McKelvey School of Engineering

Fast ‘yes’ better for brain than slow ‘no’

Ruth Okamoto uses a bowl of gelatin on a speaker as a model for the brain’s motion when the skull experiences vibrations. (Photo: Brook Haley/WashU)

Researchers are learning more about what leads to traumatic brain injury, though they have to be creative to work around limited access to the brain.

“You can’t study traumatic brain injury by running around hitting people on the head,” said Ruth Okamoto, DSc, teaching professor in mechanical engineering & materials science in the McKelvey School of Engineering at Washington University in St. Louis. Instead, Okamoto and her colleagues use magnetic resonance elastography (MRE), a non-invasive imaging technique that can map the elastic properties and stiffness of soft tissues, to illuminate key mechanical characteristics of the brain’s response to skull motion.

In new research published online July 11 in the ASME Journal of Biomechanical Engineering, Okamoto, Philip V. Bayly, PhD, the Lee Hunter Distinguished Professor and chair of the Department of Mechanical Engineering & Materials Science, and their collaborators present new data about what happens when the head is jiggled at various frequencies in two directions.

“In this experiment, we’re doing a safe test — gently vibrating your head back and forth like a bowl of gelatin — to gather information about how stiff the brain is and how it moves so we can make better computer models,” Okamoto said. “When we jiggle your head in the MRI machine, we can actually see motion of the brain, and it looks like waves, like when you throw a pebble in the water and the waves move outward. It’s the same kind of thing, except in our case the waves come inward from the skull.” 

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