Collaborative Research: Fast Functional MRI

该提案所解决的问题是，对于给定的更高认知任务，找到大脑中在执行任务时消耗氧气的一个或多个区域。研究人员的方法是使用所谓的初始负下降，这是由活跃大脑区域血液储备池中的氧气初始消耗引起的，以便在真实的时间内观察人类执行高级认知任务时大脑激活的位置和时序。标准方法依赖于更强但更慢的正向上升，这是由于激活后几秒钟血液重新供应到这些区域，不足以确定不同区域大脑活动的时间顺序。研究人员开发了一种优雅而高效的回波容积成像（EVI）采样方案，用于执行快速功能磁共振成像（fMRI），沿着图像重建和所得数据集的统计分析所需的必要工具。他们利用自己的技术，使用各种范式进行更高层次的认知实验，并始终能够检测到负向下降，并表现出其统计学意义。此外，他们还证明，根据实验范例，负向下降出现在不同的大脑区域，其时间顺序与相应的大脑激活相同，并且正向上升的时间有时会混淆。拟议的研究将进一步发展研究人员的方法，包括为最新和最强大的7特斯拉扫描仪和更复杂的多线圈系统设计EVI轨迹，以提高其方法的空间和时间分辨率。新的图像重建方法也将被开发用于多线圈数据，研究者的统计分析工具将被验证和仔细改进。拟议的研究将进一步推进和使用由主要研究者及其合作者开发的方法，以大幅提高功能磁共振成像的血氧水平依赖性技术的时间分辨率。在目前的实施中，研究人员的方法能够每100毫秒测量一次脑体积，而标准fMRI的测量时间为2000毫秒，从而使fMRI研究能够以前所未有的时间分辨率进行。快速功能性磁共振成像有望在理解大脑功能方面产生深刻而深远的影响，这是目前科学界感兴趣的核心问题。

The problem addressed by the proposal is to find, for a given higher cognition task, one or more regions of the brain where oxygen is consumed in performing the task. The investigators approach is to use the so-called initial negative dip, which is caused by the initial consumption of oxygen in the blood reserve pool in an active brain region, in order to observe, in real time the location and timing order of brain activation when a human performs the higher cognition task. The standard approach, which relies on the stronger but much slower positive rise, due to the resupply of blood to the regions several seconds after activation, is inadequate for determining the temporal ordering of brain activity in different regions. The investigators have developed an elegant and highly efficient echo-volumar imaging (EVI) sampling scheme for performing fast functional Magnetic Resonance Imaging (fMRI), along with the necessary tools needed for image reconstruction and statistical analysis of the resulting data sets. They have used their techniques to conduct higher cognition experiments using a variety of paradigms, and were consistently able to detect the negative dip and exhibit its statistical significance. In addition, they demonstrated that the negative dip appears in different brain regions in the same temporal sequence as the corresponding brain activation according to the experimental paradigms, and that the timing of the positive rise is at times confounded. The proposed research, which will further develop the investigators methods, includes the design of EVI trajectories for the newest and most powerful 7 Tesla scanners and more complicated multiple coil systems, in order to improve the spatial and time resolutions of their approach. New image reconstruction methods will also be developed for the multi-coil data and the investigators statistical analysis tools will be validated and carefully improved.This proposal focuses on developing statistical methods and related theory for performing fast fMRI. The proposed research will further advance and use the methods developed by the principle investigators and their collaborators to sharply improve the time-resolution for the blood oxygen level dependence technique of functional magnetic resonance imaging. In its current implementation the investigators method is able to measure brain volumes every 100ms compared to 2000ms for standard fMRI, thereby allowing fMRI studies to be performed at an unprecedented temporal resolution. Fast fMRI is expected to have profound and far-reaching consequences in the understanding of brain function, a problem of central scientific interest at the present time.