Hieroglyphic Brain

TIMOTHY VERSTYNEN

TIMOTHY VERSTYNEN, a post-doctoral cognitive neuroscientist at the University of Pittsburgh, wears Egyptian hieroglyphs on his arm. “The four hieroglyphic characters are the earliest written form of the word ‘brain’ and are found in the Edwin Smith Surgical Papyrus,” he writes. Dating back to seventeenth century B.C. Egypt, the papyrus is perhaps the first neurological case study describing the symptoms of head injuries and the odd fleshy matter that was often visible in the most gruesome of head wounds.

“These symbols and the story of the papyrus are the opening to the classic textbook Principles of Neuroscience, which I first came across when taking an undergraduate course in 2000. In honor of starting my graduate research career in studying the brain, I got this tattoo while attending a neuroscience conference in NYC in 2002.”

Vesalius Brain

FOR CENTURIES, medieval anatomists thought the best way to understand the brain was to read old books. They would pore through the writings of Greek and Roman scholars, like Aristotle and Galen, to learn the true nature of the human body. In the mid-1500s, an anatomist named Andreas Vesalius realized at last that the doctors of the ancient world had not actually dissected humans. They had dissected animals instead, and extrapolated to our own anatomy. So Vesalius looked for himself, and drew pictures of the body’s interior unlike anything that had come before.

KRISTIN CATTRANO

“This is a rendition of Andreas Vesalius’ ‘The Quivering Brain,’” writes Kristin Cattrano. “I admired many of his anatomy studies in art school, as I spent fifteen years as a painter, but I was always a little more interested in science than art. I even considered a career as a medical illustrator at one point. Using science as artistic reference and researching for a painting was my favorite part of painting. Actually, it was the only thing I really enjoyed. It took me many years to realize this. I got this tattoo right before going back to school to study neuroscience. It couldn’t be more perfect.”

Pyramidal Cell

MODERN NEUROSCIENCE WAS born when researchers discovered how, in effect, to tattoo a neuron. In the early 1800s, biologists came to recognize that all living things were made up of cells. But when they trained their microscopes on the brain, they could only make out a staggeringly tangled net. Most researchers agreed that the brain must be a continuous fusion of cells. But in the 1880s, a Spanish researcher named Ramon y Cajal began to stain brain cells with potassium dichromate and silver nitrate. Like a developing photograph, a few cells turned black, and Cajal could trace their tree-like structures out to their furthest twigs. “What an unexpected spectacle!” Cajal wrote. “One would have thought that they were designs in Chinese ink on transparent Japanese paper.”

KAT REINHARDT

“This is a Ramon y Cajal drawing of a human motor cortex pyramidal cell,” writes Kat Reinhardt, a graduate student at the University of Oregon studying developmental neurobiology.

Cajal would gaze at his stained neurons in the morning and then draw them from memory all afternoon. He could recognize different kinds of neurons, such as this pyramidal neuron, which is abundant in the neocortex, the outer layers of the brain. Each type of neuron had its own beautiful peculiarities, but they all had some shared anatomy. Their genes resided in a central knot called the soma, which was surrounded by branches, some for receiving signals and some for sending them on to other neurons. But the neurons did not join together in a seamless mesh. A tiny gap lay between the branches of communicating neurons, to be leaped by neurotransmitters. It was with images, such as the 1899 drawing that inspired this tattoo, that Cajal made scientists understand the true anatomy of the nervous system.

“I am a student of neuroscience and greatly admire Ramon y Cajal not only for his scientific contributions but for the artistic and beautiful quality of his images,” writes Reinhardt. “This image reminds me of the vast and incredible power of the neocortex, and of the amazing capability of the human body.”

Neuron

R AMON Y CAJAL recognized what neurons actually look like and began to sort them like an ornithologist classifying crows and robins and toucans. Today, neuroscientists can say what a lot of those different kinds of neurons actually do.

Patrick Crutchley, a research coordinator at a memory lab at the University of Pennsylvania, wears the image of a neuron known as a CA1 pyramidal cell. These neurons are found only in a pair of small patches of tissue located on either side of the brain, called the left and right hippocampus. There, they perform a marvelous trick, first discovered in the early 1970s by James O’Keefe, then at University College London and his colleagues. O’Keefe placed electrodes near CA1 pyramidal cells in the brains of rats and then let them wander around an enclosure. Each cell crackled every time the rat visited a particular spot in O’Keefe’s lab. It was as if the animals had drawn a map of the lab inside their brains.

More recent studies have shown that rats are, indeed, mental cartographers—as are we. Each CA1 pyramidal cell receives signals from many different neurons in other regions of the brain. Neuroscientists suspect that some of those signals deliver information about where we are at any moment. Other neurons deliver memories to the CA1 pyramidal cells—essentially, a model of the world as we remember it. Experiments suggest that the CA1 pyramidal cells compare what is to what we remember it to be. The harmony of those signals lets us know where we are; if they clash in discord, our brains can rewire their connections to make a better match.

