In my clinical practice, I routinely ask patients about their stress levels. It isn’t uncommon for many patients to say they have no more than “the usual” amount of stress in their lives. When I ask them to explain further, they will go on to describe their sixteen-hour workdays, teenage kids going through difficult transitions, challenging relationships, sleepless nights, dependence on caffeine, chronic fatigue, heartburn, and other vague symptoms related to being “on the run.” Most people think of stress as the acute kind that occurs with a catastrophic event like the loss of a loved one and assume that the ennui of daily life is normal for anyone living in modern society.
While it is true that there is “good stress” and “bad stress,” the body doesn’t differentiate between the stress of highly challenging life circumstances, such as extreme poverty or living in a warzone, from the kind described above. In this chapter I will explain why your body takes them to be the same and how the neurohormonal pathways that evolved to help us survive and thrive are also the harbingers of stress.
Your brain and hormonal system evolved primarily to ensure your survival and the propagation of your genes. Hormones ensuring our survival and reproduction evolved in parallel with our brains, in a “bottom-up” fashion.
Survival and Reproduction:
The Only Things That Matter
Imagine that you are among the first humans that learned to use fire and tools. On the vast savannah that is your home, you are preoccupied with staying alive and procuring food. You need to have the ability to immediately detect threats to your survival and act on it. Your reptilian brain was designed to do just that. It acts purely on instinct and has no ability to remember and learn from the past, which is the function of the mammalian brain, or the limbic system. The limbic system consists of several areas of the brain, including the hypothalamus and the amygdala, which work together in forming an emotional response to situations. This arrangement gave us a huge survival advantage since learning from the past and storing the information for future reference enables much quicker responses to animals that are bigger and have much more keenly developed senses than us.
How we react and what type of emotional charge is associated with particular situations is a complex phenomenon that occurs in early childhood and is facilitated by certain neurohormonal pathways. The amygdala seems to play an important role in assigning an emotional charge to the situation, assessing it to be fearful, benign, or one to be exploited. When it detects a threat to survival, the amygdala sends a panic signal to a part of the brain known as the locus coeruleus and to the hypothalamus. The locus coeruleus floods the body with norepinephrine and the hypothalamus activates the pituitary gland, which lies directly underneath it.
Our neurohormonal pathways have evolved to ensure our survival and propagation of our genetic material. In the following sections we will examine how these pathways continue to play out in our current sophisticated lifestyles far removed from the jungles and savannahs that they helped us survive.
Evolution of Neurohormonal Pathways
The peculiar ways in which we behave, think, and feel have to do with the pathways created for specific functions:
Take Action
The pituitary gland is called the master gland because it controls the other endocrine glands, including the adrenals that lie on top of the kidneys, the thyroid gland in the neck, and the ovaries and testicles. When the limbic system registers a stimulus as painful or undesirable, the hypothalamus activates the pituitary gland, which in turn signals the adrenals to release cortisol. What do you need to do if you are roaming around in the savannah and become aware of being hunted by a big cat? You need to take immediate action, of course! Along with norepinephrine, cortisol diverts your body’s resources in the fight-or-flight response to deal with the problem. The sympathetic nervous system jumps into action, diverting blood flow to the muscles, dilating the pupils, and increasing blood pressure and heart rate.
Fast-forward a few thousand years: you are no longer being hunted by a lion on vast plains. You’re no longer fighting for survival on a day-to-day basis, but here is the thing: your neurohormonal system cannot tell the difference between actual physical threats (like getting out of the way of a hungry lion) and imagined ones (like how you interpret your spouse’s response to your comment). It reacts to both identically based on how you learned to respond to similar situations in childhood when you learned to register pain.
Deal with Pain
Unlike other mammals, human brains are not fully “online” at birth. Even though our brains have all the neurons at birth, the synapses, or connections between them, are formed by learning through our unique life experiences. These connections are immediately imprinted by the limbic system as pain or pleasure. Imagine that you are a two-year-old toddling around the kitchen as your mother is cooking dinner. She is cooing and talking with you as she turns on the oven. She lowers the oven door and instantly there is a loud boom as flames pour out onto her outstretched hand. She screams in pain as your father rushes in to extinguish the fire.
Fast-forward twenty years: every time you hear a boom, your heart starts racing and you start hyperventilating and feel like you are going to die. Your conscious neocortex doesn’t remember the incident from your childhood, but your subconscious limbic system does. At the time the accident occurred, your amygdala registered a particular emotional response, propagating electrical impulses to produce cortisol and take action. Now, however, your neocortex tells you that there is nothing you can do about the distant boom that scares you but triggers the same pathway.
