Finding the general relationship between the diagram of mental symmetry and brain regions is easy. Adding details to this is much more difficult. Therefore, we will look first at the big picture and then try to add some of the smaller pieces. I should warn that this section assumes that you know neurology and that you are familiar with the model of mental symmetry. But first, a bit of history.
I started my research in mental symmetry in about 1985 (I first encountered that specific model of cognitive styles in about 1980) when it grew out of a research project I was trying to do for a Master’s degree in Engineering. (That is when I first learned that the university system is not set up to handle interdisciplinary research, especially if it leads to a major paradigm shift.) To put a long story short, I taught myself neurology by reading about 200 tomes and going through a few thousand papers. (I did take one graduate class in neuropsychology which was quite basic compared to what I was doing on my own.)
As I mentioned, the big picture became apparent rather quickly. But, at that point the knowledge of the human brain was too limited to go that much further. Based upon the model of mental symmetry, I worked out some of the connections that had to be in place, and the neurological discoveries that have been made since then have been remarkably consistent with those predictions. This gives me confidence that neurology will not suddenly come up with some discovery that totally contradicts my model of the mind.
Every few years, I review the current findings in neurology in order to bring my knowledge up to date. Each time I discover a few more connections between the model of mental symmetry and the wiring of the brain, but each time I also find that uncertainties remain. So far, I have not found any contradictions, only uncertainties. Having said all of this, let us now look at the big picture.
The Big Picture
Here is the general mapping between cognitive styles and the brain:
The four simple styles (the ones in the corner of the diagram) appear to emphasize cortical thought, whereas the three composite styles (the ones in the middle of the diagram) use primarily subcortical processing. The diagram above looks at the four simple styles.
Neurology tells us that the back of the cortex interprets and stores sensory information, primarily from sight and sound. The frontal lobes, in contrast, are used to build an internal world of thought. Thus, the division between the internal and the external worlds is actually built into the human brain. MBTI® says that I/E, or Introverted/Extraverted is one of the four fundamental thinking categories, and reconciling the internal world of thought with the external world of sensation is one of the main dilemmas of philosophy. It is interesting to note that one of the main differences between human and monkey is the size of the frontal lobes. In the human, the frontal lobes are far larger than in the monkey.
The literature often talks about the frontal lobes having an inhibitory influence over behavior. I find this term rather annoying because it describes how the typical person treats his internal world. The ability to construct an internal world is what makes me human. It permits me to become an individual that is different and unique. It is part of what distinguishes me from an animal. But, instead of viewing the frontal lobes as our most precious possession, we tend to see the internal world as something that inhibits us from becoming totally immersed in the external world of physical sensation. Thankfully, this adjective is starting to fall into disfavor as we start to learn the function of the various aspects of the frontal lobes.
If you really want to find out what it means to lose your frontal lobes, then I suggest reading up on the frontal lobotomy. It makes for horrifying reading. The Wikipedia article is a good starting point.
For the four simple styles, it appears that:
Each of these four cognitive styles contains an automatic part in the posterior (or back) of the cortex that deals with sensory information. This part of the mind appears to develop automatically as information comes in from the senses and organizes itself.
Each of the four simple styles also uses part of the frontal lobes to construct an internal world of thought. It appears that this part of the mind does not develop automatically, but rather takes thought and effort.
Each of the four simple styles has a brain processor (like a computer CPU) that does the actual thinking. As the case of H.M. demonstrated, if a person loses all four of these brain processors, then he is incapable of learning any new information.
Let us begin by looking at automatic thought in the back of the cortex.
Perceiver thought is very clearly connected with the right parietal lobe. Based upon lesion studies (looking at functions that are lost when specific brain regions are damaged), it is known that the right parietal lobe works with maps, object recognition, spatial construction, and awareness of body and space. All of these correspond precisely to the function of Perceiver strategy.
Server thought is very obviously related to the left parietal lobe. Damage here leads to various kinds of apraxia, in which a person is unable to carry out sequences of action. Lesions here can also cause dysgraphia, in which a person has difficulty writing, and dyscalculia, problems with arithmetic. All of these functions correspond to the thinking of Server thought.
Here is a page that gives more information about the parietal lobes.
Teacher strategy is related to the left temporal lobe through language. Many aspects of language, such as comprehension, naming, word recognition and verbal memory are carried out by the left temporal lobe. If we look at the Teacher person, we find that his thinking is heavily dominated by words. It is very difficult for him to move beyond words to include other aspects of thought. Wernicke was the first to relate part of the left temporal lobe with speech back in 1874 and Wernicke’s area is still named after him.
