Chapter 7
A Second Brain Change That Assists Reorganization of Cognition
As I did in chapter 3, in this chapter, I explain how myelination can play a role in cognitive reorganization. I propose that complete myelination of the auditory tracts to the cells of the primary auditory area (A1) of the cerebral cortex would assist the shift in cognition that begins in the Intuitive Phase.
A1 is located in the upper part of the temporal lobe of the cortex of both cerebral hemispheres. 56 Much of A1 is deep in the lateral sulcus, hidden from view. Like V1, A1 is in a protected site. See Figure 2.
In chapter 3, I explained that complete myelination of the visual and somatosensory tracts enables cells of the primary visual area (V1) and cells of area 1 of the primary somatosensory area (S1) of the cerebral cortex to become reliable gates —entry ports that selectively transmit electrical impulses to downsteam cerebral cortical circuits. Thus, both V1 and S1 gate cells segregate activation of downstream visual circuits and somatosensory circuits. The segregation of activation of the downstream visual circuits is based on edges or lines of light and movement of light that are cast upon the retina. In like manner, the segregation of activation of the downstream somatosensory circuits is based on edges and movement of stimulation of touch receptors in the skin.
Here, I propose that complete myelination of the auditory tracts enables the cells of area A1 to become reliable gates that segregate activation of downstream neuronal circuits. Again, the segregation of activation of circuitry is based on the findings that primary sensory cells —that is, the cells of A1 —respond to patterns of stimulation of external receptor organs, in this instance the cochlea —the part of the inner ear that responds to sound.
Assimilation and accommodation are sufficient to account for incremental cognitive changes. But to account for a reorganization of cognition, not merely incremental change, I, like Piaget, proposed special mechanisms. However, we differed on two points. The first is the type of special mechanism that is involved. The second is what constitutes a reorganization. Piaget invoked special psychological mechanisms. I invoke maturational mechanisms. In addition, I propose that the reorganizations that take place do so in earlier stages of cognitive development than Piaget proposed.
Here, I will discuss equilibration, a concept that is central to Piaget’s theory of cognitive development. Piaget held that equilibration is the primary impetus for cognitive change. In contrast, the maturational factors that I propose offer the child’s schemes, new tools —new ways in which input is organized. This newly organized input to the schemes supports their reorganization to interact —that is, to assimilate and accommodate —more effectively with that child’s particular world. I suggest that better equilibrium results from the effects of the new tool, not that equilibrium, itself, is a driving force, as Piaget proposed.
Equilibration and Emotion
Equilibration
Until now, I have mentioned equilibration only in passing. Piaget saw equilibration as pivotal in all cognitive transformations. He preferred the term equilibration to equilibrium, because equilibration did not imply that equilibrium is necessarily achieved (Piaget, 1977). In his model, equilibration is a basic drive: In all life forms, if there is an ultimate drive, it is toward equilibrium. He saw equilibration as a tendency toward integration, "a need for coherence" (p. 833), active at all times and essential for cognitive transformation. Piaget proposed that equilibration is a developmental factor that cannot be dissociated from hereditary, environmental, and socioeducational factors. To Piaget, assimilation-accommodation was one kind of equilibration. Other types were equilibration between subsystems and between the subsystem and the whole (Gallagher & Reid, 1981a). 57
Piaget proposed that progress in the construction of more sophisticated psychological structures or schemes resulted from equilibration when the existing ones were in a state of disequilibrium —that is, out of balance with each other —as they interacted with the world.
I question whether equilibration, as a superordinate drive, is required to account for cognitive development. I suggest that conscious or unconscious emotion, which signals to the organism what works for the organism, is sufficient.
The Role of Emotions and Their Relationship to the Brain
I propose that emotion —with its close tie to the autonomic nervous system, which serves the nutritive, vascular, reproductive, and other vital systems —signals the state of the organism, including the state of the schemes. Emotion signals to the organism that it is or is not functioning satisfactorily —for example, that it is in pain, is too warm, too cold, losing balance, hungry, satiated, sexually aroused, sleepy, tired, or rested and so on. Emotion also signals the state of the organism to others —for example, the state of the schemes may be signaled by a facial expression of fear or sadness (Ekman, 1984) and, less reliably, by posture.
Much progress has been made in understanding the relationships between emotion and the brain. "Neural substrates of feeling and emotion are distributed throughout the brain, from front to back, and top to bottom" (Berridge, 2003a, p. 42). Nonetheless, emotions are most closely related to particular regions of the cerebral cortex —such as, the cingulate gyrus or the orbitofrontal region (Figure 4) —and to particular subcortical structures. Berridge, in his extensive review of the neuroscience of emotions, cited reports that positive affect is impaired by left cortical damage, and fear by right cortical damage. These reports are variously interpreted as the damaged cortex releasing either the undamaged cortical hemisphere or as the damaged cortex releasing its subcortical structures.
Contrary to popular belief, prefrontal lobotomies —the surgical lesioning of the anterior cingulate gyrus or the orbitofrontal region —resulted in only modest cognitive-emotional changes. Prefrontal lobotomies were a common form of treatment for schizophrenics and for severe obsessive compulsives about 50 years ago —a time when there was essentially no effective treatment for such patients. Most neurosurgeons were conflicted about doing lobotomies —the cutting into normal brain tissue —and were pleased to discontinue doing lobotomies, when thorazine and reserpine —the first effective antipsychotic medications —were introduced.
It should be recognized, however, that lobotomies did not turn patients into zombies, as I have heard contended by physicians, who are too young to have ever seen a post-lobotomy patient. The most serious side effect of the surgery was the possible triggering of epileptic seizures by post-surgical scars. Often the schizophrenic patient’s hallucinations and delusions persisted, but the patient was less troubled by them. One of my colleagues, who had had considerable experience caring for post-lobotomy patients, characterized the effects of a lobotomy by referring to the severely obsessive old lady who might be terrified that she might pass gas when she was with others. After a lobotomy, she would just say, "Oops. "
I am not recommending lobotomy as a treatment, although, in the past, it offered some relief to anguished, obsessive patients. Here, my purpose is to point out that significant damage to the frontal cortex results in emotional change that is significant, but subtle.
