A Hole in the Head Page 8
These otherwise reasonable hypotheses had one fatal flaw: the nature of the evidence. Gall and Spurzheim relied almost entirely on obtaining supportive or confirmatory evidence. They collected large numbers of skulls of people whose traits and abilities were known, examined the heads of distinguished savants and inhabitants of mental hospitals and prisons, and studied portraits of the high and low on various intellectual and affective dimensions. Throughout, they were seeking confirmation of their initial hypothesis, which usually derived from a few cases. For example, the idea for a language organ in the frontal lobes come from Gall’s experience of a classmate who had a prodigious verbal memory and protruding eyes (being pushed out by a well-developed frontal lobe, Gall thought). The idea for an organ of destructiveness (or carnivorous instinct) came from examining the skulls of a parricide and of a murderer that were sent to him, from noticing its prominence in a fellow medical student who “was so fond of torturing animals that he became a surgeon,” and from examining the head of a meat-loving dog he owned. All their methods were used to seek confirmations; contradictions were explained away.35
Figure 4.5
This accurate and aesthetic drawing of the cerebral cortex is from Gall and Spurzheim, 1810–1819, vol. 1. The Roman numbers refer to the organ’s qualities as follows. Organs common to men and animals: I, instinct of reproduction; II, love of offspring; III, friendship; IV, self-defense and courage; V, carnivorous instinct, tendency to murder; VI, cunning, cleverness; VII, ownership, covetousness, tendency to steal, love of authority; VIII, pride, arrogance, haughtiness; IX, vanity, ambition, love of glory; X, caution, forethought; XI, memory of things and facts, educability; XII, sense of places and spaces; XIII, memory and sense of people; XIV, memory of words; XV, sense of language and speech; XVI, sense of color; XVII, sense of sound, music; XVIII, sense of numbers, mathematics; XIX, sense of mechanics. Organs in man alone: XX, wisdom; XXI, sense of metaphysics; XXII, satire, witticism; XXIII, poetical talent; XXIV, kindness, compassion, morality; XXV, mimicry; XXVI, religion; XXVII, firmness of purpose, obstinacy, constancy.
Figure 4.6
Phrenological head is from Spurzheim, 1834. In comparison to figure 4.5 note that the locations of the faculties are more specific, as are their names.
Gall and Spurzheim gave cogent reasons why the use of experimental lesions in animals (or “mutilations” as they called them) or the study of brain-injured humans was inadequate, in their view, to test their ideas. The state of anatomical knowledge was insufficient to remove a single organ. The organs were interconnected so that removal of one could alter the function of another. Animals would often live only a few days after surgery with the available methods. Generalizing from animals to humans was hazardous. Previous studies had not looked at complex cognitive or emotional function in animals but only such things as “sensibility” or irritability. Needless to say, however, when a clinical case that supported their view was brought to them, they would cite it as further confirmatory evidence.36
Gall and Spurzheim’s cortical localizations were of “higher” intellectual and personality traits. They accepted the prevailing view that the highest sensory functions were in the thalamus and the highest motor functions in the corpus striatum. The term “phrenology” was never used or approved by Gall. Originally he used the term “craniology” then “organology” and finally “functions of the brain” or “brain physiology” to describe his theory of punctate localization of psychological function in the brain. In 1813, Spurzheim separated from Gall and moved to England, where he substituted the term “phrenology.” There were a number of differences between Gall’s organology and Spurzheim’s phrenology, which continued to develop after they separated. Gall was much more tentative in both naming functions, often giving several terms and long description and a more approximate location whereas Spurzheim was satisfied with a single term. Gall had 27 organs (19 of which were found in animals) whereas Spurzheim extended them to 32 to 37, with sharper boundaries; later phrenologists such as Combe added more (compare figures 4.5 and 4.6). Gall continued to emphasize empirical observation whereas Spurzheim became increasingly speculative and used phrenology as a way of predicting future behavior. Furthermore, Spurzheim was much more interested in applying the phrenology to social reform and to the treatment of mental disease. The term “phrenology” was generally applied to both sets of ideas.37
Phrenology met with considerable opposition from political and religious authorities, particularly on the Continent, largely because it was viewed as implying materialism and determinism and denying the unity of the mind (and soul) and the existence of free will. On the other hand, phrenology spread widely, particularly in the United States and Great Britain, both as a medical doctrine and as a “pop” psychology. As a medical doctrine it influenced the diagnosis and treatment of mental and neurological disease. It generated widespread interest both among the general populace and among such writers and savants as Honoré de Balzac, Charles Baudelaire, George Eliot, August Comte, Horace Mann, Alfred Russell Wallace, and George Henry Lewis. In fact it rapidly became a popular fad and drawing-room amusement, particularly in Great Britain and the United States. Phrenological societies and journals continued to flourish in both countries well into the twentieth century.38
