A central aspect of the study of cognition lies in the differentiation between various major regions in the brain. The major three physiological regions display a marked difference in function as well as purpose. An increased reliance on higher technology through the phylogenetic progression of function through these brain regions leads to amelioration of interconnected human needs. This progression is continuing in modernity to include metasyntactic representations of thought as well, which I describe herein as the “fourth brain.”
In his book The Triune Brain in Evolution, Paul D. MacLean draws distinctions between the three major areas of the brain as the “reptilian,” the “paleomammalian,” and the “neomammalian.” These correspond to the cerebellum, limbic system, and cerebral cortex, respectively. Each of these areas control a set of functions, with higher technology areas of the human brain corresponding to phylogenetically younger areas.
Abraham Maslow proposed a hierarchy of human needs with which to model the interplay between physical, emotional, and social needs in a human. His model is typically presented as a pyramid with physiological and safety needs at the base, love and esteem needs above physical, and self-actualization needs at the peak. These distinctions are more clearly drawn, however, in the connectivist model presented by Levine in Neurodynamics of Higher-level Cognition and Consciousness (4). This model constructs a triune system of mutually inhibiting, self-exciting drives, with the same hierarchicalized relationship between the divisions as presented in the pyramid. Physiological and safety needs are the most self-excitative, with love and esteem needs taking lesser precedence, and self-actualization taking the least. These three function groups, however, correspond to each of the MacLean brain areas.
The oldest area of the human brain is the cerebellum, or reptilian brain. In genetically younger species, such as the fish, this area “… is concerned generally with posture, muscle tone, and coordination in a manner similar to cerebellar function in phylogenetically higher vertebrate groups.” (Goodman 33) Reptiles and other amphibians share this trait, but in humans, most of these functions are outsourced to higher areas. Many aspects of human motor control take place in the cerebral cortex, specifically the somatimotor areas. These control directed, voluntary, autonomous action, while lower-level muscle control remains largely with the cerebellum. This area roughly corresponds to the physiological and safety Maslowian needs, including the interplay with self-actualization and emotional needs.
The limbic system, known also as the paleomammalian or rhinocortex, is largely responsible for the emotional self: fear, hunger, anger, laughter, crying, and individuality (MacLain 1970, p.339). This area aids in developing a sense of individuality, the convergence-point between our internal and external worlds. This requires memory, which is also coordinated (though not entirely controlled) by the limbic areas. Nauta described Jacobsen’s experiments on decerebriated primates, that:
“The initial impression that the ‘frontal animal’ suffers from a memory loss, and while waiting for the screen to go up ‘forgets’ where he saw the food being hidden, has been effectively refuted, and it now seems certain that frontal-lobe ablation affects a response-guidance other than memory in the customary sense… ‘frontal’ monkeys [also] show an increased tendency to prefer any novel object over a tried, familiar one, even if the experiment is so arranged that the choice of a novel object is never rewarded.”(168)
Memory in this manner is required for both safety and self-actualization, though retains coordination through the limbic areas. This is a feature of the limbic functions of phylogenetically younger species in which the function of the limbic areas was largely associated with the smells by which an animal would identify members of its home or rival packs, families, and food sources. In phylogenetically higher species, these differentiations take place through higher senses of sound and sight, but smell and emotion still play large roles in memory reconstruction.
The cerebral cortex, the phylogenetic pinnacle of human evolution, is largely responsible for most of the cognitive, linguistic, and social traits axiomatic to our definition of our species. These areas correspond to Maslowian self-actualization, social, and intellectual needs. As with most attributes of biology, we know best how these things work by studying how they break. Most functions of the cerebral areas are still being studied, and debates are consistently fueled with new evidence for various areas controlling various behavior aspects, but some gestalts are already prevalent, presented through the cases of Ferrier’s decerebriated animals, and Phineas Gage.
Early in the 19th century, Sir David Ferrier evaluated the function of various vertebrates when deprived of their cerebral cortices. (MacLean 90) In fish, he noticed a lack of schooling behavior as well as a lack of interest in mates or mating. Those behaviors notwithstanding, they still behaved as normal fish. They still swim, maintain equilibrium, display coordinated motion, and can respond to some sensory stimulation. In higher vertebrates, however, he observed a complete lack of spontaneous, directed behavior. Decerebriated frogs, cats, and dogs would respond to external stimulus, but otherwise would simply sit and die. By knowing fully neither pain nor pleasure, with no capacity to fully reconstruct causal memory necessary for survival, they would interact as high vertebrates but die of starvation unless force-fed.