Mercy strategy appears related to the right temporal lobe. Damage here impairs the ability to recognize musical tones and recall faces. This area is also activated when listening to emotional music. There is also an interesting link between this region of the brain and Near Death Experiences and feelings of religious ecstasy. We know that the Mercy person is very sensitive to non-verbal language, is aware of faces and that personal identity appears to be located within Mercy thought. Finally, my postulate is that an image of God emerges as the universal understanding touches personal identity within Mercy thought.
Before we go on, notice the underlying symmetry. According to the diagram of mental symmetry, Teacher and Mercy are opposites, as are Server and Perceiver. If you take a Perceiver trait, for instance, and replace space with time, you end up with a corresponding Server trait. Similarly, even though the Teacher and Mercy persons are extremely different, every personality trait of the Mercy person seems to have a corresponding version in the Teacher person.
For instance, the Mercy person identifies with experiences, while the Teacher person identifies with theories. Both the immature Mercy person and the immature Teacher person can act as emotional dictators. The Mercy person will talk about love, but he is the one who defines love, and he gives or withholds love in order to make sure that his definition of love is accepted by others. Likewise, the Teacher person talks about universal understanding, but he is the one who defines this understanding, and he gives or withholds theoretical information in order to make sure that his version of universal understanding is accepted by others.
We see this same symmetry in the physical brain. Server uses left parietal cortex, while Perceiver uses right parietal cortex. Teacher uses left temporal lobe; Mercy uses right temporal lobe.
Perceiver strategy processing appears to occur in the right hippocampus. The link between right hippocampus and spatial processing is quite strong. For instance, brain imaging was done on London taxicab drivers (who have to pass a difficult test on navigating through the streets of London in order to get a license) and their right hippocampus lights up when they are working with mental maps and working out paths to destinations.
Server processing uses the left hippocampus. The difference between left and right hippocampus is clearly illustrated by this paper. The left hippocampus works egocentrically: Turn left, go two blocks, then turn right and go 50 meters. This describes Server processing. The right hippocampus operates exocentrically: Here is the map; this is North; here is you; here is where you want to go. That is Perceiver thinking.
Teacher processing appears to occur within the left amygdala and Mercy processing within the right amygdala. We know that both the Teacher and the Mercy persons think emotionally. Neurology tells us that the two amygdalae are emotional processors. This is even mentioned clearly in the Wikipedia article.
Relating the left amygdala to the Teacher and the right amygdala to the Mercy is a little more difficult. The indirect evidence is quite strong: the left amygdala is within the left temporal lobe, which is related to Teacher thought, whereas the right amygdala is within the right temporal lobe, connected to Mercy thought.
In the past, papers such as this have basically connected the right amygdala with unpleasant feelings and the left amygdala with positive feelings. That is because Mercy feelings tend to be negative whereas Teacher emotion tends to be positive. However, papers are now appearing that specifically relate left amygdala to Teacher thought and right amygdala to Mercy thought (20 years after I discovered this connection from personality).
This paper says that the right amygdala is used for interpreting emotionally expressive faces, something that is definitely related to Mercy thought. This one says that the left amygdala is activated when talking about fearful situations, and this one specifically connects the left amygdala with verbal emotion. This paper goes beyond verbal emotion to suggest that the left amygdala is essential for ‘representing mental states’, definitely a theoretical type of emotion. And this paper says that there is left amygdala activity when a theory is being updated or violated.
I have suggested that emotion and confidence interact. This paper specifically states that the amygdala and hippocampus affect each other when emotion meets memory.
Let us summarize our conclusions so far:
Perceiver: Right parietal lobe and right hippocampus.
Server: Left parietal lobe and left hippocampus.
Mercy: Right temporal lobe and right amygdala.
Teacher: Left temporal lobe and left amygdala.
Before we continue, I would like to mention two general principles. Obviously the brain is far more complicated than the diagram of mental symmetry would suggest. How does this all this complexity relate to the concept that the cortex contains only four different modules?
1) The cortex is arranged hierarchically. This is the general consensus of neurology. As you move from the back of the cortex to the front, you find a series of regions, like steps on a staircase. At the back, both memory and processing are very specific. For instance, there are areas in the visual cortex that respond when your eyes see lines at a certain orientation at a certain place in the visual field. However, this specific information is then fed to the next area, which looks for combination of lines. The results of this are then fed forward to the next region, and so on.
Saying this more clearly, as you move forward, the following things happen:
- Processing becomes more multi-modal. In other words, information from sight, sound, taste, and touch is combined.