In fact, a slow-growing, massive tumor of the frontal lobes may go undetected. When the patient first becomes symptomatic, he may only be a bit less inhibited than he was, and he may tend to perseverate. A classic sign of frontal lobe damage may be a kind of silliness. One person, who claimed she never could remember a joke, became a near-constant joke-teller, subsequent to her brain tumor.
Emotional changes caused by damage to subcortical nuclei are also not necessarily obvious. For example, damage to the amygdala —an almond shaped body in the temporal lobe of each cerebral cortex —appears to lessen fear in social situations. To affect emotions, generally, the damage to the amygdala, or another subcortical structure must be bilateral. Patients, such as SM, who had brain damage that is isolated to both amygdalas, are rare (Adolphs, Tranel, & Damasio, 1998). SM was described as tending "to approach and engage in physical contact with other people rather indiscriminately. " She and two other patients who had the bilaterally damaged amygdalas judged pictures of faces as "approachable" and "trustworthy," which control subjects did not. In their assessments of people from verbal descriptions, however, the three patients did not differ from control subjects. Bilateral amygdala damage appeared to interfere with acquisition of negative assessments of certain faces that other people automatically acquire. This finding is consistent with that of Baird’s and Yurgelum-Todd’s (Beckman, 2004) finding that the amygdalas of adolescents and adults were hyperactive (measured by fMRI) when they were presented with a picture of a face that expressed fear.
Additionally, these findings in humans are similar to those found in amygdala-lesioned monkeys. Amaral (1998) found that amygdala-lesioned monkeys, when introduced to a troupe of monkeys, tended to lack the initial reticence that a monkey shows when it is not acquainted with that troupe. The amydala-lesioned monkey is sociable, may more quickly become sexually active, and may induce the other monkeys to be so. Again, this behavior is subtle, not blatant.
Damasio and his colleagues (Bechara, et al. , 1995) found that SM, the patient mentioned above, showed increased skin conductance of electricity —a measure of anxiety —in response to a loud noise. However, she did not respond with such increased skin conductance of electricity to a cue —a tone or a blue light —which repeatedly preceded the loud noise. She did not become conditioned to either cue. She could, however, remember the various stimuli. A patient whose amygdala was intact, but who had a damaged hippocampus, could not remember the various stimuli, and responded to the cues with increased skin conductance of electricity. He became conditioned to the cues.
Damasio’s findings in SM are basically the same as Ledoux’s (1996) findings in rats. Ledoux found that, after pairing a tone with a shock, rats froze when they heard the tone. They were conditioned to the tone. After he destroyed both amygdals in the rats, they could not be conditioned to the tone. 58 An amygdala is required for acquisition and expression of a conditioned fear response —a conditioned response to danger.
Primarily, what we know about the actions of the drugs of pleasure —drugs that are addictive —come from studies of the effects of these drugs on the mesolimbic-dopamine system of rats. The part of the mesolimbic system that connects the neurons of the ventral tegmental area of the midbrain to the nucleus accumbens is central to experiencing pleasure. The nucleus accumbens —also known as the ventral striatum —is a cluster of cells that is located in the deep subcortical portion of the cerebral hemispheres. Dopamine is the neurotransmitter of the nucleus accumbens, which is referred to as part of the limbic system, hence the term mesolimbic-dopamine system. This system also has connections to the amygdala.
There is some indication that activation of this mesolimbic-dopamine system is appetitive generally. Because euphoriants —amphetamine, opium, alcohol, marijuana, and so on —and appetitive responses to food have been shown to act on various locations of the mesolimbic-dopamine system, the mesolimbic-dopamine system is generally thought to be the pleasure system. And it also was thought that dopamine level in the brain was pleasuring.
Berridge (1996) and Robinson have, however, found that activation of the mesolimbic-dopamine system can be split from activation of the nucleus accumbens by using behavioral indicators of pleasure in response to different tastes. For example, when they used a drug to block activity of the mesolimbic-dopamine system in rats, the rats ceased eating. However, when the investigators gave food to the rats, the rats showed their characteristic behavioral indicators of pleasure. For example, in response to a sweet taste rats lick their lips. 59 When the investigators stimulated the mesolimbic-dopamine system electrically, the rats ate, but showed no behavioral indicators of pleasure. Thus, the mesolimbic system is related to motivation —the "wanting" of food —and the nucleus accumbens is related to pleasure —the "liking" of food.
In rats, activity of the nucleus accumbens, most particularly its shell, appears to be central to pleasure generally (Berridge, 2003a). Morphine, microinjected into the shell, increased the behavioral indicators of pleasure to tasty food rewards. Both nucleus accumbens activity and dopamine release respond to palatable food, to heroin and amphetamine, and to the chance to engage in sexual activity in both males and females.
Berridge (1996) reported that Cromwell found that, in rats, lesions of ventral pallidum, also known as the substantia innominata, which is just deep to the nucleus accumbens, results in aversive responses to food. It should be noted that the primary neural outflow of the nucleus accumbens is to the ventral pallidum (Berridge, 2003b).
In human adults, winning a game and winning money in a game resulted in activation of dopamine systems in the nucleus accumbens and in related structures (Berridge, 2003a). This finding and the findings involving addictive drugs are consistent with the neurophysiologic studies of positive emotions in rats.
In the newborn human, characteristic emotional expressions indicate whether food tastes bad —for example, bitter —or tastes good —for example, sweet. These expressions appear to be part of a prewired, protective system that signals pleasure and unpleasure to the organism and to the outside world. Compounds that taste bitter, such as alkaloids, are often dangerous. Compounds that taste sweet are usually safe.
