Exuberance: The Passion for Life (16 page)

In the 1950s, James Olds and Peter Milner at McGill University in Canada carried out a famous series of experiments on the
brain’s “pleasure center.” They placed an electrode deep into the brains of rats and demonstrated that rats will press a bar connected to the electrode in order to stimulate a particular area within the hypothalamus, a part of the brain crucial to, among other things, regulating reward and punishment. Indeed, rats find the pleasure so extraordinarily reinforcing they will press the bar thousands of times an hour and actually starve to death rather than stop. A major
nerve pathway, which runs through this pleasure area of the brain, pours out dopamine when stimulated. Rats injected with drugs that block the effects of dopamine press the bar far less frequently.

Dopamine, which is concentrated in the frontal lobes of the brain and in the limbic system, or “emotional brain,” strongly influences the emotional system that motivates both exploratory and anticipatory behaviors. The anticipation of sex or food, of meeting up with a close friend, or of discovering or experiencing something new brings with it an expectation or hope that pleasure will follow. Expectation, in turn, motivates behaviors likely to lead to the desired outcome. The release of dopamine that accompanies both the anticipation and the consummation of these activities makes it more likely that the behaviors will be repeated.

Scientists believe that the
brain’s sensitivity to dopamine is correlated with extraversion. If, for example,
a drug that increases dopamine transmission is injected into the brain of a mouse, the animal will become more “outgoing” and exploratory.
A mouse born without the genes necessary to make dopamine, on the other hand, becomes essentially catatonic, unable to take action. The dopamine-deprived mouse is as pervasively uninterested in its environment as the dopamine-enhanced mouse is actively curious.

Psychologists find that
extraverts are exquisitely sensitive to rewards. Researchers at the University of Illinois at Urbana—Champaign, for example, studied individuals from
thirty-nine countries and found that only those facets of Extraversion that are most linked to reward sensitivity—Affiliation (friendliness, enjoyment in the company of others); Ascendance (leadership and social dominance); Venturesomeness (seeking out of exciting, stimulating situations); and Social Interaction (preference for being with others)—cluster together on a single higher-order Extraversion factor. This factor, in turn, correlates strongly with positive emotion. It may well be that individuals who seek out novelty and
adventure are biologically more likely to feel an intense rush from having done so and, therefore, are more likely to seek out novelty yet again.

Dopamine is strongly associated with positive affect and importantly implicated in its
most pathological manifestation, acute mania. The staggeringly high level of physical energy and mental activation that, together with an abnormally excited mood, is so characteristic of mania creates an extreme state of mental and physical exuberance.
Amphetamines promote the release of dopamine and inhibit its uptake; they usually produce hypomania if given to patients who have a genetic vulnerability to manic-depressive illness. So does the
dopamine precursor L-dopa, which is used in the treatment of Parkinson’s disease. Likewise, drugs that increase dopamine levels tend to have
an antidepressant effect. Antipsychotic medications, in turn, exert much of their
therapeutic effect against mania by selectively blocking dopamine receptors in the brain.

There are specific areas in the brain particularly linked to pleasure and high mood, as well as to exploratory behavior.
Greater activation in the left frontal area of the brain is associated with joyful emotions, for example, and is more common in highly uninhibited children and in adults who are unusually enthusiastic and energetic. The left frontal portion of the brain is associated with physical and cognitive behaviors involved in novelty-seeking and reward, and the left prefrontal cortex with the anticipation of pleasure. Neuroimaging studies show that photographs with highly interesting or positive content
activate the left amygdala but not the right (the amygdala is involved in emotional processing and the formation of emotional memories). An individual with
damage in the left frontal areas of the brain is more likely to be depressed and apathetic; damage or abnormal growths in the
right frontal region of the brain, on the other hand, not uncommonly result in inappropriate
laughter or actual mania. Recent brain imaging studies show that patients with manic-depressive illness are more likely to have a
reduction in gray-matter volume in areas of the right prefrontal cortex than in the left.

