Mapping cortical pain circuits using very high field magnetic resonance imaging

我们目前对大脑如何将有害刺激转化为疼痛感受的理解是有限的。虽然大脑成像技术已经提高了我们对疼痛在大脑中处理的位置的理解，但我们对这些大脑区域共同交流以产生疼痛的方式的理解非常有限。因此，到目前为止，人类大脑中的疼痛回路从未被研究过。极高场磁共振成像（MRI; 7特斯拉及以上）的引入通过将空间渲染提高到亚毫米级分辨率而彻底改变了人脑映射。这使得层功能磁共振成像和层状静息状态功能连接的引入，可以提高我们对人类大脑区域之间的定向连接的理解。7特斯拉磁共振成像的优点是，来自表层的大脑活动可以与皮层的深层分离。这提供了一种工具来测量位于大脑区域深层的种子（传出连接）和位于另一个大脑区域浅层的目标（传入连接）之间的定向连接。这些进展有助于识别大脑中的功能回路。这项研究计划的总体目标是使用非常高的场层功能磁共振成像来绘制人类大脑中的疼痛通路。研究1-3：短期目标是实现分层fMRI方法。我们将选择中央后回来验证这些方法。具体目标是将浅层（感觉辨别）与深层（运动）分离，再现躯体组织（手臂Vs腿），并评估增加刺激温度后的单调脑反应。研究4：总体的长期目标是使用这种方法来映射表层和深层之间的传入和传出连接，以推断大脑区域之间的方向连接。重要性：这代表了一个独特的机会，增加我们对疼痛系统的理解，特别是在皮质水平，我们目前缺乏关于疼痛感知的理论。到目前为止，人类的疼痛通路及其与疼痛的多个组成部分的关联仍有待更好的研究。增加我们对层特异性激活及其定向连接的理解对于脑成像从“哪里”疼痛是过程走向“如何”疼痛是人脑过程是很重要的。

Our current understanding of how the brain translate a noxious stimulus into a pain percept is limited. Although the brain imaging technologies have improved our understanding of where pain is processed in the brain, we have a very limited understanding about the way these brain areas communicate together to give rise to pain. Thus, the pain circuits in the human brain have, so far, never been investigated. The introduction of very high field magnetic resonance imaging (MRI; 7-Tesla and above) revolutionized human brain mapping by increasing spatial rendering to submillimeter resolution. This allows the introduction of layer fMRI and laminar resting state functional connectivity that can improve our understanding about directional connectivity between areas of the human brain. The advantage of 7-Tesla MRI is that brain activity from the superficial layers can be dissociated from the deep layers of the cortex. This provides a tool to measure directional connectivity between a seed located in the deep layers of a brain area (efferent connections) and a target located in the superficial layers of another brain area (afferent connections). These advances can contribute to identify functional circuits in the brain. The overarching goal of this research program is to use very high field layer fMRI to map the pain pathways in the human brain. Study 1-3: The short-term goals are to implement the layers fMRI methodology. We will select the postcentral gyrus to validate the methods. The specific aims are to dissociate the superficial layers (sensory discriminative) from the deep layers (motor), reproduce the somatotopic organisation (arm Vs leg), and assess the monotonic brain response after increasing the temperature of the stimuli. Study 4: The overall long-term objective is to use this methodology to map afferent and efferent connections between the superficial and deep layers to infer directional connectivity between brain areas. Significance: This represents a unique opportunity increase our understanding about the pain system, especially at the cortical level, where we currently lack theories about pain perception. So far, the pain pathways in humans and their association with the multiple components of pain remains to be better examined. Increasing our understanding about the layer specific activations and their directional connections is important for brain imaging to move from `where' pain is process towards `how' pain is process in the human brain.