Attentional modulation of SSVEP power depends on the network tagged by the flicker frequency
Attentional modulation of SSVEP power depends on the network tagged by the flicker frequency
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DOI：
10.1093/cercor/bhj044
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发表时间：
2006-07-01
期刊：
影响因子：
3.7
通讯作者：
Srinivasan, R
中科院分区：
文献类型：
--
作者：
Ding, J;Sperling, G;Srinivasan, R
利用2.5-20 Hz范围内的15个“标签”频率，详细研究了注意对稳态视觉诱发电位（SSVEP）的调制。刺激是分别叠加在两个同心彩色标记环上的两组随机圆盘搜索阵列。两个系列的阵列独立更新，一个更新在一个固定的频率（闪烁）和其他更新随机根据白色噪声分布（随机宽带闪烁，rbbf）。在每次试验中，观察者被指示关注一个环并检测偶尔出现在所关注环中的随机圆盘阵列中的目标（三角形）。SSVEP结果表明，闪烁频率的选择决定了哪一个皮层网络对闪烁的响应，两种不同的皮层网络表现出不同的注意效应。SSVEP功率和注意对SSVEP功率的影响强烈地依赖于闪烁频率和rbbf环的径向位置。在δ频带（2-4 Hz）和上α频带（10-11 Hz）中的闪烁频率处，当关注闪烁时，枕额网络似乎锁相到闪烁，从而增加SSVEP的幅度。在较低的α频带（8-10 Hz）中的闪烁频率下，当注意力被引导远离闪烁的外围刺激并朝向中央凹中的竞争性rbbf刺激时，对外围闪烁刺激（包括顶叶皮层和后额叶皮层）的全局响应具有较高的幅度。当注意力集中在外围闪烁时，SSVEP功率的增加总是与锁相的增加相关联。相比之下，在较低的阿尔法带的频率，增加SSVEP功率时，注意力被引导远离闪烁和对中央凹刺激不与相位锁定的变化。因此，是否注意到闪烁刺激增加或减少SSVEP振幅和相位锁定取决于两个皮层网络，这具有不同的空间和动态特性，是由闪烁频率选择。
Modulation of the steady-state visual evoked potential (SSVEP) by attention was studied in detail using 15 'tag' frequencies in the range of 2.5-20 Hz. The stimuli were two series of random disc search arrays superimposed on two concentric color-marked annuli respectively. Two series of arrays were updated independently; one updated at one fixed frequency (flicker) and the other updated randomly according to a white noise distribution (random broad-band flicker, rbbf). On each trial, the observer was instructed to attend one annulus and to detect a target (a triangle) that occasionally appeared in a random disc array in the attended annulus. The SSVEP results show that the choice of flicker frequency selects which cortical network synchronizes to the flicker two distinct cortical networks showed different effects of attention. SSVEP power and the effects of attention on SSVEP power strongly depend on both flicker frequency and radial position of rbbf annulus. At flicker frequencies in the delta band (2-4 Hz), and in the upper alpha band (10-11 Hz), an occipital-frontal network appears to phase-lock to the flicker when attending to the flicker, increasing the magnitude of the SSVEP. At flicker frequencies in the lower alpha band (8-10 Hz), a global response to a peripheral flickering stimulus, that includes parietal cortex and posterior frontal cortex, has higher amplitude when attention is directed away from the flickering peripheral stimulus and towards a competing rbbf stimulus in the fovea. Increases in SSVEP power when attention is directed to peripheral flicker are always associated with increases in phase locking. By contrast, at frequencies in the lower alpha band, increases in SSVEP power when attention is directed away from the flicker and towards foveal stimuli are not associated with changes in phase-locking. Thus, whether attention to a flicker stimulus increases or decreases SSVEP amplitude and phase locking depends on which of two cortical networks, which have distinct spatial and dynamic properties, is selected by the flicker frequency.