The objective of this research is to use intrinsic ongoing fluctuations in human brain activity to delineate cortical functional areas in individuals. Defining functional areas in living humans is currently only possible for a small fraction of areas. As such, the generation of cortex-wide maps of functional areas for individuals would allow for more accurate and functionally meaningful distinctions to be utilized without relying on current stereotactic or functional localizer approaches. The current study will utilize spontaneous fluctuations in the resting state fMRI BOLD signal (rs-fcMRI). rs-fcMRI across expanses of cortex show strong localized differences in patterns of correlation strength. These localized differences will then be analyzed using a set of image analysis tools to explore the plausibility of using rs-fcMRI measures to aid in the definition of widespread functional area boundaries. In addition to providing better areal labeling within individuals, this method would allow us to directly examine the variability of area extent, location, and organization across subjects, which is currently extremely difficult, if not impossible, to do with functional imaging. If the full, or even a partial, collection of functional areas can be delineated and characterized across subjects, the study of anatomical and functional differences between groups, including developmental studies, studies of normal or abnormal aging, or clinical population studies will be greatly facilitated.