The Emotional Brain, Joseph LeDoux (1986)

Chapter One

Language cannot move from the right to the left hemisphere. Much of what LeDoux [La-Dew] learned about emotions came from studying individuals who’d had split-brain surgeries, i.e., surgeries in which the connections between a patient’s right and left hemispheres were severed in order to control severe epilepsy. LeDoux and Michael Gazzaniga conducted experiments with such individuals. They found that these patients could only talk about information taken in by their left hemisphere, the hemisphere responsible for language. For instance, when a patient would see a word in print with his right eye, the eye that connects to the left hemisphere, he could repeat that word. When the patient saw a word in print with his left eye, the eye that connects to the right hemisphere, he could not say that word. However, if LeDoux and Gazzaniga asked the patient to draw the word seen with his left eye, he could do so.

However, emotional meaning can move from the right to the left hemisphere. They found that when a word was presented to the patient's right hemisphere, he could not say what that word was but could say if that word was good or bad — e.g., saying that “mom” was good and “devil” was bad. It seemed as though the right hemisphere could not share identifying information with the left hemisphere but could somehow “transfer the emotional meaning of the stimulus over.”

LeDoux previews some themes about emotions that will recur through the book.

(1) Different emotions have different neural systems. Just as we do not have one system for “perception” but rather a visual system for seeing, auditory system for hearing, and olfactory system for hearing, we have different systems for different emotions. Each of our neural systems evolved to solve specific problems.

(2) We can better understand our emotional systems by studying animals. The neural systems which produce general emotional behaviors are very similar to those existing in other animals with brains and backbones (fish, amphibians, reptiles, birds, and mammals).

(3) Most of our emotional responses are generated unconsciously. This follows because we do not need to posit “conscious feelings to explain what we would call emotional behavior in some animals.” “Freud was right on the mark when he described consciousness as the tip of the mental iceberg.”

(4) Our (conscious) feelings of an emotion is just one aspect of an emotion, other aspects being our behavioral response and our physiological response. “Feelings of fear, for example, occur as part of the overall reaction to danger and are no more or less central to the reaction than the behavioral and physiological responses that also occur, such as trembling, running away, sweating, and heart palpitations.” The fear system is activated before we know we’re in danger. “The system that detects danger is the fundamental mechanism of fear, and the behavioral, physiological, and conscious manifestations are the surface responses it orchestrates. This is not meant to imply that feelings are unimportant. It means that if we want to understand feelings we have to dig deeper.”

(5) Conscious feelings are fundamentally the same as other types of consciousness. For example, “the feeling of being afraid or angry or happy or in love or disgusted” is “in one sense no different from other states of consciousness, such as the awareness that the roundish, reddish object before you is an apple.” We have just “one mechanism of consciousness.”

(6) We do not will emotions to happen. Rather, emotions happen to us.

(7) Emotions, if powerful enough, motivate future behaviors.

Chapter Two: The Problem with Cognitive Science

We have historically separated thinking from feeling. Since Ancient Greece, humans have separated thinking from feeling. Plato argued that “emotions were like wild horses that have to be reined in by the intellect, which he thought of as a charioteer.” Similarly, Christian theology “has long equated emotions with sins.” Given this history, it is not surprising that the so-called “science of the mind,” cognitive science, “is really a science of only a part of the mind, the part having to do with thinking.”

Much of our procedural knowledge is unconscious. We often cannot say why we believe what we believe. The brain has “mechanisms for computing the shape, color, location, and movement of objects we see, and the loudness, pitch, and location of sounds we hear.” If we’re asked which of two objects is closer or which sound is louder, we can provide the right answer, “but we cannot explain what operations the brain performed to allow us to reach these conclusions. We have conscious access to the outcome of the computation but not to the computation itself.” There are countless things we can do without knowing how we do them: e.g., solving geometric problems, making the automatic calculations needed to “navigate a curve at 60 mph.”

We hold many beliefs for unconscious reasons. Gazzaniga and LeDoux demonstrated in some experiments with split-brain patients that we often make post hoc justifications for our actions. “Time after time, the left hemisphere made up explanations as if it knew why the response was performed. For example, if we instructed the right hemisphere to wave, the patient would wave. When we asked him why he was waving, he said he thought he saw someone he knew.” One of the primary jobs of consciousness “is to keep our life tied together into a coherent story, a self-concept. It does this by generating explanations of behavior on the basis of our self-image, memories of the past, expectations of the future, the present social situation, and the physical environment in which the behavior is produced.” 

