Multimodal integration of functional neuroimaging data

越来越多的非侵入性神经成像技术现在可用于研究正常的大脑功能，但也脑疾病。然而，不存在任何能够精确测量大脑中活动发生的“时间”（以ms尺度）和“位置”（以mm尺度）的理想探索技术。每一种神经成像技术都通过不同的机制（神经元电、耗氧量）来测量大脑活动的一部分，有时更致力于解决“在哪里？（良好的空间分辨率）或问题“什么时候？”（时间分辨率高）。这些技术中的每一种都有其特定的优点和局限性，单独分析它们中的每一种只能提供有关潜在大脑活动的部分信息。我的研究项目的目标是开发适当的方法来联合收割机这些多模态数据，即，数据融合方法，以检测单独考虑每种模态可能遗漏的额外信息。一个典型的挑战是将以高时间分辨率直接测量神经元活动的联合收割机模态与以高空间分辨率间接测量相同功能的其他模态（例如通过血液动力学过程）相结合。 已经开发了大多数神经成像技术，以便对不同的脑信号敏感：（1）直接测量神经元生物电活动（来自头皮记录）和（2）通过血液动力学过程间接测量脑活动，测量向活动神经元提供氧气的血流。我的工作的目的是准确地描述这两种类型的测量之间的联系时，研究正常的大脑活动，但也异常癫痫放电。第一个目标将是在大脑内定位，使用放置在头皮上的光纤测量血流的波动。第二个目标将包括使用这些不同的方式来评估神经元生物电活动和血流动力学过程之间的这种联系的完整性。第三个目标包括使用这些多模态数据提取大脑活动的相关信息来表征静息状态波动。

More and more non-invasive neuroimaging techniques are now available to study normal brain functions but also brain disorders. However, it does not exist any ideal exploration technique able to measure precisely "when" (at a ms scale) and "where" (at a mm scale) an activity occurred in the brain. Each neuroimaging technique measures through different mechanisms (neuronal electricity, oxygen consumption) part of brain activity, being sometimes more dedicated to the question "where?" (good spatial resolution) or to the question "when?" (good temporal resolution). Each of these techniques having its specific advantages and limitations, analyzing each of them individually only provides partial information on underlying brain activity. The objective of my research project is to develop methods to appropriately combine these multimodal data, i.e., data fusion methods, in order to detect additional information that could be missed by considering each modality individually. A typical challenge is to combine modalities measuring directly neuronal activity with high temporal resolution with other modalities measuring indirectly the same function with high spatial resolution, through hemodynamic processes for instance. Most neuroimaging techniques have been developed in order to be sensitive to different brain signals: (1) direct measurements of neuronal bioelectric activity (from scalp recordings) and (2) indirect measurement of brain activity through hemodynamic processes measuring blood flow providing oxygen to the active neurons. The objective of my work is to accurately characterize the link between these two types of measurements when studying normal brain activity but also abnormal epileptic discharges. The first objective will be to localize, within the brain, fluctuations of blood flow measured using optic fibres placed on the scalp. The second objective will consist in using these different modalities to assess the integrity of this link between neuronal bioelectric activity and hemodynamic processes. The third objective will consist in extracting relevant information on brain activity using these multimodal data to characterize resting state fluctuations.