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.
