Ever since his death in 1955, scientists have asked what featurs of Albert Einstein's brain contributed to his extraordinary insights into physical laws. Research on the anatomy of Einstein's genius, which dates back decades, faltered because many of the postmortem images and slides of tissue were scattered and became unavailable to researchers.

A study published online last November in Brain, based on the most comprehensive collection of postmortem images compiled to date, shows that Einstein's cerebral cortex, responsible for higher-level mental processes, differs much more dramatically than previously thought from that of a person of average intelligence. An edited interview follows with anthropologist Dean Falk of Florida State University, the lead researcher on this project.

What did you find in the study?

Einstein had extraordinary prefrontal cortices, right behind the forehead, which revealed an intricate pattern of convolutions. We know from comparative studies in primates that this part of the brain became highly specialized during hominin evolution. We also know that in humans, this area functions in higher cognition that entails working memory, making plans, bringing plans to fruition, worrying, thinking about the future and imagining scenarios. It is an extraordinarily evolved part of the brain that is related to connections between neurons underneath the surface of the brain. We're hypothesizing that what we're seeing in Einstein's brain is a lot of complexity in these connections.

Anything else unusual?

One of the most interesting things about Einstein's brain has to do with his sensory and motor cortices. We found an unusual region lower down in the motor cortex that processes information from the face and tongue and laryngeal apparatus. The motor face area in Einstein's left hemisphere was extraordinarily expanded into a big rectangular patch that I've not seen in any other brain. I am not sure how to interpret this. In a famous quotation, Einstein wrote that his thinking entailed an association of images and “feelings”—that for him, the elements of thought were not only visual but also “muscular.” What does that mean? I don't know, but in light of what we found in the motor cortex, it's a very interesting quotation.

Do you think this has anything to do with that famous photograph of Einstein sticking his tongue out?

I've been asked that four times in the past three days. The first time the question caught me by surprise, and I said I thought it was just a coincidence. Then I got to thinking about it and went to a mirror to see whether I could get my tongue out as far as Einstein had, and I came pretty close. So I think that wonderful photograph was probably Einstein just being spontaneous and impetuous.