Related Ideas of Others
Donna G. Stevenson <dgstevenson@mac.com>: This page is part of a document, titled Brain-Quadrant Integration, which examines whether imbalanced use of four parts of the brain, the left and right neocortex and limbic system, could be the source of focused intelligence, learning and mental disorders, and autism.
This page describes the long history of theories that include the idea of imbalances causing disorders, including Hippocrates and Geschwind. It discusses how one brain hemisphere can inhibit the other side from taking over functions; this would explain why we shouldn’t expect plasticity of the brain to repair imbalances. It also discusses how imbalanced development of the brain might occur, such as through the heterochronic process of neotony.
When I first wrote up my ideas about imbalances in development causing mental disorders, I was inspired by Ned Herrmann’s (1988, 1996) work on personality types. I knew that his work must draw on centuries of descriptions of personality as developed from four parts, but I didn’t see anything that connected this with mental or learning disorders. As I have continued investigating, I found that there are aspects of this that have a long history.
In the ancient Greek medical model as shown in the Hippocratic corpus, the hypothesis is that “Mental disturbances come from humoral imbalance, and the [4] humors in turn are influenced by these external factors.” (Simon, 1978, p. 48) “These crucial vitality-sustaining juices were blood, scholer (or yellow bile), phlegm, and melancholy.” (Porter, 2002, p. 37) Though clearly the details about the ‘juices’ isn’t likely to be correct, the main idea about the imbalance seems to me to be at the center of what I am proposing. So, if I am correct, it could be said that I have only rediscovered the same idea.
A detail that the Brain-Quadrant Integration theory rests on is that the different halves of the brain have different functions. “Asymmetries in hemispheric function were first discovered in the nineteenth century by observers who noted the differing effects of injury to the left and right halves of the brain.” (Springer and Deutsch, 1989, p. xi)
Researcher Andrew Young (1983) wrote:
It is clear, then, that the ideas of perfect equipotentiality and bilaterally symmetric organisation of cerebral functions in infancy are false. The cerebral hemispheres of the infant’s brain are both structurally and functionally asymmetric. (p. 152)
Linking this laterality to mental and learning disorders is a very mainstream idea. “One of the first attempts to link psychopathology with a model of hemispheric specialization was made by psychiatrist Pierre Flor-Henry about 20 years ago.” (Springer and Deutsch, 1989, p. 277)
I’ve seen many suggestions in the literature that the issue of laterality of brain functions is at the heart of different disorders. “There is an extensive literature on the relationships of psychiatric disorder laterality.” (Geschwind and Galaburda, 1987, pp. 209)
Diverse problems such as learning disabilities, stuttering, and schizophrenia have been associated with speculation about abnormalities in the division of labor between the two hemispheres. (Springer and Deutsch, 1989, p. 7)
These and other findings have led to the hypothesis that the right hemisphere is more involved than the left in producing “negative” emotions, whereas the left hemisphere is more involved than the right in producing “positive” emotions. The idea of hemispheric asymmetry for the production of emotions suggests the possibility that emotional disorders are associated with unusual aspects of hemispheric asymmetry. (Hellige, 1993, p. 246)
Although there has been far more work with schizophrenics than with patients with other forms of psychopathology, it should be noted that it has been hypothesized that other psychopathologies are also related to unusual aspects of hemispheric asymmetry. (Hellige, 1993, p. 250)
One theory that is based on this lateralization was reported by researchers Geschwind and Behan (1982) and later elaborated upon, including a book by Geschwind and Galaburda (1987) titled Cerebral Lateralization. In it they wrote:
If the growth of one portion of the hemisphere is delayed, then other regions will be larger than they normally would have been. When this increase in size is marked, superior or even remarkable talents may develop. (pp. 65-66)
Individual patterns of brain dominance have important biological associations, such as increased susceptibility to certain disorders and a higher likelihood of possessing certain talents. (p. 67)
In an overview of Geschwind’s theory, researchers McManus and Bryden (1991) wrote:
In Figure 1 it is clear that there is a broad cluster of terms which have been called “learning disorders,” all of which are presumed to share a common mechanism (so that, for instance, autism and dyslexia are both derived by a similar mechanism, of which delayed left posterior hemisphere growth is the principle one). (p. 250)
Geschwind’s work has many of the same elements that I’ve discussed. It has atypical brain development causing both disorders (including autism) and giftedness. A main focus of that work involves the role of testosterone as the mechanism for atypical brain development, and my theory doesn’t include a particular mechanism. If I am correct, then Geschwind’s theory, which only focuses on cases where the right hemisphere is more developed than the left hemisphere, would be a special case, a subset, of what I am proposing.
