In this grant we propose the continued development and application of nuclear magnetic resonance (NMR) imaging (or MRI) based methods for studying brain function. These new techniques offer cognitive neuroscientists a unique opportunity to study both the functional and anatomical mechanisms underlying perception, memory, language and image generation. The brain possesses anatomically distinct processing regions. A complete understanding of brain function requires determination of where these sites are located, what operations are performed, and how distributed processing is organized. Changes in neuronal activity are accompanied by focal changes in cerebral blood flow, blood volume , oxygenation and metabolism. These physiological changes can be used to produce functional maps of component mental operations. Recent advances in our laboratory have yielded high speed MRI techniques that are sensitive to changes in cerebral blood flow, blood volume, and blood oxygenation. These have been used to generate the first functional MRI maps of human task activation using a visual stimulus paradigm. New preliminary data presents completely non-invasive, real-time (at a frame resolution of seconds) tomographic movies of dynamic human brain activity. The spatial and temporal resolution of these tomographic maps are the highest reported to date. Our first research goal will be to optimize MRI techniques for real-time mapping of the human visual system. The visual system will be explored first because of its robust activation and our prior knowledge of its functional organization derived from PET and non-human primate studies. Second, optimized techniques will be applied to study the functional architecture of primary and secondary visual cortex (V1 and V2), and two areas to which they project, V4 and MT (V5). Finally, higher order areas involved in visual object recognition, visual word recognition, visual memory, and visual imagery will be mapped. The latter can only be studied in humans.
