Philip Bayly has spent years trying to figure out the best way to jiggle a brain.
The mechanical engineer is part of a team of researchers at Washington University studying how a jolt to the head can shake the brain — the kind of injury a football player suffers when crashing into an opponent. Using a specially-designed device that vibrates volunteers’ heads, they hope to better understand the effects of repeated brain injuries.
Many people think of the brain as a hard ball bouncing inside your head, Bayly said, but it’s more like soft pink Jello tethered to your skull.
“Your brain doesn’t just rattle around loosely,” he said. “It’s connected to the skull by a really intricate system of membranes. I liken it to a bungee jumper, where the cord protects you from a dramatic collision.”
The membranes offer some cushion to the brain, but even a seemingly minor bump on the head can twist and deform the delicate organ. Repeated head injuries can lead to serious neurodegenerative diseases, including chronic traumatic encephalopathy.
Researchers do not recreate brain injuries in the lab because that would be unethical and unsafe for patients. But they can collect data on how the brain moves in response to slight vibrations and use it build mathematical simulations of head trauma, which Bayly calls “virtual crash tests.”
“You can run a simulation on the computer and have someone in a car or playing football and see how that experience is causing their brain to respond,” Bayly said. “But first, we have to provide insight into how those computer models should be built based on rational scientific data, as opposed to just guesswork.”
Jostling brains for science
To understand how the live human brain moves, Bayly and his colleagues at the Washington University School of Medicine plan to shake dozens of them beginning this year.
They’ve designed a special device that cradles and vibrates the head while a volunteer is inside an MRI machine. A loudspeaker vibrates a pillow filled with air under the volunteer’s head, creating a buzzing sensation.
“If you were at a dance club, feeling the pounding base, it would be similar to this,” said Bayly, holding his hand over a vibrating model of a human head encased in an orange frame.
The plastic head is connected to a laptop with a bundle of wires — and with a few keystrokes, WashU graduate student Christie Crandall turns off the vibrations.
Although the setup looks simple, the design process has been challenging. For one thing, the team has had to be creative when it comes to which materials they can use.
“In an MRI, you can’t have anything magnetic, so you can’t use metal,” Crandall said. “There are not a lot of options that are not metal to do this kind of data acquisition.”
'It's a tangled web'
The research team will enroll about 100 local men and women ranging from teenagers to people over 50 for one-hour MRI sessions. While the device vibrates their heads for 10 to 15 minutes, the MRI machine will take multiple high-resolution images of their brains.
Previous research has often focused on young, healthy adult males, Bayly said.
By examining the brains of men and women of various ages, the team hopes future researchers will be able to use the data to understand chronic brain injuries across a broader range of people, including military service members and domestic abuse victims.
Bayly has spent more than a decade figuring out how to measure the movement of a live human brain, but he said there are still many questions left to answer.
“It’s a tangled web that we’re trying to uncover,” he said. “And we’re trying to uncover it beginning with the mechanics.”
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