Today’s scholars of the human brain and mind owe a great debt to Thomas Willis. Working in England in the middle of the 17th century, he meticulously observed and cataloged the anatomy of the human brain through dissection. Working in a medieval house at Oxford known as Beam Hall, Wil- lis-a short man with a mop of hair an observer once described as “like a dark red pigge”-cut open cadaver skulls to observe and examine the brains and nervous tissue inside. He snipped the nerves that held fast to the nose and eyes. Then he flipped the brain to gently remove the membranes clustered around the nerves, veins, and arteries at its base. Finally, he held up the brain and described it for his audience of natural philosophers, doctors, and the merely curious who had assem- bled to watch the spectacle.

Watching carefully, Willis’s assis- tant sketched the brain as he saw it laid bare. That anist, who illustrated Willis’s 1664 book Cerebri ANATOME (Anatomy of the Brain), was none other than Christopher Wren, who went on to design St. Paul’s Cathedral in London. Wren’s careful drawings of the human brain reproduce with nearly photographic clarity the contours and divisions easily recognized by modern medical students.

“I ADDICTED MYSELF to the opening of heads,” wrote Thomas Willis, the founder of neurology. Willis (1621- 1675) found direct examination of the human brain so much more enlightening than the course of study that had dominated medicine for 2,000 years: reading the works of Aristotle and Galen.

Willis Dreamed of nothing less than to “unlock the secret places of man’s mind.” He performed countless autopsies during his practice as a doctor in Oxford, England. He knew that the classic descriptions of the brain didn’t match what he saw with his own eyes. Thus, he set about removing and dissecting brains.

Wren developed a revolutionary method of inserting chemicals into the blood vessels of animals to better highlight the networks between them. Working with Willis, Wren injected india ink mixed with a hardening agent into vessels entering the brain. The ink made the vessels stand out like rivers and their tributaries drawn on a map.


Willis examined the com- plicated flesh of the brain and discarded the notion that its key functions lay in its ventricles, or spaces, where the ancients had conceived of spirits flowing and animating flesh. Instead, he correctly settled on the substance of the brain itself as the location of all the action.

Christopher Wren's 1664 drawing traces the brain's blood supply.
Christopher Wren’s 1664 drawing traces them brain’s blood supply.

Willis fancied fanciful language. He likened the brain’s two main hemispheres to a pair of military towers, stronger for their reliance on each other. He also compared two masses that shared an artery to two provinces bordering a river. But in the significance of his observations, Willis, who was a founder of the Royal Society, stayed true to sCience. He argued that in the brain’s convoluted folds and wrinkles, all memories, ideas, and passions found a home. All had a physical basis in the brain, he said. His studies became the first scientific investigation of the brain and nervous system. He called his work neurologie.

Willis’s dissections were crude by modern standards. Yet neuroscientists continue to follow the methods of Willis and Descartes: Look at the brain and the nervous system. Examine their parts. Trace the workings of the small bits and try to assemble them into a greater whole.

How far down the rabbit hole can the process go? Today’s neuroscientists are examining not just molecules, but also the atoms- and subatomic particles-that the universe of brain chemistry comprises. Like peeling an onion, each layer takes the researcher deeper and deeper, closer to the heart of the matter.

He examined the cerebellum, cerebral hemispheres, medulla oblongata, and other distinct parts. He tried to show how damage to particular areas of the brain might correspond with symptoms of diseases observed before death.

Willis experimented on a dog to demonstrate that blood reached the brain even if all but one artery were tied off. He got the idea from a human autopsy. The man had complained of headaches, but they went away and he lived for years. After the man’s death, Willis’s autopsy revealed that one carotid artery had become clogged, while the other had grown larger than normal. Willis guessed that the initial blockage of one artery had caused the head- aches, and the enlargement of the other had made them disappear. Willis and his experiments with a dog set him on a path any modern scientist would have recognized: observe, hypothesize, and test.

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