My hypothesis is only a small step away from some of the current views - atypical brain development creating both gifts, mental illness, and learning disorders. What I would add to these views is to change the simpler two-hemisphere model to the slightly more complex quadrant model, and to suggest that overdevelopment of any part of the brain, not just the right hemisphere, could create these gifts and problems.
One comment that I received on an earlier version of this document was that the person didn’t think this theory could be true because they felt that the plasticity of the young brain would mean that it would naturally recover from imbalanced development of the brain. This is an excellent point, because at the far end of the spectrum, on a practical level, I am suggesting that there are cases of autism where someone may have excellent use of their fully-functioning right neocortex, and they are having difficulty with speech because of a poorly developed and/or poorly connected left neocortex (which is known to have a key component for speech).
I believe that our current understanding of the development of the brain would support the idea that plasticity wouldn’t change the development, because one hemisphere would inhibit the other hemisphere from developing that function. Researchers Hiscock and Kinsbourne (1995) wrote:
In the presence of an intact left hemisphere, speech production (but not comprehension) remains limited to the left side, even if the hemispheres are callosally disconnected. (p. 662)
It follows that both hemispheres have neuronal substrate for generating speech. The left hemisphere usually suppresses the right hemisphere’s speech potential by inhibitory interaction at the brainstem level (Kinsbourne, 1974c). Left brain damage may release the right hemisphere’s speech capability from inhibition. (pp. 562-563)
In fact, I have found that there are cases in which a left hemispherectomy has allowed patients to develop speech. An example is from a paper by Vargha-Khadem et al. (1997):
Case Alex, with Sturge-Weber Syndrome affecting the left hemisphere, failed to develop speech throughout early boyhood, and his comprehension of single words and simple commands remained stagnant at an age equivalent of 3-4 years. But then, following left hemidecortication at age 8.5 years and withdrawal of anticonvulsants when he was more than 9 years old, Alex suddenly began to acquire speech and language. [Whole quote was italicized.] (p. 159).
Researcher Andrew Young (1983) wrote:
The right hemisphere, then, can show considerable ability to support language in the face of left hemisphere injury, but it does not attain the same level of linguistic competence as an uninjured left hemisphere. (p. 162)
So, a fully functional left neocortex would suppress the right side’s ability for speech, a damaged left neocortex might allow for speech controlled from the right side, and the removal of the left neocortex should allow the right hemisphere to take over the speech function. This leads me to conclude that even an underdeveloped and/or underconnected quadrant of the brain should still be able to inhibit the latent ability of the opposite hemisphere.
In the Brain-Quadrant Integration theory, I do not attempt to explain important details such as why imbalanced brain development might occur. In this section, I try to show that there are possible answers that could be compatible with this theory.
In a general sense, if the imbalanced development does occur, then there seems to be some things that would point us in the right direction. One is the issue of gender. “When it comes to gender, the consistent story has been that men and women have nearly identical mean IQs but that men have a broader distribution.” (Herrnstein & Murray, 1994, p. 275) “Waber (1976) noticed that girls gained physical maturity much earlier than boys (with an approximate 2-year advantage over the male gender; thus she reasoned that differences in cortical organization would arise from these maturational changes.” (Iaccino, 1993, p. 141). Simon Baron-Cohen (2003) is an advocate of autism being an extreme form of maleness. All of this points to the idea that we may learn something by looking more closely at the differences in development between males and females.
Another aspect to consider is that dogs are very much like us. They are prone to the same types of psychological illnesses, and many dogs are geniuses at narrowed occupations. I will admit that I like dogs so much that I sometimes ponder the idea of a co-evolution in which humans picked out quirky dogs who liked to spend time with humans, and dogs made successful those quirky humans who liked to spend time with dogs. Putting my dog fantasy aside, I do think their nature can give us clues to our own.
