Our Emotions: Why We Feel the Way We Do

They rush through you menacingly on a mountain trail when you mistake a twisted stick for a snake. They wash over you gently when your newborn looks your way. And when you gaze upon a Monet or call to mind a lilting line of verse, they bring you warmth.

Feelings are woven through every human experience. But for all the anguished attention emotions have drawn from poets and lovers, science has done little to decipher their mysteries.

For years, passions were considered base leftovers of our animal selves, imprisoned in the primitive portions of our brains, enemies to “pure” reason. Or they were seen as the ineffable ingredients of the human spirit, too elusive for capture.

Now, all those ideas are falling away.

Capitalizing on advances in brain scanning, pharmacology and animal research, scientists are beginning to trace feelings on their journeys through the corporeal landscape. With the go-for-broke enthusiasm of youngsters trying out new toys, they are shaking up centuries-old notions of how humans feel, why we differ from one another emotionally, and what has made us this way.

“We must now acknowledge . . . this constant exquisite shifting interplay between the physical substrates of our brain and the thoughts and emotions which they emit,” said Dr. Philip O’Carroll, a Newport Beach neurologist who has seen patients’ emotions go awry after brain injuries.

“It is a revolutionary concept,” O’Carroll said, “because all of our philosophy and all our religion tend to separate out the body from the soul or mind. . . . All is changed by these insights. Utterly.”

The new map of emotion may bear scant resemblance to the terrain humans have sketched in their imaginations.

Many researchers believe that emotion and reason, far from adversaries, are probably close mental companions. And though people tend to heap emotions into one sloppy category, envisioning them flowing from a single source, our pleasures and pains seem to emanate from scattered sites in our brains.

Moreover, our traditional notions of how feelings fit together will not necessarily be borne out in biology. Happiness is not the neural opposite of sadness, and depression is not just sadness exaggerated, research suggests.

Perhaps, to no one’s astonishment, men, in a very physical sense, feel differently than women. Now, contrasting the glows on brain scans, researchers can see just how.

Finally, scholars say, they have worthy vessels with which to explore the New World of the mind.

“I think of myself as Magellan,” said Medical University of South Carolina psychiatrist Mark George, almost giddily, of his probes with a positron emission tomography scanner.

“We are only now getting clues to these hidden universes,” said John Tooby, an evolutionary psychologist at UC Santa Barbara, who takes plain delight in humans’ emotional complexity. “We are both more evolved and more biologically determined than anybody thought.”

The Core of Our Lives

Emotion is at the core of our lives, underlying perhaps our every motivation, many researchers now agree. It is “what we are about,” said UC San Francisco psychologist Paul Ekman, an expert decoder of facial expressions.

It is one slippery subject to study, though--this massive, motley pile of interacting experiences. Feelings can be conscious or unconscious, expressed or unexpressed, positive or negative--or simultaneously positive and negative.

“When you get right down to it,” said Department of Veterans Affairs psychiatrist Leslie Brothers, “emotion is just a fuzzy, moving target. . . . It’s like trying to grab fog. Your hand keeps moving through it.”

Yet our feelings could not be more substantive.

A zap from an electrode embedded deep in the brain can send fear or anger coursing through the body. A psychiatric drug can rejigger a personality. Just by making yourself smile, you actually can brighten your mood, Ekman has found.

Some of the first clues to the biology of emotion came in the late 1840s, when a tamping iron blasted a hole through a young railroad worker’s forehead. Model employee Phineas Gage’s intellect was spared, but his emotions were knocked so askew that he degenerated into a drunk and ne’er do well.

It is a long march, though, between suspecting that feelings are physiologically based and tracing them inside the head.

Where to start?

Fear, for researchers, often has been the first choice. It is one of the oldest and most powerful of instincts among animals, present--at least in rudimentary form--in species ranging from sea slugs to primates.

Thanks largely to rats, who have been subjected to countless foot shocks and startling sounds, scientists know much about fear’s basic circuitry and how it can be conditioned.