 Amos Tversky and Daniel Kahneman have shown that “people use their implicit understanding of the way the world works, often relying on educated guesswork rather than formal principles of logic, to solve the problems they face in their daily lives.” Economist Robert Frank showed that our decision-making is often not rational: “Many actions, purposely taken with full knowledge of their consequences, are irrational. If people did not perform them, they would be better off, and they know it.” Examples include “battling endless red tape to get a small refund on a defective product or weathering a snowstorm to cast a ballot that will on its own have little impact in a race.” Daniel Goleman explains that success in life depends on EQ, not just IQ. Antonio Damasio explains the importance of using gut feelings to make decisions in Descartes’ Error.

Emotions are important and largely unconscious. Emotions “did not evolve as conscious feelings. They evolved as behavioral and physiological specializations, bodily responses controlled by the brain, that allowed ancestral organisms to survive in hostile environments and procreate.”

Chapter Three: The Stimulus-to-Feeling Sequence

Emotional researchers have long tried to establish the stimulus-to-feeling sequence. William James: Stimulus 🠊 Response 🠊 Feedback 🠊 Feeling. Example: I see a bear 🠊 I run from the bear 🠊 running causes physiological changes in me (e.g., my heart rate increase, my muscles contract) 🠊 this physiological response sends signals to the brain that induces the emotion of fear. 

Magda Arnold: Stimulus 🠊 Appraisal 🠊 Action Tendency 🠊 Feeling. Arnold “defined appraisal as the mental assessment of the potential harm or benefit of a situation and argued that emotion is the ‘felt tendency’ toward anything appraised as good or away from anything appraised as bad. Although the appraisal process itself occurs unconsciously, its effects are registered in consciousness as an emotional feeling.”

Cognitive model: Stimulus 🠊 Appraisal 🠊 Feeling. Cognitive therapists hold that “the best way to find out about appraisals is the old-fashioned way — to ask the subjects to introspect and figure out what went through their minds when they had some past emotional experience.” LeDoux believes that this model came close to getting it right: “the evaluation of a stimulus is clearly the first step in the initiation of an emotional episode; appraisals occur unconsciously; emotion involves action tendencies and bodily responses, as well as conscious experiences.”

 
Robert Zajcon’s Affective Primacy Theory: Stimulus 🠊 Unconscious Affect 🠊 Feeling. Zajonc performed several experiments using the mere exposure effect. He found that if individuals are shown “novel visual patterns (like Chinese ideograms)” and then asked to choose between those patterns or new ones, they will prefer the patterns they had previously seen. “Mere exposure to stimuli is enough to create preferences.” Zajonc then subliminally showed subjects the patterns; subjects were not aware of previously seeing the patterns. “Nevertheless, the mere exposure effect was there. The subjects judged the previously exposed items as preferable over the new (previously unseen) ones.” These experiments showed that preferences (emotions) could be formed “in the absence of conscious awareness of the stimuli.” 

There are several pieces of evidence that “emotional processing can take place outside of conscious awareness.”

(1) Research has found “that ‘dirty words’ have a higher threshold for stimulus recognition than comparable words that lack sexual, scatological, or other taboo connotations.” In these experiments, subjects are shown words on a screen; it took them longer to recognize “taboo” (e.g., bitch, fuck, Kotex, cancer) than for words “lacking taboo connotations.” “The results were interpreted in terms of Freudian defense mechanisms, particularly repression: the taboo words were subconsciously and censured (prevented from entering consciousness) because their appearance in consciousness would have elicited anxiety.”

(2) Robert Bornstein gave his subjects brief exposure to pictures of faces. “As expected, they were unable to identify which ones they had seen before, but when asked to rate how much they liked the pictures, the preexposed ones received more positive ratings.” Subjects were then given subliminal exposure to one of two people (Person A or Person B); after that, they met with both Person A and Person B and were asked to settle a dispute between them. “As predicted by the mere exposure hypothesis, the subjects tended to side with the person whose face they had been unconsciously exposed to.”

(3) Bornstein later conducted a meta-analysis and found that “mere exposure is much stronger when the stimuli are subliminally presented than when the stimuli are freely available for conscious inspection.” This suggests that “our emotions are more easily influenced when we are not aware that the influence is occurring.”

