fMRI ABILITY TO MAP COLUMNAR STRUCTURES IN HUMANS

描述(由申请人提供)： 功能磁共振成像提供了无与伦比的空间和时间分辨率的组合，继续被推向新的水平。最近，大胆的功能磁共振成像的极限已经被挑战到亚毫米结构的水平。这些地图的可靠性和重复性，以及获取这些地图的功能磁共振方法的优化还没有确定，特别是在人类身上。使用梯度回波的微分映射已经在人类中使用，由于众所周知的大血管伪影(在低场下更明显)，这在一般情况下可能不可靠。我们最近在R21提案的资助下，以亚毫米的空间分辨率展示了高场哈恩自旋回波(HSE)粗体信号的优势。高场下GE和HSE BOLD信号对神经活动的特异性差异尚未得到解决。优化的粗体信号映射大脑功能可以允许映射功能结构，而不需要事先知道正交条件(即单一条件映射)。对于许多神经科学应用来说，这将是一个无价的工具，在这些应用中，通常不知道正交条件和柱状组织。这项工作将推进我们之前的R21方案的基础，该方案研究了高磁场下的T2加权功能磁共振成像。这项应用的中心假设是，与低场(4特斯拉)和/或具有梯度回声的情况相比，在清醒的人中，高场(7特斯拉)下基于HSE的BOLD fMRI信号可用于获得更高的空间特异性，从而获得更可靠的皮质柱图。最后，利用这项工作中开发的功能磁共振成像技术，可以解决人类中从未显示过的定向柱的存在。

DESCRIPTION (provided by applicant): Functional magnetic resonance imaging offers an unmatched combination of spatial and temporal resolution that continues to be pushed to new levels. Recently, the limits of BOLD fMRI have been challenged to the level of sub-millimeter structures. The reliability and reproducibility of these maps, as well as the optimization of the fMRI methods to acquire these maps has not yet been established, especially in humans. Differential mapping using gradient echoes, which may not be reliable in the general case because of the well known large vessel artifacts (more significantly at low fields), has been used in humans. We have recently demonstrated, made possible by funding from an R21 proposal, at sub-millimeter spatial resolutions, the advantages of high field Hahn spin echo (HSE) BOLD signals. Differences in specificity to neural activity between GE and HSE BOLD signals at high fields has not yet been addressed. Optimized BOLD signals to map brain function could allow for mapping of functional architecture without apriori knowledge of orthogonal conditions (i.e. single condition mapping). This would be an invaluable tool for many neuroscience applications where orthogonal conditions and columnar organizations in general are not known. This work will advance the foundation of our previous R21 proposal which investigated T2 weighted fMRI at high magnetic fields. The central hypothesis of this application is that HSE based BOLD fMRI signals at high fields (7 Tesla) can be used to attain a higher spatial specificity and therefore more reliable maps of cortical columns, in awake humans, than at lower fields (4 Tesla) and/or with gradient echoes. Finally, the existence of orientation columns in humans, which has never been shown, can be addressed using fMRI techniques developed in this work.