A key player in the process is a little cluster of cells on both sides of the brain, known as the amygdala. In humans, it is about the size and shape of an almond, buried a few inches in from each ear.

In rats conditioned to associate shocks with jarring tones, auditory signals make their way through the brain into this tiny bulb. The well-connected amygdala then can send messages throughout various brain systems--and from there, throughout the body--prompting the animal to freeze, run or maybe attack another rat.

Moving up the evolutionary ladder, when a monkey’s amygdalae and connected structures are removed, it becomes unnaturally tame, consorting fearlessly with its keepers.

We humans are more sophisticated with our highly developed cerebral cortex, but our fundamental circuitry is similar.

Consider the case of an Iowa woman with encrusted amygdalae, rendered useless by a rare congenital disease. Researchers in Antonio Damasio’s neurology laboratory at the University of Iowa found that she is not subject to classic fear conditioning. Although she repeatedly was exposed to a blue slide before being blasted by a boat horn, she could not be emotionally aroused, as normal subjects could, at the mere appearance of the slide.

The woman also was unable to recognize fear in another person’s face. She simply does not know what the expression means.

Other patients with amygdalae damaged later in life do seem to recognize fearful expressions. The difference, according to the researchers, may be that the Iowa woman, whose disability probably existed from an early age, needed a functioning amygdala to encode the meaning of a horrified expression. The other patients had intact amygdalae long enough to learn the signs of fear.

The amygdala, then, may be responsible for assigning emotional significance to events--especially threatening external events (as opposed to terrors we dream up). Well-tied to the cerebral cortex, the structure can influence, and be influenced by, thoughts from our conscious mind.

At UC Irvine, brain imaging recently has helped demonstrate the amygdala’s crucial role in forming conscious emotional memories.

How is it that people can recall where they were 33 years ago when President John F. Kennedy was shot, but not, say, where they had lunch the day before yesterday? Scientists in James L. McGaugh’s neurobiology lab at UC Irvine are starting to find out.

When they studied people’s recall of a gruesome story about a boy wounded in an accident, they found that stress hormones such as adrenaline help to embed shocking events in memory.

A subsequent PET scan study suggested that the amygdala, possibly stimulated by stress hormones, was key to encoding negative memories. The activity in people’s right amygdala, measured in scans while they viewed emotionally jolting film clips, correlated nicely with how well they remembered the clips three weeks later.

“You remember things in relationship to how important they are to you,” said Larry Cahill, lead author of the PET study. “The next time you see the stimuli, you draw on what you already know.”

Historically, it has worked in humans’ favor to vividly recall, for example, where they were last jumped by a lion. “It makes very good evolutionary sense,” Cahill said.

Other researchers have shown that the amygdala is overactive in clinically depressed patients. But with so many disparate areas of the brain involved in emotion and the amygdala’s role in positive emotion uncertain, scientists are far from calling the nut-shaped node an emotional “center.”

“The amygdala is not very big, and there’s a hell of a lot of other brain tissue [that has] got to be doing something,” said Dr. Lewis Baxter, a psychiatry professor at the University of Alabama and UCLA.

The Search for Passion

This quest for passion’s somatic source has been a frustrating one.

The ancient Egyptians thought feeling flowed from the heart, and some poets would argue for that still. Descartes, in the 17th century, placed emotions in the brain--but in the pineal gland. Earlier this century, scientists proposed the “limbic system,” a circuit surrounding the brain stem.

But brain researchers are finding that emotion does not derive from any one structure or any one set of structures in our heads. To Baxter and many other scientists, it makes the most sense to speak of emotional circuits and systems--plural.

Neurologist Damasio proposes an elaborate scenario in which a collection of brain systems interact with the body to shape feelings that guide decisions and behavior.

“Emotion and feeling can help us be more efficient with our reason,” he said. “Emotions are a way of marking and qualifying things. Given your experience, you edge more toward one thing than another. Otherwise, you are lost.”

Of course, feelings can derail thought, but more often they point it in the right direction.

