The beginning of the last chapter highlighted similarities in conceptions of “the self” between modern philosophers (specifically David Hume), Buddhist doctrine, and neuroscience. This chapter will further explore connections between neuroscience and eastern religion. This exploration will also extend the Perceptual Blindness section of Chapter 4, where in Activity 4.2 you were invited to explore different habits of attention in order to see what blindspots may be produced by habitual ways of attending. Meditation is one method for such exploration.

Most contemplative methods, such as many varieties of meditation, have their origin in spiritual traditions which date back millenia. However, academic research on secularized forms of meditation has exploded in the past 15 years or so. The figure below shows the number of published articles about “mindfulness”, one of the most common outcomes of interest for contemplative scientists.

Contemplative scientists—a significant percentage of whom are psychologists and neuroscientists, but also includes philosophers, anthropologists, historians, and religious studies scholars, amongst others—are particularly interested in contemplative methods as tools for investigating the mind and promoting well-being. For example, meditation has been characterized as a method for attention training. I have also shown some of the effects of an emotion-focused meditation (which you can explore in Activity 6.3) on attention in my own research. Perhaps of even greater interest is how meditation provides an accessible means for enhancing well-being. For example, I have shown how meditation is associated with decreases in negative affect (an array of negative emotions) both in oneself AND in a relationship partner! In a fun, exploratory study, I also showed that in some respects, 15 minutes of meditation can be like a day of vacation. Because contemplative practices both offer the possibility of improved well-being, through effects like decreased anxiety, and have been studied through the lens of neuroscience, this chapter is playfully titled, Contemplating “Nervous” Systems. Contemplative practices facilitate not only an exploration of select areas of neuroscience, but, in keeping with the title of this book, other areas of study as well!

The Tao of the Autonomic Nervous System

All the myriad things carry the Yin on their backs, and hold the Yang in their embrace, Deriving their vital harmony from the proper blending of the two vital breaths

– Tao Te Ching, 42

The relationship between the two divisions of the autonomic nervous system can be likened to the dynamic interplay and balance of opposites—a quintessential concept in Taoism—which is represented by the iconic taijitu symbol of Yin and Yang. With every in-breath, there is widespread activation of the sympathetic nervous system. With every out-breath, activation of the parasympathetic nervous system. Sympathetic nervous system activation causes an increase in heart rate, pupil dilation, vasoconstriction, and a host of other effects on various organs of the body. The parasympathetic nervous system has the opposite effect: heart rate decreases, pupils constrict, blood vessels dilate. A circular dynamic oscillation of the body’s organs occurs in a single respiratory cycle of inhalation and exhalation. Bodily homeostasis, from this perspective, is not a single state, but a cycle of bodily states driven by two opposing forces.

In Taoism, antagonistic forces are not competitors locked in a struggle for victory, but multiple dimensions of a whole whose harmony follows from their appropriate coordination. That is why, in the taijitu, the whole is constituted by two images shaped so as to evoke a sense of circular movement. The black teardrop represents Yin and is associated with “femininity” and a host of archetypal (rather than sex-linked) characteristics such as receptiveness, gentleness, and softness. The white teardrop represents Yang. Yang is associated with “masculinity” and its opposite archetypal characteristics like activeness, aggressiveness, and hardness. That the whole is constituted by the harmonious interaction of Yin and Yang (such that the whole is greater than the sum of its parts) entails that both are necessary and equally important.

However, the contexts in which each is called for are fluid and changing. At times, there may be an imbalance of “masculinity”. The antidote to excessive (“toxic”) masculinity is more “femininity”. Likewise, an excess of “femininity” calls for increased “masculinity”. To give an example in terms of studying, sometimes we need to kick out of passivity or procrastination and apply ourselves to the task of studying. At other times, the problem may not be one of preparation but of relaxation. Acute stress, or lack of rest, can impair our ability to optimally draw on our preparation. Perhaps you recognize this kind of dynamic in approaching a large exam or assignment; certainly you’d recognize this in considering your entire student career.

