The Human Connectome Project aims to reveal and understand the complex neural pathways supporting brain function. Understanding the human brain remains one of the great-est scientific challenges of the 21 st century. The Washington University/University of Minnesota consortium leads the Human Connectome Project (HCP), a five-year initiative funded by the National Institutes of Health Blueprint for Neuro-science Research, and was awarded $30 million in September 2010 to comprehensively map brain circuitry, which will yield information about brain connectivity and its relationship to genetic, environmental factors and behavior. It will pave the way for future studies on changes during development and aging, or in the context of neurological and psychiatric dis-orders. Nine participating research centers will use powerful neuroimaging and electrophysical recording techniques, such as magnetic-resonance imaging (MRI), magneto-and electro-encephalography (MEG, EEG), computational analysis, infor-matics, and visualization to study 1200 healthy adults, aimed at better understanding the intricate workings of the human brain. To obtain high-quality maps of brain connectivity, the HCP will use cutting-edge MRI hardware and mathematical mod-els. During the first two years, we will focus on optimizing a Siemens Skyra 3 Tesla (3T) system at the University of Min-nesota's Center for Magnetic Resonance Research (CMRR), to achieve faster data acquisition and increased spatial resolution. The instrument will then be shipped to Washington University to scan the 1200 subjects (twin and nontwin siblings from 300 families). Additionally, CMRR scientists will use their ex-tensive experience with ultrahigh-field imaging to exploit the numerous advantages of the 7T scanner, including higher signal-to-noise ratio, improved spatial accuracy and functional resolution, greater anatomical detail, 1 and enhanced parallel-imaging capabilities. 2 To better understand the 3T data, 200 subjects will also be scanned at 7T. Figure 1. (left) Anatomical and (right) functional connectivity of the area identified by the blue dot. (Source: M. Glasser, T. Laumann, D. Van Essen, Washington University in St. Louis.) Two complementary imaging modalities will be used to resolve anatomical and functional connectivity. First, we will use diffusion imaging, 3 or—more precisely—high-angular-resolution diffusion imaging (HARDI), to chart the fiber bun-dles of white matter throughout the gray-matter regions of the brain. Combined with advanced computational techniques 4 and software (FSL: University of Oxford Centre for Functional MRI of the Brain Software Library, Caret), use of HARDI will allow reconstruction of fiber-bundle orientation at each volume element (voxel) with exquisite angular precision to generate probability maps of anatomical connectivity (see Figure 1, left). Second, resting-state functional MRI 5 (fMRI) will provide comprehensive descriptions of the functional connectivity be-tween different gray-matter regions, based on correlations in the fMRI blood-oxygen-level-dependent signal among functionally interacting brain regions. We will obtain additional information about brain function us-ing Task-fMRI, where subjects carry out behavioral tasks while in the scanner. MEG and EEG will provide this kind of informa-tion on millisecond timescales. Furthermore, extensive behav-ioral testing of each subject will enable comparisons between brain connectivity and behavioral phenotypes. Genome-wide association studies evaluating the influence of genetic factors on brain circuitry will be conducted through genotyping of all subjects.