Every time you experience the stress of the stimulus and struggle to put an end to it, the neurohormonal pathway is reinforced. It becomes progressively easier for the electrical system to fire in the exact same way and produce the exact same hormones. It has become a conditioned response. Depending on how you handle stress, cortisol levels come down in as little as thirty minutes or a couple of days. If you have many pathways that lead to the same response, your cortisol levels remain chronically elevated since the limbic system wrongly detects that there is always something that threatens your survival.
Cortisol and similar hormones create the unpleasant feeling that we call pain, which jumpstarts us into doing whatever we can to make it stop. Our very large neocortex that helps us take appropriate action has a peculiar trait: because of its sheer size, it can make a very large number of connections with our past experience and concoct dangerous “what if” situations. The brain associates current situations with past ones because these connections fire and activate the limbic system, which activates the release of cortisol.
Because of our ingrained need to survive, we tend to remember bad experiences more vividly than good ones. Although this trait gave our ancestors a survival advantage, it no longer serves us in the current era, where our limbic system pushes us with an urgent do-or-die kind of feeling even when our rational neocortex knows that we are not in imminent danger of death. The amygdala, which coordinates fear, is unable to resist negativity and suffering. This is what appeals to us when we search out the worst kind of tragedies in the news, read and watch dark material in books, magazines, and movies, and hold discussions of doom with others. Negativity is a survival trait, except that it turns the body-mind against itself when survival is no longer an issue.
The inherent need for survival becomes apparent in other traits that cause us suffering, such as seeking pleasure.
Seek Pleasure
We don’t learn only pain and stress responses as we grow up. We also learn the ones that make us feel good and flood us with pleasure. For instance, you may not remember the very first time you tasted chocolate. The sugar and fat in it made your limbic system register it as pleasurable and caused a surge of dopamine, the feel-good hormone. Dopamine is produced by neurons in several areas of the brain as well as in the adrenal gland, and it makes us seek out what is pleasurable.
When dopamine floods the body, the limbic system registers it as a great feeling and nudges us to seek more of it. However, dopamine doesn’t last long in the body and breaks down quickly, taking the pleasurable feeling with it. So we seek the pleasure again and again. Dopamine’s other quirk is that it makes us quickly get used to the stimulus. This is why the first lick of your favorite ice cream is much more exciting than the subsequent ones.
Seeking pleasure gave us an evolutionary advantage—sugar and fats in the face of chronic scarcity were important for metabolism. Seeking such foods fueled by pleasure ensured our survival. Similarly, the pleasure of sex ensured progeny, and the pleasure of having more notoriety or possessions ensured our hierarchy and bettered our chances for living longer.
Fast-forward to now, and dopamine continues to push us into endless seeking. We seek more and more of whatever the limbic system registers as good, be it chocolate, drugs, relationships, sex, achievement, fame, or wealth. Now, however, it is no longer about survival but simply about feeling good. My life, for example, was marked by constantly chasing academic success. Did I need to be so ambitious? No, but success felt good until I saw that it never lasted. In this mode of constant seeking, we are never satisfied with what we have and tend to live in anticipation of the future, when “things will be better”—as in having more of whatever we seek.
Endorphins are the other “feel good” hormones in the body and represent another example of our brains doing their job to keep us safe and alive. Endorphins are produced by the pituitary gland in response to physical pain. It evolved to allow us to escape danger by numbing us to the sensation of pain. You may have heard of a situation where somebody was gravely injured and never felt the pain until much later; that is the merciful action of endorphins. However, they are also produced with extreme physical exertion, such as in a “runner’s high.” While a good laugh or cry can also induce endorphin production, our social pain, disappointments, and hurts don’t induce endorphin production like bodily pain does.
As with dopamine, there is a price to pay for this high. Endorphins are produced only if you push yourself beyond your capacity and to a point of discomfort. Like dopamine, greater and greater levels of physical pain are needed to produce a high. Originally evolved as your brain’s way of keeping you alive, dopamine and endorphins have turned us into pleasure-seeking beings. They keep us on the edge by inducing what is known as “good stress,” where we are turned on by the seeking of challenges in our daily lives—exciting things like promotions and new relationships and life situations.
