Development Of New Techniques For Functional Magnetic Resonance Imaging Of The Brain

New techniques covering a wide range of clinical and scientific applications will be developed, tested and evaluated. These include 1. Investigation of sensory stimulus processing and cognitive processing, both in normal subjects and patients with psychiatric disorders, 2. Early detection of stroke and other ischemic injury, and 3. Characterization of tumor distribution and activity. The new techniques will routinely need to be tested with respect to the following: 1. Sensitivity to blood oxygenation versus blood flow versus blood volume contrast mechanisms, 2. Signal-to-noise and contrast-to-noise ratio, 3. Spatial and temporal resolution, 4. Distribution and severity of image artifacts, and 5. Duty cycle limitations. Most clinical applications will require coverage of the entire brain and consequently high duty cycle operation, which needs to be traded off with spatial and temporal resolution, as well as contrast mechanisms. The work will also involve the testing of different experimental paradigms (time sequence of stimuli or cognitive tasks) to identify that which provides the highest signal change associated with the specific brain activity of interest. Although 3T provides twice the signal of 1.5T systems, for some research applications this image quality advantage of 3T may be outweighed by other effects of higher field on the signal. Consequently, most new techniques will be evaluated on both the 1.5T and 3T systems, and a decision will be made based upon the overall image quality, regarding which system is to be used. The Protocol does not involve injection of any contrast agent or drug, or other minimally-invasive or invasive procedure. It is intended specifically for those studies in which the subject is required, in addition to trying to relax and lie still, only to experience and respond to various non-harmful sensory stimuli, or to perform common cognitive (e.g. math calculations) and or motor (e.g. finger tapping) tasks.