At about 6 weeks, the infant smiles when she hears a familiar sound. Shortly thereafter, her smile signals whatever is pleasant. Still later, her face signals the relationship between what is and what could be with the expression of fear, and between what was and what-appears-as-if-it-will-never-be-again with the expression of sadness (Malerstein, 1968). Finally, emotion signals, at least to the self, many refinements of feelings —shame, jealousy, guilt, pride, and so on.
But evidence suggests that, to begin with, the infant has two closely related, prewired emotional responses —one for pleasure or liking and one for unpleasure or not-liking. The emotional system is very complex, perhaps more complex than the cognitive system. There is much to be discovered about both. Nevertheless, based on current knowledge, it is possible that the activation of cells of the nucleus accumbens is the nidus for the brain’s construction of pleasure, and that the inhibition of activation of cells of the ventral pallidum is the nidus for the brain’s construction of unpleasure, just as activation of the red-sensitive cone cells is the nidus for the brain’s construction of redness.
Emotion is the part of a scheme that signals whether or not that scheme is working to serve the organism —to help it to survive and to prosper. In this way, emotion acts as a guide. It has a go/no-go impact on ongoing scheme activity. It indicates whether the scheme that is active should be allowed to continue, or whether it should be interrupted or diverted. 60 I propose that emotion plays a role in incremental change, but ordinarily does not in itself account for the major developmental reorganizations that are addressed here.
As I have mentioned, my positions concerning major cognitive reorganizations differ from those of Piaget in two ways. I differ as to when the reorganizations begin. And I differ as to what mechanism probably facilitates the reorganizations.
In chapter 3, I proposed that the change from Stage-3 to Stage-4 cognition in the Sensorimotor Period marked the beginning of a reorganization of cognition. Here, I will propose that the change from Symbolic-Phase cognition to Intuitive-Phase cognition marks the beginning of another reorganization of cognition.
Piaget’s Special Mechanisms
I assume that Piaget believed that the major cognitive reorganizations took place between Stage 5 and Stage 6 of the Sensorimotor Period, and between the Preoperational Period and the Concrete Operational Period. I make this assumption, because he invoked special mechanisms to account for the changes at these points of cognitive change.
Mechanism of Change to Stage-6 Cognition
Recall that in chapter 5, I described how Piaget’s Stage-5 daughter imitated the opening of a box by opening her mouth. She then opened the box wider and retrieved the object that she wanted from the box. She had made use of an action symbol. Her opening her mouth symbolized the opening of the box. In Stage 6, when she was able to open a box without opening her mouth, Piaget proposed that she had interiorized her action symbol to form a mental image. He proposed that interiorization of an action symbol —for example, the opening of the mouth —was the mechanism that accounted for the change to Stage-6 cognition —and particularly for the formation of mental images. An action symbol is transformed into a mental symbol —a mental image.
Mechanism of Change to Operational Cognition
Piaget (1970) conceived of Intuitive cognition as a half step toward better equilibration. He proposed that Intuitive cognition used a semilogic —one that lacked reversibility. For example, when Intuitive-Phase children see candies that are spread out to look like more, they fail to consider that the candies could be bunched up again. To deal with this incomplete equilibrium, Piaget invoked reflective abstraction as the mechanism that made possible the change from Intuitive to Concrete Operational cognition. 61
Piaget (1971) distinguished between simple abstraction and reflective abstraction. Simple abstraction is knowledge abstracted from experience with objects themselves. For example, by lifting objects the child may abstract from her experiences that large objects are usually heavier than small objects. Similarly, the child may use simple abstraction to understand that higher-in-the-glass is usually more. This kind of abstraction typifies Intuitive-Phase cognition.
Reflective abstraction, however, is knowledge abstracted not from the objects themselves, but from the coordination of the child’s actions on the objects. In this context the term reflective has "at least two meanings…the transposition from one hierarchical level to another level (for instance, from the level of action to the level of operation)…[and] the mental process of reflection" (Piaget, 1971, pp. 17-18) —that is, thinking about his actions. Piaget reported the example of a child who placed pebbles in a row and in a circle, and counted. The child began his counting at different points, and counted in different directions. No matter how he arranged the pebbles or where he started his counting, he realized that the sum was the same. The "sum was not from the physical properties of the pebbles, but from the actions that he carried out on them. " It was he who united the pebbles into a sum. What the child learned came from his reflection on his own coordination of his actions —his reflecting on the results of his counting, and on his changing the order in which he counted.
My Mechanism
In chapter 3, I described how complete myelination of the visual and somatosensory tracts in the latter part of Stage 3 62 would assist the cognitive shift from Stage 3 to Stage 4 by segregating downstream schemes in accordance with sets of edges and movement of visual or touch stimuli. I inferred that, in stages, this segregation of schemes could then be employed to aid the further differentiation of object schemes —including, as I explained in chapter 5, the differentiation of the mental image of an object from the perception of that object.
As I pointed out, a set of edges and their movement is the single best discriminator of different objects. However, edges and their movement, by themselves, are not adequate to define an object. For example, Piaget’s daughter, when she was in the Symbolic Phase, defined two different objects as the same object —that is, she referred to two different slugs that were 10 yards apart as "the slug. " Presumably she did this because the two slugs were similarly shaped: Their edges were similar. Recall that older children and adults talk about objects that do not move as distinct objects —for example, a mountain. Movement of an edge does not help one to understand that a mountain is an object. They also refer to objects whose edges are not visible —for example, the earth —or not touchable —for example, the moon —as distinct objects. Edges and movement are important in the early discrimination of objects. However, when objects are measured by sophisticated language, sets of edges and movement of visual or touch stimuli are no longer sufficient in understanding what is meant by the idea or word object.