- Processing becomes more integrated. Instead of just looking for specific links, mental processing looks for connections between connections between connections.
- Processing becomes more internalized. At the back, all information comes from the four senses. (Smell enters the orbital frontal lobes.) At the front, processing is almost entirely independent of sensory information, allowing the mind to think about other times and places than the present. In other words, there is a progression from the external world to the internal world.
My premise is that what remains the same is the type of processing. For instance, at the back of the brain, Perceiver processing may be looking for connections between one specific visual Mercy image and another, while at the front it will be searching for a connection between one imaginary visual concept and another. However, what remains constant is the fact that Perceiver thought is looking for connections between Mercy images.
Thus, much of mental development involves moving from the back to the front of the brain by developing increasingly internalized ways of thinking. What happens when the growing mind does not develop more frontal and internalized ways of thinking? ADHD. This study, for instance, found that ADHD children who act impulsively use less of their cortex in general, and less of their frontal cortex, in specific.
2) The cortex integrates various modes of thought. In the back of the cortex, this is clearly illustrated by the angular gyrus, which lies between the parietal lobe and the temporal lobe.
In the left hemisphere, I have suggested that Server thought uses the left parietal lobe and Teacher thought uses the left temporal lobe. The left angular gyrus appears to be acting as a bridge between Teacher and Server thought, functioning as the ‘arrow’ in the diagram of mental symmetry that leads from Teacher to Server strategy. This area is important for mental arithmetic, reading and writing, and operates abnormally in dyslexia, both functions that combine Teacher and Server processing. (Thus, the dyslexic uses Perceiver thought to try to make up for a deficiency in Server processing.)
In the right hemisphere, Perceiver strategy uses the right parietal lobe and Mercy strategy is associated with the right temporal lobe. I have suggested that the interaction between Perceiver and Mercy thought generates self-image. Stimulating this region of the brain can lead to feelings of depersonalization, and damage in this general area can cause a person to neglect parts of his body.
- The left angular gyrus ties together Server and Teacher.
- The right angular gyrus ties together Perceiver and Mercy.
We have looked at the regions in the back of the brain that are related to Mercy, Perceiver, Server and Teacher processing. I suggest that each of these four modes is also related to a region in the frontal lobes.
A lot of confusing terms are used to describe the frontal lobes. The frontal cortex refers to all of the frontal lobes, whereas the prefrontal cortex describe the part that is in front of the motor strip. There are four main regions: the dorsolateral, the part of the frontal lobe that you see when looking at a brain, the medial, the part where the two hemispheres touch one another, the orbital, the bottom of the frontal lobes, and the polar, which is at the very front.
Here are two diagrams from Wikimedia that map out the various brain regions fairly clearly:
This is a lateral view of the brain:
And here is a medial view:
Let us look first at the basic connections from back to front in the brain. There is a major neuronal pathway, called the superior fasciculus, leading from the parietal lobes forward to the dorsolateral and medial frontal lobes, strongly suggesting that these regions of the frontal lobes are related to Perceiver and Server thought. Studies in the monkey show that the amygdala connects to the ventral and medial frontal cortex, but not the dorsolateral frontal cortex.
Put these two simple facts together, and you conclude that the dorsolateral frontal cortex is related to Perceiver and Server thought, the orbital frontal is related to Teacher and Mercy, while medial frontal activity involves an interaction between these modes of thought. That basically summarizes my hypothesis:
- Left dorsolateral frontal cortex: Server internal world.
- Right dorsolateral frontal cortex: Perceiver internal world.
- Left orbitofrontal cortex: Teacher internal world.
- Right orbitofrontal cortex: Mercy internal world.
- Left medial frontal cortex: Interaction between Teacher and Server
- Right medial frontal cortex: Interaction between Mercy and Perceiver.
It appears that, unlike the back of the cortex, the frontal lobes are not programmed automatically. Instead, information has to be permitted to enter the frontal lobes; it has to be placed within this area. As far as I can tell:
- Commitment places information into the internal Server world.
- Belief places information into the internal Perceiver world.
- Understanding places information into the internal Teacher world.
- Identification places information into the internal Mercy world.
Before we look at the details, I need to make a clarification. In the same way that research is only now beginning to distinguish between the left and the right amygdalae, so analysis of frontal cortex function is also only starting to differentiate between left and right regions. For instance, traditionally, most papers on the dorsolateral frontal cortex have treated it as a single system spanning both left and right hemispheres. However, with the advent of transcranial magnetic stimulation, papers are now starting to appear describing the difference between left and right dorsolateral regions.
