The blood oxygen level-dependent (BOLD) fMRI signal exhibits spontaneous fluctuations in a variety of conditions, even in the absence of task. Remarkably, these fluctuations are correlated in regions of the brain that are functionally and anatomically related, suggesting an intrinsic organization is present that supports ongoing brain activity. Neurologic disorders and psychiatric diseases have been shown to disrupt these fluctuations in characteristic ways which may one day have diagnostic and prognostic value. The objective of this research is to understand the organization of these spontaneous fluctuations. Not only will this further our understanding of how the brain functions in health, but also how to interpret disturbances in these signals in disease. Using spontaneous BOLD fluctuation data that will be collected in this fMRI study, novel methods will be applied to determine preferential connectivity among member regions in intrinsic networks (Aim 1) and the directionality of influences in these regions (Aim 2). These two pieces of information are key components to how any network functions, from brain architecture to social interactions to economics. The objective of this study is to understand the intrinsic functioning of the human brain. Alterations in intrinsic brain activity are associated with a variety of neurologic and psychiatric diseases. This research will provide information relevant for brain function both in health and disease.