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 distributed patterns of human brain activity associated with perceptual, congnitive, emotional and behavioral processes, in health and disease. Work in this field is methodologically intensive, requiring an interdisciplinary team of scientists to develop and apply rapidly advancing techniques. Here we focus upon the principles and methods of functional imaging, from hypothesis generation and study design, to subject recruitment and clinical characterization, neuropsychological paradigm development, image acquisition, image processing and statistical analysis, and data interpretation. The strengths and limitations of the various techniques are discussed, with an emphasis on positron 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 (EEG) and magnetoencephalography (MEG), which provide greater temporal information, is outlined. An understanding of such methodological issues is a necessary prerequisite to the development of new imaging methods with improved capabilities, to the careful application of existing methods to neuropsychological problems, and to the critical examination of planned or published studies.