Department of Psychology, University of Milano-Bicocca, Milan, Italy.
BMC Neurosci. 2010 May 6;11:59. doi: 10.1186/1471-2202-11-59.
Karns and Knight (2009) 1 demonstrated by using ERP and gamma band oscillatory responses that intermodal attention modulates visual processing at the latency of the early phase of the C1 response (62-72 ms) thought to be generated in the primary visual cortex. However, the timing of attentional modulation of visual cortex during object-based attention remains a controversial issue.
In this study, EEG recording and LORETA source reconstruction were performed. A large number of subjects (29) and of trial repetitions were used (13,312). EEG was recorded from 128 scalp sites at a sampling rate of 512 Hz. Four square-wave gratings (0.75, 1.5, 3, 6 c/deg) were randomly presented in the 4 quadrants of the visual field. Participants were instructed to pay conjoined attention to a given stimulus quadrant and spatial frequency. The C1 and P1 sensory-evoked components of ERPs were quantified by measuring their mean amplitudes across time within 5 latency ranges 40-60, 60-80, 80-100, 100-120 and 120-140 ms.
Early attention effects were found in the form of an enhanced C1 response (40-80 ms) to frequency-relevant gratings. LORETA, within its spatial resolution limits, identified the neural generators of this effect in the striate cortex (BA17), among other areas.
Karns 和 Knight（2009）1 通过使用 ERP 和伽马波段振荡反应表明，跨模态注意在 C1 反应（62-72ms）的早期阶段调节视觉处理，该反应被认为是在初级视觉皮层中产生的。然而，在基于对象的注意中，注意对视觉皮层的调制时间仍然是一个有争议的问题。
在这项研究中，进行了 EEG 记录和 LORETA 源重建。使用了大量的被试者（29 人）和试验重复次数（13312 次）。EEG 从 128 个头皮部位以 512Hz 的采样率记录。四个方波光栅（0.75、1.5、3、6 c/deg）随机出现在视野的 4 个象限中。参与者被指示联合注意到给定的刺激象限和空间频率。通过在 5 个潜伏期范围内（40-60、60-80、80-100、100-120 和 120-140ms）测量时间内的平均振幅，对 ERP 的 C1 和 P1 感觉诱发电位成分进行了量化。
以增强的与频率相关的光栅的 C1 反应（40-80ms）的形式发现了早期注意效应。在其空间分辨率限制内，LORETA 确定了该效应在纹状皮层（BA17）等区域的神经发生器。
