The Uncommitted Cortex: The Child's Changing Brain
Born in the United States, DR. WILDER PENFIELDstudied at Princeton, Johns Hopkins, and Oxford universities, and began his scientific and clinical career at Columbia and at the Presbyterian Hospital of New York City. He has been a citizen of Canada since 1934 and became the first director of the Montreal Neurological Institute of McGill University. In addition to his reputation as a scientist and neurosurgeon, he is the author of four books, the most recent of which,THE SECOND CAREER,was published in January by Little, Brown.
Wilder Penfield, M. D.
UNLESS there is action in the brain, a man has no thoughts and no consciousness, no awareness. This is a surmise of science, and there is as yet no good scientific reason to doubt it. Action, when it takes place within the brain, spinal cord, and nerves, is electrical. During effective brain action, electric potentials or impulses travel in everchanging patterns along the integrating circuits within the brain. It is then that the mind is alert. But we are only just beginning to be able to match the patterns of electric movement through the brain with the varying nature of thoughts or sensations or memories.
William James, the Harvard philosopher, observed that consciousness is a river, forever flowing, forever changing. He meant to indicate that the content of consciousness is never the same from moment to moment. If that is the case, we must assume that the electric potentials passing along the central system of connections within the brain never follow a pattern that is quite the same as the previous pattern. The flowing of the river seems to stop during sleep and in coma and in death. The traveling of the electric potentials slows down or stops also. When I refer to the river of the mind, it is only honest to say “seems to stop,” for although science can detect and measure the passage of electric potentials, it can neither define nor measure consciousness and thought. It can only measure the results of thinking as soon as they are expressed through body activity.
Some philosophers adopt the hypothesis that thought and brain action are one, but the physiologist, who works with the brain, cannot take this as proven, for it is the very thing he has set out, with an open mind, to prove or to disprove. Meanwhile, he can only use the language of dualism, referring to brain and mind as related phenomena. Since he is a workman, he can see that a “creative thought” may precede brain action. He can see that brain action may accompany or may be followed by thought. That is as far as his evidence goes.
Take as an example a man. A, who is talking to a second man, B. The thinking of A must either precede or accompany or follow the action of his brain. In any case, his brain activity causes him to speak. The sound vibrations reach the ears of B, and corresponding potentials pass along B’s auditory nerves into his brain, creating there a pattern of traveling electric impulses similar to that of A moments before. The result is that B thinks A’s thoughts with certain inevitable modifications of his own drawn from his memory and the conditioning of his own past experience. B’s thinking has been evoked, and it is either simultaneous with the action of his brain or immediately subsequent to it.
Sir Charles Sherrington, the great physiologist and student of the integrative action of the nervous system, has this to say: “That our being should consist of two separate elements, offers, I suppose no greater inherent improbability than that it should rest on one only.” I would add that if the basic element is unitary, it still remains for us to explain its dual manifestation.
The human brain is a living, growing, changing organ. It can even carry out its own repairs to some extent. But it is bound by the inexorable evolution of its functional aptitudes, and no one can alter this, not even an educator or psychiatrist. One can draw up a functional timetable for the brain of a child. One might well say there is a built-in biological clock that tells the passing time of educational opportunity.
In India in 1957, while visiting some of the universities, I received a surprising request from the Department of Education to give a series of two broadcasts over the All-India Radio on the teaching of secondary languages. Following that came a plan to print 10,000 copies ot the broadcasts and send them out to teachers in the schools of India. Some educator, I reflected, must indeed be desperate, to ask advice from a brain surgeon! I knew quite well that the teaching of secondary languages was in some ways the most urgent problem of modern education in India, with its many local dialects and its plan to teach all the people two secondary languages, English and Hindustani.
I am not a language teacher. My own studies of three secondary languages were truly remarkable, but only because so much toil, after the age of sixteen, resulted in such a pitiful harvest. My wife tried to reassure me by pointing out that our own children had gained a reasonable command of two extra languages because we had arranged to have them hear German and French well spoken in their early childhood. Was it, after all, as simple as that?
From a scientific point of view, the problem of speech was not new to me. For ten years I had been working on the manuscript of a book on the subject with the help of an associate, Dr. Lamar Roberts. It was self-evident that the beginning of mastery of at least one language is the prerequisite to formal teaching. Speaking and reading and writing are the basic skills of education.
During most of my years of medical practice I had had the advantage of living in a bilingual society in Montreal, where my patients spoke French as often as English. All the while, the problem had grown more challenging, the findings more exciting. I had seen children under the age of ten or twelve lose the power of speech when the speech convolutions in the left hemisphere of the brain had been destroyed by a head injury or a brain tumor. I had seen them recover after a year of dumbness and aphasia. In time they spoke as well as ever, because the child’s brain is functionally flexible for the start of a language. They began all over again and established a speech center located on the other side of the brain in what is called the nondominant hemisphere. (In a right-handed person, the left hemisphere is normally dominant for speech that is, it contains the specialized speech centers.)
