The nineteenth-century “science” of phrenology held that cognitive functions are localized in specific areas of the brain. A professional examination of a person’s skull could supposedly reveal the strengths or weaknesses of each.
The Theory of Cognitive Modes rests on a principle universally accepted today: Different regions of the brain carry out different specialized functions. In other words, functions are not spread throughout the organ. In neuroanatomical terms, highly specialized brain functions are localized, not holistic.
But this consensus about how the brain works is comparatively new, especially when the long history of brain study is considered.
Neuroscience has roots in several ancient traditions. Perhaps the oldest is the prehistoric practice of trepanation, which entailed opening a hole into the skull to expose the brain, apparently in an attempt to cure disease, treat trauma, or ward off demons. Another, highly developed tradition traces back to the ancient Egyptians. They practiced sophisticated medicine and surgery—but failed to grasp the true importance of the brain. They devised treatments for brain injuries, but otherwise thought so little of the organ that they disposed of it when mummifying a body for the journey to eternal life.
The great Greek philosopher and polymath Aristotle was only somewhat less dismissive, believing that the brain serves to cool the blood; he believed that the heart was the seat of intelligence and emotion—a misconception that has symbolically persisted in imagery of love and affection (try escaping it on February 14). Hippocrates, often called the “Father of Medicine,” came closer to the truth. “It ought to be generally known that the source of our pleasure, merriment, laughter and amusement, as of our grief, pain, anxiety and tears, is none other than the brain,” he wrote in his landmark “On the Sacred Disease,” an essay about epilepsy. But Hippocrates apparently did not conceive the possibility that this three-pound mass of tissue might actually be a complex mechanism composed of multiple parts.
The concept of holistic functioning—the idea that the brain works as a single integrated organ to accomplish all of its feats, much as the liver and lungs function as integrated wholes—would endure through the Middle Ages, when the rate of progress in science in general slowed. With the Renaissance, anatomists such as the seventeenth century’s Franciscus Sylvius (for whom the Sylvian fissure is named) began to push neuroscience forward.
The Oxford professor of natural philosophy Thomas Willis, a contemporary of Sylvius, was apparently the first to propose that different (large) regions of the brain were responsible for different functions. Willis’s 1664 book Cerebri Anatome, illustrated by the great English architect Christopher Wren, proved influential in establishing the principle of localization—the idea that different parts of the brain do different things. Not everyone embraced his findings, but they received significant support some eighty years later, when the Swedish scientist Emanuel Swedenborg published a book describing neurons and areas of the brain that he believed controlled muscle movement. Foreshadowing a basic tenet of modern neuropsychology, Swedenborg also postulated that the frontal lobes give rise to critical cognitive functions. “If this portion of the cerebrum is therefore wounded,” he wrote in his classic Oeconomia Regni Animalis,1 “then the internal senses—imagination, memory, thought—suffer; the very will is weakened, and the power of its determination blunted.”
Four decades after Oeconomia Regni Animalis, the Czech physiologist and anatomist Jiří Procháska took Swedenborg’s observations a step further. Within larger regions of the brain, Procháska theorized, smaller parts could be identified with individual responsibility for different cognitive functions; he argued that these smaller parts, each of which he called an “organ,” must act together to accomplish the complex processes of the human mind.
“It is therefore by no means improbable that each division of the intellect has its allotted organ in the brain,” he wrote, “so that there is one for the perceptions, another for the will, and imagination, and memory, which act wonderfully in concert and mutually excite each other to action.”
Procháska did not use the term “brain systems,” but that is what he was describing (even though he characterized the systems incorrectly). He had intuited a fundamental assumption of brain function as we understand it today.
Ironically, it was the advent of psychology’s first mass-market fad that would prove a major factor in settling the debate about whether brain function is localized or holistic—a debate that preoccupied scientists during much of the nineteenth century.
Proposed by the eccentric Viennese doctor and neuroanatomist Franz Joseph Gall, phrenology was based on the premise that the brain is the home of the mind and is divided into specialized regions. Like Procháska, Gall called these specialized regions “organs.” Unlike the Czech anatomist, Gall claimed to have identified these regions and their supposed mental functions. In his uniquely titled work (translated into English), The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular, with Observations upon the possibility of ascertaining the several Intellectual and Moral Dispositions of Man and Animal, by the configuration of their Heads, published in 1819, Gall maintained that as a person develops, brain growth affects the structure of the skull according to the respective size and shape of each underlying organ. A bump, he asserted, signified prominence in a particular aspect of personality, whereas an indentation suggested a deficit. Thus, examining a person’s skull was a way to assess the nature of his or her brain—and a way to assess the mental functions that are accomplished by specific parts of the brain. Later research showed that although skull structures indeed do differ from person to person, these differences do not reflect variations in the size of brain areas; cranial variations do not influence personality or mental capacity.
The nineteenth-century “science” of phrenology held that cognitive functions are localized in specific areas of the brain. A professional examination of a person’s skull could supposedly reveal the strengths or weaknesses of each.
But in its time, Gall’s theory caught fire. Here, at last, was a simple, easily understood theory of psychology. An ordinary person didn’t need microscopes or fancy formulations to benefit—a painless visit to the local phrenologist did the trick. (And cost money, of course.)
The examination was straightforward: A phrenologist ran his fingertips across the scalp to discern the tangible features of the skull, and sometimes used calipers and measuring tape. He then pronounced his findings, often with the assistance of a drawing or bust of the brain’s “organs.” Among the original twenty-seven organs that Gall identified were those that produced friendly attachment or fidelity; murder, carnivorousness; sense of cunning; good nature, compassion, moral sense; faculty for words, verbal memory; and theosophy, sense of God, and religion.