Damasio, in his 1994 book “Descartes’ Error,” cites the case of “Elliot,” who, despite above-average intelligence, faced an endless ordeal just deciding when to schedule his next appointment.

A formerly successful businessman, Elliot had a brain tumor surgically removed and part of his prefrontal cortex was damaged. When he managed to make choices, he erred badly, alienating his family and hopelessly botching business deals.

After exhaustive tests, Damasio concluded that Elliot had been cut adrift from his emotional moorings; he had no guideposts, no gut feelings by which to make decisions.

The case reminded Damasio of Gage, the railroad worker. Sure enough, when Damasio’s wife, neuroscientist Hanna Damasio, used computers to reconstruct an image of Gage’s brain and skull, she determined that he and Elliot had suffered damage to similar areas.

The effects of such injuries can be dramatic, ranging from profound emotional withdrawal to utter moral abandon.

O’Carroll, the Orange County neurologist, recalled a vivid example of an injury similar to Gage’s in a patient who suffered from a form of encephalitis.

An accountant, sober and hard-working, he was given to spending off hours locked in Scrabble duels with his wife. During one New Year’s Eve contest, he suddenly had a seizure, lapsing into a coma that lasted a week.

After he awoke, his IQ was unscathed--yet his emotions knew no restraint. He fondled himself in public; he grabbed at passing women. O’Carroll was forced to clear his office for the man’s appointments, lest he molest every female in the waiting room.

A brain scan showed portions of his prefrontal cortex had shriveled to little more than “bags of water,” Carroll said.

What is going on in the fleshy folds behind our foreheads, in this vaunted seat of reason known as the cortex?

The prefrontal cortex, many experts believe, may be acting as the mind’s chief executive, switching emotional impulses on and off. Perhaps that’s why some cortical injuries result in reckless behavior and others in emotional retreat.

Brain scanning research suggests that the prefrontal cortex sets emotional tone. It modulates not just minute-by-minute emotional states, but overall disposition.

Neuroscientist Richard Davidson and colleagues at the University of Wisconsin have detected “stable individual differences” in activity of people’s right and left prefrontal lobes. Those with livelier left sides tend to be more energetic and optimistic; those with busier right sides more jittery and distressed.

The differences are there even in infants. Davidson’s group found that 10-month-old babies with high right-sided activity cried hysterically in the first minute after separation from their mothers, whereas left-siders tended to explore their surroundings.

The left prefrontal cortex, acting in conjunction with the amygdala, may dampen negative feelings, Davidson suggests.

This could be one reason people react so differently to similar circumstances, he said. And heavily one-sided activity in patients may signal vulnerability to emotional disturbances. Right-siders, for example, could be more susceptible to depression and anxiety disorders.

“These [brain] differences really are at the roots of personality, psychopathology and our own self-concepts,” Davidson said. “They tell us something important about the affective core of our being.”

Intriguing Clues

Still, so much about our desires and drives eludes understanding. “I don’t think we know yet how to parse this terrain,” Davidson said. “My own view is that a better understanding of brain circuitry will provide better clues.”

Some of the most intriguing clues to the brain’s circuitry--its elaborate neural interconnections--come from tinkering with its chemistry. Though often it is not possible to do this in humans, animal research hints at almost unimaginable variety and complexity in brain wiring.

Inject a young chick in the middle of a flock with corticotrophin releasing factor--a chemical messenger in the brain--and the bird will cry for six hours. Why? Bowling Green State University psychobiologist Jaak Panksepp has discovered that the response is actually separation anxiety. It has a different circuitry and chemistry than fear or other types of worry. Interestingly, the same chemical and its byproducts are elevated in the spinal fluid and bloodstreams of humans who are depressed.

Inject a young rat with another chemical messenger, Panksepp says, and it will increase the intensity of its “rough-and-tumble play,” another specific circuit with another still-mysterious chemistry.