In a 2003 study reported in
Science
,
Carl Schwartz, Jerome Kagan, and their colleagues reported that at least one aspect of brain functioning associated with temperament is relatively consistent from infancy through early adulthood. They used functional magnetic resonance imaging (fMRI) techniques to measure the response of the amygdala to neutral expressions on either a novel face or a familiar one. Their subjects were young adults who, in the second year of their lives, had been categorized as having either an inhibited or uninhibited temperament. When shown novel faces, those who had been evaluated as inhibited at two years of age showed greater responses in both the left and right amygdala than those who had been categorized as uninhibited. There was no difference between the two groups when they were shown familiar faces. Kagan suggests that
the amygdala is primarily responsive to novelty, rather than to a fear-inducing stimulus, and that exuberant individuals seek and enjoy new experiences in part because of their amygdalar chemistry (not because they are not fearful).

Exuberance is not only greatly influenced by the biological activity of the brain, it in turn exerts its own sway over mind and body. That effect is a salutary one. “
A merry heart doeth good like a medicine,” says Proverbs, and mirth, wrote Robert Burton four hundred years ago in
The Anatomy of Melancholy
, is one of the true nepenthes: it “
purgeth the blood, confirms health, causeth a fresh, pleasing, and fine colour … whets the wit, makes the body young, lively, and fit for any manner of employment.” The merrier the heart, alleged Burton, the longer the life. Modern science tends to support his contention: positive emotions such as joy act as breathers from stress and in doing so they help to restore physical and psychological health after draining or stressful times.

In one test of this idea, Barbara Fredrickson and her colleagues at the University of Michigan conducted an experiment in which they
induced a high-arousal, negative emotional state in their research subjects. The experimenters measured the cardiovascular effects of the negative induction; they then followed up the negative induction with one that produced either a neutral mood, mild joy, sadness, or contentment. They found that subjects who received positive inductions, of joy or contentment, took far less time to return to their normal level of cardiovascular functioning than those who had not.

Shelley Taylor of the University of California at Los Angeles, along with others, suggests that
positive attitudes such as optimism and the propensity to find benefit in difficult experiences—such as chronic or terminal illness, natural disaster, or being the parent of an acutely ill newborn—may improve the course and outcome of the illness or distress. Psychologists increasingly believe that positive emotions and expectations may improve the body’s immune functioning, make it more likely that an individual will act in healthy ways, and increase the chances of having better and more sustaining personal relationships. (
A study of 180 nuns who had been asked when they were in their twenties to write brief autobiographical statements found that 24 percent of those who had expressed the most positive emotions had died by the age of eighty; in contrast, 54 percent of those who expressed the least positive emotions had died.) William Hazlitt wrote that our attachment to life depends upon our interest in it, that “
passion, imagination, self-will, the sense of power, the very consciousness of our existence, bind us to life, and hold us fast in its chains, as by a magic spell.” Those who are exuberant or positive by nature hold on to life and move forward when many others cannot.

Positive emotions affect not only physical health but thinking and behavior as well. “
Lively passions commonly attend a lively imagination,” wrote David Hume over 250 years ago, and his
observation finds support in recent psychological research. Alice Isen at Cornell University has, with others, developed a variety of ways to temporarily induce elevated moods in experimental subjects in order to compare changes in their behavior and thinking with those of subjects whose moods have not been elevated. Methods used to evoke mood changes include music, film comedies, cartoons, and unexpected gifts or praise. Most of these inducers are relatively mild but the results are nonetheless striking. (It would perhaps require drugs, dance, or ecstatic music to provoke actual exuberance.) Those who have had their mood experimentally elevated are
more likely to make decisions quickly and efficiently, to help others when given the opportunity, to speak more and faster, to be more sociable, and to take greater risks. They also
more actively explore their surroundings and engage in a greater variety of activities. It is as if a dollop of galumphing had been injected into their brains.

