Overview of the Human Connectome Project

The HCP (a.k.a."original" or main HCP, HCP Young Adult, HCP-YA) is mapping the healthy human connectome by collecting and freely distributing neuroimaging and behavioral data on 1,200 normal young adults, aged 22-35.

The project was carried out in two phases by a consortium of over 100 investigators and staff at 10 institutions. In Phase I (years 1–2, Fall 2010–Spring 2012), data acquisition and analysis methods were optimized, including refinements to pulse sequences and key preprocessing steps.. In Phase II (years 3 – 5, Summer 2012–Fall 2015), neuroimaging and behavioral data were acquired from 1,200 healthy adults recruited from ~300 families of twins and their non twin siblings.

To obtain brain connectivity maps of the highest quality, HCP employed cutting-edge MR hardware, including 3T and 7T MR scanners and customized head coils. 3T MR was completed on a single Siemens Skyra Connectom scanner for 1113 subjects at Washington University, 7T MR was collected on a subset of 184 subjects on a Siemens Magnetom scanner at UMinn, and MEG data was collected on 95 subjects at St. Louis University (see Phase II: Logistics of Data Acquisition). Datasets have been released publicly at regular intervals, thereby enabling many explorations and analyses of brain circuitry even as data was collected.

Brain connectivity is explored using two powerful and complementary MR imaging modalities: diffusion imaging and resting-state fMRI.

Diffusion imaging is used to chart the trajectories of fiber bundles coursing throughout the brain’s white matter. This is being done using HARDI (High Angular Resolution Diffusion Imaging) to acquire the data and probabilistic tractography to estimate fiber trajectories and generate maps of structural connectivity between gray matter regions.
Resting-state fMRI (R-fMRI) is providing individual functional connectivity based on correlations in the fMRI BOLD signal among functionally interacting cortical and subcortical gray matter brain regions.

Additional information about brain structure and function was obtained using Task fMRI, in which subjects carry out a variety of behavioral tasks in the MR scanner. Behavioral testing using a large battery of tests to assess individual differences and sensory, motor, and cognitive function enables assessment of brain circuits associated with particular behavioral features or traits.

95 subjects (~50 twin pairs) were additionally studied using magnetoencephalography (MEG), yielding information about brain function on a millisecond time scale.

HCP subjects include twins and their non-twin siblings (see Recruitment), which enables exploration of the heritability of various brain circuits. Genotyping of all subjects will enable genome-wide association studies (GWAS) to evaluate genetic influences on brain circuitry.

The massive amounts of experimental data of many different types obtained by the HCP allow for integration (see: multi-modal integration) using a variety of analysis and visualization tools, including network modeling tools.

A robust, reliable, and user-friendly informatics platform facilitating data mining, analysis, and visualization has enabled investigators around the world to capitalize on these enormously rich datasets. Extensive outreach efforts continue to support and educate the scientific community about using these datasets and how to apply HCP methods in subsequent studies. We provide a variety of training opportunities including an annual HCP course to promote utilization of the data and the associated tools.

The Human Connectome Project is providing a treasure trove of neuroimaging and behavioral data at an unprecedented level of detail. This data continues to shed light on the profound anatomical and functional complexity of the healthy human brain (see A Neurobiologically Grounded Connectome).