I propose that in the Intuitive Phase, children begin to understand what older children and adults mean when they refer to objects, and that this shift from Symbolic-Phase cognition to Intuitive-Phase cognition involves a major cognitive reorganization.
Not every language necessarily has an equivalent single word for object that refers equally to the moon, the earth, a mountain, and a toy. So for a child to learn what older children and adults mean, the child must learn the language of his or her culture. In this context, it is relevant to consider Nelson and Kessler Shaw’s (2000) analysis of language.
Language Development
Nelson and Kessler Shaw stated that adult language is characterized by four S’s. Language is S ocial, S hared, and S ymbolic, and the symbols are a part of a S ystem of symbols. They warn us not to assume that the early use of words necessarily indicates that children are using words as symbols —that is, they warn us not to assume that the word is used to represent something in its absence. 63 Early in development, many of the child’s words merely refer to an object or event that is present.
These authors point out that language is social from the outset. Mothers in our culture bathe their children in words as they interact with them around feeding, changing, dressing, and playing. In other cultures, in which mothers engage in little talk with their young children, the child must "extract patterns of conversation from those of adults and children talking together in groups" (p. 30).
Nelson and Kessler Shaw note that in the last half of the first year, mother and child show a new kind of interaction —the sharingof attention to objects and events. The attention of the other is enlisted by pointing and by following each other’s gaze. They respond to the other’s emotional reactions and imitate each other’s actions. The authors see this behavior as leading into a sharing of words. However, these words are used to refer to an object or event that is present. Such words are not symbols.
It is not always easy to be certain when the child is using words as symbols as Nelson and Kessler Shaw define the term. To them, the child uses words as symbols when they "represent a state of the world that is not present… with the intention of communicating that representation to another" (p. 33). "[T]he essential function of a symbol is to provide a means for communicating with another about things and relations that cannot be pointed to" (p. 36). In language, words "connect a part of the world as understood by one person to that of another" (p. 35).
Nelson and Kessler Shaw note that even though the child’s first words are usually nouns and verbs, children often do not use them that way. My daughter’s first word was stadt, presumably her version of that. To her, stadt appeared to mean "look (at that)," "I want (that)," and "that particular object. "
To Nelson and Kessler Shaw, language is "systems of symbols conventionally used in constructions that convey meaning between people…[that] goes beyond talking about objects to talking about ideas…The task is to understand how children solve the " symbol construction problem" (pp. 43, 44). Furthermore, in some measure, language determines thought structure, in that language is a public construction for communication that is used in private thought.
In natural language, words relate to conventional concepts that are widely used and understood in a society. Used as symbols, first words may form a private language that is understood by close relatives. This language is social, shared, and symbolic, but not cultural. It is not a conventional language. It is not part of an established S ystem of words. To become a language, the child’s initial conceptual organization of the world needs to be reorganized. The "child needs to ’re-parse’ the world conceptually in response to learning words…attending to the extensions of words and their constructions in grammar as used by adults, reflecting the conventional meaning systems" (p. 36).
In "learning to engage in conversation, and to construct sentences, the child amasses bits and pieces of language that are not mapped to the parsing of experience, but are used as elements of the language itself…[T]hese bits have importance in leading the child to a new level of function, its function as a symbolic system that represents meaning in its own right" (p. 41).
Parsing of words into bits and pieces is what complete myelination of the auditory tracts to A1 does. But before I elaborate on that, I will describe two studies that shed light on acquisition of bits and pieces of language and their understanding.
Bowerman (2000) stated that it has been widely accepted that as children learn language, they often are in search for words that express a meaning they already have —that their concepts are "already in place when the words are acquired" (p. 207 —for example when they first say "allgone," "upmama," "milk," or " nana" (i.e. banana). However, she found that children may first use and understand certain words that express meanings that are specific to a particular language. She studied children’s use of words to designate spatial relationships between objects —that is, in and onin English.
To designate containment, Dutch speakers use a word that corresponds to the English word for in. Korean speakers use one word to designate containments that fit loosely, and a different word to designate containments that fit tightly, such as a book in a fitted case, a ring on a finger, or a Lego on a Lego stack. English speakers use the word on to designate a ring on a finger, a Lego on a Lego stack, and a towel on a hook. Dutch speakers use different words to designate a ring on a finger, a Lego on a Lego stack, and a towel on a rack. Korean speakers use some words that correspond to the words used by Dutch or English speakers and other words that are specific to the Korean language. Bowerman reported that children understood and used language-specific words before they understood and used words that would be universal designations of containment and support —that is, in and on.
So it appears that children both find meaning in a language as it is spoken and seek language to designate the meanings that they already have.
Not surprisingly, Brown, Cazden , and Bellugi-Klima (1969), in their study of the development of language, found that, at its inception, many components of the child’s language correlated with the mother’s speech. More interesting for us here is their finding that, when the child is first learning to speak, the mother tends to respond to the meaning (the authors refer to it as the truth) of her child’s speech, not to the syntax. If the child says, "Ball red," Mother tends to agree. She does not tend to correct the child’s expression unless the ball is blue. The mother’s tendency helps her child to sort meaning —what the word sounds represent —from just sound.
When nuances of sound segregate the word schemes, they are, at the same time segregating not just parts of sound, but also the meaning of such sounds. Meaning is part of the definition of communication or language.
What About Myelination?
I propose that complete myelination of the third major sensory tracts —the auditory tracts —would assist a cognitive reorganization late in the Symbolic Phase. The complete myelination of the auditory tracts then would assist the reorganization of cognition that is first manifest in the Intuitive Phase.