Flourens Attacks Gall
In the scientific world the most important and influential critique of Gall came from Pierre Flourens (1794–1867). Starting in the 1820s and continuing for over twenty years Flourens carried out a series of experiments on the behavioral effects of brain lesions, particularly with pigeons. Flourens reported that lesions of the cerebrum had devastating effects on willing, judging, remembering, and perceiving. However, he found that the site of the lesion was irrelevant: all regions of the cerebrum contributed to these functions. The only exception was vision, in that a unilateral lesion produced only contralateral blindness, but again there was no localization within the hemisphere. These holistic results tended to eclipse Gall’s ideas of punctate localization, but only in scientific circles and only temporarily.39
Flourens’s finding of cognitive losses after cerebral lesions was actually a confirmation of Gall’s emphasis on the cognitive role of the cortex, a viewpoint that had been virtually absent before Gall. The cortex had been termed a “superadded” structure lying hierarchically and physically above the highest sensory structure, the thalamus, and the highest motor structure, the corpus striatum. This view of the “higher” functions of the cortex combines Haller’s view of the insensitivity of cortex and both Gall’s and Flourens’s attribution of “higher faculties” to the cortex.40
Broca “Confirms” Gall
In spite of the bitter attacks of Flourens, Gall’s idea of punctate localization and even many of his specific localizations such as language in the frontal lobes and sexuality in the cerebellum continued to be actively debated in the middle of the nineteenth century. At least in the scientific community, the supposed correlations between skull and brain morphology were quickly recognized as erroneous. Yet, Gall’s ideas stimulated the search for correlations between the site of brain injury and specific psychological deficits in patients as well as in experimental animals. Reports of such correlations were published in both the phrenological and mainstream neurological literature, and the question of the localization of psychological function in the brain was hotly debated at scientific meetings.41
Thus, in 1848, J. B. Bouillard (1796–1881), a powerful figure in the medical establishment and a supporter of Gall, offered a cash prize for a patient with major frontal lobe damage who did not have a language deficit. The debate about localization reached a climax at a series of meetings of the Paris Société d’Anthropologie in 1861. At the April meeting, Paul Broca (1824–1880), a founder of the society, announced that he had a critical case on this issue. A patient with long-standing language difficulties, nicknamed “Tan” because that was all that he could say, had just died. The next day Broca displayed his brain at the meeting and inde
ed it had widespread damage in the left frontal lobe (actually much more widespread than today’s “Broca’s area”). He presented several similar cases in the next few months. Not only did Broca’s cases finally establish the principle of discrete localization of psychological function in the brain, but the discovery itself was hailed as a vindication of Gall. Broca himself had regarded Gall’s work as “the starting point for every discovery in cerebral physiology in our century.”42
In spite of its absurdities and excesses, phrenology facilitated the development of the study of the brain and behavior in several ways: by stressing that the human mind could be subdivided into specific functions and that specific brain mechanisms underlay specific mental abilities and behavior; by emphasizing the importance of the cerebral cortex; and by stimulating a great surge of research on the psychological effects of human brain damage, experimental lesions in animals, and attempts to electrically stimulate the brain. After Gall, less radical divisions of brain function, such as those of Flourens, Fritsch and Hitzig, and Ferrier, were much more readily accepted. The search for organs in the cerebral cortex led directly to cytoarchitectonics and myeloarchitectonics—attempts to distinguish cortical areas on the basis of structure—and to the tracing of sensory pathways to specific cortical areas. The phrenologists also influenced the development of physical anthropology: they were the first to develop methods and instruments for measuring the cranium.43
The cytoarchitectonic, PET, functional MRI, and other imaging maps of the cerebral cortex that are now ubiquitous in neuroanatomy, neurophysiology, and neuropsychology textbooks bear more than a coincidental resemblance to phrenological charts. They are the direct descendants of the ambitious, albeit heavily flawed, program of phrenology to relate brain structure and behavior.