I should mention that, to some extent, this mixing of the hemispheres does make sense:
- As one travels further to the front of the brain, modules appear to interact more heavily.
- Contributor thought does tie together Perceiver and Server strategies.
- Exhorter strategy bridges Mercy and Teacher thought.
- A situation can often be approached from either a left or a right hemisphere approach. The conclusions may be similar, but the approach is totally different.
Orbital Frontal Cortex
Now let us look at the details, beginning with the orbital frontal (also known as the orbitofrontal), which I suggest is related to the Mercy and Teacher. This area is heavily interconnected with the amygdala and the front part (the frontal pole) of the temporal lobe (regions also related to Mercy and Teacher).
Neurology clearly relates this region to the internal world of emotional thought. This paper, for example, connects the region with emotional perspective taking. It lights up when a person sees a beautiful face. Individuals with brain damage here are impaired at judging social appropriateness and may be completely lacking in knowledge about moral and social convention. It is an important area for processing personal reward and punishment, with more abstract rewards and punishments processed in the front of the region and more concrete ones in the back. One author describes it as the brain region that links reward to hedonic experience, definitely referring to the internal world of emotions.
This paper suggests that autism may be related to a dysfunctional orbitofrontal—amgydala circuit. The autistic person has problems interacting socially with other individuals, suggesting a deficiency in Mercy processing and in the internal Mercy world. He also has difficulty constructing a general understanding of his environment, indicating a problem with Teacher thought. Lacking an overall understanding, the autistic person must build understanding through the use of repetitive behavior or restrict himself to a limited environment.
Looking specifically at one hemisphere, this paper suggests that the left orbital region is related to feelings of anxiety. Anxiety is the type of emotion that arises when understanding is inadequate, suggesting that the internal world of Teacher thought is sensing pain.
Patients with right orbitofrontal damage are especially crippled at recognizing emotions in others, consistent with a deficit in the internal world of personal Mercy identification.
Dorsolateral Prefrontal Cortex
The classic way of testing for damage in this part of the brain is the Wisconsin Card Sorting Test. The patient is given a set of playing cards, each of which contains a certain number of shapes with different color and shape. The patient is then told to sort the cards but not instructed whether to sort them by number, color, or shape. Instead, he is simply given a feedback of right or wrong. Without telling him, the tester will change the sorting method several times through the test. A person with dorsolateral frontal damage will continue with his sorting strategy and not change to a new one. He may say, “I know that you are now sorting the cards by shape,” and yet continue to sort them by color.
This describes the function of the Perceiver and Server internal worlds. Internal Perceiver thought works out the facts, holds on to them as truth, and then uses these facts to determine behavior. Similarly, internal Server thought works out what to do, holds on to it, and then carries out this action. Talking about a plan involves Teacher thought. Carrying it out requires Server thought.
Which brings me to a personal peeve. I am a stubborn, idealistic Perceiver person who has devoted half of my life to working on a theory of the mind simply because I believe that it is true and I insist that truth will guide my behavior, even over the l-o-n-g term. In other words, as far as I can tell, my behavior has been heavily guided by content within dorsolateral frontal cortex, the area of the mind which I propose contains the internal world of the Perceiver and Server. In terms of the Wisconsin Card Sorting Test, while others have been using ‘color’ to sort their life cards, I have looked at my surroundings, concluded that ‘shape’ is the important factor and have continued for decades to ‘sort by shape’ even though everyone else continues to ‘sort by color’. Therefore, I get rather annoyed when researchers talk about dorsolateral frontal cortex being the location for ‘working memory’. While others may be using this module to hold on to some information for a few seconds, I have been using it to hold on to information for a few decades.
Moving on, this paper says that the dorsolateral prefrontal cortex is active when learning about connections between items, but not when learning about individual items themselves. As we know, Perceiver and Server thinking looks for connections between items.
This paper states that disrupting the left, but not right, dorsolateral cortex causes a person to practice less self-control and to choose immediate short term rewards while ignoring longer term payback. That is definitely related to the internal world of Server thought, which uses internal generated sequence to guide behavior.
These researchers found that disrupting the right dorsolateral frontal cortex causes a person to gamble more with his choices and make riskier decisions. The Perceiver internal world contains that facts that are required to determine value. When these connections are disrupted, then you will ignore the facts and choose what feels good. In contrast, exciting the right dorsolateral frontal cortex while suppressing the left dorsolateral frontal causes a person to choose safe prospects even when the reward is fairly great. In other words, you know the Perceiver facts but you now lack the Server skills that are needed to reach the goal.