Likewise, the story of Phineas Gage presents an example of prefrontal cerebral cortex function. Involved in an accident while tamping blasting powder in the construction of a railroad, Gage was met with his iron through the front of his skull. With considerable damage to his prefrontal areas, his previously refined, tactful, and organized social behaviors became lewd and scattered. Much like Ferrier’s vertebrates, Gage presented a deficiency in socially directed behavior after damage to the social processing areas of his cerebral cortex. All of his linguistic capacities were intact, as well as his memory, but he couldn’t function as a member of any society for the remainder of what was a tragically short life.
The function of the cerebral cortex, then, most closely correlates with Maslowian self-actualization needs: the ability to perform creatively, with directed, spontaneous action to solve problems as presented.
As societies evolve through industrialization, self-actualized humans are becoming increasingly dependent on external technology to meet emerging human needs. In order to be a productive member of the modern society, people are increasingly required to externalize memory and processing capabilities. In his article The Downside of the Outboard Brain, Merlin Mann presents a startling survey:
This summer, neuroscientist Ian Robertson polled 3,000 people and found that the younger ones were less able than their elders to recall standard personal info. When Robertson asked his subjects to tell them a relative’s birth date, 87 percent of respondents over age 50 could recite it, while less than 40 percent of those under 30 could do so. And when he asked them their own phone number, fully one-third of the youngsters drew a blank. They had to whip out their handsets to look it up. (1)
This practice of externalizing isn’t limited to memory, however. This generation of Americans consistently performs more poorly than many first-world countries on standardized math exams. These forms of externalized metasyntactic representations, whether supplanting mathematical reasoning or rote memorization, are becoming increasingly commonplace as a basis for recall and some forms of reasoning.
These functions, which for the majority of human history have taken place in the cerebral cortex and limbic areas, are now externalized. This externalization creates cognition through sociolinguistic apparata, causing Brocha’s and Wernicke’s areas to bridge the same functional gap between the cerebral cortex and externalities as the anterior cingulate, orbital prefrontal, and dorsolateral areas bridge between the cerebral cortices and the limbic areas. This simultaneously causes knowledge work to be more prevalent through natural ease in manipulation of linguistic structure, but also appears to cause deficiencies in regions which in earlier generations would process this sort of data.
Through each phylogenetic succession, various functions become more or less necessary for survival based on both the technology they employ and the competitive advantage they grant to members of an overwhelmingly sexually dimorphic species. This is the driving force of evolution: those who are best fit to capitalize on their environments, both internal and external, are those whose genetic material is passed on to successive generations. This same force drives the outsourcing of behaviors to phylogenetically newer and more advanced brain regions.
When a member of a species begins this process of outsourcing during its lifetime, some functions will atrophy, and others will creatively fill in. In a neurological sense, the latter takes place through plasticity: the brain’s ability to adapt to new surroundings and cognitive domains.
The environmentally competitive path of adaptive memory systems, which began with muscle control, became overwhelmingly limbic, then later grew to be shared with the cerebral cortex is now becoming a social externality based on these same drives. While the other three brain areas will always carry functions for memory, the most competitive form of capitalizing on this in modernity is through outsourcing to the higher technologies: axons have become silicon, and synapses the communications modality of digital text.
Goodman, Donald C. The Evolution of Cerebellar Structure and Function. American Zoologist 4 (1964): 33-36.
Levine, Daniel S., How does the brain create, change, and selectively override its rules of conduct? In R. Kozma & L. Perlovsky (Eds.), Neurodynamics of Higher-level Cognition and Consciousness. Heidelberg: Springer-Verlag, 2007, p. 4.
MacLean, Paul D. The Triune Brain in Evolution: Role in Paleocerebral Functions. Springer; 1 edition (January, 1990), pp. 520-526.
MacLean, Paul D. 1970 The Triune Brain, Emotion, and Scientific Bias. In The Neurosciences: Second Study Program. F. O. Schmitt, ed. pp. 336-349.
Mann, Merlin. “The Downside of the Outboard Brain.” http://www.43folders.com/2007/10/11/downside-ou… cited 14 December 2007.
Nauta, Walle J.H. “The Problem of the Frontal Lobe: A Reinterpretation.” Journal of Psychiatric Research 8 (1971): pp. 167-187.
The Gift of Speech and the Brain. Edward Podolsky. The Modern Language Journal, Vol. 25, No. 8 (May, 1941), pp. 595-597.
Copyright © 1998-2010 Dann Stayskal. Some rights reserved. Print this page.
