)00134-1
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发表时间：
2001-09-01
期刊：
影响因子：
1.8
通讯作者：
Morrone, MC
中科院分区：
文献类型：
--
作者：
Di Russo, F;Spinelli, D;Morrone, MC
本研究探讨了注意对逆相正弦光栅稳态视觉诱发电位(VEP)对比度响应曲线的影响。在亮度或色度(等光红绿色)上调制I CyC/DIG栅格。亮度光栅在9赫兹反相(有利于激活巨细胞系统)，而色差光栅在2.5赫兹反相(有利于激活微小细胞系统)。通过要求受试者检测并对随机发生的对比变化做出反应，注意力被引导到栅格(显示在左侧视野中)。在控制条件下，通过要求受试者在对侧视野中短暂闪现的分心物中检测目标字母，可以最大限度地减少对格栅的注意力。注意力增加了亮度和彩色刺激的VEP幅度，高对比度比低对比度时更明显，增加了对比度幅度曲线的斜率(在对比度的非饱和范围内)。通过外推幅度来估计对比度阈值不受注意力的影响。注意力也改变了视觉诱发电位的相位，但仅限于亮度栅格。它的作用是通过对比度降低相位推进的幅度。注意对色栅的平均位相没有影响。结果与注意力作用于皮质增益控制机制的概念一致，众所周知，对于大细胞系统和微小细胞系统来说，这两种机制是不同的。(C)2001爱思唯尔科学有限公司。保留所有权利。
This study investigated the effect of attention on the contrast response curves of steady-state visual evoked potentials (VEPs) to counter-phased sinusoidal gratings. The I cyc/deg gratings were modulated either in luminance or chromaticity (equiluminant red-green). The luminance grating counter-phased at 9 Hz (to favour activation of the magno-cellular system), and the chromatic grating at 2.5 Hz (to favour activation of the parvo-cellular system). Attention was directed towards the gratings (displayed in the left visual field) by requiring subjects to detect and respond to randomly occurring changes in contrast. In the control condition, attention towards the grating was minimised by requiring subjects to detect a target letter amongst distracters briefly flashed in the contra-lateral visual field. Attention increased VEP amplitudes for both luminance and chromatic stimuli, more so at high than at low contrasts, increasing the slope of the contrast amplitude curves (over the non-saturating range of contrasts). The estimates of contrast threshold from extrapolation of amplitudes were unaffected by attention. Attention also changed the VEP phases, but only for luminance gratings. where it acted to reduce the magnitude of phase advance with contrast. Attention had no effect on the average phases for chromatic gratings. The results are consistent with the notion that attention acts on cortical gain control mechanisms, which are known to be different for the magno- and parvo-cellular systems. (C) 2001 Elsevier Science Ltd. All rights reserved.