As V1 is to vision and S1 is to touch and proprioception, so A1 is to sound. A1 —the primary auditory area of the cerebral cortex —is the entry port into the cerebral cortex for electrical patterns of stimuli that originate in a part of the ear that responds to sound —that is, the cochlea. Located in the inner ear, the cochlea is a spiral-shaped structure that is lined with hair cells. The hair cells convert different sounds —different frequencies of airwaves —into electrical impulses that are transmitted to relays in the medial geniculate nuclei of the thalamus and then via the auditory radiations to A1 cells of the cerebral cortex.
Complete myelination of the auditory tracts to A1 —the primary auditory area of the cerebral cortex —takes place much later than complete myelination of the visual and somatosensory tracts to their primary areas of the cortex. The auditory radiations connect the medial geniculate ganglion to A1. These auditory radiations are the last segment of the auditory tracts from the cochlea to A1 to be completely myelinated. This takes place at about 3 ½ to 4 years of age (Yakovlev & Lecours, 1967) —late in the Symbolic Phase of the Preoperational Period. This complete myelination of the auditory tracts from the cochlea to A1 offers a newly stable organization of neuronal circuits, or schemes, that are downstream from area A1 cells.
As I explained in chapter 3, only a completely myelinated neural tract consistently transmits impulses to approximately the same downstream neuronal circuits when the impulses are repeated. After complete myelination of the tracts involved, depending on the pattern that activates the cells of a primary sensory area of the cortex, neuronal circuits or schemes, which are downstream from that area, are reliably and selectively activated when that pattern is repeated.
In rats, Zhang, Tan, Schreiner, & Merzenich, (2003) found that the pitch, which characteristically activates an A1 cell correlates with the rate of change in pitch, which also activates that cell. A1 cells, which are characteristically activated by a low pitch tone, are also activated by a sound whose pitch is increasing. And, A1 cells, which are activated by a high pitch tone, are activated by sound whose pitch is decreasing.
Another finding is that A1 cells of cats respond to novel sounds (Ulanovsky, Las, Farkas, & Nelken, 2004). For example, if a particular tone is repeated 90 % of the time and another tone 10% of the time, the rare tone will activate A1 cells more—that is, their firing rate will be greater—whether the rare tone differs in pitch or loudness.
Complete myelination of the auditory tracts from the cochlea to area A1 would bring on reliable gating function of A1 cells. If the above findings hold, when the auditory tracts between the cochlea and A1 are completely myelinated, the activation of neuronal circuits, or schemes, downstream from area A1 cells are stably and selectively activated by pitch, rate of direction of change in that pitch, and novelty of either pitch or loudness. This stable selectivity of downstream circuits is affected both by the child’s hearing other people’s voices and by the child’s hearing his or her own voice.
Before age 3 ½ to 4, when myelination of auditory tracts is still incomplete, the neuronal circuits that are downstream from A1 cells would be in flux. Pitch, change in that pitch, and novelty of pitch or loudness would activate one neuronal circuit in one instance. A little later, as additional neuronal axonal fibers that constitute the auditory tracts become completely myelinated, the same pitch parameters—bits of sound—activate a different neuronal circuit. When the auditory tracts to the cells of A1 are completely myelinated, the A1 cells become reliable gates. Then, whenever the same sequences of these bits of sound are repeated, the impulses that correspond to these sounds will, in effect, pass through A1 gate cells to activate approximately the same downstream neuronal circuits in the cerebral cortex.
This new, stable organization of neuronal circuits, or schemes, which occurs just before the onset of the Intuitive Phase, would assist the child’s understanding of seriation and classification in the Concrete Operational period. It should help the child to think in nuances of words and word relationships.
Age 3 ½ to 4, when complete myelination to A1 cells takes place, is late in the Symbolic Phase, just before the onset of the Intuitive Phase. It is true that Intuitive-Phase children are not sophisticated at seriating or classifying attributes. They have, however, begun to understand that an attribute such as blueness or length comes in degrees —have begun to understand that objects may be ordered in terms of how blue they are or how long they are. They have begun to understand seriation. They have also begun to understand that a difference in an attribute, such as the difference between blue and green or the difference between long and short, may be used to distinguish one group of objects from another. They have begun to understand classification.
As I mentioned earlier, Intuitive-Phase children falter when they are asked to order a large series of objects, and they do not understand transitivity, which is part of a complete understanding of seriation. They falter when culling one type of object from a large assortment of objects, and they do not understand the relationship of subclass to class, which is part of a complete understanding of classification. Nonetheless, they have begun to understand both seriation and classification.
At age 3 ½ to 4, the already-existing auditory portions of the child’s schemes can begin to be reliably segregated in terms of nuances —that is, bits and pieces —as the speaker says, "Jane is t all, Mary is tall er, and Joe is tall est," or "Jane is f ast, Mary is fast er, and Joe is fast est. " In the Intuitive Phase, the child tries to use and understand more and most; r ed, redd er, and redd est; lotsand all; a and the; similar and same. Reliable conduction of the nuances of sounds, brought on by complete myelination of the auditory tracts, should assist refinements of understanding that are required by such communication. The rich pre-existing 3 ½ to 4 years of schemes may now be redefined, or at least refined — re-parsed, in Nelson’s and Kessler Shaw’s terms —by such nuances of sound that the community uses in its language.
All of this depends on the child’s exposure to a language and culture that emphasizes seriation and classification of attributes. It is difficult to believe that a child who lacks such exposure would develop an understanding of the distinctions that are involved in fully understanding attributes. Adults and older children model such distinctions in their speech. Sometimes, they deliberately teach these distinctions to the child. Most often, the child picks up the distinctions automatically —presumably from the models and from her interactions with the models.