John Hughlings Jackson
The first intimations of a somatotopically cerebral motor mechanism (aside from Swedenborg’s lost ideas) came from John Hughlings Jackson (1835– 1911), who is often called “the father of English neurology” because of his many neurological discoveries. Jackson reasoned that the cerebrum should have basic sensory-motor functions and gathered clinicopathological evidence for this view. In studying epileptic seizures, including those of his wife, he noticed that there was a consistent systematic spread of convulsions from one body part to the next. From this he inferred that different parts of the brain must be involved in the control of different muscle groups and that these parts must be arranged in a way to mimic the organization of the body.44 Before 1870, he appeared unsure whether this somatotopy was found in the corpus striatum, the traditional highest motor structure, or in the cortex. But by 1870, Jackson placed the somatotopically organized structures that are responsible for movement primarily in the convolutions.45
Fritsch and Hitzig had not mentioned Hughlings Jackson in their first paper, an omission that upset David Ferrier, an admirer of Jackson who replicated Fritsch and Hitzig’s 1870 study as described below46 . However, it should be noted that Jackson did not clearly implicate cortex until 1870, and then only in the Transactions of St. Andrews Medical Graduates’ Association, which the Germans may well have not seen. 47 Much later Hitzig commented that his experiments with Fritsch “had only confirmed the conclusions reached by Jackson on clinical evidence.”48 Jackson himself later claimed he had been clearer about the role of cortex earlier than his numerous, difficult and ambiguous writings in scattered medical journals demonstrate.49
THE EXPERIMENTS ON MOTOR CORTEX
What led Fritsch and Hitzig to electrically stimulate the cortex of a dog? As described above, this was a period of very active exploration of the nervous system with electrical stimulation. While there were reports of effects of stimulation of the spinal cord and brain stem, all attempts at eliciting effects of stimulation of the cerebral cortex had been universally ineffective, including those made by such skilled experimenters as Albrecht von Haller, François Magendie (1783–1855), and Carlo Mattecci (1811–1868). As Fritsch and Hitzig put it in the introduction to their paper,
Even in other fields than in physiology, there can hardly be a question about an opinion which seems to be so unanimous, which seems to be so completely settled as that of the excitability of the cerebral hemisphere.50
One impetus to their experiment was the paradox that some central nervous system structures were excitable and yet the cortex didn’t seem to be. Another was their own previous observations. Hitzig had tried electrical stimulation of the human head for therapeutic purposes and had noticed it caused eye movements.51 He then tried rabbits and also elicited movements. Fritsch, while working as a battlefield surgeon, is said to have noticed that the contralateral limbs twitched while dressing an open head wound.52
Ferrier’s Replication and Subsequent Developments
In 1866, James Crichton-Browne (1840–1938, later Sir) was appointed head of the West Riding Lunatic Asylum in West Riding of Yorkshire.53 In addition to transforming the West Riding Lunatic Asylum into an enlightened mental hospital, he made it a major center for research on brain anatomy, brain physiology, and brain pathology with laboratories, weekly seminars, visiting lecturers, and visiting researchers. He also founded the first journal devoted to brain research, the West Riding Lunatic Asylum Medical Reports, which published a series of important papers for seven years.54
Soon after the Fritsch and Hitzig paper appeared, Crichton-Browne invited his fellow medical student and Scotsman David Ferrier to come to the West Riding hospital and research center to follow up the Germans’ work on motor cortex.55 Ferrier had been heavily influenced by John Hughlings Jackson and realized that Fritsch and Hitzig had confirmed Jackson’s ideas. He was eager to study the relation of their findings to Jackson’s observations about epilepsy as well as to determine the generality of their findings across a variety of species, especially monkeys.