When the major speech center is severely injured in adult life, the adult cannot do what the child does. He may improve, but he is using the remaining uninjured cortex on the side of injury. He cannot establish a complete new center on the nondominant side, not because he is senile, but because he has by that time taken over the initially uncommitted convolutions of his brain for other uses. This uncommitted cortex is the part of the human brain that makes man teachable and thus lifts him above all other species.
GRAY matter is made up of many millions of living nerve cells that are capable of receiving and sending electric impulses. The cerebral cortex, which is the thick layer of gray matter covering the outer surface of the brain, has been called “new” since it is found to be more and more voluminous as one ascends the phylogenetic scale from fish to man. It covers the convolutions and dips down into the fissures between the convolutions. The white matter beneath is made up of the branching connections of the nerve cells, which are capable of transmitting electric potentials like insulated wires. Some of the connections pass inward into the “old” gray matter of the brain stem (the old brain); some pass through it to the eyes and ears; some pass down the spinal cord and along the nerves to the muscles and the skin.
Certain parts of the cerebral cortex, the so-called “sensory cortex” and “motor cortex,” can be used only for sensory and motor purposes because these parts have fixed functional connections from birth onward.
But there is a large area of cortex underneath the temples and covering a given part of each of the two temporal lobes that is uncommitted at birth. This uncommitted cortex will in time be used for language and for perception. It will make possible the memory and use of words, as well as the memory and interpretation of experience. As the child begins to understand, electric currents must pass in corresponding patterns through this cortex. After each time of passage, it is easier for the later currents to follow the same trail, this tendency toward facilitation of electric passage results in man’s amazingly permanent records of the auditory and visual stream of his conscious life.
Now, if the posterior half of the left uncommitted cortex is used by the child for speech, as it usually is, it becomes the major speech cortex. Then the remaining three quarters is used for interpretation of experience (interpretive cortex). Functional connections are gradually established by the child, and the general uses of the uncommitted areas are fixed for life.
Much of this information about mechanisms of speech and perception has come to us during long operations on conscious, alert patients who were kept from pain by local novocaine injection into the scalp while a trapdoor opening was made in the skull. In the attempt to relieve each patient of his attacks of focal epilepsy, a preliminary survey of the brain was made after it was exposed. A gentle electrical stimulus was applied by touching the cortex here and there with an electrode. This served to map the sensory cortex by causing sensation (visual, auditory, or bodily, according to which of the different areas was touched) and the motor cortex by producing crude movement of the face or limb. When an abnormal area of brain was suspected of being the cause of fits, the electrode might produce, by stimulation there, the characteristic beginning of the attack from which the patient sought relief. Excision of areas of bad cortex is the method of treatment.
THE most precious and indispensable portion of the adult’s cortex is the major speech area. It might be worthwhile to forfeit other areas and so lose other functions in order to gain a cure, but never speech. Thus, the need of a method to map the exact territory devoted to speech was urgent.
When the electrode was applied to the speech cortex, it did not cause a man to speak. It seemed to have no effect. But if the patient tried to speak while the electrode was in place, he discovered that he could not find his words. If shown a pencil, he knew what it was and could make appropriate movements with the hand, but he had lost the power of speaking. He was aphasic. The gentle electric current was blocking the action of the speech cortex and its underlying connection without disturbing the function of the adjacent areas. When the patient was shown an object and was asked to name it, he perceived its nature, and he must have dispatched electric potentials along the brain’s integrating circuits to the speech mechanism. But, to his surprise, he drew a blank.
Normally, when the appropriately patterned potentials reach the speech mechanism, the word is instantly available to consciousness — its sound, how to write it, how to speak it, and how to recognize the written word. As long as the electrode paralyzed the action of the speech unit, none of these was possible. But as the electrode was lifted, the patient, not knowing what was done, would exclaim, “Now I can speak! That was a pencil.”
So we had a new method of mapping out the major speech area exactly, and the minor ones as well. And we could remove less useful cortex right up to it without fear of losing the precious jewel of the brain, speech function. We mapped out the cortical area thus in hundreds of cases and acquired precise scientific information to take the place of anatomical conjecture.
