Mapping the Brain on a Massive Scale

Graphic: Christine Daniloff, MIT

A massive new project to scan the brains of 1,200 volunteers could finally give scientists a picture of the neural architecture of the human brain and help them understand the causes of certain neurological and psychological 1) ___. The National Institutes of Health announced $40 million in funding this month for the five-year effort, dubbed the Human Connectome Project, which will use new imaging technologies, some still under development, to create both structural and functional maps of the 2) ___ brain.

The project is novel in its size as most brain-imaging studies have looked at tens to hundreds of 3) ___. Scanning so many people will shed light on the normal variability within the brain structure of healthy adults, which will in turn provide a basis for examining how neural “wiring“ differs in such disorders as autism and schizophrenia. The project also plans to collect genetic and behavioral data, testing participants’ sensory and motor skills, memory, and other cognitive functions, and deposit this information along with brain scans in a public database without any of the patients’ personal information. Scientists around the world can then use the 4) ___ to search for the genetic and environmental factors that influence the structure of the brain.

“We want to learn as much as we can, not only about the typical patterns of brain connectivity, but also about the differences in 5) ___ that make each of us a unique individual,“ says David Van Essen, a neuroscientist at Washington University in St. Louis, who is one of the project leaders. “If you’re good at math, and I’m better at certain types of memory, can we identify some of the wiring characteristics that account for those differences?“

The most detailed studies to date of the neural 6) ___ that connect one brain cell to another have focused on animal brains, because scientists can examine the animals’ living tissue cells and their networks under a microscope. Because researchers will be scanning only identical and 7) ___ twins and their siblings, the scientists can get a sense of the role that genetics and environment play in shaping brain structure. Structures of the brain that are highly dictated by genes will be more similar in identical twins than in fraternal twins, for example.

Most human brain imaging studies have employed magnetic 8) ___ imaging (MRI) to examine the gross anatomy of the brain or functional MRI to detect which regions are active during specific tasks. But advances in brain imaging technologies in recent years, as well as growing computing power, have made it possible to look at the fine wiring connecting brain regions. “If we want to understand the brain, we need to know what individual areas are doing and how they talk to each other,“ says Russell Poldrack, director of the Imaging Research Center at the University of Texas at Austin.

Van Essen and his collaborators plan to scan participants using two relatively recent variations on MRI. Diffusion imaging, which detects the flow of water molecules down insulated neural wires, indirectly measures the location and direction of the fibers that connect one part of the brain to another. Functional connectivity, in contrast, examines whether activity in different parts of the brain fluctuates in synchrony. The regions that are highly correlated are most likely to be 9) ___, either directly or indirectly. Combining both approaches will give scientists a clearer picture. Collaborators at the University of Minnesota and Massachusetts General Hospital are optimizing existing scanners with new magnets and custom analysis programs so that they are better suited to detecting these circuits. This will be a landmark study, and may have the same kind of impact on neuroscience that the Human Genome Project had on human 10) ___.

ANSWERS: 1) diseases; 2) human; 3) brains; 4) database; 5) wiring; 6) circuits; 7) fraternal; 8) resonance; 9) connected; 10) genetics

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