(4) Zajonc’s subliminal emotional priming involves giving someone “a priming stimulus with some emotional connotation, such as a picture of a frowning or smiling face, is presented very briefly (5 milliseconds or 1/200th of a second) and is immediately followed by a masking stimulus, which eliminates the subject’s ability to consciously recall the prime.” After a delay, the subject is presented with a target stimulus for long enough to be consciously perceived. This sequence happens several times, and the target is then asked how much they liked each target stimulus.” Zajonc “found that whether the subjects like or disliked a stimulus (for example, a Chinese ideogram) was related to whether the stimulus was primed by an unconscious smile or frown.”

(5) Otto Poetzl performed studies in 1917 “in which a complex visual picture, like a landscape, was shown to subjects subliminally. He then asked the subjects to draw as much of the picture as possible. Afterward, the subjects were instructed to go home and have a dream that night, and come back the next day.” They came back the next day and were asked to talk about the dream and draw pictures related to the dream. “Poetzl claimed that features of the original picture that were not included in the first drawing emerged in the drawing of the dream.”

(6) Matthew Erdelyi “presented subjects with “a complex visual scene for 500 milliseconds,” too long for this to be subliminal. “The purpose of using this duration was to allow some but not all of the scene to be consciously perceived.” Subjects were then asked to draw the scene. They were then divided into two groups and half were told to spend time free associating and fantasizing and the other half to play a game of darts. The first group often remembered new aspects of the scene but not the second group. Erdelyi believes that this “recovery of a previously inaccessible memory” “represents the release of memories from suppression by other factors.”

(7) John Bargh’s experiments showed that “emotions, attitudes, goals, and intentions can be activated without awareness” and can “influence the way people think about and act in social situations.” In one experiment, subjects participated were given words on cards and asked to make sentences out of them. Some of the subjects had words involving elderly people, and it took these people longer to walk out of the first room down a hall to a second room than the control group. In another study, subjects were asked to unscramble sentences having to do with “politeness” or “assertiveness.” They were then asked to walk down a hall and tell the experimenter something; in each case, the experimenter was found already in a conversation, and those who had unscrambled words involving “politeness” took longer to interpret him than those who had unscrambled words involving “assertiveness.” Bargh concluded that “a goal of social psychology should be to make people aware of these nonintuitive, scientifically discovered unconscious factors that affect thought and behavior.”

Chapter Four: Brain Regions and Functions

Most functions are made possible by a system involving more than one brain region. For example, the visual cortex (in the rear of the cerebral cortex) is essential for sight, but vision is not localized to the visual cortex; rather, the visual cortex is part of a system , other parts of the system found in other brain regions.

We can learn much from stimulating or ablating specific cortical areas. Darwin influenced us to study other animals to help us understand ourselves. Early studies involved stimulating or ablating (removing) cortical areas (i.e., areas involving the cerebral cortex, the outer part of the brain). 

The cerebral cortex enables emotional regulation but not emotional reactivity. One early finding was that when you removed an animal’s cerebral cortex, the animal showed normal signs of emotional reactivity (e.g., when provoked, a cat still arched its back, unsheathed its claws, hissed, etc.) but they had a diminished ability to regulate their emotions. 

Thalamus, Cerebral Cortex, and Hypothalamus. Moving up the vertical axis from the hindbrain to the midbrain to the forebrain, the brain becomes more and more psychologically sophisticated. The amygdala and hippocampus are toward the bottom of the brain; as you move up, there is the hypothalamus, the thalamus, and the cerebral cortex.

Sensory input from the outside world goes to the thalamus; the thalamus in turn sends some of these messages to different parts of the cerebral cortex (e.g., input from the eye goes to the visual cortex, input from the ear to the auditory cortex), some of these messages to the amygdala, and some of these messages to hypothalamus. The messages sent to the cerebral cortex become perceptions, thoughts, and memories. The messages sent to the hypothalamus become emotions.

Chapter Five: The Functions of Emotions

Evolution and reverse engineering. Unlike engineering machines, living organisms were not predesigned. Stephen J Gould and Rube Goldberg describe organisms as “patchworks of quick fixes and partial solutions that shouldn’t work but somehow do the trick.” Richard Dawkins writes that “it would have been foolish to try and construct the first jet engine by modifying an existing gasoline engine.” Steven Pinker writes that figuring out how the brain works requires reverse engineering. “We’ve got the product and want to know how it works. So we pick the brain apart in the hope that we will see what evolution was up to when it put the device together.”

The brain is composed of several systems, each with its own function. Although it’s common to talk about the brain as having a function, “the brain itself actually has no function. It is a collection of systems, sometimes called modules, each with a different function.” And there is not one emotional system but a system for different emotions. LeDoux has focused his career on fear; in what follows, he will focus on fear in hopes that this will help to better understand other emotions.

