06/30/98 This award supports the development of new methodology to enhance the NMR imaging and spectroscopy performance of the 7T horizontal bore spectrometer at Yale Magnetic Resonance Center for quantitative blood-oxygenation level dependent (BOLD) functional MRI (fMRI) image-contrast. The main significance of this project is that it will provide the fundamental basis for converting the BOLD images into neuronal activity maps. Autoradiography studies on animals and PET studies on humans have provided the standards for quantitative measurements of changes in cerebral activity by detecting alterations in cerebral perfusion and metabolism at high spatial resolution. However, the major disadvantages of these techniques are that both methodologies require radioactive tracers and temporal alterations in neuronal activity cannot be monitored. The BOLD fMRI method, in contrast, does not require exogenous tracers and provides a dynamic measure of brain activity. The proposed project will allow the BOLD signal to be quantitatively related to cerebral metabolism and perfusion, providing a quantitative MRI method of probing the physiological parameters that are coupled to cerebral activity. A non-invasive and non-radioactive method for quantitatively mapping alterations in neuronal activity in the mammalian brain would be a very important tool in neuroscience. Applications would include brain mapping of sensory and cognitive functions, assessment of altered cerebral activity in the diseased or injured brain, and long- term investigations of brain development and functional plasticity.