The timing of complete myelination of the neural tracts from the cochlea to area A1 cells is opportune. As the child is about to enter the Intuitive Phase, the complete myelination of these tracts provides reliable downstream cerebral circuit activation that is segregated, based on nuances of sound. This is a time when children differentiate object schemes from attribute schemes, begin to understand distinctions between attributes, and begin to understand that attributes may be graded. Precise hearing of sounds in specific contexts is a necessary, if not sufficient, requirement for the child to distinguish the language that begins to deal with such aspects of attributes —a language that distinguishes a and the, similar and same, or fa st , fast er , and fast est.
As the bits and pieces are repeated, complete myelination of the auditory tracts to area A1 cells should reliably deliver each bit to what are essentially its own cortical neuronal circuits —circuits that are downstream from A1. The repeat sound of the word a should activate basically the same circuits each time, and the repeat sound of the word the should activate its own circuits. Each time the words are heard, the circuits that are activated should be essentially the same for the same words, and the circuits that are activated should be essentially different for different words. The same applies to the words he or she. The bit sound of ed in learned, in waited, in asked, and even in goed,or standed should activate the same basic neuronal circuit, or scheme, and the sound of s in toys, in books, in rocks, and in foots should activate its own basic neuronal circuits or scheme. After complete myelination to A1, each of these bits and pieces, which has its own meaning —for example, gender, tense, or plurality —in the systems of words in adult language, should have its own reasonably consistent circuits. And all of these circuits should be somewhat distinct from one another.
These sets of neuronal circuits are segregated in terms of bits —bits that are imposed by language and culture, and which form wholes. These aggregates of bits that indicate dimension —for example, er in faster —and those that indicate kind —for example, he or she —can be used to better "connect a part of the world as understood by one person to that of another" (Nelson & Kessler Shaw, 2000, p. 35). That is, they enable the child to communicate more successfully. This conventional sorting works for the child in his or her social world and in turn may provide a tool for self-exploration —a way for the child to understand his or her own meanings.
The mechanism that I have described helps explain how a child picks up the parts of a language that are regular. English is particularly irregular. Nonetheless, after a while, most children trade feet for foots,went for goedand stood for standed, but some do not. They still say gooder or tooken, and may never distinguish know from think. Sometimes the parsing of sounds is counterproductive. For example, the sounds my, el, and nay as in nation do not help us to understand the meaning of myelination, but myelin and tion do. So we must continue to learn —assimilate and accommodate —to the bits and pieces that work for us in our land, whether our land is medicine or auto repair, and whether it is France or America.
Complete myelination to A1 not only would help the child to master the language of his or her culture. But it would also help to shift conscious cognition to thinking in words and word organizations rather than thinking in visual, touch, or postural images.
If the language of your culture does not have the right words, does that impair your thinking? There is some evidence that it may.
Gordon’s (2004) studies of the Piranha~ confirm that language is critical to certain types of thinking or understandings —particularly, certain Concrete Operational understandings. The Piranha~ —a tribe of about 200 who live in small villages along the Amazon —have their own language. In their language, He and they are the same word. The Piranha~ have no word for number, more, several, all, or each. They have a word for one, for two, and for many as well as for the same. Their word for one also means a small quantity. 64
On various tasks, Gordon found that they did not comprehend numbers much above two or three. Generally, when they were asked to match what he presented —for example, sticks, nuts, or line drawings —they could not do so much beyond 2 or 3 items. They responded similarly on a task that involved subtraction and memory. He placed nuts in a can as they watched, and then asked them if the can was empty each time as he removed a nut from the can. Also as the Piranha~ watched, he put candies in a box that had pictures of a number of fishes that corresponded to the number of candies that were put in the box. He passed the box behind his back and then presented it along with a box that had one more picture of a fish on it or one less picture of fish on it. At about 50% of the time, for as little as three or four correspondences of fish to candies, they selected the box that contained the candy. It should be noted that they prized the candies and, as part of the procedure, would get the candies. Tests that involved either memory or that involved spacial transposition showed similar results. The Piranha~ did poorly on tasks that depended on understanding numbers greater than three.
Interestingly, Gordon thought that if he arranged 8 or 10 objects into small groups that the Piranha~ would have increased difficulty in matching the arrangement. In fact, they performed well in that matching task. Apparently in that task, they could match two or three at a time. Finally, it is known that persons are able to make reasonably good estimates of large amounts of single objects —such as a pile of crushed nuts —estimates that do not employ counting. The Piranha~ were poor at such estimations, but their estimates were not random. Gross judgment of amount was partially intact.
Thinking in words works better for most situations in our world. Thinking in words does not abolish thinking in visual, touch, or postural images. But thinking in words or fragments of words tends to dominate thinking in images, for various reasons. Although a single gesture or picture may sometimes be worth a thousand words, thinking in words is generally more efficient and precise. Even American Sign Language is predominantly a form of thinking in words, although the medium is gestures and vision. 65
Complete Myelination of the Major Sensory Tracts to the Cerebral Cortex
I have proposed that complete myelination of three sensory tracts —the visual, the somatosensory, and the auditory —probably play a role in basic cognitive shifts. Electrical impulses conducted by each of these three tracts activate synaptic relays of their own specific nuclei in the thalamus 66 that then transmit electrical impulses to the cells of their own primary sensory areas —their principal entry points into the cerebral cortex. The thalamus is a complex way station between these specific sensory tracts and the cerebral cortex.
In addition to the specific sensory tracts for vision, touch, and hearing, nonspecific tracts transmit impulses from the thalamus to the cerebral cortex and from the cerebral cortex to the thalamus. The nonspecific thalamocortical tracts are completely myelinated at about age 7 (Yakovlev & Lecours, 1967), just before the Concrete Operational Period. Complete myelination of these nonspecific tracts stabilizes the relationship between the thalamus and the cerebral cortex. After that, all of the input routes through the thalamus to the cerebral cortex are basically set.