But what about the similar area in the nondominant hemisphere and the uncommitted temporal cortex farther forward on both sides? So far, neurologists had found no function for these areas. Stimulation in them never produced aphasia. What were they used for? One day I stumbled on a clue. I applied the electrode to the right temporal cortex (nondominant). The patient, a woman of middle age, exclaimed suddenly, “I seem to be the way I was when I was giving birth to my baby girl.” I did not recognize this as a clue. I could not help feeling that the suddenness of her exclamation was strange, and so I made a note of it.
Several years later during a similar operation, the electrode caused a young girl to describe, with considerable emotion, a specific experience she had had when running through a meadow. There is no sensation in the cortex, and she could not know when I had touched the electrode to her right temporal lobe, but each time I did so she described the experience again and stopped when the electrode was removed. Since that day we have been on the alert and have gathered more and more cases which could be studied critically.
Our conclusion is as follows: There is within the adult human brain a remarkable record of the stream of each individual’s awareness, his consciousness. It is as though the electrode cuts in, at random, on the record of that stream. The patient sees and hears what he saw and heard in some earlier strip of time, and he feels the same accompanying emotions. The stream of consciousness flows again exactly as before, stopping instantly on removal of the electrode. He is aware of those things to which he paid attention in this earlier period, even twenty years ago. He is not aware of the things that were ignored. The experience evidently moves forward at the original pace. This is demonstrated by the fact that when the music of an orchestra or song or piano is heard and the patient is asked to hum in accompaniment, the tempo of his humming is what one would expect. He is still aware of being in the operating room, but he can describe this other run of consciousness at the same time.
The patient recognizes the experience as having been his own, although usually he could not have recalled it if he had tried. This complete record of his auditory and visual experience is not subject to conscious recall, but it is evidently used in the subconscious brain transaction that results in perception. By means of it, a man in normal life compares each succeeding experience with his own past experience. He knows at once whether it is familiar or not. If it is familiar, he interprets the present stream of consciousness in the light of the past. Careful comparison of all the brain maps we have made shows no overlap of the boundaries that separate speech cortex, which endows a man with memory of words, and the interpretive cortex, which gives him access to the memory of past similar experience and thus enables him to understand the present.
Before the child begins to speak and to perceive, the uncommitted cortex is a blank slate on which nothing has been written. In the ensuing years much is written, and the writing is never erased. After the age of ten or twelve, the general functional connections have been established and fixed for the speech cortex. After that, the speech center cannot be transferred to the cortex of the lesser side, which is then fully occupied with the business of perception.
The brain of the twelve-year-old, you may say, is prepared for rapid expansion of the vocabulary of the mother tongue and of the other languages he may have heard in the formative period. If he has heard these other languages, he has developed also a remarkable switch mechanism that enables him to turn from one language to another without confusion, without translation, without a mother-tongue accent.
IN MY broadcast to the teachers of India, I could only reason as follows: Do not turn without question to the West for your model of teaching secondary languages. Consider first the changing functional capacities of the child’s brain. Most of our schools in the West begin the teaching of foreign languages by the dead-language technique. It was designed for adults learning Greek and Latin by means of word lists and grammar. Your hope that the people of India will speak English and Hindustani as living languages is doomed to failure if you follow this technique. It has its place, no doubt, but it should not be used in the years when the child is a genius at language initiation, the time when the uncommitted cortex can still be conditioned to foreign tongues.
But there is another method of beginning a language— the direct method that mothers use. It was used to teach foreign languages as well as the mother tongue in the families of ancient Ur and during the Roman Empire. It is used by some parents in the West and in the East today. Even a nursemaid or inexperienced tutor can use the mother’s method for a second language. The mother does her teaching when the child’s brain is ready for it. In three or four years she may give the child only a few hundred words, but he gets the set, acquires the units, creates the functional connections of the speech cortex. In unilingual countries the mother conducts the first stage of language learning by the direct method and the school carries on easily with the second stage, vocabulary expansion. If a nation is to be bilingual or trilingual or multilingual, the schools should adopt the mother’s direct method for the first stage of foreign-language teaching.
I ventured the opinion that India’s problem was not at all insuperable. Use the mother’s method at the beginning. Do not use translation at that stage. Conduct the kindergarten and the earliest grades in English for a year or two and in Hindustani for the same length of time. Better yet, make the elementary schools bilingual, teaching in English in the morning and in Hindustani in the afternoon. After two years of bilingual kindergarten and one in the first grade, the children will have started reading and writing. They are ready to carry on in either language smoothly and without accent or confusion. If desired they could start in still a third language. You must employ teachers who have begun the language they speak by the mother’s direct method, and they must teach school in the language, not making language a subject in itself. To find such teachers is your primary problem, whatever your method may be.
The child is the genius in our society when it comes to acquiring the early set or the units of a language. The enlargement of vocabulary is another story. The ten-year-old or the twenty-yearold expands vocabulary, as he expands knowledge, far faster than the young child.