Understanding emotions. Following Darwin, many posit basic emotions, defining them “by universal facial expressions that are similar across many different cultures.” Based on these facial expressions, SilvanTomkins believed there were eight basic emotions. Carroll Izzard believes there are eight basic emotions, Paul Ekman believes there are six. Robert Plutchik and Nico Frijda “do not rely exclusively on facial expressions, but instead argue for the primacy of more global action tendencies involving many body parts. Plutchik points out that as one goes down the evolutionary scale there are fewer and fewer facial expressions, but still lots of emotional expressions involving other bodily systems.” Jaak Panksepp “has taken a different approach, using the behavioral consequences of electrical stimulation of areas of the rat brain to reveal four basic emotional response patterns: panic, rage, expectancy, and fear.” Many basic emotions theorists believe there are also nonbasic emotions “that are the result of blends or mixes of the more basic ones.”

Understanding feelings. Feelings can only occur when an organism has “the capacity to be consciously aware of oneself and the relation of oneself to the rest of the world.” Since consciousness is a late evolutionary development, emotions came before feelings.

Chapter Six: Fear Conditioning

Conditioning allows us to understand how neurons communicate. We have billions of neurons; neurons are connected by axons (fibers); synapses travel through axons to allow communication between neurons. We can understand how neurons work in fear by studying fear conditioning.

Conditioning involves an Unconditioned Stimulus (meat), Conditioned Stimulus (bell), and Conditioned Response (salivation). Pavlov “observed that his dogs salivated when a bell was rung if the sound of the bell had previously occurred while the dog had a juicy morsel of meat in its mouth.” Meat was the unconditioned stimulus (UC), the bell the conditioned stimulus (CS), and the salivation elicited by the bell the conditioned response (CR). The bell is the conditioned stimulus because its ability “to elicit salivation was conditional upon its relation to the meat, which elicited salivation naturally, which is to say, unconditionally.”

An example of fear conditioning. A rat is in a cage; the experimenter sounds a tone (CS) and after that applies a shock to the rat’s feet (US); soon, the rat acts afraid when hearing the sound (CR): “it stops dead in its tracks and adopts the characteristic freezing posture,” its fur “stands on end, its blood pressure and heart rate rise, and stress hormones are released into the bloodstream.” 

Fear conditioning is universal, fast to take hold, and long-lasting. Conditioned fear learning occurs quickly, sometimes after the first shock, the evolutionary reason for this being clearn, as “[a]n animal in the wild does not have the opportunity for trial-and-error learning.” And conditioned fear learning is long-lasting. Although repeated exposure to the tone (CS) without the shock (US) can lead to extinction, the rat will still retain the memory of the tone-shock pairing and can quickly be conditioned again.

The rat does not need to have a conscious experience of fear before being conditioned. One piece of evidence for this is that “fear conditioning procedures can be used to couple defensive responses to neutral stimuli in worms, flies, and snails,” and it’s doubtful that these animals “consciously experience fear in the presence of CS that predicts danger.” Another piece of evidence for this is that fear can be elicited unconsciously in humans.

Freezing: “Many predators respond to movement and withholding movement is often the best thing to do when danger is near. Freezing can also be thought of as preparatory to rapid escape when the coast clears, or to defensive fighting if escape is not possible.”

Fear is produced in the amygdala, not the cerebral cortex. LeDoux set out to determine “which parts of the auditory system are required for auditory fear conditioning (fear conditioning tasks in which an auditory stimulus serves as CS). He found that damaging the auditory cortex had “no effect at all on the conditioning of either the freezing or the blood pressure responses” but damaging the auditory thalamus prevented fear conditioning. In other words, “the auditory stimulus has to rise through the auditory pathway from the ear to the thalamus, but does not have to go the full distance to the auditory cortex.” After the message goes to the thalamus, it goes to four different regions, including the amygdala, and damaging the amygdala also prevented fear conditioning.

Why emotions are automatic (non-cognitive) responses. “The fact that emotional learning can be mediated by pathways that bypass the neocortex is intriguing, for it suggests that emotional responses can occur without the involvement of the higher processing systems of the brain, systems believed to be involved in thinking, reasoning, and consciousness.” “Why should the brain be organized this way? Why should it have the lowly thalamic road when it also has the high cortical road?” Answer: “Although the thalamic system cannot make fine distinctions, it also has an advantage over the cortical input pathway to the amygdala. That advantage is time. In a rat it takes about twelve milliseconds (twelve one-thousandths of a second) for an acoustic stimulus to reach the amygdala through the thalamic pathway, and almost twice as long through the cortical pathway. The thalamic pathway is thus faster. It cannot tell the amygdala exactly what is there, but can provide a fast signal that warns that something dangerous is near.” By the time the cortex has figured out whether there is in fact a snake, for example, “the amygdala is already starting to defend against the snake.” And “[t]he cost of treating a stick as a snake is less, in the long run, than the cost of treating a snake as a stick.”