After age 7, the cerebral cortex, itself, still retains considerable plasticity. For years to come, myelination is incomplete for many tracts between and within different areas of the cortex. For this reason alone, much change of the neuronal circuitry of the cerebral cortex takes place after age 7. However, once the nonspecific thalamocortical tracts are completely myelinated, the opportunity for the three major sensory tracts to find an alternate route through the thalamus to the cortex is basically cut off.
The complete myelination of the nonspecific thalamocortical tracts essentially closes out a final avenue for change, as well as for feedback from the cortex. The nonspecific thalamocortical tracts can no longer be co-opted by the visual, touch, or auditory peripheral sense systems. Some of the mechanisms that the child has available to build certain ideas about physical and social objects and their attributes are basically stable. What remains is use of, or correction for, input to schemes that are reliably segregated by edges and movement of activation of the three sensory systems, as the child (or more precisely, his cognitive-emotional organizations) continues to interact with the world.
After this myelination is complete, overall organization of sensory schemes that has worked for that child in that child’s setting will persist. The kind of organization will differ, however, based on what has worked for that child in his particular early setting.
It is not be surprising that the Roman Catholic Church wants the child by age 7; that children who become blind before 7 experience no visual imagery, awake or dreaming (Blank, 1958); and that cerebral hemispherectomy after about 7 is problematic. 67
My Hypothesis
My hypothesis that complete myelination of the three specific thalamocortical sensory tracts assists and possibly induces cognitive reorganizations is an example of how timing of a type of maturation of the brain probably interacts with cognition. It explains how maturation of the nervous system could influence psychological function.
Myelination is particularly suited to play such a role, especially in view of Merzenich’s (1998) finding that the first stimuli to arrive in a brain area stake a claim, and that maintenance of that claim is a the result of competition with stimuli from neighboring neurons. See chapter 1, Footnote 13. 68
I have proposed how complete myelination of the visual, somatosensory, and auditory tracts could be expected to influence two major cognitive reorganizations —how maturation of the brain would help to reorganize cognitive development. My proposal is an attempt to integrate four domains of knowledge. These are, first, what we know about the timing of full myelination of these tracts; second, what we know about the operation of the cells of the primary sensory areas of the cortex; third, what we know about the development of cognitive structures as described by Piaget; and fourth, what we have recently learned about the development of language. My proposal does not preclude the influence of other factors.
Based on current knowledge, my proposal is reasonable. Reasonable proposals are not necessarily correct. As we learn more about neural maturation, about the neurophysiology of sensory processing, about cognitive restructuring, and about the development of language, it will be necessary to modify my proposal.
Studies of sign language raise a question about the significance of myelination of the tracts from the cochlea to the auditory area of the brain in development of language. Clearly in congenitally deaf children, complete myelination of the auditory tract has little relevance to acquisition of sign language.
It is argued that sign languages are complete languages. Sign languages are composed of bits that correspond to what may be understood as the syllabic, morphological, and syntactic aspects of spoken language (Hickock, Bellugi, & Klima, 2001). Additionally, the acquisition of a sign language roughly parallels the acquisition of a spoken language —that is, syllabic babbling, first words, and two word combinations, each, appear at about the same age, whether the child’s native language is signed or spoken (Petitto et al. , 2000). And in deaf signers, Hickock, Bellugi, and Klima (2001) found that brain damage of areas of the left cerebral hemisphere resulted in expressive and sensory aphasias of sign language, much like aphasias found in hearing patients with corresponding lesions in the left hemisphere. In deaf subjects, however, viewing someone sign words activates the auditory areas bilaterally —not just the left auditory area (Petitto et al. , 2000).
Thus far, the investigations of sign language have not shown that the auditory area is somehow preordained for processing language —that the area is a preordained symbol processing module. That it becomes so, is evidenced by studies of adult aphasics. These studies do not show that the auditory area, particularly the left auditory area, is absolutely designed to become so. F inding that in congenitally deaf adults the volume of the left primary auditory cortex is larger than right comparable region, as is true for hearing adults, suggests that left lateralization of auditory processing of the cerebral cortex has a genetic component (Penhune et al. , 2003). However, i t remains possible that language is primarily a natural consequence of the fact that we have a large amount of association cortex in our brains and that we interact with a culture that evolved over time.
This would be consistent with the finding that chimps can be taught sign language at about the level of a 3-year-old child, and that monkeys cannot be taught sign language. Chimps have less association cortex than we do, and monkeys have even less. It also is consistent with the finding that left hemispherectomy in the young child does not compromise language development. Assimilation and accommodation by schemes with sufficient potential crossmodal, associative, connections could account for the similar timing of appearance of babbling, of first words, and of two word combinations, regardless of whether the child’s culture uses sound and speech or gesture and sight to communicate. Nonetheless, as more is known about the relationships between development of language and the brain, investigators will discover what role brain morphology plays in language function’s usual location in the left auditory area.
Complete myelination of the auditory tracts to the auditory area, also, does not explain Head’s and Luria’s finding that adults with lesions to the left parieto-occipital area manifest semantic aphasia (Goldberg, 1999). Semantic aphasia is characterized by disruption of comprehension and expression of spatial and temporal relational constructions. Such adults have difficulty dealing with below versus above, to the right of versus to the left of, before versus after, smaller versus larger, and/or taller versus shorter. These are all bits and pieces that typify Concrete Operational cognition. This lesion study does not contradict my thesis that complete myelination of the tracts to A1 assists understanding of smaller and larger, and so on. The lesion study shows that part of the cerebral cortex that is downstream from A1 plays a role in these understandings, and that such understandings are space-committed in an adult.
One thing appears certain. Without complete myelination of the three sensory tracts to their entry ports —V1, S1, and A1 —into the cerebral cortex, any functions downstream from the entry ports —whether they involve subsequent maturation or learning —operate with less-organized input. At this point in our understanding of brain-mind interaction, complete myelination of the three sensory tracts appears to assist two reorganizations of cognitive development.