Which brings me to my second peave. It annoys me when inhibition is referred to as a trait that can be assigned to some region of the frontal lobes. As a stubborn Perceiver person, my behavior often appears inhibited to others. That is because they are practicing behavior that I regard as risky. As far as I am concerned, they are gambling their life away in order to obtain temporary benefits, and I refuse to do that. That is because I have programmed my frontal cortex with the theory of mental symmetry—it determines my Perceiver truths, my Server commitments, my Mercy loves, and my Teacher understanding. A person doesn’t refuse to play on the freeway because he is inhibited. Instead, he refuses because he has an internal world that guides his behavior. End of peave.
One curious paper says that the left dorsolateral prefrontal cortex is less active in an obese person when he finishes eating than in a thin person. If this region is related to the internal world of Server thought, then this could be interpreted as the Server knowing in the thin person that the task of eating has been completed and that it is now time to move on to another task, whereas in the obese person, this mental step of moving on from the meal is not being taken.
Returning to the Wisconsin Card Sorting Test, one experiment found that disrupting the left dorsolateral region made it more difficult for a person to change his sorting strategies, whereas disrupting the right had no effect. When I am sorting cards, I am not trying to reach some Mercy goal. Instead, I am building a Teacher understanding of the situation and then carrying out a Server action that reflects my current understanding. Thus, this would primarily involve the Server internal world, located within the left dorsolateral region.
I have mentioned that the brain seems to be organized in a hierarchy of regions moving from back to front and from external to internal. There is a region in front of the dorsolateral frontal cortex called the frontal polar region. This area of the brain is used when thought is driven entirely by internal content. Thus, I suggest that this region is the highest and most abstract area for Perceiver and Server thought. When Perceiver facts and Server sequences are completely internally driven, then the frontal polar region is being used, whereas Perceiver and Server thought that manipulates external elements involves the dorsolateral frontal cortex.
Medial Prefrontal Cortex
Interaction between Perceiver and Mercy, and between Teacher and Server, appears to occur within the medial prefrontal cortex. In the same way that Perceiver/Mercy interaction in the right angular gyrus leads to physical body image, so this interaction in medial prefrontal region leads to an internal image of self, as described in this paper. As a Perceiver person, I naturally think of self-image as something related to the internal world of Perceiver and Mercy, but interaction between internal Teacher and Server thought would also generate a form of self-image—my personal Server skills in relation to universal Teacher understanding.
Here is an excellent summary paper on the medial prefrontal cortex, from which I took the liberty of copying a picture. According to these authors, prMFC monitors actions to look for consistency and avoid errors; arMFC is activated by self-knowledge, person perception, morality and mentalizing; and oMFC is related to feelings of personal reward and punishment.
Unfortunately, this paper does not make any distinction between left and right medial prefrontal cortex. Therefore, we have to interpret this information both in terms of Mercy and Perceiver, and in terms of Teacher and Server.
prMFC appears to involve an interaction between Perceiver and Server content and Contributor planning. It activates when you notice you have a mistake and correct your error. The anterior cingulate, part of this region, is colloquially known as the ‘oh sh-t’ detector, the mental region that lights up when you realize that you just made a major mistake.
Mistakes can take one of two forms. One violates Perceiver truth and the other exceeds Server skills. For instance, suppose that I am flying an airplane. This is a Contributor plan being executed. If I suddenly see the ground appearing in front of my plane, then my plan is about to violate Perceiver truth. On the other hand, if my plane starts to fall apart because I am flying too fast or too high, then my plan is on the verge of exceeding Server skills. When such a situation arises, then there is a need to come up with a plan right now and to start implementing it ASAP.
arMFC is clearly related to self-image, both of me, and how I view others, as described in this paper. As I mentioned previously, in the right hemisphere, Perceiver thought works out facts about the Mercy experiences that involve me and other people. Likewise, in the left hemisphere, Server strategy knows what skills I can perform, along with the skills or others, and how they all fit in to the grand scheme of general Teacher order.
oMFC would be the main location for conscience. In the right hemisphere this would describe how Perceiver facts affect me, whereas in the left hemisphere, it would examine whether my personal actions and skills support universal Teacher order or contradict order.
Notice the difference between self-image and conscience. Both involve an interaction between Mercy and Perceiver (or between Teacher and Server), but self-image views this interaction from the angle of Perceiver (or Server) thought, whereas conscience sees it from the side of Mercy (or Teacher) thought.
Again, notice that both Teacher-Server interaction and Mercy-Perceiver interaction end up producing similar traits. Therefore, it does make some sense to treat both right and left frontal regions as having similar functions. However, the way in which these conclusions are being reached is quite different.
