Mapping cortical pain circuits using very high field magnetic resonance imaging

点击翻译按钮获取中文摘要

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.