The New York Times just ran a three-page spread* reporting on major brain research initiatives. The focus is on mapping the brain, much as the Human Genome Project successfully brought together scientists around the world to map the human genome. David Van Essen of Washington University (St. Louis, MO), is in charge of the “Human Connectome” project, a large collaborative effort to understand what happens in healthy brains when we do everything from curl our toes to remember our phone number. Van Essen was quoted in the article: “A century ago, brain maps were like 16th-century maps of the Earth’s surface…Now our characterizations are more like an 18th-century map.”
Much as literal mapping has leapt in sophistication from compasses to Google Earth, brain mapping is benefiting from dramatic technological advances. One new tool is “optogenetics“. It uses light to turn on different parts of the brain in laboratory animals to open and shut modified genes. Coupled with technological advances in microscopy, researchers can monitor what happens to individual neurons as the light is switched on and the mouse finds the proverbial cheese. Being able to view how individual neurons behave is essential to mapping the neuronal connections that make the brain work.
An earlier post reported about using worms for Parkinson’s research. Optogenetics was an essential tool to support the hypothesis that the unlikely (but fast breeding!) lab animals displayed Parkinsonian symptoms. Scientists at the University of Texas took light-sensitive “switches” from algae and jacked them into the worm’s dopamine neurons. Because the worm’s body is transparent, the scientists were able to shine a light directly through the worm to the modified neurons. “These molecular switches allow us to turn neurons on with a flash of light,” said lead researcher Jon Pierce-Shimomura. “We did that when the animal was in water, and it would immediately switch from swimming to crawling. If you kept the light on for 10 minutes, it would crawl for 10 minutes, and if you switched off the light, it would go back to swimming.” Researchers observed that worms with low dopamine had an extraordinarily difficult time switching from swimming to crawling, just as human Parkinson patients can have a very difficult time switching gaits. This finding provided support for using worms as an animal model of Parkinsonian symptoms.
To see some of the mapping results enabled by optogenetics and many other research tools, check out the Human Connectome Project gallery — who knew “the little gray cells” could look so colorful!