MEG Scanners Are Mega Powerful

Researchers at the University of Alabama at Birmingham's Magnetic Source Imaging Laboratory are studying the magnetic fields of neurons , using MEG (magneto-encephalography) scanners to learn more about the intricacies of brain pathology.

While other types of brain scans detail the geography of the brain or detect blood flow, the MEG scanners track the magnetic signals that neurons throw off as they communicate. "You can look at how the networks of the brain are talking to each other in real time," said Greg Simpson, director of the Dynamic Neuroimaging Laboratory at the University of California at San Francisco. The machines are designed to "measure the magnetic field pattern around the entire head and deduce from those patterns where the current flows are occurring within the brain," said Eugene Hirschkoff, vice president of engineering at 4-D Neuroimaging, a MEG scanner manufacturer.

This allows scientists to study magnetic changes in the brain and figure out which areas are busy doing things each millisecond. By contrast, functional magnetic resonance imaging, or fMRI, technology measures the movement of blood within the brain. The scans reveal which brain areas are active and need oxygen from the blood, Simpson said.

But it takes a while for oxygen-filled blood to move in the brain. "If a brain area was active for a 10th of a second, the blood-flow response to that area would take a second or two to start," said Simpson.

That may not sound like a long time, but this is the lickety-split world of the brain. "If I had you read a sentence during an fMRI scan, we'd see the visual cortex light up, the language cortex light up, and other things that would light up," Knowlton said. "But they'd all be lit up, and you wouldn't know which one was first (to become active), which one was most important."

"With the MEG, the sequence becomes more clear," Knowlton said.

One thing they can't do is analyze the physical parts of the brain, so MEGs become even more powerful when combined with other technologies.

When combined with fMRI scans, in particular, "you get the best of everything," Knowlton said.

In a recent experiment, scientists tried to figure out what you might call the Grey's Anatomy effect. When characters on the show get lonely, they act out -- drinking too much at the local bar, baking up a storm in the kitchen, having sex with a guy who ends up with a permanent erection.

Self-medication? Maybe. But a team of scientists prefers to describe the tendency toward bad behavior as cognitive disruption brought on by social exclusion -- a process they think they can see with the help of the MEG.

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