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Finding a cure for diseases like Alzheimer's will require a much better map of the brain. So a coalition involving hundreds of scientists has been working on one. NPR's Jon Hamilton reports on what this international community of brain cartographers has found so far.
JON HAMILTON, BYLINE: Their research appears in the form of 17 studies, all published today in the journal Nature. Together, these studies chart the location, function and appearance of brain cells in the motor cortex, which controls movement. Researchers created three separate maps for mice, monkey and human brains. John Ngai directs the National Institutes of Health Brain Initiative, which played a key role in organizing and funding the massive project.
JOHN NGAI: Some problems are so large and complex that it really does require not just a village, but a city.
HAMILTON: The studies offer a highly detailed look at the organization of healthy brains in both people and animals. Ngai says that will make it easier to see how brains are altered by disorders ranging from Alzheimer's to schizophrenia.
NGAI: In order to understand how things go wrong, we need to understand what the basic principles are to begin with.
HAMILTON: The first step was to conduct an exhaustive inventory of cell types, says Hongkui Zeng, director of the Allen Institute for Brain Science in Seattle.
HONGKUI ZENG: To understand how the system works, you first need to obtain a parts list of that system, be it a car, a computer or a brain.
HAMILTON: So teams of scientists classified each cell by studying its genes, shape, electrical properties and connections. The result was a parts list that includes more than 100 types of cells. The next step was to create a map for each species showing where these parts are found in the motor cortex. Zeng says, ultimately, scientists will need to chart the entire brain, a task that is likely to take many years.
ZENG: Generating a map of what a motor cortex is really the first step towards that goal.
HAMILTON: Zeng says a complete map will help scientists understand how the brain works as a whole.
ZENG: How the cells and the other cells in other parts of brain work together to carry out a particular function or behavior - like, even as simple as moving your arm - how does that happen?
HAMILTON: The mapping project showcases some of the innovation scientists will need to answer that question. One involves finding a way to study human brain tissue while it is still alive. Ed Lein of the Allen Institute says several labs have teamed up with local hospitals to do this. The labs receive bits of healthy brain tissue that is removed by surgeons in order to reach a tumor or other diseased area.
ED LEIN: This turns out to be rather healthy tissue that can be used for live tissue experiments to understand the properties of cells.
HAMILTON: By quickly transporting brain tissue from the operating room to the lab, scientists have been able to compare living human brain cells with those found in monkeys and mice. Lein says, overall, the cells are remarkably similar.
LEIN: However, when you get down to the finer levels, the really fine-grained types of cells that we can see with these assays, you start to see some differences then.
HAMILTON: For example, Lein says mice have very few brain cells that are able to make long-distance connections.
LEIN: In humans, as the brain has gotten bigger, as the cortex has gotten bigger, you have more cells that connect across the cortex, and some of these seem to be selectively vulnerable in Alzheimer's disease.
HAMILTON: Lein says that sort of discovery could help explain why, for example, drugs that cure Alzheimer's in mice haven't worked in people. And he says the finding was a direct result of having so many scientists working together and sharing what they found.
LEIN: I hope that this is sort of a model for the future because this type of work really is much more open, and it accelerates science dramatically.
HAMILTON: Which could mean a shorter wait for new treatments.
Jon Hamilton, NPR News.
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