In this Q&A, we talked to Elise Yoon, a first-year Osteopathic Medicine student at Michigan State, who works at the Neuroscience Program lab. She recently went to Make Central to create 3-D printed brains as part of the lab’s research and to display the results at the MSU Museum.


The hypothesis? It’s part of the “Social Brain Hypothesis.” The researchers used CT scans of skulls and 3-D images of brains of various carnivores to test if social challenges have driven the evolution of a larger frontal cortex. The frontal cortex is responsible for judgement, decision making, processing social information and changing behaviors. So, according to Yoon, the hypothesis essentially means, the more social your species, the larger your frontal cortex.

The hypothesis has been proven in primates, but the researchers wanted to expand beyond this group.

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Q: The researchers use skulls of specimen that are over 100-years-old. How do they make them digital?   

Elise: The Department of Radiology does the CT scan [of the skull]. The digital file from the skull scanner appears in slices, so it’s an X-Ray, but it comes in slices like a loaf of bread.

We go into the computer program medical imaging software, which is basically like fancy paint, and go slice by slice and fill in the brain cavity so we can recreate the brain from the skull (that is, creating the brain by mimicking the characteristics of the skull that it sits in). We do carnivores, and we have really good impressions of the brain on the skull -- all of the bumps and grooves. We get really good resolution from just the skull.

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Q: So how exactly do we turn this CT scan into a printed, 3-D object?

Elise: We export the brain endocast and convert it to an STF [text-only] file and send it to Erica at Make Central, and they print it right out. It’s really easy for us -- it’s like magic. I send them a file and I go pick up 3-D brains! And the skulls at the exhibit are real skulls of lions, cheetahs, wolverines, hyenas and more.

When we get the 3-D model we can turn it around and cut it, add landmarks to sections, get info about the volume and other measurements. Volume is important: Is it larger in the frontal cortex or in the back?

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Q: From a research perspective, what’s the value of having 3-D skulls?

Elise: For us, it’s important because feeling it and holding it is not the same as turning the brain around in a computer program. [The computer program] is still really valuable, because we can get the volume measurements of the brain. But from a research perspective, it’s really good to be able to look at different models and to have them lined up -- we can compare the shapes of these brains and the shapes of specific areas. It’s important to be able to compare them in 3-D software and look at them in our hands.

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Q: What is the importance of having this technology and these 3-D skulls available to the public?

Elise: For the exhibit, I was really excited about this because I know the general public, people are getting really excited about 3-D printing. And thinking of the different uses for 3-D printing is an important thing to get kids excited about, because they have a much better imagination. I’m excited to see kids growing up right now with this technology come up with ideas that we could never think of. It will be interesting to see 20 to 30 years from now.

And, from our research perspective, we’re funded by the National Science Foundation. An agreement to get our grant money is we need to help educate the public about science, and what we’re doing is a model for this cool technology.

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Q: As for the results, was your original hypothesis correct?

Elise: Some of our results were not what we expected, correlation does not equal causation. In science, we get some answers but always have more questions and so we keep asking more questions. Research is the only way we move forward. The brain is so fascinating because, compared to every other single organ, we know nothing about the brain -- it’s like the Wild West -- we don’t know much.

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So the results were not 100 percent of what the researchers expected. The social challenges are not the only explanation for the evolution of frontal cortex sizes. But, as Yoon said, the mystery of the brain is what makes it so fascinating to study. You accept science as a highly-researched guessing game that you have to play again and again and again until you win. It’s long and repetitive, but it’s necessary to keep moving forward and keep learning more.

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