Advances in functional neuroimaging methodology for the study of brain systems underlying human neuropsychological function and dysfunction

Functional neuroimaging allows the non-invasive identification of distribut ed patterns of human brain activity associated with perceptual, congnitive, emotional and behavioral processes, in health and disease. Work in this fi eld is methodologically intensive, requiring an interdisciplinary team of s cientists to develop and apply rapidly advancing techniques. Here we focus upon the principles and methods of functional imaging, from hypothesis gene ration and study design, to subject recruitment and clinical characterizati on, neuropsychological paradigm development, image acquisition, image proce ssing and statistical analysis, and data interpretation. The strengths and limitations of the various techniques are discussed, with an emphasis on po sitron emission tomography (PET) and functional magnetic resonance imaging (fMRI), which have proven to be powerful tools for human brain mapping. The integration of these techniques with electroencephalography (EEC) and magn etoencephalography (MEG), which provide greater temporal information, is ou tlined. An understanding of such methodological issues is a necessary prere quisite to the development of new imaging methods with improved capabilitie s, to the careful application of existing methods to neuropsychological pro blems, and to the critical examination of planned or published studies.