The symbols of Yin and Yang in the taijuti also have their opposites embedded within themselves. There’s a white circle within the black teardrop and a black circle within the white teardrop. This implies that the antidote to excess in one dimension is not entirely foreign: it exists within that dimension itself. Just as the concept of “more” is inextricably linked with “less”, so are the concepts of “masculinity” and “femininity” and “activation” and “deactivation”.

Returning again to the autonomic nervous system, the sympathetic nervous system is commonly referred to as the “fight or flight” system. It is responsible for preparing the body to actively address a threat. It does this through systemic bodily changes. Dilated bronchioles increase oxygen intake by the lungs. Increased heart rate pumps that oxygenated blood out more quickly and at a higher volume. At the same time, certain bodily functions are not necessary during an acute threat. Digestion, for example, is inhibited until a threat passes. The sympathetic nervous system constricts blood vessels in the gastrointestinal track, decreasing its blood supply, which causes more of the increased blood volume to be pumped to skeletal muscles needed for fighting or fleeing (e.g., the arms and legs).

The parasympathetic nervous system is often referred to as the “rest and digest” system. After an acute threat has passed, fewer energetic resources need to be provided for immediate activity and so slower, but equally vital processes, can resume. These include digestion and bodily repair. A fuller range of the relative effects of the sympathetic and parasympathetic systems on bodily organs is summarized in the image below.

Note that I have now discussed the activities of the sympathetic and parasympathetic nervous systems on two different timescales. There is a dynamic cycle of sympathetic and parasympathetic activity during the inhalation and exhalation phases of the breath cycle. And there is differential activation of these two systems during and between bouts of acute stress. Both nervous systems are always active, with their degrees  of activity fluctuating both moment to moment and over longer time periods as well. From breathing to going through an academic school year, your two nervous systems are constantly and reciprocally waxing and waning.

As we know all too well, we sometimes (or often) feel quite stressed out. Stress itself is not a problem. Indeed, we have built-in systems, like the sympathetic nervous system, for adaptively responding to stressful situations! But our autonomic nervous system evolved to respond to acute threats, like the sudden appearance of predators. As a consequence of our ability to imagine the future, however, we can anticipate (which as we saw earlier, is a core activity of cognition) many future threats. Whether or not these future threats actually materialize (often they don’t), anxiety about them means that our bodies now become subject to chronic, rather than just acute, stress. A large body of scholarship over the years has documented the various ways in which the imbalance of chronic stress taxes our bodies and causes health problems, not to mention the psychological discomfort of anxiety and rumination, which can lead to depression.

For many of us, relaxation means “getting away” or distracting ourselves from the things that stress us out. We take a vacation, watch something on YouTube, check Instagram, etc. This makes sense. If things which cause stress are the problem, getting away (either physically or mentally) from those things can be a solution. In terms of your autonomic nervous system, this strategy is one of decreasing or stopping the excess activation of your sympathetic nervous system.

The taijitu-like organization of your autonomic nervous system offers another solution to stress: you can further stimulate your parasympathetic nervous system. Because the parasympathetic and sympathetic nervous systems are antagonistically linked, by activating your parasympathetic nervous system, you will correspondingly reduce activity in your sympathetic nervous system. In other words, rather than only removing or distracting yourself from a stressor, you can also dampen the stress response directly, tipping your internal scales more in favor of the “rest and digest” mode.

Perhaps the simplest way to increase parasympathetic activity is to modulate your breathing. When we feel stress, our breathing becomes quicker and shallower. Taken to the extreme, for example during a panic attack, we hyperventilate. We can restore balance by purposely slowing down our breathing, which initiates a cascade of neuroregulatory effects associated with decreased stress and anxiety. For example, slow breathing alters activity levels of the amygdala, an area of the brain associated with anxiety and arousal. One increasingly well-known technique for slowing down your breath is called box breathing.