- In the orbital medial prefrontal cortex, Mercy is being influenced by Perceiver, and Teacher is being influenced by Server. This produces conscience, and a feeling for reward and punishment.
- In the anterior medial prefrontal cortex, Perceiver is working with Mercy, and Server is working with Teacher. This produces self-image, and an ability to put myself ‘in other peoples’ shoes’.
- In the posterior medial prefrontal cortex, Perceiver and Server are interacting with Contributor. This indicates when an existing Contributor plan is in error and needs to be corrected with a new plan.
Perceiver strategy looks for similarities between individual situations. In the internal world, this would manifest itself as conscience, holding on to truths that apply equally to all people. It has been found that the right dorsolateral frontal cortex is crucial for maintaining an attitude of fairness—applying the same rules to everyone.
The brain contains a loop that starts from the cortex, goes through the basal ganglia, and then returns through the thalamus on its way back to the cortex. Twenty years ago, when I first looked at the neurology, it seemed rather obvious that this loop corresponded to the ‘three stage pump’ of Exhorter to Contributor to Facilitator, with Exhorter and Contributor thought using the basal ganglia and the Facilitator using the thalamus. However, it did not make sense how two modes of thought could both share the basal ganglia, and not enough was known about the basal ganglia to tie things down.
Since then, incredible progress has been made. I still remember reading the paper by Schell and Strick in 1984 that first worked out what was happening to this loop as it traversed the thalamus. And then, I believe it was Ann Graybiel at MIT who discovered that the basal ganglia was divided into striosomes and matrix. Now, finally, it appears that the essential circuits have been worked out. And, they appear, thankfully, to be totally consistent with the diagram of mental symmetry. And, also thankfully, I managed to find most of the pertinent details summarized in this book.
‘Borrowing’ one of the illustrations from that book, notice that all of the complicated paths have now been boiled down to four basic paths: the direct and indirect paths, along with the striosomal and subthamalic or hyperdirect path.
My hypothesis is that Exhorter strategy uses the direct path and Contributor thought uses the indirect path.
The direct path enables activity in a general way; the indirect path narrows this down to decide precisely which option will be enabled. Similarly, when we look at the Exhorter and the Contributor, we find that the Exhorter comes up with a general idea, and then the Contributor narrows this down to a specific choice. If you observe the Contributor person, you see that he likes to be in control, but he often does not realize how limited his choices are. As with the typical communist election, one could choose between comrade A and comrade B, but all of the choices had to belong to the communist party.
Dopamine appears to be related to the activity of Exhorter thought. All addictive behavior appears to involve dopamine, and Exhorter strategy is the part of the mind that pushes and prods and fixates. Dopamine encourages the direct path with D1 type dopamine receptors stimulating the direct path and D2 type receptors inhibiting the indirect path.
Dopamine modulates this subcortical loop in order to promote learning. Whenever a step is taken which leads to an expected reward, extra dopamine will be released, encouraging that step to be taken again. In contrast, if the reward is not present, then the level of dopamine will temporarily drop, discouraging that specific step from being repeated. The Contributor person is highly driven by reward and punishment—they motivate him strongly. The Exhorter person lives within reward and punishment; he uses emotional approval and disapproval to motivate the responses of others. In simple terms, the Exhorter person makes a great animal trainer; the Contributor person can be trained by reward and punishment.
This paper says that dopamine plays a major role in the initial stages of learning, but is less active when learning turns into habit. Similarly, the Exhorter person is great at starting a project, but finds it rather difficult to finish something. Instead, he is apt to drop what he is doing and move on when something else comes up that is new and exciting.
Tying together the direct and indirect path is a set of local connections which use acetylcholine, the brain chemical which I suggest is related to concentration. (There are two other acelylcholine circuits in the brain that appear to be related to Teacher and Mercy concentration.) The Contributor person is capable of concentrating upon a plan, ignoring everything that lies outside of this plan as meaningless. Anyone who tries to be in the presence of a Contributor person and carry out a plan which is different than the plan of the Contributor knows what this means. The Contributor person will give off very strong ‘vibes’ that you, along with everything you do, are totally worthless because you are not part of his plan. The Contributor person excels at optimization, taking an existing plan and making it better. This probably involves acetylcholine and loops within the basal ganglia.
What drives all of this is the ‘bottom line’. In the right hemisphere, the bottom line is some Mercy object or experience that is supposed to be improved, such as money, fame, fortune, or some more specific goal. In the left hemisphere, the ‘bottom line’ expresses itself as a Teacher theory that needs to be improved, or some system of structure or order that needs optimizing.