More specifically, one aspect to consider is what is meant when I use the word ‘develop’. In this, I’ve gone forward with the idea that if there is a pattern of parts of the brain developing together, someone will figure out what aspect of development causes it. I have read some interesting work by researcher George Bartzokis (2005) which implicates issues of myelination in the development of autism and other disorders such as ADHD and schizophrenia. His concern, though, seems to be with the “very vulnerable myelination process” (p. 71), and environmental issues, which would seem to take his work in a different direction from what I am suggesting. Myelination may be that aspect of development which this Brain-Quadrant Integration theory rests on, but I don’t know enough to attempt to judge how this aspect of development would fit with the rest of what I am proposing.
Looking at the issue from a different perspective, since there is a large heritable component to intelligence, one would wonder how that modification in development would occur. Issues of heterochrony seem to fit what we know, “Essentially, heterochrony can be defined as change to the timing and rate of development.” (McNamara, 2002, p. 1) and “slight changes in growth rates or timing at critical periods of development can, with very little genetic change, produce profound phenotypic effects” (McNamara, 1997, p. 18)
Complicating this is that cells that aren’t connected enough die off. “Heterochronically, this discussion [about neural competition and regression] lead to the notion that changes in the rate and timing of neural development may not only affect the number of nerve cells but may alter patterns of connectivity as well.” (McKinney and McNamara, 1991, p. 287)
It has been argued that aspects of heterochrony have been key in the development of humans.
Montagu (1981) in particular wrote a book, Growing Young, which had the basic premise that we owe virtually all of our cultural capabilities to neotenic retention of juvenile ape characteristics: curiosity, educability, and many others, such as optimism and honesty (Table 7-2). (McKinney and McNamara, 1991, p. 309)
McKinney and McNamara (1991) argue against this by saying that this would mean that we would have deficits compared to our ancestors.
Here we encounter the truly crucial distinction between neoteny and hypermorphosis: the former is a process of paedomorphosis such that the descendant adult (us) never attains behaviors possessed by the ancestor. In stark contrast, hypermorphosis is a process of paramorphosis such that the descendant adult goes beyond behaviors of the ancestor. (p. 309)
I agree that reading Growing Young by Ashley Montagu (1989) might leave one with the idea that neotony could not produce the exclusively expanded abilities that he talks about. His view of children is exceedingly positive, and he completely rejects the idea that there are also negatives attached to this childlike nature.
I am not speaking of those qualities we visit upon the child and to which we pejoratively refer as “childish,” for most of those allegedly childish traits, such as whining, crying, temper tantrums, and the rest, are conditioned in children by the adults whose charges they are. (p. 95)
If you add back in the idea that deficits, which might lead to a vulnerability to temper tantrums, etc., would be the natural result of neotenous development, then neoteny seems to be the ideal heterochronic process to produce the kind of uneven development, and vulnerability to disorders, which is postulated by the Brain-Quadrant Integration theory. This would answer McKinney and McNamara’s objections to neotony since it would show that ‘the descendant adult (us) never attains behaviors possessed by the ancestor’.
Changing to an even smaller level of detail would be in identifying the key genes involved. Though I have no idea of what they might be, I was very interested in the news stories about researcher Bruce Lahn and colleagues who have studied two genes, called microcephalin and ASPM, that might be involved in the evolution of the brain. The press release about this from The University of Chicago Hospitals stated:
Each variant emerged around the same time as the advent of "cultural" behaviors. The microcephalin variant appears along with the emergence of such traits as art and music, religious practices, and sophisticated tool-making techniques--which date back to about 50,000 years ago. The ASPM variant coincides with the oldest-known civilization, Mesopotamia, which dates back to 7000 BC. (Gianaro, 2005)
This time frame is also consistent with the work of archeologist Richard Klein (2002) who wrote The Dawn of Human Culture with Blake Edgar. “The fourth and most recent event [proposed to lead to the dawn of modern culture] occurred about 50,000 years ago and it was arguably the most important of all, for it produced the fully modern ability to invent and manipulate culture.” (pp. 23-24) and “Arguably, the most plausible cause was a genetic mutation that promoted the fully modern brain.” (p. 24)
Lastly, there is the idea of understanding the environmental influences. Researchers Geschwind and Galaburda (1987) wrote
Our thesis is that although genes contribute importantly, many influences that lie outside the gene pool of the fetus can alter lateralization patterns. The most powerful factors are variations in the chemical environment in fetal life and, to a lesser extent, in infancy and early childhood. (p. 10)
Though genetics may be the key to understanding our history and what makes us different from other species, on a personal level, I suspect that our DNA doesn’t define our personality and intelligence as completely as I might have once supposed. When we ponder the question of why we succumb to mental illness, or why we are gifted, the seeds of that difference may be within the early environment.
