Thomas Willis

Cerebri Anatome (1674)

Thomas Willis's Cerebri Anatome
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  Thomas Willis's Cerebri Anatome was one of the foundational texts of modern scientific anatomy and physiology, and in it Willis first coins the term "neurologie" [Greek: neuron, nerve ; logos, ordered knowledge] for the scientific study of the brain. It characterised a new approach to medicine, based not so much on reverencing the Classical precepts of Hippocrates and Galen (whom Willis nonetheless did reverence, in their proper context) but upon the new method of dissection and experimentation which came to epitomise the work of the early Royal Society. Fundamental here had been William Harvey's Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (1628) [An anatomical exercise upon the motion of the heart and blood in living creatures] - commonly known as De Motu Cordis - which provided crucial experimental evidence for the novel idea that the systolic, or contracting, force of the heart drives the blood first in the lungs then into the arteries, and via as yet, 1628, postulated yet undiscovered tiny capillary vessels, into the veins, and back to the heart, to accomplish a complete and constant circulation. Willis saw the brain as receiving its primary blood supply via the two carotid arteries, thereby nourishing the cortex, while some of the blood became the saltwater-like Animal Spririts [cerebri-spiral fluid] which he came to see as powering the brain in a kind of hydraulic system of pressures, pipes, and valves.

Willis was a member of Christ Church [College], Oxford, though four things give him a Wadham connection: (1) his friendship with Dr John Wilkins, Warden of Wadham, and his "Club" of experimental scientific friends that in 1660 would become the Royal Society; (2) Willis employed the young Robert Hooke as his chemical assistant, c.1658, and almost certainly taught him anatomy and how to conduct physiological research, and Hooke - though also a Christ Church man - went on to learn his astronomy and physics from Wilkins, and Seth Ward, Professor of Astronomy, who resided in Wadham [see portraits in Hall]; (3) Wadham's Dr [later Sir] Christopher Wren worked closely with Willis and acted as his anatomical draughtsman, carefully drawing the brain sections that, when engraved, would become the printed illustration in Willis's Cerebri; (4) In May, 1666, Willis would dissect the brain of the Wadham undergraduate Samuel Mashbourne, who was killed by a bolt of lightning.

Cerebri Anatome is a magisterial study of the brain and nervous system, which structures Willis saw as lying not only at the root of perception, but also of thought, emotion (contra the earlier Aristotelian idea that the heart controlled emotion - hence "kind-heartedness") and even mental illness. He put forward evidences suggesting that different zones of the cortex related to different functions. He made detailed studies of the cortex, external convolutions and nervous appendages, seeing the brain and spine and nerves as part of a great system that somehow activated the intellectual, the emotional, and the motor functions of the body. His view of the brain was essentially hydraulic, for which he went beyond the Classical, Medieval and even Renaissance anatomists in seeing the cortial mass as dynamic in itself, and not just providing packing for the animal spirits fluid stored in the lateral ventricles, he put forth a model for brain and nervous function which was based on the flow of liquids or tenuous spirits. For blood, animal spirits, and other fluids moved about through a network of organic pipes and valves, and this was part of a thorough-going mechanistic model of physiology, with cognates linking it to the earlier speculative models of Descartes and Gassendi and even the Greeks, not to mention valve-controlled circulation physiology of Harvey.

Perhaps the greatest single discovery presented in the book was his description of that large circular artery at the base of the brain, into which both carotid arteries pump blood, and from which it is distributed to the cortex, by a host of local lesser vessels. Willis made this discovery after dissecting a man (whom one suspects that he knew in life) whose right carotid had been long-term blocked and become stony hard. His right vertebral artery, however, had swollen up to three times its normal size, and as both arteries discharged eventually into the same great vascular circle (and hence maintained the brain's overall blood supply un-impaired) it explained why the left hemisphere of his brain had not ceased to function - as Classical physiology said it should have done. This great circular vessel immortalized its discoverer's name as "the Circle of Willis".

[Galen, 2nd century A.D. and other Classical physiologists argued that the carotids entered each brain hemisphere after breaking down into a network of small arteries: the rete mirabile (Latin) or "wonderful net". Certain animals do indeed possess such a network, and as Galen had based most of his physiological theories upon dissected animals and not humans, one can understand how the idea became a clinical orthodoxy. Willis, however, belonged to the new late Medieval and Renaissance tradition of the research dissection of human cadavers, and only dissected animals for veterinary or comparative anatomical purposes.]

On the 10th May 1666, a Wadham College undergraduate, Samuel Mashbourne, was killed instantly on being struck by lightning while boating with friends on the river. As death by lightning electrocution was not understood in the 17th-century, Thomas Willis and some other doctors performed a detailed post mortem. They were surprised to find that, with the exception of some superficial burn marks (probably caused by Mashbourne wearing metal buttons on his clothing) his body, brain, and internal organs were completely healthy in their appearance. [See John Wallis, 'A relation of an accident of thunder and lightning at Oxford', Philosophical transactions of the Royal Society, 1 (1666), pp.222-226; also, The life and times of Anthony Wood, vol.2., ed. Andrew Clark (Oxford, 1892), p.77].

In the Cerebri, Pathologiae Cerebri (1667), De Anima brutorum (1672) [On the living forces of beasts] and other works dealing with the brain, we see Willis as not just a research anatomist, but also as a clinician of genius. His ideas about headaches, depression, vertigo, dreams and hallucinations were remarkably original and far-reaching in their influence. These insights, moreover, were based not just on dissections and laboratory work, but also on an extensive practice as a working physician, and one suspects that he had, in many cases, known in life the persons whom he dissected, and looked constantly to tie in peculiarities of anatomical structure with traits manifested by living individuals. His published casebooks and Oxford lectures reinforce this belief.

Willis was also fascinated by the brain-mind-soul connection. For though a thorough-going mechanist as far as anatomy, physiology and science were concerned, he was also a deeply devout Christian in the High Church Anglican tradition, with a firm belief in the Immortal Soul. Seeing the brain as the "Chapel" of the Deity within the living body, he nonetheless had few qualms about dissecting that "Chapel", along with the rest of the body, once the soul had flown to God. For Willis saw no conflict between scientific rigour and his Christian Faith, for cadavers, just like any other objects in nature, were amenable to experimental scientific study. During the Puritan period in the 1650s, Willis's house, Beam Hall, in Merton Street, Oxford (now with a stone plaque by the front door) was used for the celebration of illicit Anglican services, often conducted by Bishops and senior clergy whom the Puritans had expelled from their cathedrals and churches. The Anglican Church was restored, along with the monarchy in 1660. It is interesting to note that the most far-reaching and scientifically radical study of the brain conducted up to that date, the Cerebri Anatome, was dedicated to Thomas Willis's patient and very good friend, Gilbert Sheldon, Archbishop of Canterbury.

Text kindly provided, especially for this exhibition, by Allan Chapman