Another way to balance parasympathetic nervous system activity is through meditation. “Meditation” is like the word “sport” in that there are a huge variety of both which can be found across the world. Whereas sport involves physical exercises that can improve physical health, meditation involves mental exercises that can improve mental health.

Look at the figure below, which plots my heart rate over time. Typically, we think of the heart rate as being pretty regular, only speeding up or slowing down when you exercise or relax. However, there is actually quite a bit of variability in the timing between successive heart beats. This is called heart rate variability (HRV). In the figure below, I’m first engaged in one activity, and then another. Can you see when the transition occurred?

There is a marked qualitative difference about halfway through! Prior to that transition, I was simply reading a book. Then I began to meditate. There are two principal differences in my HRV when I’m reading compared to when I’m meditating. First, there is more variability. The magnitude of changes in my heart rate is greater when I’m meditating. Second, that variability is more patterned (cyclical). Both are associated with health. The pattern of variability, in particular, reflects the relationship between sympathetic and parasympathetic nervous system activation. When the two nervous systems are relatively balanced, you see a very regular, sine wave-like rise and fall in HRV, like in the right half of the graph. However, when they are imbalanced, a more chaotic pattern is evident, like in the left half.. A more regular HRV pattern is associated with a number of positive emotional, cognitive, and health outcomes.

The particular meditation I did was a classic form of breath meditation. By attending to the rise and fall of my breath, my breathing naturally slowed down and became more regular. In this way, meditation can have similar effects as Sama Vritti Pranayama (“box breathing”) practice. It can also do much more, such as training attentional networks in the brain. Indeed, in the scientific literature, this form of meditation is called focused attention meditation. Before going further, try it for yourself!

How was your experience? Did you find that your mind sometimes (or often!) wandered away, thinking about other things?

Mind-wandering is inevitable. Sometimes it seems like that’s all that’s happening! Mind-wandering during meditation is so common, in fact, that it has a name in Buddhism: monkey mind. Our minds swing from one thought to another as a monkey swings from one branch to another.

Remember that meditation, like physical exercise, really requires regularity of practice to “get in shape”. Every time you bring your attention back to your breath, you are strengthening neural pathways responsible for that activity. Rather than seeing mind-wandering as a failure, see it as an opportunity to grow your attentional muscles. You’re also invited to continually practice being kind to yourself when you notice your mind-wandering. In this way, you can strengthen pathways of self-compassion as well.

Trying to attend to an object like our breath over time involves cyclical processes. This is illustrated on the left side of the figure below. When we begin, we are (more easily) focused on our breath. At some point, our minds begin to wander, thinking about other things. Only a little bit later do we recognize that our mind has wandered from the breath. Then, we can let go of those thoughts and re-engage our attention with our breathing. The middle circle describes this experiential cycle in terms of attentional processes. When we are focused on an object, we are sustaining our attention on that object. When our minds wander, we are inattentive (distracted). Meta-cognitive processes responsible for monitoring our current activities will eventually recognize that we are mind-wandering and that this differs from the goal of attending to the breath. This discrepancy can then drive task-switching processes so that we disengage from mind-wandering and shift back to breath. Each of these attentional processes, in turn, are hypothesized to correspond to distinct brain networks, shown in the outer circle and at the right of the figure. Of these networks, one in particular has received a lot of attention (pun intended) in recent decades!

The Default-Mode, Buddhism, and Eudaimonia

The default-mode network (DMN) is the only meditation-related network not associated with an attentional process. Instead, it is active during periods of distraction, when we are mind-wandering. We can get a sense of the activities of the DMN by remembering and reflecting on what our minds were doing when we were not actively attending to our breath.