Emotions are automatic, involuntary responses, taking place “before the brain has had the chance to start thinking about what to do.” “While many animals get through life mostly on emotional autopilot, those animals that can readily switch from automatic pilot to willful control have a tremendous extra advantage.” Cognition “allows the shift from reaction to action.” Evolution “could work toward making cognition faster, so that thought could always precede action, eliminating involuntary action altogether from the behavioral repertoire. But this would be quite costly. There are many things we are better off not having to think about, like putting one foot in front of the other when we walk, blinking when objects come near the eye… responding quickly and appropriately to danger, and so forth. Behavioral and mental functions would slow down to a crawl if every response had to be preceded by thought.” 

 “Emotional plans are a wonderful addition to emotional automaticity. They allow us to be emotional actors, rather than just reactors. But the capacity to make this switch has a price. Once you start thinking, not only do you try to figure the best thing to do in the face of several possible moves that a predator (including a social predator) is likely to make you also think about what will happen if the plan fails. Bigger brains allow bigger plans, but for these you pay in the currency of anxiety.”

Chapter Seven: Memory Systems

We have explicit and implicit memory systems. In the early 1900s, French physician Edouard Claparede had a patient whose brain damage prevented her from creating new memories. “Each time Claparede walked into the room he had to reintroduce himself to her.” One day Claparede entered the room and stuck out his hand but pricked her hand instead of shaking it. In subsequent meetings, the woman still didn’t remember Claparede, but she refused to shake his hand, although she could not say why she wouldn’t shake his hand.

Claparede thus discovered that there were two memory systems, “one involved in forming memories of experiences and making those memories available for conscious recollection, and another operating outside of consciousness and controlling behavior without explicit awareness of the past learning.” Conscious memory is referred to as declarative or explicit memory. Unconscious memory is referred to as nondeclarative or implicit memory. Nondeclarative memories “are created through the mechanisms of fear conditioning — because because of its association with the painful pinprick, the sight of Claparede became a learned trigger of defensive behavior (a conditioned fear stimulus).”

We have short-term and long-term memory systems. In the mid-twentieth century a man known as HM had large regions of his temporal lobes removed in response to his severe epilepsy. As a consequence, HM “lost his capacity to form explicit, declarative, or conscious long-term memories,” although he could remember events from his childhood. His problem was “one of depositing new learning into the long-term memory bank, rather than withdrawing information placed there earlier,” a function of the hippocampus.

Tests performed on HM and other individuals who had suffered damage to the temporal lobe memory system showed that such individuals struggle with declarative memory but not procedural memory. These individuals can still learn certain skills over time; for example, HM became better at copying “a picture of a star while only watching a mirror reflection of his hand,” other patients became better at reading mirror images of words and learning “some complicated rule-based strategies required to solve certain mathematical problems.” “Skill learning, priming, and classical conditioning are all examples of implicit procedural learning.”

We have emotional memories and memories of emotions. Example of an emotional situation: you have an auto accident in which your car horn gets stuck; when you you later hear a car horn, your implicit and explicit memories are activated. The sound of the horn has become “a conditioned fear stimulus” and goes “straight from the auditory system to the amygdala and implicitly elicits bodily responses that typically occur in situations of danger: muscle tension (a vague freezing), changes in blood pressure and heart rate, increased perspiration, and so on. The sound also travels through the cortex to the temporal lobe memory system, where explicit declarative memories are activated. You are reminded of the accident. You consciously remember where you were going and who you were with. You also remember how awful it was. But in the declarative memory system there is nothing different about the fact that you were with Bob and the fact that the accident was awful. Both are just facts, propositions that can be declared, about the experience.”

The explicit memory system is more forgetful than the implicit memory system, “conditioned fear responses exhibit[ing] little diminution with the passage of time. In fact, they often increase their potency as time wears on, a phenomenon called ‘the incubation of fear.’” The potency of the conditioned response (CR) can be diminished if the conditioned stimulus (CS) occurs again and again with the unconditioned stimulus (UC), although even if the CR is extinguished, it can reappear during times of stress.

