Yamagishi Noriko, Callan Daniel E, Goda Naokazu, Anderson Stephen J, Yoshida Yoshikazu, Kawato Mitsuo
ATR Computational Neuroscience Laboratories, 2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0288, Japan.
Neuroimage. 2003 Sep;20(1):98-113. doi: 10.1016/s1053-8119(03)00341-0.
The effects of attentional modulation on activity within the human visual cortex were investigated using magnetoencephalography. Chromatic sinusoidal stimuli were used to evoke activity from the occipital cortex, with attention directed either toward or away from the stimulus using a bar-orientation judgment task. For five observers, global magnetic field power was plotted as a function of time from stimulus onset. The major peak of each function occurred at about 120 ms latency and was well modeled by a current dipole near the calcarine sulcus. Independent component analysis (ICA) on the non-averaged data for each observer also revealed one component of calcarine origin, the location of which matched that of the dipolar source determined from the averaged data. For two observers, ICA revealed a second component near the parieto-occipital sulcus. Although no effects of attention were evident using standard averaging procedures, time-varying spectral analyses of single trials revealed that the main effect of attention was to alter the level of oscillatory activity. Most notably, a sustained increase in alpha-band (7-12 Hz) activity of both calcarine and parieto-occipital origin was evident. In addition, calcarine activity in the range of 13-21 Hz was enhanced, while calcarine activity in the range of 5-6 Hz was reduced. Our results are consistent with the hypothesis that attentional modulation affects neural processing within the calcarine and parieto-occipital cortex by altering the amplitude of alpha-band activity and other natural brain rhythms.
利用脑磁图技术研究了注意力调制对人类视觉皮层内活动的影响。使用彩色正弦刺激来诱发枕叶皮层的活动，通过一个条形方向判断任务将注意力指向或远离刺激。对于五名观察者，将全局磁场功率绘制为从刺激开始的时间的函数。每个函数的主要峰值出现在约120毫秒的潜伏期，并且由靠近距状沟的电流偶极子很好地模拟。对每个观察者的非平均数据进行独立成分分析（ICA）也揭示了一个距状起源的成分，其位置与从平均数据确定的偶极源的位置相匹配。对于两名观察者，ICA在顶枕沟附近揭示了第二个成分。尽管使用标准平均程序没有明显的注意力效应，但对单次试验的时变频谱分析表明，注意力的主要作用是改变振荡活动的水平。最值得注意的是，明显有来自距状和顶枕起源的α波段（7 - 12赫兹）活动持续增加。此外，13 - 21赫兹范围内的距状活动增强，而5 - 6赫兹范围内的距状活动减少。我们的结果与以下假设一致，即注意力调制通过改变α波段活动和其他自然脑节律的幅度来影响距状和顶枕皮层内的神经处理。
