ELECTROPHYSIOLOGICAL STUDIES OF HUMAN ATTENTION

描述(由申请人提供)：神经成像研究提供了大量关于认知任务期间活跃的人脑皮质和皮质下区域的信息。最近的研究表明，在任务期间被共同激活的区域，即使在休息时，也保持着高水平的区域间关联，或“功能连接”。然而，这些区域间的相关性是在很长的时间尺度(例如分钟)上衡量的。相比之下，人们对这些脑区在短时间内(如秒或毫秒)的时间动力学和相互作用知之甚少，这是大多数任务的典型特征。时间动力学和相互作用的分析受到神经成像方法(功能磁共振成像，fMRI；正电子发射断层扫描，PET)的低时间分辨率和记录颅外电磁活动的方法(脑电，脑电，脑磁图，脑磁图)的低空间分辨率的强烈限制。为了解决这些基本的局限性，我们将血氧水平依赖(BOLD)信号的fMRI测量与从侵入性监测的人类受试者记录的皮层脑电(ECoG)信号结合起来。我们已经开发了用fMRI定位的功能网络与记录表面皮质局部场电位(LFP)的颅内电极共同注册的方法。我们应用这些新的方法来研究涉及空间注意的大脑皮层网络的动力学和相互作用。我们的初步结果表明，在空间注意任务中，用fMRI观察到的大脑皮层网络显示了皮层脑电的多重相干调制。空间注意的维持与多个枕叶、顶叶和额叶任务相关区域的Delta频段(1-3赫兹)的持续相位同步有关，而空间注意力的转移与theta频段(3-7赫兹)的相位同步的瞬时增加有关。我们提出了一系列实验，在这些实验中，我们首先使用专门用于空间注意的fMRI皮层区域/网络进行定位，然后研究它们的动力学以及在具有良好特征的认知任务中与ECoG的相互作用。我们的第一个具体目标是确定在空间注意的自愿定向过程中，Delta/theta频段的相位同步在连接皮质区域中的作用。我们的第二个具体目标是研究任务的时间结构如何影响Delta/theta频段的相位同步。我们的第三个具体目标集中在刺激驱动的重新定向过程中两个不同的注意网络(背侧，Dan；腹侧，VAN)之间的相互作用。

DESCRIPTION (provided by applicant): Neuroimaging studies have provided a wealth of information on the cortical and subcortical regions of the human brain active during cognitive tasks. Recent studies have shown that regions that are co-activated during tasks maintain, even at rest, a high level of inter-regional correlation, or 'functional connectivity'. However, these interregional correlations are measured over long time scales (e.g. minutes). In contrast, little is known about the temporal dynamics and interactions of these brain regions over the short timescales (e.g. sec or ms) that are typical of most tasks. The analysis of temporal dynamics and interactions is strongly limited by the low temporal resolution of neuroimaging methods (functional magnetic resonance imaging, fMRI; Positron emission tomography, PET), and the low spatial resolution of methods for recording extracranial electro-magnetic activity (electroencephalography, EEG, magnetoencephalography, MEG). To solve these fundamental limitations, we have combined fMRI measures of blood-oxgyenation-level- dependent (BOLD) signals with electrocorticographic (ECoG) signals recorded from invasively monitored human subjects. We have developed methods to co-register functional networks localized with fMRI with intracranial electrodes that record surface cortical local field potentials (LFP). We have applied these novel methods to study the dynamics and interactions of cortical networks involved in spatial attention. Our preliminary results indicate that cortical networks observed with fMRI during a spatial attention task show multiple coherence modulations with ECoG. Maintenance of spatial attention correlates with sustained phase synchronization in the delta band (1-3 Hz) across multiple occipital, parietal, and frontal task-relevant regions, while shifts of spatial attention are associated with transient increases of phase synchronization in the theta band (3-7 Hz). We propose a series of experiments in which we first localize with fMRI cortical regions/networks specialized for spatial attention and then study their dynamics and interaction with ECoG on well- characterized cognitive tasks. Our first specific aim is to determine the role of delta/theta band phase synchronization in linking cortical regions during voluntary orienting of spatial attention. Our second specific aim studies how delta/theta band phase synchronization is affected by the temporal structure of a task. Our third specific aims focuses on the interaction between two different attention networks (dorsal, DAN; ventral, VAN) during stimulus-driven re-orienting.