The seeking creates temporary bursts of cortisol and norepinephrine that help us function in the focused mode (The Pathways of the
Body-Mind Connection) and complete challenges we set for ourselves. Modern society thrives on this type of “good stress” (or eustress), since it propels advances in human achievements. However, there is a fine line between good and bad stress, since the dopamine that rises and falls makes us seek more and more of whatever gives us pleasure or a sense of fulfillment. Since we can never be guaranteed of getting what we seek, the neocortex sends “what if” distress signals that chronically stimulate the stress pathways. Pleasure-seeking becomes stressful.
Our innate drive to survive not only leads us to seek pleasure and avoid pain, but it sets us up for comparison and judgment in relationships.
Compare and Judge
Picture yourself again in the savannah a few thousand years ago. Not only are you struggling to stay alive, but you are competing with your tribe for access to food and mates. You lose if you snooze, and therefore you feel the need to dominate. When you become the dominant one in your tribe, the others show you respect and reverence and your limbic system registers this as a favorable thing, activating the production of serotonin. Serotonin makes you feel safe and that you are assured of having your needs met.
Fast-forward to current times: even though our survival is no longer dependent upon dominating the tribe, these impulses remain in our need to be seen as worthy, respectable, or admirable. Even when we don’t verbalize it, our minds are creating a hierarchy and gauging where we stand. Like TV shows and politicians, we are always aware of our approval ratings. When we gain approval from others, the limbic system notes it as good and the electrical pathway releases serotonin. How we view ourselves depends on comparing ourselves with others and judging others against the standard we set for them.
Our societies are far more evolved and refined now, thanks to logic and reasoning arising from the neocortex. We don’t bully our way to domination, where we may not gain approval and respect from others—we can’t induce enough serotonin to make us feel good. Instead, we unconsciously strive to be on top, leading to an onslaught of stress hormones. Since the hypothalamus is always looking to keep balance, the brain is constantly assessing how to gain others’ approval without producing too much cortisol. What we call self-esteem or self-confidence is often the good feeling that comes from subtly (or overtly) comparing ourselves. When we are assured that we are more fortunate or endowed in comparison, the limbic system recognizes it as a good feeling.
Comparison, judgment, and one-upmanship are the building blocks of modern society. From college applications to job opportunities, we are encouraged to outsmart others and come out on top. We push our children to recognition and better opportunities to give them an edge over others. We feel gratified with likes and comments on our social media posts and feel let down if nobody notices. Our mind automatically sizes up someone as they walk into the room. If our brains register them to be at a lower level, we relax. If not, we feel a vague sense of unease. The conscious brain has no idea why we feel the way we do, and often we can’t even articulate it. The limbic system, on the other hand, is just doing its job of ensuring our survival and that of our offspring. As far as it is concerned, our genes have the best chance of propagation if we and our offspring come out on top.
What began as a survival mechanism is now fraught with stress because our evolved society makes us carry a social, cultural, and moral conflict about comparison and judgment. Our logical neocortex tells us that we are not supposed to compare or judge, which the limbic system detects as internal conflict, so it activates more stress hormones. Not only are we constantly comparing and judging, but we are also stressed about it!
As we see, survival is a complex physical, mental, psychological, and biological process. In addition to the above traits, survival in mammals (including us) is deeply dependent on forming social structures through the important trait of attachment.
Become Attached
Okay, we are back on the savannah struggling for survival, where we quickly learn that it is to our great advantage to band together. Not only do we stand a better chance of surviving the dangers of the terrain, but we can thrive when we cooperate. Our chances of finding food and mates are much higher in a group. Most importantly, a group ensures that our offspring get off to a good start by learning from our experiences, and for this we need neurohormonal pathways that ensure attachment.
The hypothalamus not only initiates hormone secretion by other glands but is also a potent endocrine gland itself and produces oxytocin, which is needed for you to feel attachment and bond to your family and children, to want to take care of others, and to find pleasure in social structures. Oxytocin is the hormone that makes us long for companionship. It makes us trust others, flowing from the neuron connections that make us feel good in our interactions. The greater the oxytocin, the higher the attachment to mate, offspring, and group.
Attachment is one of the significant advances of the mammalian brain over the reptilian one. The larger a mammal’s brain, the lower the number of pregnancies a mother can have over her lifetime. Thus, she must do everything in her power to ensure her babies’ survival so that her genes can thrive. Oxytocin fosters attachment and ensures our survival, considering how helpless we are as newborns. Attachment facilitates our learning from others, particularly our parents and caregivers.
