Inferring Cortical Feed-Forward and Feedback Processes with Human Neuroimaging

描述（由申请人提供）：与人脑信息流相关的一个核心问题是：自下而上和自上而下的影响如何在大脑皮层中相互作用？提出了一个假设，可以形成一种使用非侵入性神经成像来解决这个问题的新方法的基础。具体来说，磁图和脑电图（MEG， EEG）检测到的电流偶极子的方向预计是一个函数，即被测量的激活是自上而下（反馈）还是自下而上（前馈）在皮层流动的结果。这一假设是建立在前馈和反馈连接到皮层区域具有突触输入特征的层流模式的原则之上的。因此，了解哪一层皮层接收了特定的输入，可以对该输入的来源提供大量信息，并更广泛地了解皮层间的交流。这种关于层状结构的见解超出了人类神经成像的分辨率。然而，不同类型的层流输入可能导致具有不同极性的宏观偶极子的提议有可能提供一个强大的非侵入性解决方案。研究人员使用三种不同的方法来评估整个假设：生物物理现实计算模型（Aim 1），体感脑磁图/脑电图反应与颅内灵长类动物记录的比较（Aim 2），以及基于视觉物体感知的认知神经科学理论对脑磁图/脑电图源极性的实验预测（Aim 3）。该研究有望实现对皮层区域网络信息流的非侵入性推断。这将为将脑磁图/脑电图记录应用于认知加工研究和在大尺度脑整合理论背景下解释脑磁图/脑电图提供一种新的途径。它可以更好地理解认知功能背后的神经机制，以及揭示神经障碍机制的潜在应用。

DESCRIPTION (provided by applicant): A central question related to information flow in the human brain is: how do bottom-up and top-down influences interact in the cerebral cortex? A hypothesis is proposed that could form the basis for a novel way to use non-invasive neuroimaging to address this question. Specifically, the direction of the current dipoles detected by magneto- and electroencephalography (MEG, EEG) is expected to be a function of whether the measured activation is a result of top-down (feedback) or bottom-up (feed-forward) flow in the cortex. This hypothesis is founded on the principle that feed-forward and feedback connections into a cortical area have characteristic laminar pattern of synaptic inputs. Consequently, knowing which of the cortical layers received a certain input could be highly informative about the source of this input, and more generally about inter- cortical communication. Such insights about the laminar structure are beyond the resolution of human neuroimaging. However, the proposal that the different types of laminar inputs might result in macroscopic dipoles with different polarities has the potential to provide a powerful non-invasive solution. The overall hypothesis is evaluated using three different approaches: biophysically realistic computational modeling (Aim 1), comparison of somatosensory MEG/EEG responses with intracranial primate recordings (Aim 2), and evaluation of experimental predictions about the polarity of MEG/EEG sources derived from a cognitive neuroscience theory of visual object perception (Aim 3). This research is anticipated to enable non-invasive inference of information flow in networks of cortical areas. It will provide a novel way to apply MEG/EEG recordings to studies of cognitive processing and interpret MEG/EEG in the context of large-scale integrative theories of the brain. It could lead to a better understanding of the neural mechanisms underlying cognitive functions, as well as to potential applications for revealing mechanisms of neural disorders.