DESCRIPTION (provided by applicant): The instrument requested is a whole-cortex high-density magnetoencephalography (MEG) system. The system also will record up to 128 channels of EEG simultaneously. It will be located within a high-performance magnetically shielded room, and will have additional software and hardware features to permit recordings of cortical activity with excellent signal to noise. The system will include behavioral stimulation equipment and computers to control perceptual, cognitive and motor experiments as well as clinical studies. The proposed instrument will be located at UCSD's Center for Functional Magnetic Resonance Imaging (CFMRI), and will be operated and administered through the existing infrastructure of the CFMRI. The CFMRI already is the hub of a broad research effort in functional MRI (fMRI) that serves many NIH-funded research programs. Major Users of the proposed MEG instrument come from the Radiology, Psychiatry, Neuroscience, and Cognitive Science Departments at UCSD, as well as from UCIrvine. MEG directly and instantaneously reflects synaptic current flows. It thus has excellent temporal resolution to complement the excellent spatial resolution provided by fMRI. The faculty and staff of the CFMRI provide a wide range of relevant expertise, including advanced techniques for localizing distributed cortical sources by integrating MEG and EEG with structural and functional MRI. The featured NIH-supported projects that will immediately benefit from the MEG system include studies of selective attention and language in normal subjects, as well as the changes in cognitive function that occur in autism, normal aging, Alzheimer's disease and early focal brain damage. Other studies explore novel methods for analyzing MEG signals, their underlying physiological bases, and their relation to the BOLD effect.