Not only do our rapidly developing brains absorb vast amounts of information, but they are also equipped with mirror neurons, which fire in response to someone else getting a reward or punishment. For instance, we are less likely to touch a hot stove if we watched someone else do it and squeal in pain. These special neurons make us learn from others’ experiences.
Fast-forward to now, and we see that these responses that evolved to ensure our survival are also sources of stress. Social living is fraught with many challenges, including competition, struggle for dominance, and the need to form bonds with the other members of the group, even when we don’t want to. You are forced to tolerate your mother-in-law when she visits just to keep peace with your husband, even when she pushes all your buttons. Your mirror neurons make you feel miserable around miserable people because your limbic system triggers an alarm signal.
Not only do mirror neurons enable empathy, but they also make us band together in a shared sense of threat. Remember how our brains are wired to respond more strongly to negative situations (real or imagined) than positive ones? Add the effect of mirror neurons to our inherent need for social structures and we have the perfect set-up for cortisol-powered and fear- or hatred-fueled groups acting against others based on imagined threats to their survival. This is what makes us bond together in gossip, heated political and religious discussions, and shared likes and dislikes. Paradoxically, this cortisol-powered sense of threat harbors attachment. Belonging in a group is much more desirable even with all the stress, compared to loss of attachment and the drop in oxytocin that makes us feel miserable. We’d rather stay in toxic groups and relationships because the alternative is unthinkable.
Social structures also come with the potential for heartache. If our trust was challenged in early childhood, the limbic system stores it away as pain and infuses us with suspicion in future relationships. If our sense of trust is betrayed (in reality or imagination), the neurohormonal pathways of pain are triggered and the limbic system immediately concludes that this is a situation you must run from, either literally or figuratively. Stress hormones pour into your system. The neocortex, which is capable of logic and reasoning, weighs the options and draws conclusions about who to trust and whether you should trust at all. The limbic and hormonal systems respond accordingly, producing oxytocin or stress hormones in relationships.
Despite their challenges, social structures ensure our survival by ensuring the propagation of our genes through reproduction.
Reproduce
Let’s return to the savannah again (this is the last time, I promise!), but now to a much earlier time in evolution. Mammalian females lose precious resources, including energy, with every pregnancy and childbirth, and because of the toll it takes on them, attachment to their offspring is assured by the production of hormones like oxytocin, as we saw earlier. It is a huge disadvantage for the female to be fertile all the time, considering her limited resources and her need to take care of her young. Cyclical hormonal regulation provides her with the evolutionary advantage of ensuring quality of offspring over quantity.
On the other hand, the male has no binding attachment to his young since much of the attachment in humans stems from social and cultural structures rather than being purely biological; he is driven to inseminate as many females as possible to ensure the survival of at least some of his progeny. Quantity trumps quality for mammalian males. In such a disparity, males are required to woo the females with the unique traits that tell her that he is an acceptable mate with good genes, which translates to greater chances for her offspring to survive. Not only must a male appear attractive to a female in the group, but he also must compete with the other males for her attention. The females, on the other hand, are not particularly pressured to attract males. These evolutionary differences between the sexes gives rise to dimorphism, where sex hormones act differently on males and females to give them their unique characteristics.
Estrogen is the main hormone responsible for dimorphism and is produced in both sexes. Estrogen produces permanent changes in developing male brains by establishing nerve connections in the neocortex and the limbic system, which ensure behaviors like aggression in adult males. Estrogen is also required for activation of adult male behaviors and works by being converted to testosterone in different parts of the brain. In females, estrogen production starts much later, when it can no longer masculinize the brain or induce male behaviors. Even though estrogen is responsible for the sexual dimorphism we see in the brain and behavior of both sexes, testosterone controls the intensity of masculine behavior in adult males during times when they are trying to attract a mate or fight off a rival.
Unlike other hormones that work on the outer membrane of the cell via gateways known as receptors, sex hormones can enter the cell’s nucleus and influence the genetic material. The relationship between sexual dimorphism and behavior is highly complex because it is difficult to sort out whether we do what we do based on our neurohormonal systems or our social and cultural conditioning. In any case, the limbic system registers what makes a mate potentially more attractive, signaling the release of sex hormones that drive reproduction.