During and after his work on motor cortex, discussed in the next two sections, Ferrier studied the effects of stimulating throughout the accessible cortex and cerebellum. In some of these experiments, Ferrier thought that he might be stimulating sensory rather than motor areas. For example, when he stimulated the superior temporal lobe he elicited ear movements, which he interpreted as suggesting some auditory functions, and stimulating the parietal lobe resulted in eye movements, suggesting some visual functions. He then set out in a long series of experiments to test these possibilities by studying the behavioral effects of lesions of frontal, temporal, parietal, and occipital cortex. These experiments, described in papers, two editions of The Functions of the Brain and The Localization of Cerebral Disease, were major contributions to the understanding of the cerebral cortex.56 They also resulted in Ferrier being charged under the Cruelty to Animals Act in 1881 (see box 4.1) and being knighted in 1912. Ferrier continued his clinical work and is said to have been one of the last physicians to conduct rounds in “the traditional top hat and black tailcoat.”57 A portrait of Ferrier is shown in figure 4.7.
Ferrier’s Experiments on Motor Cortex
Ferrier’s initial experiments on motor cortex were carried out at West Riding primarily on dogs but also on cats, rabbits, jackals, and other animals.58 He asked three main questions: could seizures similar to those observed by Hughlings Jackson be elicited by electrical stimulation? What was the effect of stimulation beyond the limited region explored by Fritsch and Hitzig? Were the effects of stimulation similar in different species?
Ferrier used faradic stimulation, a type of alternating current (see figure 4.8) and he usually stimulated for longer durations than Fritsch and Hitzig. He found he could induce seizures in the variety of animals tested as long as the duration of the electrical stimulus was 5 seconds or more. The seizures, he thought, were strikingly similar to the “marching seizures” observed by Hughlings Jackson in his wife and other patients.
Box 4.1
Ferrier’s Arrest
In England in the 1870s there was an intense campaign to ban all experiments on live animals (“vivisection”; French, 1
975). Private bills were introduced into Parliament, European physiologists who practiced vivisection like François Magendie and Claude Bernard (see chapter 8) were vilified, and Disraeli, then Prime Minister, was besieged by antivivisectionist memos from Queen Victoria. The most militant group was the Society for the Protection of Animals from Vivisection, known as the Victoria Street Society because of the location of its headquarters. Its leader was the very formidable Frances Power Cobbe (1822–1904). Many of its members were abolitionists, feminists, vegetarians, and opponents of immunization. The Victoria Street Society demanded total abolition of animal experimentation. Finally, in response to the widespread antivivisectionist agitation, a Royal Commission was set up. (One of the very few occasions that Darwin left Down House in Kent to come to London was to testify at the Royal Commission against antivivisection legislation.) Its report led to the Cruelty to Animals Act of 1876 that regulated animal experimentation in the United Kingdom until 1986. This act required annual licenses for specific experimental procedures at specific sites. The required protocols had to justify the experiments in terms of medical applications and to minimize pain. It was a compromise that certainly did not satisfy the more militant antivivisectionists. They were determined to prove it ineffective in order to get it strengthened (French, 1975; Richards, 1987; Rupke, 1987; Elston, 1987; Hampson, 1987).