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Advances reveal mysteries of brain

Lasers, magnetism allow glimpses of the organ at work

NEW HAVEN, Connecticut – To the untrained eye, it looked like a seismograph recording of a violent earthquake or the gyrations of a very volatile day on Wall Street – jagged peaks and valleys in red, blue and green, displayed on a wall. But the story it told was not about geology or economics.

It was a glimpse into the brains of Shaul Yahil and Shaw Bronner, two researchers at a Yale lab, as they had a little chat.

“This is a fork,” Yahil observed, describing the image on his computer. “A fork is something you use to stab food while you’re eating it. Common piece of cutlery in the West.”

“It doesn’t look like a real fancy sterling silver fork, but very useful,” Bronner responded. And then she described her own screen: “This looks like a baby chimpanzee ...”

The jagged, multicolored images depicted what was going on in the two researchers’ heads – two brains in conversation, carrying out an intricate dance of internal activity. This is no parlor trick. The brain-tracking technology at work is just a small part of the quest to answer abiding questions about the workings of a 3-pound chunk of fatty tissue with the consistency of cold porridge.

How does this collection of nearly 100 billion densely packed nerve cells, acting through circuits with maybe 100 trillion connections, let us think, feel, act and perceive our world? How does this complex machine go wrong and make people depressed, or delusional, or demented? What can be done about that?

These are the kinds of questions that spurred President Barack Obama to launch the BRAIN initiative in 2013. Its aim: to spur development of new tools to investigate the brain. Europe and Japan are also pursuing major efforts in brain research.

The mysteries of this organ, which sucks up about 20 percent of the body’s energy, are many and profound. But with a collection of sophisticated devices, scientists are peering inside the working brains of people for clues to what makes us tick.

After all, while a lot can be learned from dissecting brains after autopsy or studying animal brains, there’s nothing quite like watching a human one work. A brain is like a car motor, says researcher Joy Hirsch. You can study it at rest, but “until you start that car up and run it, you don’t really see how all the working parts work together and what the dynamics are.”

The Yale Brain Function Lab, which she directs, is investigating how our brains let us engage with other people. That’s one of the most basic questions in neuroscience, as well as an ability impaired in autism and schizophrenia, she said: “It’s probably one of the most fundamental functions of the human species, and yet we know very little about it.”

Hirsch turned to a decades-old brain-mapping technique that only recently has developed far enough for her task.

As Yahil and Bronner chatted to demonstrate the technology, each wore a black-and-white skullcap from which 64 slender black cables trailed away like dreadlocks. At the tip of half of those fiber-optic cables, weak laser beams slipped through their skulls and penetrated about an inch into their brains. There, the beams bounced off blood and reflected back to be picked up by the other half of the cables.

Those reflections revealed how much oxygen that blood was carrying. And since brain circuits use more oxygen when they’re busier, the measurements provided an indirect index to patterns of brain activity as Bronner listened to Yahil and replied, and vice versa.

The technique monitors only areas close to the brain’s surface, and so misses signals from its emotional centers, for example. But it does show, for example, that watching a conversational partner’s face makes a difference in what brain circuits turn on during a chat.

Using a similar setup, researchers in China recently created groups of three college students who were given a topic and told to discuss it. Results showed that students who emerged as leaders showed greater synchronization of brain patterns with their followers than pairs of followers did. The better the leader’s communication skills, the more profound this link was.

Such studies are unusual in that they monitor multiple brains simultaneously. Usually, experiments examine just one at a time.

Researchers have caught glimpses of human brain activity since the 1920s, when scalp electrodes first eavesdropped on the electrical chatter of brain cells to produce the zig-zag lines of EEG. Early images appeared in the late 1970s and 1980s through other techniques, like PET scans.

But the coming-out party for the brain-mapping technique most widely used today came at a 1991 meeting in San Francisco. Scientists watched what one observer called a “jaw dropping” movie that showed activation of a part of the brain that handles visual information. That movie was created through functional magnetic resonance imaging, or fMRI.

Basically, fMRI does what Hirsch’s laser system does: It uses oxygen levels in blood as tracers of brain-cell activity. But it penetrates much deeper into the brain, using powerful magnetic fields. That lets it seek subtle magnetic signals to track blood oxygen levels on a tiny scale; a bump in oxygen levels indicates active brain cells nearby.

The result is visually striking: detailed brain images with bright blotches of color that indicate where the action is. That’s not a direct picture, like an X-ray showing a broken bone, but rather a reconstruction that involves some key assumptions and a lot of sophisticated number-crunching.

On the net

BRAIN initiative: https://www.whitehouse.gov/brain

European brain project: https://www.humanbrainproject.eu

Japanese brain project: http://brainminds.jp/en



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