The default-mode network is involved in self-referential and introspective mental activities. It is active during spontaneous thinking, mind-wandering, and day-dreaming. Research has shown that nearly half of this DMN-linked thinking is about the past or future. The DMN is considered a resting-state network, which can be measured by neuroscientists when participants are idly lying in an fMRI scanner, not performing a specific task. In this situation, where people are likely to be mind-wandering and day-dreaming, a network of brain regions is co-active. Because this network of regions is active whenever participants are not asked to do anything in particular, it was given the name of default-mode network. Accordingly, our default activity is one of spontaneous thinking, mind-wandering, and daydreaming.

When we are actively engaged in a task, our DMN is suppressed. Instead, various task-related networks are active. Indeed, the DMN is anti-correlated with other attentional networks, such as the executive network shown above and below.^[2] Principal areas of the DMN include the medial Prefrontal Cortex (mPFC, below) and Posterior Cingulate Cortex (PCC, below), which are hubs of the kind discussed in the last chapter.

Over time, brain activity tends to toggle back and forth between the more spontaneous, introspective DMN and the more task-directed, often externally-oriented task-related networks. You experienced this network toggling during meditation. When you were attending to your breath, your attentional networks would have been engaged. When your mind wandered, your DMN was more dominant. These two networks, and these two experiences, alternate back and forth throughout a meditation session. At the beginning, it can feel like you have little control over which network will remain active. This can change over time.

What could be the value of having a default-mode that seems to be self-centered and introspectively-oriented? This is an active area of investigation and there are a number of promising proposals. For example, the DMN may encourage and support goal-directed thinking by revisiting past problems or simulating future ones. Alternatively, the DMN may have a critical role in memory consolidation, helping to sort, select, and reactivate those memories most worth storing. Or the DMN could underpin key aspects of our ability to reflect upon our own and others’ mental states. These proposals are not incompatible with each other and additional research is needed to paint a fuller picture of the role of the DMN in our cognitive architecture.

However, one thing is clear: the DMN presents a challenge for our subjective well-being!

The issue is succinctly summarized by the title of a well-known paper published in the leading journal Science: A wandering mind is an unhappy mind. This research showed that we spend 47% of our time not paying attention to what we are doing. And during these times, we are less happy than when we are paying attention!

If our DMN is associated with mind-wandering, and mind-wandering is associated with unhappiness, it would seem that our DMN is associated with unhappiness.

Could our default-state be one of unhappiness?

This tendency toward unhappiness is the starting point of Buddhist philosophy. The first of the Four Noble Truths is commonly translated as “Life is suffering”. Psychoanalyst, Buddhist practitioner, and author Mark Epstein suggests that a better translation may actually be, “Life is pervasive unsatisfactoriness”. We often want more than we currently have, or want things to be other than they currently are. And even in those times when we have exactly what we want, we worry about losing it. That’s the meaning of pervasive unsatisfactoriness.

Much, if not all, of our experience of life is colored by the successes and failures of our attempts to reduce pervasive unsatisfactoriness and increase happiness. This is captured visually in the “wheel of life”, called the Bhavacakra, in Tibetan Buddhism. The center of the wheel contains representations of our fundamental drives, limited by incomplete knowledge, that fuel our activities. These have certain positive and negative effects, shown in the more lightly and darkly colored semi-circles surrounding the center. These positive and negative effects lead us to experience the world in very particular ways, as symbolized by six “realms” in the next concentric layer outward. All of these experiences are governed by chains of cause and effect, represented by the outermost ring. Finally, because everything in life is impermanent and changing (represented by the demonic-looking figure holding the wheel), our experience of life tends to cycle between a number of different “realms”. Sometimes we feel we are in a good place and hope to stay there. Sometimes we hope to escape where we are to get to a better place. Sometimes things change for the better. Sometimes they change for the worse.

The remaining three of the Four Noble Truths in Buddhism point to and conclude with the solution to the problem of pervasive unsatisfactoriness:

Perhaps amusingly, the end of the list of the Four Noble Truths points to another list, the Eightfold Path:

How many of the items on this list might correspond with the items on your list from the last reflection?