A comprehensive analysis could be completed in about an hour’s time. Employers hired phrenologists to screen prospective employees, and couples frequented them for insight into their relationships. Parents consulted phrenologists for advice on raising their children. Individuals seeking only to improve themselves were counseled.
Not everyone believed the claims made by the phrenologists. No less a figure than Mark Twain judged phrenology nonsense, lampooning it in The Adventures of Huckleberry Finn when writing of “[t]he celebrated Dr. Armand de Montalban, of Paris,” a charlatan who also claimed powers of divination. Writer Ambrose Bierce was harsher, skewering phrenology in his satirical lexicon The Devil’s Dictionary (originally titled The Cynics’ Word Book) as “[t]he science of picking the pocket through the scalp. It consists in locating and exploiting the organ that one is a dupe with.”
Phrenology never gained traction in scientific circles because certain of its fundamental assumptions are incorrect. Skull shape doesn’t reflect cognitive functioning, and single, localized areas of the brain do not give rise to “firmness,” “conjugal love,” “carnivorousness,” and the like. These sorts of complex functions arise from multiple cognitive and emotional processes (which are often accomplished by multiple brain areas working together).
And yet, long after Gall died, phrenology continued to attract believers and practitioners. The British Phrenological Society was not disbanded until 1967, and in October 2007 the state of Michigan extended its sales tax to include astrology, numerology, palm reading—and phrenology. A website, phrenology.org, continues to promote it today. Charts and busts are offered for sale on eBay. Some fads die hard.
Phrenology proved false, but it was not without value. It further established the concept of specifying and analyzing mental abilities; even if the mental abilities the phrenologists identified proved incorrect, the idea of breaking the mind down into components proved correct. And it reinforced an emerging consensus that brain functions are localized.
Still, some scientists in rejecting phrenology continued to reject localization. Into this continuing scientific disagreement stepped the Parisian physician and neuroanatomist Pierre Paul Broca, who in the 1860s showed that the production of speech relies on front portions of the left hemisphere—convincing evidence, he argued, for localization.
Broca reached this conclusion after studying two patients with brain damage. One, despite being cognitively functional in other respects, could say only five words (in his native French): yes, no, three, always, and “Lelo,” a mispronunciation of his surname, Lelong. Broca’s second, more famous, case was Leborgne: a fifty-one-year-old man who could produce only a single syllable, “Tan,” whenever he attempted to speak; “Tan” became the nickname the staff gave him at the institution where he was hospitalized. Believing that these two speech-restricted men suffered brain lesions—areas of damaged brain tissue—Broca autopsied their brains after they died in 1861. As he had suspected, he found lesions in the same area of the left hemisphere in both brains. Given Broca’s stature in the international scientific community, his support for localized over holistic function carried significant weight.
Broca’s work influenced psychologists, including Harvard’s William James, a giant in the field. Twelve years in the writing, James’s landmark The Principles of Psychology, published in 1890, was his life’s achievement. “Psychology is the Science of Mental Life, both of its phenomena and of their conditions,” James wrote at the book’s opening. And in a single line in the first chapter, “The Scope of Psychology,” he emphatically completed the circle from brain function to thought and behavior. “Our first conclusion, then,” he wrote, “is that a certain amount of brain-physiology must be presupposed or included in Psychology.” The idea that consciousness itself is seated in the anatomy of the brain may seem obvious today, but in the late nineteenth century, some held it to be revolutionary.
Aided by new technologies, scientists by the 1940s not only had accepted the idea that different regions of the brain support different broad functions (such as the role of the parietal lobes in registering locations of objects in space) but also could demonstrate that smaller, identifiable areas may have very specialized functions (for instance, Area V5 plays a key role in allowing us to detect motion). A pioneer in this pursuit was the American-born Canadian neurosurgeon Wilder Penfield.
Penfield found research possibilities in epileptics who sought surgical treatment of their disease. Epilepsy occurs when the neurons in a small region of the brain begin to fire in synchrony and recruit other nearby neurons until a large portion of the brain is in spasm. This spasm creates uncontrollable movements, which are often dramatic and can be violent. In many—but not all—cases, medication can control the disease. When medication fails, patients sometimes are desperate for a treatment and volunteer to undergo new surgical procedures designed to quell or prevent the brain spasms. Penfield developed such procedures, notably the so-called Montreal procedure, in which portions of brain tissue are removed. Prior to surgery, he tried to identify the functions accomplished by specific parts of the brain, so that he did not inadvertently disrupt crucial functions. Because the brain has no pain receptors, Penfield was able to stimulate electrically the exposed brains of his patients, who had been locally anesthetized but were awake after their skulls were opened. Penfield monitored their verbal responses as he moved the site of electrical stimulation, millimeter by millimeter; in this way, he was able to map precisely small areas of the brain, showing correlations with language, motor control, and other functions.2
During the same period, psychologist Donald O. Hebb, a colleague of Penfield’s at Montreal’s McGill University, confirmed one of James’s fundamental assumptions by definitively linking cognitive and biological functioning. In the introduction to his 1949 book The Organization of Behavior: A Neuropsychological Theory, Hebb wrote:
“Mind” can only be regarded, for scientific purposes, as the activity of the brain. . . . Psychologist and neurophysiologist thus chart the same bay—working perhaps from opposite shores, sometimes overlapping and duplicating one another, but using some of the same fixed points and continually with the opportunity of contributing to each other’s results. The problem of understanding behavior is the problem of understanding the total action of the nervous system, and vice versa.
And thus the stage was set. In the next chapter we return to the duplex brain, examining in more detail what’s been learned about the functions of these two portions of the organ.