24 July 2012
Scientists have had a pretty comprehensive understanding of the human brain and its structures for quite some time now. What has always been missing is a clear understanding of the significance of the connections between these various areas of the brain.
“We were missing the wiring diagram, if you will,” says Arthur Toga, director of the Laboratory of Neuro Imaging (LONI) at the University of California, Los Angeles (UCLA) and one of the principals of the Human Connectome Project (HCP). The goal of the HCP is to create a comprehensive, 3-D map of the neural connections in the human brain that will do for our understanding of the brain what the Human Genome Project has done for DNA.
White matter architecture as shown by data collected from the Connectome Project scanner.
“It’s those connections that form the circuits that allow us to perform behaviors, so it’s a really a critical piece in the puzzle of trying to understand the human brain.” Toga says.
Using a form of MRI called diffusion imaging, researchers are able to create a map of a neural pathway by tracking water in the human body as it moves along the neurons in the brain. Because water naturally moves along the length of a fiber, rather than diffusing across it, tracing the path of the water enables the creation of a detailed map of the neural network. Patients are scanned for one-hour sessions in a resting state (i.e., lying still and doing nothing). Following this methodology, the HCP will eventually collect enough data to form a full map of the brain’s neural pathways.
The HCP is an offshoot of a program called the Human Brain Project, which was started by the NIH in 1993 to create 3-D maps of the human brain’s grey matter (the part of the brain containing neurons) using in vivo scanning techniques. The results of the project provided databases of the brain that are still used today for control studies, disease management, and other tasks. When the NIH decided the time had come to create an even more detailed map, the HCP was born through a research grant awarded to teams at UCLA and Harvard.
Once complete, the HCP promises scientists new insights into all manner of neurological disorders, from schizophrenia and autism to multiple sclerosis and more. “Having a database that describes all these things in normal subjects is a prerequisite to understanding what you’re seeing in diseased [subjects],” Toga says.
It will also potentially give great insight into other areas of brain function. “The maturation of the brain during the development is incredibly interesting,” Toga says. “The wiring diagram is refined quite a bit from in utero all the way through and beyond your teen years, and it’s a very dynamic process that a lot of us are very interested in trying to map.”
While the HCP is moving along well, it is still in its infancy in terms of applications. Though as an openly shared project, meaning the databases it generates will be free and publicly available, it provides a lot of potential for scientists and engineers working on the next generation of medical devices, including brain and computer interfaces.
Imagine, for example, how the improved surgical robots, artificial limbs, or similar devices that could be created with a better understanding of human neurological connections. “You can use these databases to study all manner of things. By giving this away, it is our hope to encourage people to ask all sorts of innovative questions that we didn’t think about.” Toga says. “I’m very encouraged by these things because it allows people of different disciplines to have access to something they might not have access to. And hopefully something previously unthought of will emerge.”