This bottom line is obviously being provided by the striosomal path. It receives its major input from the amygdala and the orbital Frontal cortex—the Teacher and Mercy emotional processors and the Teacher and Mercy internal worlds. And, it sends dopamine back to the basal ganglia (from the substantia nigra pars compacta) with which it can reinforce behavior that enhances the bottom line. And if you place electric probes in the striosomal region of the basal ganglia of rats, then they like to press the button in order to get a small jolt of electricity delivered to their brains. Imagine the poor research assistant who has to observe the rats. One wonders how much his striosomal region is getting stimulated.
The hyperdirect path appears to be another aspect of Contributor thought. It has a fast direct path which is capable of quickly stopping or shutting down the basal ganglia. Damage here can lead to hemiballismus, in which arms or legs literally flail around. The behavior of the Contributor person suggests that he can operate in one of two radically different styles. He can emphasize either control or confidence. The controlling Contributor always has his mental foot on the brake. He is continually shutting down both himself and those around him. The confident Contributor, in contrast, allows his mind to flow and gives freedom to those who are around him. We would conclude that the controlling Contributor is emphasizing the hyperdirect path which uses the subthalamus, whereas the confident Contributor is permitting Exhorter strategy to come up with ideas and then using Contributor choice to choose between these alternatives.
Serotonin is the neuromodulator that appears to be related to Contributor thought. This chemical is used throughout the body, but in the brain it is related to pecking order. The dominant animal in a group will have higher levels of serotonin than his peers. Similarly, the most common way of treating depression and phobia is by increasing brain levels of serotonin. Both of these traits remind one of the confident Contributor, who feels that he is at the top of the pecking order and who decides easily and confidently as he faces situations which would drive other mere mortals into depression or fear.
It is also known that the basal ganglia contains a high level of serotonin receptors, that serotonin modulates motor behavior and that there is significant interaction between dopamine and serotonin, with one tending to inhibit the other. This interaction is hard to decipher because of the many subtypes of serotonin receptors. For instance, serotonin inhibits the activity of dopamine in the ‘striosomal path’. Dopamine release combined with amygdala activity can lead to aggression, which can be suppressed with serotonin. In other words, if you feel strongly about something and get motivated to do something about your feelings, then Contributor strategy can bring you back under control.
This paper contains a simple venn diagram, which I have reproduced here, summarizing current views of dopamine and serotonin. Exhorter strategy is the part of the mind that provides mental energy and emotional motivation. When dopamine is low, then this mental processing becomes inactive. Contributor strategy takes Exhorter energy and channels it and controls it. When serotonin is low, then Exhorter strategy is free to obsess about emotional fixations because Contributor thought is unable to rechannel Exhorter drive. And, without Contributor control, Exhorter drive will express itself through impulsive thought and action.
- Exhorter strategy uses the basal ganglia direct path and is associated with dopamine.
- The bottom line comes from Teacher and Mercy via the striosomal path and affects behavior through dopamine.
- Contributor strategy uses the basal ganglia indirect path and is associated with serotonin.
- Contributor strategy uses the hyperdirect subthalamus path to control behavior.
And, here is a mathematical engineer who sums up the neuromodulators quite nicely. According to him, dopamine encodes the ‘reward learning signal’, consistent with Exhorter thought; Serotonin evaluates if a ‘given action is worth the expected reward’, definitely a main aspect of Contributor thought; acetycholine affects learning rate through memory updates, which could be related to concentration; and Noradrenaline ‘controls the width or randomness of exploration’, consistent with the Facilitator role of blending, balancing, and adjusting.
Two main loose ends remain:
1) The theory of mental symmetry says that Exhorter ties together Mercy and Teacher, whereas Contributor bridges Server and Perceiver. I have looked thoroughly on the internet and cannot find anything that says which part of the cortex projects to the direct path and which is connected with the indirect path. Therefore, it may be that my hypothesis about the functioning of the basal ganglia needs to be modified to the following form:
- Exhorter strategy uses the striosomal path, which comes from Teacher and Mercy regions of the brain, and uses dopamine to control the basal ganglia.
- Contributor strategy uses the indirect path along with the subthalamus.
- Exhorter and Contributor strategies interact through the direct path.
2) I am not sure how Exhorter and Contributor thought relate to the cortex. Let me elaborate. As a Perceiver person, I am consciously aware of the interaction between Perceiver and Contributor strategies. From observation, I conclude that the Perceiver and Contributor use the same information in different ways. As a Perceiver person, I am always looking for connections between facts, and relationships that tie information together. Most Contributor persons that I meet are not interested in all of these connections. If my information lies outside of their plan, then they ignore it as useless. If it falls within the plan, then they want just enough information to solve their current problem and no more.