Fast-forward to now, and we are in the age where we can control our reproduction and choose our mates without immediate or imminent threat to our own survival or that of our children. However, social and cultural conditioning render sex as an object that fulfills the dopamine-
powered reward pathways. As we have seen, seeking is stressful. Additionally, the complicated neurohormonal pathways related to living in a social structure and maintaining relationships affects how we view sex, which is not used solely for reproduction but also as a means of control, showing affection, and bonding. Our complex behaviors have a propensity to create chronic stress through the limbic system, which interprets various situations and activates the cortisol pathways.
Cortisol inhibits the production of the hormone in the pituitary that activates sex hormone production in the ovaries and testes, leading to low levels of estrogen in women and testosterone in men. Low levels of estrogen in the brain lead to greater susceptibility to stress and trauma in women, whereas higher levels of estrogen make her more resilient to stress. Insulin resistance and metabolic syndrome resulting from stress create further havoc in the ovaries, resulting in erratic sex hormone production with menstrual disorders and infertility. Similarly, high cortisol is associated with low testosterone in men, leading to fatigue, insomnia, and sexual dysfunction.
So there we have it: a very simplistic view of the neurohormonal pathways that mammals have developed to survive. Even though we humans have developed language and complex thinking thanks to the neocortex, our reactions and responses to life still arise from the relatively primitive limbic system. The neurohormonal pathways determined by the limbic system become established into how we think, feel, and act on a daily basis.
As we will see below, these pathways become superhighways, predisposing us to developing habit-based diseases and making it difficult to heal from our own nonserving ways.
Neurohormonal Superhighways:
Creating Habits
Do you ever wonder why you do things specifically the way you do? Whether I’m reading a patient’s echocardiogram or loading the dishwasher, I have “a way” to do it, which is different from someone else’s “way.” How does this happen?
Recall that unlike other mammals, we are born helpless and clueless. Our brains have all the neurons, but the synapses are formed through experience. When signals flow through the same neurons in response to pain and pleasure, those neurons develop a casing of protein known as myelin. If you’re going to do the same thing repeatedly, you might as well discover a shortcut; this is exactly what the neurons do. Signals travel much faster with myelin, which develops through the same response repeated via the limbic system.
To become more efficient, new synapses are formed between the neurons that we use the most. Electrical signals jump from one neuron to another through chemicals. The first produces a chemical that floats over to the other that has its receptors, which are protein bits in precise shapes that fit the chemical molecule perfectly. If the same pathway is used again and again, more receptors are produced. If not, they decrease. Pathways fortified through acting and feeling the same way become superhighways. While the frequently used neurons become superhighways, the ones that are not used wither and die.
This does not mean we become helpless slaves of the limbic system. The situation is to the contrary, thanks to our very well-developed neocortex. Recall that the prefrontal cortex is the part of the brain that chooses. This part of your brain is continually weighing your options in response to the limbic system’s automatic firing. This is where your decision to act on the impulse or to find another way rests. Once you decide, the limbic system responds to tell you if it is going to make you feel pain or pleasure. At the same time, different parts of your brain are processing information coming in from the world around you and within you. And it all happens in milliseconds, without your conscious effort or awareness.
If you give in to the impulse again and again, you help create the superhighway of habit. Driven by dopamine and the intricate web of hormones produced in response to the electrical pathways in the nerves, you seek the object again and again even when your neocortex advises you against it. The conflict between your reasoning and the habit superhighway creates stress—you know what is good for you, but you simply can’t help it.
The Toll of Stress
By now, I hope that the connection between the brain, hormones, emotions, and behavior is becoming clear. How you think, feel, and respond to your situation results in the release of various hormones, triggering the autonomic nervous system (ANS) to fire in specific ways to affect the organs. Growing research in the past two decades is demonstrating the intricate ways in which the mind influences the ANS in the causation and progression of heart disease.
The heart is a pump, but it is much more than a pump. Along with the brain, hormonal system, ANS, metabolic and immune systems, the cardiovascular system helps the body cope with stress. If our outlook toward life is one of resilience, the spurts of cortisol and other stress hormones tend to come down in hours or days. However, when we don’t deal with stress in wholesome ways, these hormones remain in the bloodstream chronically.
The brain cannot differentiate between acute and chronic stress and responds to the levels of stress hormones circulating in the blood by redirecting the body’s resources for immediate action. Cortisol mobilizes glucose from the liver. The pancreas reacts to increased blood glucose by releasing more insulin. Over time, the organs are overwhelmed by cortisol, increased insulin, and the constant battle between themselves. The result of chronically elevated insulin is metabolic syndrome, with an increase in serum triglycerides and a chemical known as plasminogen activator-1 that increases blood clotting, and a decrease in high-density (good) lipoprotein. In addition, cortisol inhibits the immune response, sensing that fighting off infections can wait. Instead, it prepares the body to fight by increasing intravascular volume and rearranging fatty tissue.