PATRICK CRUTCHLEY

Neural Net

GABRIEL PATO

GABRIEL PATO, a Brazilian biologist, and Martin Roth, a philosopher at Drake University, both carry the same principle on their body: the brain is a network. Neurons send signals to thousands of other neurons, and it is the number and the strength of those connections from which our thoughts emerge. There is no single homunculus-like neuron in which a person’s mind resides. There is not even a single neuron for memories, or for smells, or for joy. Instead, our perceptions flow into layered networks, and out of those network come responses. If you hike too far into the brain, you lose the forest for the trees.

MARTIN ROTH

Gestalt

J.C. DWYER

“THE BROKEN TRIANGLE is an illustration of the Gestalt law of closure,” writes J.C. Dwyer. “The law of closure demonstrates how the mind creates wholes out of parts—and a world out of sensory information—by filling in the gaps. Although I’m no longer a professional social scientist, the law is a useful one in the realm of public policy, where I’m currently employed. Personally, I use it as a reminder to stay humble, because you never know how much of the world you’re making up as you go along.”

SANDRA KIUME

Ganglion Cell

THE BACKS OF our eyes—the rods and cones—are carpeted with neurons. Some types are covered with receptors that can capture different wavelengths of light. These neurons relay signals down the optic nerve, which whisks them to the back of the brain, where we begin to recognize images. But along with those familiar neurons are other light-catchers. Mental health advocate Sandra Kiume wears a tattoo of an intrinsically photosensitive retinal ganglion cell. It is sensitive to blue light, but it does not help paint the blue of a bluebird. Instead, it sends its color elsewhere: to neurons that control the size of the pupil, to regions of the brain that set the body’s clock, to other regions that release hormones that make us sleepy and wakeful.

A rare disorder can wipe out all the photoreceptors of the eye, save for the intrinsically photosensitive retinal ganglion cells. It leaves people blind, yet not completely unaware of the lit world. In 2007, Steven Lockley of Harvard Medical School and his colleagues examined a blind 87-year-old woman who had lost all her rods and cones decades before. They would switch on a light for ten seconds and then turn it off; in other trials, they kept it off for ten seconds and then turned it on. The scientists asked the woman to tell them during which interval the light was on. She was perplexed that they wanted her, a blind woman, to tell them about a light she could not see. But she gamely guessed. When they showed her red light, she got the right answer about half the time—no better than chance. The same went for yellow, green, and all the other colors of the rainbow, except blue. If she saw the blue light in her right eye, she guessed right seven out of ten times. And if she saw the blue light in her left eye, she gave the right answer almost every time. The intrinsically photosensitive retinal ganglion cells must tap into the higher regions of the brain, without ever ruffling our consciousness.

Serotonin

HAYLEY MILLER

“HERE IS A picture of my serotonin tattoo,” writes Hayley Suzanne Miller. “I don’t know that it needs much more explanation than it’s my favorite neurotransmitter.”

If you gathered up all the serotonin in our bodies, it would weigh less than a grain of rice. Yet it shapes our experiences during every moment of our lives. Most of it is produced by our guts, where it triggers our intestines to contract in response to food. A barely measurable amount is made by the brain—or rather, a small clump of neurons near its base. This serotonin suffuses through our heads and is taken up by neurons that make a suitably shaped receptor. Those neurons are responsible for our cycle of sleep and waking, for our body temperature, for our hunger, our ability to learn and remember, and, most importantly for drug makers—legal and otherwise—our happiness.

Neuron

LINDSAY REESE

“WHEN I WAS 18, my dad passed away from Lou Gehrig’s, which is a disease of motor neurons that innervate muscles,” writes Lindsay Reese, a postdoctoral fellow at the Oregon Health and Science University. “His battle with neurodegeneration helped me decide on a career in medical research.”

JOHN OLTHOFF

Sleep of Reason

JOHN OLTHOFF, a graduate student in the Department of Neurobiology & Behavior at Cornell, chose for his tattoo a print made by Francisco de Goya in 1799, “The Sleep of Reason Produces Monsters.”

“I wouldn’t say my tattoo directly relates to my research in neurobiology, but more to scientific and critical thinking in general,” writes Olthoff. “I was a natural scientist and skeptic, always interested in biology and how we know things. So when my AP art history teacher put Goya’s ‘Sleep of Reason’ up on the screen one day in class, it took me less than five seconds to know that it would be my first tattoo. It reminds me of the importance of rational thinking not only in my work as a scientist, but also how the lack of it more broadly can lead to dangerous things.”