Many questions have been raised by those who are charged with the task of planning the curriculum of school and college: Does multilingualism decrease the eventual excellence of intellectual performance in any one culture? Does it increase the embarrassment of the child who already has a reading problem or a writing problem? Does a second language, started too soon, confuse the child? The answer that I would give to these questions, based on observations and physiological study, is no. Double learning may well confuse the scientist who seeks to discover how it is done, but not the child.
The secret of the child’s success lies in the action of the switch mechanism, a conditioned reflex that works in his brain automatically. When the English child (or adult) hears a French word or meets a French person or enters a French school, he unconsciously switches on his French network with its vocabulary, however meager it may be. What he proceeds to learn is then added to the French network. In the brain, French, English, and Chinese, if learned, utilize the same area of speech cortex without demonstrable separation into different areas. Every adult who speaks second languages is aware of this subconscious reflex which brings the word bleistift to his mind, instead of pencil, as he turns to a German companion, or crayon as he enters the class conducted in French.
It is preferable, in my opinion, that in the early stages a bilingual adult should not switch back and forth from one language to another in conversation with a young child. But it works well to do what a bilingual mother of my acquaintance has done — establish upstairs in the home as a Frenchspeaking area and downstairs for English. Her little children accepted it as no problem at all. Language to them is only a way of getting what is wanted or expressing ideas. Imitation of words comes only after months of hearing them in the earliest years. According to W. F. Leopold’s careful study, there is a lag of two to seven months after the child first hears a word in the second year of life before he uses it in a meaningful manner. Baby talk shows that the set of the brain for language is not established immediately. It takes time, and the baby’s accent and the formal phrasing and organization of sentences alter gradually to those of the adult without the need of lectures on grammar.
In our own home the children heard German in the nursery from a governess who could speak nothing else. When she took them to French nursery school they switched to French as they entered the door and switched back again when they found her waiting outside at the close of school.
At the bilingual school conducted by the Sisters of Notre Dame de Sion in Montreal, the two years of kindergarten and the first year of school are conducted in French in the morning and, by a different set of teachers, in English in the afternoon (or vice versa). The children may be Frenchspeaking or English-speaking at home, or even speak Italian or Polish. If so, they should be ‘earning all the while in the mother’s tongue at home and in the church — learning the folk songs and nursery rhymes, and also, one hopes, religion and moral values.
A unilingual adult who begins the learning of a second language late speaks it with a mothertongue accent and tends to learn by translation. However, the adult who has previously learned some other second language in childhood is likely to learn a later third and fourth language faster and better than a unilingual adult. This greater facility of the bilingual adult may be due to the welldeveloped switch mechanism which he acquired in childhood. He is able to switch off the mother tongue easily, and thus to learn directly.
It follows that in a school district where the only foreign native-born teachers available are Swedish or Spanish, for example, it would be the part of wisdom to have beginning years taught in Swedish, or on a bilingual basis — Swedish in the mornings and Spanish in the afternoons. Those children who continue their schooling in English and eventually go on to college and into professional schools will be better prepared to learn the Russian and Chinese which intelligent Englishspeaking adults of the future will want to understand. English pronunciation and literature can be taught after the age of eight or ten. The bilingual child prepared for formal education by mother and nursemaid, or mother and a second - language kindergarten, has undoubted advantage over other children, whatever the second languages may have been and whatever the eventual work of the individual may prove to be.
In a study supported by the Carnegie Foundation and conducted under W. E. Lambert, professor of psychology at McGill University, it was concluded recently that bilingual children at the ten-year level in Montreal showed greater intelligence than unilingual children of the same age. Perhaps the key to success is to be sought in the elementary school.
The uncommitted cortex must be conditioned for speech in the first decade. This is the miracle that makes man’s education possible. Time was, not so long ago, when all well-educated people had had basic training in the classics. But men no longer turn to the cultures of Greece and Rome. We are close to many contemporary races from whom we have much to learn and with whom we must be friends. In these changing times, educators, like other specialists, are turning to science for new horizons, chiefly seeking technical aids. While questioning traditions and classical methods, they might well examine the findings of human neurophysiology. By definition, well-educated people are multilingual.
Educators must consider the mind as well as the brain, two sides perhaps of the same golden coin. On the one side they deal with behavior, morals, hopes, fears, school spirit. But on the other side they deal with the basic problem of education, the training of the brain. What the brain is allowed to record, how and when it is conditioned — these things prepare it for great achievement, or limit it to mediocrity. Boy and man are capable of so much more than is demanded of them! Adjust the time and the manner of learning; then you may double your demands and your expectations.