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In the beloved children’s book, Happy Birthday to You!, Dr. Seuss writes, “Today you are YOU, that is TRUER than true. There is NO ONE alive who is YOUER than YOU.” Those who study the brain understand that the complex interplay of genetics and environment give rise to that “you-ness” of which Dr. Seuss spoke. And, as it turns out, it also makes for unique changes to brain anatomy—so much so that one can be uniquely identified by the brain, much like with fingerprints or the eye’s iris pattern.
Lutz Jäncke, a neuropsychologist at Switzerland’s University of Zurich, has spent his career studying individual differences. His work looking at brain differences in musicians, dancers, and chess players demonstrated that the human brain is profoundly shaped by experience.
“Thirty years ago, we didn’t anticipate that the human brain is so plastic,” he explains. “In learning that training and experience can have such a profound influence on the human brain, even in terms of anatomical and morphological aspects, we wondered if it was possible to identify individuals on the basis of anatomical features in the brain.”
To test the idea, Jäncke and colleagues analyzed brain imaging data from 191 participants that were put into specialized data sets highlighting 148 anatomical features. Using statistical techniques, they then came up with a model that could identify individuals based on their specific brain anatomy. The results were published in the April 4, 2018 issue of Scientific Reports.
“I was a bit surprised that we could identify participants with almost 100 percent accuracy,” says Jäncke. “But, later, when we thought about the morphological characteristics of a human being—things like eyebrows, eye color, hair color, whether the hair has curls or not—you would expect to easily identify a single person with 10 to 15 of these features. Now we’ve just done the same in the human brain.”
While science fiction enthusiasts may want to focus on the potential to use brain scans to identify individuals in the future, this study raises a more pressing concern about the way the neuroscience community currently “normalizes” brains to compare and contrast activation patterns. Back when I was a research assistant, I remember using software to “normalize” individual brains before analysis—that is, using specific anatomical landmarks, we would instruct the software to massage each participant’s brain into a common brain-shaped space. While, most of the time, you could “normalize” each study participant with little difficulty, I do recall one participant’s brain being so uniquely shaped that we had to leave his data out of the study altogether. Given Jäncke’s findings, this raises a question: If human brains are this unique, do we need to rethink this process in future neuroimaging studies?
“Today, the neuroimaging community uses tools to lump together lots of brains by stereotactically normalizing the brain and doing this and that statistically to make the brains fit into a common template,” he says. “I would say, in strong terms, this is not correct. You have to anticipate that you are introducing errors if you are averaging in this way. We have such strong individual differences that we will not be able to get at them if we continue to lump all brains together. And this is something we should carefully consider.”
Jäncke plans to follow this study to see if this method can be made even more specific—and identify those with perfect pitch, or who dance, or who sing, or who play the piano versus a string instrument—just by looking at the brain’s anatomical features. He believes that we should be able to see hints of each person’s “you-ness” hidden somewhere among all those folds and grooves.
“Each experience, those specific levels of expertise or specific skill training, must have left some kind of history in the brain,” he says. “I think we can find it.”