He makes many more interesting points about memory. For instance, a flashbulb memory is “a memory that is made especially crisp and clear because of its emotional implications,” e.g., people remember where they were when they learned that JFK was assassinated. We remember such emotional memories because such events are accompanied by increased releases of adrenaline.

Chapter 8

Anxiety and fear are similar but different. Both anxiety and fear are “reactions to harmful or potentially harmful situations.” Unlike fear, anxiety lacks “an external stimulus that elicits the reaction — anxiety comes from within us, fear from the outside world. The sight of a snake elicits fear, but the remembrance of some unpleasant experience with a snake or the anticipation that you may encounter a snake are conditions of anxiety.” All anxiety disorders (e.g., panic disorder, PTSD, etc.) “reflect the operation of the fear system of the brain.”

According to both psychoanalytic and conditioning theories, the origin of all anxiety is a traumatic memory experience or fear conditioning. The main counterargument to this claim is that “some clinically anxious persons do not recall any particular traumatic event that might be the cause of their anxiety.” One rebuttal is that “stressful events can cause malfunctions in the hippocampus,” thus making it possible that “at least in some instances the failure to recall the instigating trauma may be due to a stress-induced breakdown in hippocampal memory function.” Indeed, exposure to stress releases a certain hormone to be released into the bloodstream, and if the stress lasts for too long, “the hippocampus begins to falter in its ability to control the release of the stress hormones,” which can in turn impair our cognitive abilities, including our ability to form explicit memories.

However, “stress does not interfere with the workings of the amygdala” and may in fact “enhance amygdala functions.” Consequently, it is possible “that one might have poor conscious memory of a traumatic experience, but at the same time form very powerful implicit, unconscious emotional memories through amygdala-mediated fear conditioning.” It is tough to convert such implicit memories into explicit memories and tough to extinguish such unconscious fears.

Just as stress can cause amnesia, it can also “amplify implicit or unconscious memories that are formed during the traumatic event.” For example, “a snake phobic might be in remission for years but upon the death of his spouse the phobia returns.” Research suggests that it is probably impossible “to get rid of the implicit memories that underlie anxiety disorders. If this is the case, the best we can hope for is to exercise control over them.”

Phobic Fears. Research evidence suggests that preparedness theory helps us to understand some phobias. Preparedness theory states that evolution has prepared us “to acquire fears of ancestral dangers easily,” or put differently, that evolution “has equipped contemporary humans with a propensity to associate fear with situations that threatened the survival of our ancestors.” One evidence for this is that humans are more resistant to overcome phobias that would have been phobias for our ancestors (e.g., snakes and insects) than modern phobias (e.g., guns and knives). Thus, preparedness theory helps us to see why exposure to certain unconditioned stimuli (US) will be more traumatic than exposure to others.

Sensory input starts in the thalamus, and from there can be directed to the neocortex and the amygdala. Although in some cases of phobic learning, more messages are sent to the amygdala than the neocortex. “This might explain why phobias generalize broadly — as Ohman has pointed out, phobias can sometimes lose track of what they are afraid of when fear generalizes. The subcortical pathway, not being very capable of making fine distinctions, may produce learning that more freely spreads to other stimuli. And this pathway, being subcortical, would also presumably be particularly difficult to gain conscious, cortical control over.”

Phobias involve both explicit and implicit memory. A phobic memory “might be established during the initial traumatic learning situation, but some phobies do not recall such a learning experience, possibly because of stress-induced memory loss. In such instances, the conscious memory of being phobically afraid could be established in later experiences with the phobic object. When the object is encountered, the amygdala will unconsciously detect the stimulus and produce the bodily expression of fear. Upon becoming aware of this bodily response, the person attributes the arousal to the most likely object and forms the memory that they are afraid of objects of this type.”

PTSD. In PTSD, the uncontrolled stimulus (US) must be more extraordinary than in phobia. The uncontrolled stimulus “bombards the amygdala with electrical and chemical signals that are particularly potent as reinforcers of Pavlovian conditioning.” Later, the controlled stimulus (CS) (e.g., “the sounds, sights, and smells of the battle”) “also reach the amygdala. Later, the occurrence of these same conditioned stimuli, or stimuli related to them, elicit profound fear responses by reactivating these powerfully potentiated amygdala circuits.”