Neurology tells us that the dorsolateral frontal cortex is the part of the brain that builds connections between one context and another. In contrast, the basal ganglia narrows down to focus upon one specific context. Thus, one concludes that Perceiver thought is located in the dorsolateral frontal whereas Contributor thought is located in the basal ganglia and is accessing memory that resides within the cortex. For instance, this paper says that dorsolateral frontal cortex is involved in the more abstract aspects of planning behavior, such as working out the rules, the goals, and the overall significance. It may be that Contributor and Perceiver strategies are connected with the same cortical region but are accessing different cortical layers.
Generalizing, I presume that Contributor and Server, Exhorter and Mercy, and Exhorter and Teacher interact in a similar fashion; Server, Teacher, and Mercy are located within the cortex, and Exhorter and Contributor access the cortex.
For the four simple styles of Teacher, Mercy, Perceiver and Server, I suggested that they have an automatic part in the back of the cortex and an internal world in the front. The input to the basal ganglia comes from both the back and the front, suggesting that Exhorter imagination and Contributor plans can involve either automatic thought, the internal world, or some combination of the two.
There is, however, a region of the cortex that appears to be related specifically to Contributor, and that is the SMA, or supplementary motor area. I have postulated that the region right in front of it—the anterior nucleus accumbens—appears to be where Contributor plans interact with Perceiver facts and Server skills.
The final stage of the ‘three stage mental pump’ of Exhorter to Contributor to Facilitator involves the thalamus. Information from the basal ganglia, where Exhorter and Contributor processing occurs, passes through the thalamus on its way back to the cortex. In addition, the thalamus sends and receives information from most of the cortex. As well, four of the five senses (not smell) pass through the thalamus on their way to the cortex.
The most studied area of the thalamus is the lateral geniculate nucleus, through which visual information passes on its way from the eyes to the visual cortex at the very back of the brain. Research has shown that this area can change the relative levels of the visual signal, allowing the mind to focus upon something in the visual field and selectively enhance it. It is thought that the rest of the thalamus operates in a similar manner.
All of this matches precisely the behavior of the Facilitator person. He is conscious in the mental module that is the observer of the mind. He can see everything that is happening in the mind and can adjust the relative levels of all of this activity. While his mental awareness appears to be very broad, it is not very deep. In other words, he seems to be mentally ‘standing on the sidelines’, watching and adjusting everything but unable to tune in closely on any specific activity.
The Facilitator person is also more aware of his physical senses than the other cognitive styles. But, this is not a deep emotional awareness. Instead, it is as if he is watching himself experience physical sensation. In addition, the Facilitator person is able, to some extent, to control his sensation of physical pain, and it is known that the thalamus has some control over the intensity of pain.
Finally, the Facilitator person excels as an executive secretary to the Contributor person, taking the plans of the Contributor person and adjusting them to suit circumstances and people.
Surrounding the thalamus lies the thalamic reticular nucleus, which intercepts and modulates all traffic heading between cortex and thalamus. This is the most likely candidate for the Facilitator processor, for it appears to do precisely what the Facilitator person does. As this paper quotes, “if the thalamus is the gateway to cortex, then the thalamic reticular nucleus is the guardian of the gateway.”
The reticular thalamus appears to be most sensitive to change, responding more strongly to information that is new. Similarly, the Facilitator person demands continual, incremental change. He is continually making small adjustments, and when change is no longer possible, then he moves on to something else.
And what controls the ‘guardian of the gateway’? Research has shown that the reticular thalamus appears to be under the control of the dorsolateral frontal cortex. In other words, Facilitator thought is guided by the internal world of the Perceiver and Server.
This explains a major aspect of Facilitator behavior. The Facilitator person blends and balances. But, he can only do this if his mind is anchored by fixed reference points. He wants freedom within structure. When there is chaos, he calls for structure; when there is rigidity, he calls for freedom. The core of mental structure comes from dorsolateral frontal cortex, the location for the internal world of Perceiver belief and Server skill.
This faces the developing Facilitator person with a paradox. On the one hand, he needs solid structure to guide his thinking. On the other hand, this solid structure can only enter his mind by successfully passing through the thalamic Facilitator filter, which naturally looks for consensus and tends to block out all information that is ‘too extreme’. So, the Facilitator person needs extreme information to think clearly, but his natural tendency is to exclude any extreme information from entering his mind.