Neurotransmitters such as serotonin and norepinephrine, well known for their role in mood regulation, exert their powers in various circuits with widespread effects. Imbalances can lead to emotional disorders.

The brain’s circuits, though discrete, interact. Anger and fear, for example, may be processed in some of the same structures by different neural routes.

“The [brain] structures are large, like cities, and the circuits are like roads. Just because we’re in the city should not lead us into thinking we know the roads,” Panksepp said.

Indeed, the brain’s geography is just beginning to be charted. Already there are surprises.

In a PET study of 11 healthy women, psychiatrist George found that happiness and sadness are not polar opposites, neurologically speaking.

Sadness, induced partly by recall of grim experiences, lit up a widespread area, especially the prefrontal cortex and so-called anterior limbic structures deep behind the nose and between the ears. In contrast, during happy reminiscences, a part of the cortex involved in planning and worry--the secondary association cortex--was relatively shut off.

The two feelings actually can coexist, George said. “It’s not one side up or down. Many of our emotions are quite bittersweet.”

Similarly, brain images suggest that depression is not a simple extension of sadness. Among clinically depressed people, the prefrontal cortex is largely shut down, especially on the left side. (George’s team found the limbic system blunted in depression as well, although others have found hyperactive amygdalae.)

Prolonged sadness or grief may cause the brain to overuse the circuits of sadness, effectively burning them out, George said. Perhaps that explains what depressed patients long have told their doctors, George said--that they are “just numb.”

The glow of the PET scans varies with gender. Women activate about eight times as much of their limbic systems as men during temporary sadness, George said. If the burnout theory is correct, that may explain why women report greater rates of depression.

Even when average men and women are asked to make their minds blank, brain scans show different parts of their minds are churning.

When men’s brains are idle, metabolism is higher in the more primitive portions associated with action and movement, a team led by University of Pennsylvania psychology professor Ruben C. Gur found. Women showed more activation in the brain’s more recently evolved regions, tightly linked to language areas.

One implication: Men may be more prone to act on their feelings, and women more prone to talk about them. No surprise--but it gives some biological context to common causes of gender warfare.

Link to the Past

To understand human feelings now, we must remember our ancestors.

Imagine the daily demands of hunter-gatherer life: Run like hell from big animals, eat, procreate, nurse the young and don’t stray far from the tribe.

These basic impulses seem to be hard-wired into our brains, and though we live in a world of cars and computers, they still drive our everyday actions, scientists believe.

Ironically, computer models often help experts make sense of human emotional evolution.

Tooby of UC Santa Barbara describes emotion as a mode of operation for the brain, helping it call up appropriate behavioral programs. He says many situations--social exchange, friendship and hazards--probably have their own specialized circuits.

A man walking along the savanna may be consumed with jealousy, suspecting his sexual partner of betrayal. Then he spots a lion. Instantly, the sexual jealousy circuit goes offline, the hazard circuit goes on, and he starts sprinting.

He hasn’t stopped reasoning. But he has focused his mental powers on fleeing. “The emotion mode makes you reason intensively with some circuits and not others,” Tooby said.

Whatever emotional circuit goes online probably has protected humans in the past, kept them alive and reproducing, Tooby said. Of course, our ancestral responses might be inconvenient or even harmful today: We are not well served when we get the fight-or-flight impulse as our in-box piles high.

Eventually, in their quest to discover what drives human behavior, researchers hope to identify our basic emotional circuits and to determine what gets activated and when.

Not that every feeling will be traced to this or that cubic centimeter in the brain. In Tooby’s view, emotion is a way of being; its circuitry is everywhere.

Nor are our emotional selves entirely hard-wired. A baby’s vision system requires outside stimulation to develop the brain connections resulting in sight. So it is with emotion: Our brain circuitry and chemistry influence our lives--but our lives, from the outset, influence them in return.

There are those who will say we are just machines, Tooby said, no more than the sum of our parts. But he joins many other scientists, theologians and philosophers in passionately arguing that we are far greater than that.

