Task-related coupling from high- to low-frequency signals among visual cortical areas in human subdural recordings
Task-related coupling from high- to low-frequency signals among visual cortical areas in human subdural recordings
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DOI：
10.1016/j.ijpsycho.2003.07.001
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发表时间：
2004-01-01
影响因子：
3
通讯作者：
Eckhorn, R
中科院分区：
文献类型：
--
作者：
Bruns, A;Eckhorn, R
认知需求期间的皮层协同性包括高频和低频活动，这就提出了一个问题，即快速和慢速过程之间是否存在相互依赖关系，以及它们如何反映在脑电信号中。我们有机会记录信号颅内从枕叶视觉区的癫痫患者和量化区域间的信号耦合，而病人进行视觉延迟匹配到样本的任务。我们计算了相干性，相位一致性和幅度包络相关性，我们还通过低频信号分量和高频分量的幅度包络之间的相关性来确定频率间耦合。在来自上级（枕叶）的γ波段（28-70 Hz）信号包络和来自下级（枕叶）视觉区的低频（0-3.5 Hz）信号之间存在明显的任务相关性增加，持续约1 s，可能反映了短期记忆编码过程。包络和低频成分之间的相关延迟为40 ms。相比之下，连贯性，相位一致性和包络相关性显示事件，但没有任务相关的区域内的变化和区域间的耦合没有变化。我们的数据表明，在上级的γ-活动对低频活动在下级地区的具体影响。我们认为，传导延迟的时间分散可能会阻止高频信号的相干传输，从而解释伽马相干性的缺乏。由于这种分散是长程投射的一般性质，因此信号与信号的相关性可能反映了一般的神经元机制。因此，我们的方法提供了一个强大的工具，用于检测这种区域间的相互作用不可见的与传统的线性耦合措施。(C)2003 Elsevier B. V.保留所有权利。
Cortical cooperativity during cognitive demands includes high- and low-frequency activities, which raises the question whether there are interdependencies between fast and slow processes and how they are reflected in electrical brain signals. We had the opportunity to record signals intracranially from occipital visual areas in an epileptic patient and quantified inter-areal signal coupling while the patient performed a visual delayed-match-to-sample task. We computed coherence, phase consistency and amplitude envelope correlation and we also determined inter-frequency coupling through correlation between low-frequency signal components and amplitude envelopes of high-frequency components. There was a pronounced task-related increase of correlation between gamma-band (28-70 Hz) signal envelopes from a superior (occipital) and low-frequency (0-3.5 Hz) signals from an inferior (occipital) visual area, lasting for approximately 1 s and possibly reflecting a short-term memory encoding process. The correlational delay between envelopes and low-frequency components was 40 ms. In contrast, coherence, phase consistency and envelope correlation showed event-, but no task-related changes of intra-areal and no changes of inter-areal coupling. Our data suggest a specific effect of gammsa-activity in the superior onto low-frequency activity in the inferior area. We argue that temporal dispersion of conduction delays might prevent coherent transmission of high-frequency signals and thus account for the absence of gamma-coherence. As such dispersion is a general property of long-range projections, envelope-to-signal correlation possibly reflects a general neuronal mechanism. Hence, our method provides a powerful tool for detecting such inter-areal interactions not visible with conventional linear coupling measures. (C) 2003 Elsevier B.V. All rights reserved.