Conditioned stimuli (CS) reach the amygdala but also “the temporal lobe memory system and can lead to the recall of the initial trauma or to the recall of recent episodes in which the initial trauma is relived. These conscious memories, together with the awareness of now being in a state of strong emotional arousal (due to the unconscious activation of fear responses through the amygdala), then give rise to conscious anxiety and worry. These cognitions about the emotional arousal, in turn, flow from the neocortex and hippocampus to further arouse the amygdala. And the bodily expression of the amygdala’s responses keeps the cortex aware that emotional arousal is ongoing, and further facilitates anxious thoughts and memories.”

Panic. Whereas phobias and PTSD are responses to external stimuli, panic is a response to internal stimuli.

Psychoanalysis and behavior theory hold that “anxiety is the result of traumatic learning experiences that foster the establishment of anxiety-producing long-term memories.” But while psychoanalysis seeks to make the patient conscious of the traumatic experience, behavior therapy seeks to implement extinction therapy. Extinction therapy begins with relaxation training; when the patient feels comfortable, he is then “asked to produce emotional images, starting with less frightening images and working toward more frightening ones” (systematic desensitization). The patient eventually moves to “real objects and situations that cause anxiety, again starting with the least and moving toward the more frightening.” In the language of conditioning, “present the CS in degrees until the conditioned emotional responses drop out. The CS comes to be associated with a new US, safety, and the new conditioned response is no response.” Psychoanalysis and behavior therapy have the same goal, “extinction of the learned emotional reaction.”

Both psychoanalysis and behavior involve helping the patient to gain control of the amygdala. Psychoanalysis involves gaining “control of the amygdala by explicit knowledge through the temporal lobe memory system and other cortical areas involved in conscious awareness.” Behavior therapy involves “a form of implicit learning involving the prefrontal-amygdala circuit.” Psychoanalysis may take longer because “the connections from the cortical areas to the amygdala are far weaker than the connections from the amygdala to the cortex.”

Chapter 9: Consciousness

LeDoux now takes up the issue of conscious emotional experience. Simply put, we can be said to have a conscious emotional experience “when we become consciously aware that an emotional system of the brain, like the defense system, is active.”

But what is meant by “consciousness”? LeDoux acknowledges that many different thinkers answer this question differently, but he notes that “many of the theories that have been proposed in recent years are built around the concept of working memory.” Working memory, largely a product of the lateral prefrontal cortex, is “a temporary storage mechanism that allows several pieces of information to be held in mind at the same time and compared, contrasted, and otherwise interrelated.”

LeDoux gives a helpful history of the development of working memory. George Miller showed that working memory is generally limited to holding seven pieces of information at a time. Alan Braddeley later conducted an experiment in which subjects were asked to remember six digits. Braddeley then asked them to say the six digits out loud while “reading sentences and pressing buttons to verify whether the sentence referred to something true or false. certain tasks. Braddeley found that sentence comprehension was greatly slowed down, but to his surprise the subjects could still do it to some extent.”

Many cognitive scientists define consciousness as “the awareness of what is in working memory.” What “we know about the one present moment is basically what is in our working memory.”

“Consciousness seems to do things serially, more or less one at a time, whereas the conscious mind, being composed of many different systems, seems to work more or less in parallel.” Consciousness is a serial processor that “create[s] representations by manipulating symbols, and we are only conscious of information that is represented symbolically. Information processing by the lower level parallel processors occurs subsymbolically, in codes that are not decipherable consciously.” Philip Johnson-Laird writes that since consciousness “is at the top, its instructions can specify a goal in explicitly symbolic turns, such as to get up and walk. It does not need to send detailed instructions about how to contract muscles. These will be formulated in progressively finer detail by the processors at lower levels… [Consciousness] receives the results of computations from the lower processors, but again in a high-level and explicitly symbolic form.”

“Working memory is the limited-capacity serial processor that creates and manipulates symbolic representations.”

LeDoux next explains how the defense system “might come to be represented in working memory and thereby give rise to the feeling we know as fear.” Imagine you’re walking down a path in the woods and see a rabbit. The signal picked up by your eyes are “transmitted through the visual system into your visual thalamus, and then to your visual cortex, where a sensory representation of the rabbit is created and held in short-term visual object buffer. Connections from the visual cortex to the cortical long-term memory networks activate relevant memories (facts about rabbits stored in memory as well as memories about past experiences you may have had with rabbits). By way of connections between the long-term memory networks and the working memory system, activated long-term memories are integrated with the sensory representation of the stimulus in working memory, allowing you to be consciously aware that the object you are looking at is a rabbit.”

