Galen on the Brain: Anatomical Knowledge and Physiological Speculation in the Second Century A.D. (review)

The brain is the part of the animal body to which Galen devoted much of his research as a physician and of his speculation as a philosopher. His many books and chapters on brain anatomy and physiology witness to his effort, almost a cultural mission, to demonstrate that the controlling center of the body, the hegemonikon, resided in the head—rather than in other body parts, such as the heart, as maintained by the adherents to the Stoic and Peripatetic doctrines. Galen's main weapon against such false theories, says Julius Rocca in this interesting monograph, was the evidence from his dissection and vivisection experiments.

Galen's arguments and data in support of his cephalocentric theory are the core subject of this work. The author has collected in three sections all the passages of the vast Galenic Corpus regarding the structure and function of the brain: the first section is devoted to Galen's anatomical methodology, the second to brain architecture, and the last to brain physiology—that is, the vivisection experiments on the cerebral ventricles and Galen's theory of the elaboration and function of the psychic pneuma.

In an introductory chapter, Rocca provides a concise survey of the medical and philosophical background on the concept of a hegemonic organ and the related cephalo- and cardiocentric theories, and describes the pre-Galenic knowledge of cerebral anatomy. Chapter 2 reports Galen's methods and the material used in his investigations, with a detailed account of the animal species, including nonhuman primates, that he dissected and vivisected.

Chapters 3 and 4, the second part of the study, are possibly the most exhaustive report ever written on Galen's cerebral morphology which, together with the results from his studies of the spinal cord and peripheral nervous system, represents a major contribution to the history of anatomical science. Indeed, for little less than a millennium, Galen's description of brain anatomy was the sole text available to physicians; though obtained from nonhuman material, his work was the starting point for the researchers who, in the Renaissance, (re)founded human anatomy by dissecting human corpses. Galen's brain anatomy, says Rocca, was not bettered until Thomas Willis. To compile this part of the monograph, he has drawn on his medical expertise and his own brain dissections on the ox, the animal that Galen used for most of his anatomical brain investigations. Reading these chapters, one has the impression that the author has checked, using a fresh brain, Galen's passages describing the different brain components. Rocca's anatomical competence and erudition in comparative anatomy are amply reflected in his exhaustive notes to the text.

Chapters 5 and 6 form the third part of the monograph. In chapter 5 Rocca describes Galen's famous experiments on living, unanesthetized animals to show that the cerebral ventricles, the containers of the psychic pneuma, are the sites of the controlling center. Galen was convinced that his maneuvers on the brain (compressions and incisions) actually affected the ventricles, resulting in various degrees of stupor—that is, loss of sensation and voluntary motion, and eventually death—but his experiments were a true scientific pastiche. Unfortunately, readers not familiar with the technique of current, controlled-lesion experiments on a delicate controlling organ such as the brain in living creatures cannot realize this. The final chapter addresses Galen's pneumatology, describing in detail the anatomy and function of the retiform plexus and the choroid plexuses, and the vivisection experiments of ligature of the carotid arteries performed to show how the brain could elaborate a sufficient amount of psychic pneuma independently of the supply of vital pneuma originating from the heart.

In conclusion, this volume is recommended to all students of ancient neuroscience and medicine, both professional and amateur.