Originality and fluency of thinking are particularly affected by changes in mood. This has been shown not only in mood induction studies but also in research that has looked at cognitive changes during mild manias. (Mild mania is almost always accompanied by a vivid elevation in mood; exuberance, as we shall see later, is a frequent feature of both mild and more severe manias.) Mood induction studies repeatedly show that individuals whose moods have been experimentally elevated give
a larger number of responses, as well as a larger number of unusual responses, to neutral words presented during a word association task, a measure that is linked to creativity. (If, for example, a subject is asked to offer as many words as possible in response to the word “tulip,” both the number of words, and the number of unusual words, can be compared with the responses of thousands of others who have been given the same task.) They are also more likely to classify visual forms and verbal concepts
in a global way than in a specific way. An individual in a
positive mood tends to see the forest and the pattern among the trees; an individual who is in neither a positive nor a depressed mood picks out the trees. Someone who is depressed focuses in on the bark (and then notes, as well, where it is peeling). “
Not by constraint or severity shall you have access to true wisdom, but by abandonment and childlike mirthfulness,” wrote Thoreau in his journal. “If you would know aught, be gay before it.”

In a typical study of positive mood induction, twenty-two eighth-grade students were given tests designed to assess creativity and problem-solving ability. One task required the students to come up with as many words as possible in response to the words “fruit” and “bird.” In the other, each child was given a box, some tacks, a candle, and a book of matches and asked to set up the candle vertically so that it could act as a lamp without dripping wax. Positive mood was induced in half of the students and a neutral mood in the other half. Those students in the positive mood group generated significantly more words than those in the neutral group (twenty-nine and sixteen words, respectively), and the words they generated were much more likely to be unusual. Seven out of eleven in the positive mood group were able to solve the candle problem, whereas only two of the eleven in the neutral mood group were able to do so.

Positive mood, in this and in other studies, increased creativity and flexibility in thinking. No one really understands how these changes in thinking are brought about. To some extent, positive mood may work simply because it is
incompatible with anxiety and other negative emotions that hinder productive thought. But it is of course more complicated than that. Isen and her colleagues suggest that positive mood influences
the way in which cognitive material is organized and retrieved from the memory, a sensible hypothesis that has yet to be adequately tested. Because positive mood is associated with increased dopamine levels in the brain, they also speculate
that the increase may account for the facilitation of cognitive processing during elevated mood states.
Surges in dopamine appear to draw attention to unexpected events or conditions, including those that predict reward; this, in turn, may make more likely the active pursuit, exploration, and understanding of the circumstances surrounding such events.

The effect of positive mood on thinking and behavior is by no means straightforward,
nor is it consistent across studies. Scientists at Washington University in St. Louis found that college-age subjects in whom a positive mood had been evoked did better on verbal tasks but worse on visual ones. Subjects in whom an anxious mood had been generated, however, did precisely the opposite: they performed better on visual tasks and less well on verbal ones. Perhaps because the detection of physical danger is based largely on visual cues, it makes sense that anxiety and fear, which are highly primitive and instinctive emotions, focus and improve visual perception. Language, a far more recent addition to the brain’s repertoire, may be more obviously linked to younger systems in the brain that generate pleasure.

It is not obvious to what extent mental activation, and not just mood, is important in increasing cognitive fluency. Too-great activation may overwhelm and ultimately undermine originality and productivity. But some activation is crucial to attentiveness, motivation, and the capacity to translate thought into action. Intellectual and creative advantages prompted in a laboratory situation may not be important in the real world, unless the individual is also physically alert and compelled to act.

Manic-depressive illness, because it is strongly heritable and often characterized by exuberance (as well as being related to a spectrum of exuberant temperaments), is a particularly important, naturally occurring psychological laboratory for looking at the effects of mental activation and euphoric and expansive mood
states on thinking and behavior. Manic-depression, also known as bipolar disorder, is unique in its importance to understanding these effects. It is possible to see in mania and depression the impact of powerful mood changes on an individual and to compare in the same individual the effects of positive mood changes (for example, those of mild mania) with those that are negative (for example, those of depression).