Activation of the sympathetic nervous system by stress releases epinephrine, a hormone that increases the heart rate and decreases heart rate variability, an indicator of ANS health. If your ANS is healthy, your heart rate should fluctuate greatly from moment to moment. It should increase with inhalation and decrease with exhalation. It should increase when you exercise and return to normal within a few minutes of stopping the activity. This tells us that the two arms of your ANS are working as they should. Decreased heart rate variability is an indicator that the ANS is out of balance.
Both the cortisol and the epinephrine pathways cause endothelial dysfunction, and the overcharged sympathetic arm of the ANS stimulates the production of chemicals known as cytokines that activate the inflammatory response, as we have seen in How Risk Factors
Turn into Disease. With the presence of endothelial dysfunction, inflammation rapidly leads to atherosclerosis, heart failure, arrhythmias, and other potentially fatal conditions. In addition, stress hormones affect learning and memory through their effects on various areas of the brain, including the hippocampus.
The most dramatic effect of stress on the heart is seen in stress cardiomyopathy, a condition more commonly seen in women. In this condition, acute emotional or psychological stress causes patients to present with symptoms that are indistinguishable from a heart attack. However, no blockage can be found on angiography, and patients are found to have elevated sympathetic activation and stress hormones in the blood. The heart muscle is transiently weak, often regaining function over time. In fact, the discovery and exploration of stress cardiomyopathy has given more credence to the role of emotional and mental stress in heart disease.
Default Versus Bliss Model Perspectives
on Neurohormonal Pathways
Notice that everything we have been discussing with regard to the neurohormonal pathways refers to the default model. Our quest for survival that drives our behaviors arises from taking ourselves to be the body-mind, which thrives on seeking pleasure and avoiding pain, struggling to find fulfillment in objects and relationships, and being distressed when these goals are not achieved. The body pays a price for this fundamental misunderstanding, turning against itself by using the very neurohormonal pathways that keeps us bound to the identity as the body-mind.
The bliss model describes these pathways from a different perspective, as we will soon see. In this model the various pathways of the brain are seen to result in mental modifications that obscure our true nature. They are like a covering of dust upon a mirror, which obscures our reflection. We become so enchanted with the dust that we forget what lies underneath it. We can rearrange the dust by turning bad feelings into good ones, but that doesn’t change the fact that it is still dust and that it still obscures the mirror. Neurohormonal pathways are vital to our identification as the body-mind and keep us steeped in dualities such as good and bad, pain and pleasure, desirable and undesirable, and so on. Wherever there is good, we can be sure that there will be its opposite, bad. Hence, we can never successfully convert all bad to all good. Even if we succeed, as long as we are identified as the body-mind, we will eventually come face-to-face with something that causes us pain or distress. The solution is not merely to reduce stress or suffering but to examine the very basis of it, which is false identification.
Can this be done? Can we get off the neurohormonal superhighways or are we doomed to their effects? Let’s see in the next chapter.
Summary
- Our neurohormonal pathways have evolved primarily to ensure our survival and the propagation of our genes and are regulated by the limbic system.
- When the limbic system registers as painful or undesirable, it activates the production of stress hormones such as cortisol to spur the body to take action against the perceived threat.
- The neurohormonal system cannot tell the difference between actual and imagined threats to our survival.
- Because of our ingrained need to survive, we tend to remember bad experiences more vividly than the good ones.
- Dopamine and endorphins make us seek pleasure.
- Comparison and judgment that make us rise to the top make us feel good by the release of serotonin.
- Oxytocin is the hormone that makes us feel attachment and form bonds with others.
- Estrogen is responsible for sexual dimorphism, or differences between male and female brains, traits, and behavior.
- When we act and feel again and again in the same ways, our pathways become superhighways, or deeply ingrained habits.
- Stress induces endothelial dysfunction and inflammation, leading to several deleterious effects on the heart and other organs.
- Neurohormonal pathways are vital to our identification as the body-mind and keep us steeped in the default model of dualities such as good and bad, pain and pleasure, desirable and undesirable, and so on.
- The lasting solution to our stress or suffering is not to merely change habits but to examine the very basis of it, which is taking ourselves to be the body-mind.