Clearly, even if the Brain-Quadrant Integration theory were true on some high level, it would not answer all the questions related to intelligence and disorders. In this section, I have tried to show that there is work by others which may fit into the overall picture that I am describing.
Baron-Cohen, S. (2003). The Essential Difference: The Truth About the Male and Female Brain. New York, New York: Basic Books.
Bartzokis, G. (2005). Brain Myelination in Prevalent Neuropsychiatric Developmental Disorders: Primary and Comorbid Addiction. Adolescent Psychiatry, 29, 55–96.
Geschwind, N., & Behan, P. (1982). Left-handedness: Association with Immune Disease, Migraine, and Developmental Learning Disorder. Proceedings of the National Academy of Science, 79, 5097-5100.
Geschwind, N. and Galaburda, A. (1987). Cerebral Lateralization: Biological Mechanisms, Associations, and Pathology. Cambridge, Massachusetts: The MIT Press.
Gianaro, C. (September 8, 2005). University of Chicago Researchers Find Human Brain Still Evolving. Press release. Retrieved October 26, 2006, from http://www.uchospitals.edu/news/2005/20050908-humanbrain.html.
Hellige, J. B. (1993). Hemispheric Asymmetry: What’s Right and What’s Left. Harvard University Press: Cambridge Massachusetts.
Herrmann, N. (1988). The Creative Brain. Lake Lure, North Carolina: Brain Books.
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Hiscock, M. and Kinsbourne M. (1995). Hemispheric Asymmetry for Components of Visual Information Processing. In R. Davidson & K. Hugdahl (Eds.), Brain Asymmetry (pp. 100-121). Cambridge, Massachusetts: The MIT Press.
Iaccino, J. F. (1993). Left Brain-Right Brain Differences: Inquiries, Evidence, and New Approaches. Hillsdale, New Jersey: Lawrence Erlbaum Associates, Publishers.
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Klein, R. G. and Edgar, B. (2002). The Dawn of Human Culture. New York: John Wiley & Sons.
McKinney, M. L. and McNamara, K. J. (1991). Heterochrony: The Evolution of Ontogeny. New York and London: Plenum Press.
McManus, I. C., & Bryden, M. P. (1991). Geschwind’s Theory of Cerebral Lateralization: Developing a Formal, Causal Model. Psychological Bulletin, 110 (2), pp. 237-253.
McNamara, K. J. (1997). Shapes of Time: The Evolution of Growth and Development. Baltimore and London: The Johns Hopkins University Press.
McNamara, K. J. (2002). What is Heterochrony?. In N. Minugh-Purvis & K. McNamara (Eds.), Human Evolution through Developmental Change (pp. 1-4). Baltimore and London: The Johns Hopkins University Press.
Montagu, Ashley. (1989). Growing Young. New York: Gergin & Garvey Publishers.
Porter, R. (2002). Madness: A Brief History. Oxford: Oxford University Press.
Simon, B. (1978). Mind and Madness in Ancient Greece: The Classical Roots of Modern Psychiatry. Ithaca and London: Cornell University Press.
Springer, S. P. and Deutsch, G. (1989). Left Brain, Right Brain. New York: W. H. Freeman and Company.
Vargha-Khadem, F., Carr, L. J., Isaacs, E., Brett, E., Adams, C., & Mishkin, M. (1997). Onset of Speech After Left Hemispherectomy in a Nine-year-old Boy. Brain, 120, 159-182.
Young, A. W. (1983). Development of Right Hemisphere Abilities. In A. Young (Ed.), Functions of the Right Cerebral Hemisphere (p. 147-169). New York: Academic Press.
Brain-Quadrant Integration