Chapter 9, which centers on the formation of character structure, is a continuation of chapters 6 and 7. My theory of the formation of character structure fits the hypothesis that, ordinarily, complete myelination of the auditory tract would assist the cognitive reorganization that begins in the Intuitive Phase and remains unsettled until sometime in the Concrete Operational Period.
However, before proceeding to chapter 9, in chapter 8 I will return to some tag ends of subjects that I dealt with in earlier chapters. These involve conscious and unconscious processing, memory storage and retrieval, and potential objections to my theory of the formation of consciousness.
56 In chapter 3, I used A1 to refer to an arbitrary neuron when I illustrated how complete myelination stabilizes downstream neuronal connections. A1 should not be confused with A1, which designates a particular area of the cerebral cortex. This area is composed of many, many neurons.
57 Without considerable equilibrium with the surround, life could not exist. Of course, not all that we do is survival-related. In addition, many parts of our genetic repertoire are happenstance —once they are included in our genome they abide, as long as they do not kill us before we reproduce.
58 Even if the rat’s auditory cortex was lesioned bilaterally, Ledoux (1996) could still condition the rats to the tone. Apparently, the cerebral cortex is not essential to fear conditioning in rats. The auditory part of the thalamus has a direct connecton to the amygdala. When Ledoux lesioned that part of the thalamus or lesioned the amygdala, itself, the rats’ ability to be conditioned to the tone was "lost". Berridge (2003) cites findings that rats that had their amydalas lesioned could be still be conditioned to a cue that heralds a shock, provided they were subjected to many more trials. Hence, damage to the amygdalas does not eliminate fear conditioning. But such damage eliminates rapid, conditioned response to danger.
59 "Many nonhuman species from primates to rodents…display facial affective reactions to taste with a degree of similarity to human expression that corresponds closely to their…evolutionary distance from humans" (Berridge, 2003b).
60 Piaget (1981b) wrote about emotion similarly. As I noted earlier, he argued that cognition and emotion never occur one without the other. He also contended that emotion is not the standard starter of scheme activity, although at times he contradicted himself, saying that emotion provided the gas for the car and cognition provided the steering. As is clear from chapter 1, once a scheme has been active, an approximation of that scheme will tend to be reactivated as long as the brain is physiologically turned on. Other theorists, including Freud and some of his disciples, proposed that cognition derived from affective —emotional —energy. That cognition may tame emotion at times can be observed. But, that does not mean cognition is tamed emotion. My position agrees with Piaget’s usual position —that emotion, although always in play, is not the source for cognition.
Although operating as a guide or a selector, emotion plays a role in incremental change, it may have profound effects on thinking and behavior. The tenth child in a sibship of ten lost his next two older brothers and his father in a plane crash. After that, he seemed to chart his own course. He found reading interesting and pursued that. He basically never studied, and was never intimidated by his teachers no matter, what they did. "Nothing could be worse" than what had already happened. He became a comedian.
61 Like Piaget, Luria (1976) along with his colleague Vigotsky saw the shift from Preoperational to Operational cognition as a major reorganization. They proposed that environmental factors explained the shift in illiterate adults —that the illiterate adults passed from Preoperational, graphic thinking to Operational, categorical thinking and self-awareness under the impact of literacy and the collective. Like Cole —Luria’s translator —I question whether a true reorganization of thinking took place in these adults. Cole theorized that the change that Luria and Vigotsky found resulted from applying a previously available organization to new content. I would explain the cognitive change differently. I would propose that a second-order cognitive correction could have accounted for the changes that Luria and Vigotsky found. See chapter 6, Footnote 53. Second-order cognition is discussed more fully in chapter 9.
62 Perhaps a bit later for the somatosensory tract.
63 Nelson and Kessler Shaw use the term symbol differently than Piaget did. As I noted earlier, Piaget used symbol to refer to something that resembles the absent object in some way. He referred to words as signs, because their relationship to what they represent is arbitrary.
64 They resemble a Preoperational child. Additionally, efforts to teach a number system to the children succeeded, but failed with adults (Holden, 2004).
65 Using a series of image schemes works more effectively when we think about finding something we have lost, about taking a complicated path, about using a map, about learning to make a turn when skiing, or about assembling a chair. We can, however, use organizations of words to think about these actions as well. Some people tend to do this, although visualizing or feeling kinesthetically how one is going to do such tasks is probably more efficient.
66As I noted in chapter 4, Footnote 34, the thalamus is situated in the center of the brain , surrounded by the cerebral hemispheres, the outer surface of which is the cerebral cortex. The thalamus is composed of a number of discrete nuclei that coordinate activity between various parts of the central nervous system.
67 As I noted in chapter 1, hemispherectomy —the removal of an entire cerebral hemisphere —is sometimes done to control intractable epilepsy. If the surgery is done early enough in development, it results in very little impairment. Speech and motor control are unaffected. The affected side of the body —the side that is opposite to the missing hemisphere —may be a bit smaller than the unaffected side of the body.
68 Merzenich also, using differential rewards, trained a monkey to alternate which finger it used to respond to a stimulus. He then trained the monkey to alternate its finger responses faster and faster. At a certain point, the monkey ceased using its fingers separately and used its whole hand like a mitten. That is, at this point, the monkey failed to distinguish among its fingers. Merzenich found that the brain area activations that ordinarily corresponded to the individual fingers had become undifferentiated. So speed of transmission —which myelination enhances —is of special importance in the dedication of brain areas and brain function. Complete myelination under ordinary circumstances closes the door to early competing neurons in the vicinity that conduct stimuli from adjacent fingers. Yet the door may be forced open by a maneuver such as the one that Merzenich performed.
< Chapter 6 | Contents | Chapter 8 >
Do you have a comment or would like to open a discussion? The author would be pleased to hear from you. Contact AJ Malerstein here.