The Eightfold Path represents examples of eudaimonic strategies for decreasing suffering and increasing happiness. Eudaimonia (“happiness”) is often contrasted with hedonia (“pleasure”), though these are not necessarily incompatible.

Hedonic strategies revolve around the pleasure principle, where we pursue and repeat what is rewarding. The pursuit of reward is a critical drive for our daily behavior and essential for survival. Natural reinforcers, like food and sex, increase the reward neurotransmitter dopamine in critical centers of the reward pathways. Our decisions, from the very small to the very large, are shaped by our preferences, which are linked to the reward system. Reward-based learning is also a central learning strategy, in both animals and machines, for sculpting informational circuits and driving adaptive behavior.

The difficulty with the pleasure principle is that our brains adapt to changing amounts and predictability of reward. This results in hedonic adaptation. The more we engage in a pleasurable activity, the less pleasurable it becomes. The first bite of cake is always better than the fifth bite. The pursuit of pleasure is therefore likened to a treadmill: no matter how much effort we exert, we don’t really get anywhere. While hedonism is biologically necessary, it is psychologically fraught.

Eudaimonic strategies for happiness are more centered around meaning and fulfillment. Aristotle identified eudaimonia with “living well and doing well”. This suggests that “well-being” might be a better way of thinking about eudaimonia than happiness per se. The Eightfold Path provides an elaborated list of what it might mean to live well and do well.

Research has shown that there is actually a pathway by which mindfulness and meditation, the last two of the Eightfold Path, build eudaimonic meaning. According to this mindfulness-to-meaning theory, mindfulness (whether dispositional or cultivated by meditation) expands our psychological space so that we are less reactive to particular thoughts. Reactivity can exacerbate “monkey mind”, solidifying and extending stress-related story lines, which makes our stress worse. By taking a psychological “step back”, we can increase our meta-cognitive awareness and use a broadened attentional focus to notice other contextual sources of information (e.g., other thoughts, insights, perspectives, and emotional nuances). This, in turn, can facilitate positive reappraisal of a stressor, subsequently enabling adaptive or prosocial behaviors. These positive reappraisals and adaptive behaviors are accompanied by positive emotions which allow us to savor experiences (including hedonic experiences!). This upward spiral of well-being culminates, according to the model, in a greater sense of purposefulness and meaning in life.

From the mindfulness-to-meaning model, we can begin to appreciate how eudaimonic well-being is the product of a number of reinforcing processes and effects which make it both more stable and capable of further growth. Psychological flourishing comes from the “right understanding” of the relevant contributors toward well-being and the “right intention” and “right effort” to incorporate appropriate tools in our lives.

A related model to the mindfulness-to-meaning theory is called the broaden-and-build theory. This model also proposes a pathway to well-being, but is grounded in positive emotion rather than mindfulness. A robust effect of positive emotion is that it broadens our attention. Think of your own experience when you’re in a good mood compared to when you’re in a bad mood. When you’re in a good mood, you’re much more likely to be looking around, engaging with others, considering new ideas, trying new activities, etc. These cognitive and behavioral changes help you to build enduring resources. You might learn new things, acquire new skills, and make new friends. These, in turn, increase resilience and enhance health and fulfillment. This greater well-being increases the likelihood of experiencing more positive emotions, which can further reinforce all of the preceding processes. The image below succinctly summarizes the positive feedback loop proposed in the broaden-and-build theory.

In the final activity of this chapter, you are invited to practice a second type of meditation, which has been directly linked to both positive emotion and increased life-satisfaction. Loving-kindness meditation is an emotion-oriented meditation, in contrast to focused attention meditation, which is more cognitively oriented. As noted earlier, there is as much variety in types of meditation as there are types of sports. Just as different sports will engage and train different sets of muscles, so different types of meditation target and develop different sets of psychological capabilities. If “loving-kindness” sounds a little too “hokey” to you, perhaps first watch this humorous talk, “The benefits of not being a jerk to yourself.” Then, enjoy exploring this next practice.