Leopold David A, Murayama Yusuke, Logothetis Nikos K
Max Planck Institut für biologische Kybernetik, Spemannstrasse 38, 72076 Tübingen, Germany.
Cereb Cortex. 2003 Apr;13(4):422-33. doi: 10.1093/cercor/13.4.422.
We examined fluctuations in band-limited power (BLP) of local field potential (LFP) signals recorded from multiple electrodes in visual cortex of the monkey during different behavioral states. We asked whether such signals demonstrated coherent fluctuations over time-scales of seconds and minutes, and would thus serve as good candidates for direct comparison with data obtained from functional magnetic resonance imaging (fMRI). We obtained the following results. (i) The BLP of the local field displayed fluctuations at many time-scales, with particularly large amplitude at very low frequencies (<0.1 Hz). (ii) These fluctuations exhibited high coherence between electrode pairs, particularly for BLP signals derived from the gamma frequency range. (iii) Coherence in the BLP, unlike that in the raw LFP, did not fall off sharply as a function of cortical distance. (iv) The structure and coherence of BLP changes were highly similar under distinctly different behavioral states. These results demonstrate the existence of widespread coherent activity fluctuations in the brain of the awake monkey over very long time-scales. We propose that such signals may make a significant contribution to the high variability observed in the time course of physiological signals, including those measured with functional imaging techniques. The results are discussed in the context of combined fMRI/electrophysiological recordings.
我们研究了在不同行为状态下，从猴子视觉皮层的多个电极记录的局部场电位（LFP）信号的带限功率（BLP）波动情况。我们询问这些信号在秒和分钟的时间尺度上是否表现出连贯的波动，从而是否可作为与功能磁共振成像（fMRI）获得的数据进行直接比较的良好候选对象。我们得到了以下结果。（i）局部场的BLP在许多时间尺度上都有波动，在非常低的频率（<0.1Hz）下幅度特别大。（ii）这些波动在电极对之间表现出高度的连贯性，特别是对于源自伽马频率范围的BLP信号。（iii）与原始LFP不同，BLP中的连贯性不会随着皮层距离的增加而急剧下降。（iv）在明显不同的行为状态下，BLP变化的结构和连贯性非常相似。这些结果表明，在清醒猴子的大脑中，在很长的时间尺度上存在广泛的连贯活动波动。我们提出，这些信号可能对生理信号时间过程中观察到的高变异性有重大贡献，包括那些用功能成像技术测量的信号。在fMRI/电生理联合记录的背景下讨论了这些结果。
