Inferring Cortical Feed-Forward and Feedback Processes with Human Neuroimaging

描述(申请人提供)：与人脑中的信息流有关的一个中心问题是：自下而上和自上而下的影响如何在大脑皮层中相互作用？提出了一种假说，可以形成一种新的方法来使用非侵入性神经成像来解决这个问题。具体地说，磁和脑电(MEG，EEG)检测到的电流偶极子的方向预计是测量到的激活是自上而下(反馈)还是自下而上(前馈)大脑皮质流动的结果的函数。这一假说建立在这样的原理之上，即进入大脑皮层的前馈和反馈连接具有突触输入的特征层状模式。因此，知道哪些大脑皮层接受了特定的输入，可能会对这种输入的来源，更广泛地说，关于大脑皮层间的交流有很高的信息量。这种对层状结构的洞察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种强大的非侵入性解决方案。整个假设使用三种不同的方法进行评估：生物物理上真实的计算模型(目标1)，体感MEG/EEG反应与脑内灵长类动物记录的比较(目标2)，以及从视觉对象感知的认知神经科学理论得出的关于MEG/EEG来源的极性的实验预测的评估(目标3)。这项研究有望对大脑皮层区域网络中的信息流进行非侵入性推断。这将为将脑磁图/脑电记录应用于认知加工的研究和在大规模脑整合理论的背景下解释脑磁图/脑电提供一种新的途径。这可能会导致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.