Imagine you next see a snake. The same cognitive processes that occurred when seeing with the rabbit occur when you see the snake, but something additional happens, something that turns seeing the snake into an emotional experience. What happens with the snake is that the visual message is also sent to the amygdala. “A whole host of output pathways will then be activated.” “These outputs provide the basic ingredients that, when mixed together in working memory with short-term sensory representations and the long-term memories activated by these sensory representations, create an emotional experience.”

Ingredient 1: Direct Amygdala Influences on the Cortex. The amygdala initially receives a signal from the cortex. The amygdala then sends signals to different parts of the brain, including to different parts of the cortex and parts of the hippocampus; by communicating with the hippocampus, long-term memories might be activated that are “relevant to the emotional implications of immediately present stimuli.” The amygdala sends connections to other parts of the brain that in turn influence the prefrontal cortex and the individual’s working memory. “In sum, connections from the amygdala to the cortex allow the defense networks of the amygdala to influence attention, perception, and memory in situations where we are facing danger.”

Ingredient 2: Amygdala-Triggered Arousal. The amygdala sends signals to different parts of the brain that release chemicals that in turn cause arousal. “Arousal locks you into the emotional state you are in. This can be very useful (you don’t want to get distracted when you are in danger), but can also be an annoyance (once the fear system is turned on, it’s hard to turn off — this is the nature of anxiety).”

Ingredient 3: Bodily Feedback. As he has explained elsewhere in the book, “activation of the amygdala results in the automatic activation of networks that control the expression of a variety of responses: species-specific behaviors (freezing, fleeing, fighting, facial expressions), autonomic nervous system (ANS) responses (changes in blood pressure and heart rate, piloerection, sweating), and hormonal responses (release of stress hormones, like adrenaline and adrenal steroids, as well as a host of peptides, into the bloodstream). The ANS and hormonal responses can be considered together as visceral responses — responses of the internal organs and glands (the viscera). When these behavioral and visceral responses are expressed, they create signals in the body that return to the brain.”

We know that “the ANS, which controls the viscera, has the ability to respond selectively, so that visceral organs can be activated in different ways in different situations. Recent studies show, for example, that different emotions (anger, fear, disgust, sadness, happiness, surprise) can be distinguished to some extent on the basis of different autonomic nervous system responses (like skin temperature and heart rate).” See Ekman, P., Levenson, R.W., and Friesen, W.V. (1983). Autonomic nervous system activity distinguishes among emotions. Science 221, 1208-10; and Levenson, R.W. (1992). Autonomic nervous system differences among emotions. Psychological Science 3, 23-27.

Nonetheless, visceral responses are too slow “to be the factor that determines what emotion you experience in a given moment.” It takes 1-2 seconds for a message to travel from the brain to the viscera and another 1-2 seconds for a message to travel back to the brain. Moreover, visceral organs respond “much more slowly than the striated muscles that move our skeleton during behavioral acts.” However, it’s possible that “visceral feedback” can cause one emotion to change into another over time.

However, “the somatic system clearly has the requisite speed and specificity to contribute to emotional experiences (it takes much less than a second for your striated muscles to respond to a stimulus and for the sensations from these responses to reach your cortex).” This idea was proposed by Silvan Tomkins and developed by Carroll Izard. More recently, Antonio Damasio has argued that somatic and visceral feedback “underlies ‘gut feelings’ and plays a crucial role in our emotional experiences and decision making processes.”

“When all the interactions between the various systems are taken together, the possibilities for the generation of emotion-specific patterns of feedback are staggering.”

LeDoux agrees with William James “that it is impossible to imagine an emotional experience occurring in the absence of the bodily responses that accompany it.” He provides four pieces of evidence for this belief. (1) “Most of us feel our emotions in our body, which is why we have such expressions as ‘an aching heart’ and a ‘gut-wrenching’ experience.” (2) The “evidence against feedback playing a role is weak,” and here he writes that a number of spinal cord studies have been inconclusive. (3) There is “plenty of feedback available during emotional responses, and quite a bit of it is fast enough and specific enough to play a role in subjective experiences.” (4) Paul Ekman and Paul Zajonc “have shown that feedback is indeed used.” Ekman showed that asking subjects to change their facial expressions changed their emotions. Ekman, P. (1992b). An argument for basic emotions. Cognition and Emotions 6, 169-200; Ekman, P. (1993). Facial expression and emotion. American Psychologist 48; Adelman, P.K., and Zajonc, R.B. (1989). Facial efference and the experience of emotion. Annual Review of Psychology 40, 249-80.