“We are immense works of complex intricate causal pathways,” he said. “Even though it’s perfectly understandable, it’s not the right way to feel that all we are is a machine. How I feel is, I am in total awe.”

Still, researchers say, there is no harm--and much to be gained--in checking out our parts.

“If I understand . . . all there is to know about the sound coming from a violin, striking my ear and then going into my brain, this does not detract from the joy of a well-played symphony,” psychiatrist George said. “Knowing mechanisms does not detract from the joy of experience, and often adds yet another dimension.”

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A Mind-Boggling Accident

Phineas Gage was a railroad worker who survived an explosion in 1848 that drove an iron rod through his skull, shown in this computer reconstruction done in 1994 by neuroscientist Hanna Damasio of the University of Iowa.

Gage made medical history because of the distinct damage done to his emotions. The iron destroyed sections of the prefrontal cortices in the ventral and inner surfaces, associated with emotion, leaving intact the regions necessary for motor function and language.

Gage’s intellect survived, but his personality underwent a profound change, and he degenerated from being a responsible worker to a profane ne’er do well. Damasio used photographs of Gage’s skull--housed at Harvard Medical School--and a high-powered computer to simulate the rod’s trajectory.

Source: Hanna Damasio, University of Iowa

THE BRAIN: A WORK IN PROGESS / Scientists are shaking up centuries-old notions of how humans feel, why we differ from one another emotionally, and what has made us this way.

THE MYSTERY OF EMOTIONS

‘When you get right down to it, emotion is just a fuzzy, moving target. . . . It’s like trying to grab fog. Your hand keeps moving through it.’

--Department of Veterans Affairs psychiatrist Leslie Brothers.

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WHAT STICKS IN THE MEMORY?

“You remember things in relationship to how important they are to you. The next time you see the stimuli, you draw on what you already know.’

--Larry Cahill, lead author of a PET study.

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THE BRAIN STRUCTURES

‘The [brain] structures are large, like cities, and the circuits are like roads. Just because we’re in the city should not lead us into thinking we know the roads.’

--Bowling Green State University psychobiologist Jaak Panksepp.

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Glossary

Amygdala: An almond-shaped structure in the brain’s temporal lobe, believed to be involved in emotion, emotional learning and memory.

Neurotransmitter: A complex molecule that acts as a chemical messenger, conveying electrical signals between brain cells, orneurons.

Prefrontal cortex: The part of the brain’s cortex, behind the forehead, linked with making decisions and judgments, as well as setting emotional tone.

Limbic system: A group of interconnected structures around the brain stem involved in emotion, learning and memory. It was once thought to be our emotional center, but now scientists are finding our brain’s emotional universe is much more sprawling.

Functional brain imagining: Any of the techniques used to take pictures of the brain at work. These include Positron Emission Tomography (PET), functional Magnetic Resonance Imaging (FMRI), electroencephalography (EEG) and other methods.

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About This Series

Who are we? Where did we come from? While many scientists search for clues to these ultimate questions by probing the far reaches of the universe, others think the answers lie inside our own heads. Their probes are uncovering galaxies of neural cells, each twinkling with the brain’s life forces. As it orchestrates human behavior, this symphony of electrochemical communication may indeed constitute our very essence.

Sunday: The explosion of knowledge in the field of brain development, where researchers are finding that those first few years of life are far more critical than anyone had guessed.

Today: Understanding emotions

Tuesday: Brain researchers are overturning traditional ideas about mental illness.

Wednesday: Poised at what may be the last frontier of science, researchers are trying to discover the nature of human consciousness.

This series will be available on The Times’ Internet site beginning Wednesday at: https://www.latimes.com/thebrain

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Treating Depression

The PET scan at left depicts a depressed patient’s brain before treatment. After successful treatment (right), the scan shows much more activity (glowing areas) in the prefrontal cortex, which is at the top of the scan. Other researchers have found depressed patients have increased activity in the amygdala, a nut-shaped node in the brain’s limbic system, not pictured here.

Source: National Institute of Mental Health