The Making of the Mind: The Neuroscience of Human Nature (20 page)

Delusional false memories require more than suggestion and false beliefs, however. They further require an experience that arises internally but is misattributed to an external source. The mind becomes confused as to what is real and what is not. Just as in perception it might be difficult to tell the difference between a real object and a mirror image of an object, the same confusion can arise in judging the source of memorial experiences.

For example, if an event occurred in a dream, it is important to know when later recalling the dream that the event was not real. But this source information can be forgotten over time. The dream itself is wholly determined by the internal forces of past episodes and past beliefs. The interpreter attempts to weave together hallucinated perceptual experiences into a narrative, albeit often a bizarre and incoherent one. A delusional false memory might then occur if one forgets that the bizarre event was only a dream. Misattribution of source is most likely for individuals with strong beliefs that a bizarre event could actually occur. The social circles of the individual support and find entirely credible the narrative reports of a person experiencing a delusional false memory. There is no check on the misattribution of source, but only affirmation.

Consider stories about encounters with a UFO, for example. Betty Hill was an avid believer in UFOs before the night she and her husband, Barney, claimed to have seen a strange light following their car. Betty's sister suggested that she and her husband may have been “irradiated” by the light, and soon Betty began to have nightmares in which she and Barney were abducted by aliens who took them on board a UFO, communicated with them telepathically, performed medical tests, and showed Betty a star map. A psychotherapist who treated Betty for her nightmares used hypnosis to elicit detailed reports of these events from both her and Barney, who had heard these accounts from his wife numerous times. The therapist concluded that the reports were delusional false memories shared by the couple and were nothing more than fantasies.
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THE HAZARDS OF TIME TRAVEL

The phenomenon of false memories—whether they are plausible or implausible—highlight for us that episodic memory can operate both in the past and in the future. The reconstructive processes that allow us to remember the gist of an actual past life episode can also encourage us to fabricate one that never happened. The ability to envision future events—when turned backward in time—can result in confabulating a false past. Absent effective reality monitoring, the mind cannot discern factual events from fictional events. In this sense, false memories represent a hazard of mental time travel. It is not the only one.

Mental time travel gives human beings enormous power in the ability to recall the past and to plan for the future. Civilization itself is a result of the awesome capacity to envision how things could be in the future and the ability to recollect and learn from the past. But the escape that mental time travel provides from the present can become a disability rather than an adaptive cognitive tool. Clinical depression is characterized by the arrow of time persistently pointing backwards in rumination about the past, with life experiences being repetitively replayed and repented. Anxiety disorders, on the other hand, can be understood as a preoccupation with the future, not in joyful anticipation, but in worry and dread. Brooding over the future as well as
repenting of the past can be pathological. Anxiety and depression can also co-occur, when one alternates between anxiety about the future and worrying about the past. The very capacity that frees human beings from the here and now can also trap us in a nightmarish past, a frightening future, or even both.

Imagining bad things that could happen in the future, anticipating situations and events that more often than not never occur in reality, is the hallmark of debilitating anxiety. Anxiety is difficult to define, but as human beings we know it when we feel it. It is something less specific than simple fear of an immediate danger. Fear can be a friend when it prepares a person to take action, to flee or to fight. Anxiety, by contrast, is not proportional to the threats of the immediate environment. In fact, it is not driven by the present situation at all, but rather by the mind's anticipation of future problems. Some anxiety is normal and beneficial when kept constrained, because it allows for planning and preparation to meet future demands. The problem arises when one constantly broods over the future and anticipates only negative events. Then, the machinery of imagination that can be so useful in planning for the future is turned against us as it persistently conjures dangers that will rarely, if ever, occur.

Imagining that the worst will happen naturally spurs negative emotional thoughts or worry. Worry is known to be highly verbal rather than visual-spatial in nature; individuals who worry excessively report an abundance of negative self-talk rather than unpleasant visual images.
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It is expressed through inner speech and reverberated in verbal working memory. As such, worry is a product of an agitated interpreter fretting about the contents of conscious experience. Thus, those who suffer from anxiety disorders can be understood as having an overly active episodic memory focused on future problems. Through mental time travel, negative future events are fabricated and given context as visual-spatial images. Actual past events can serve as a starting point for these fabrications as they are embellished with troubling details and imbued with darker emotional tones. What had been an actual mild annoyance in the past can be envisioned as a calamity in the future. The interpreter, then, provides a narrative commentary of inner speech to accompany the gloomy visions of future miseries and possible catastrophes. The chattering of the interpreter only worsens the outlook through verbal worry.

We are an itinerant species, not only in our wanderings through the past and future, but also in our spatial movements all over the planet. Human beings have traveled from their place of birth since the origin of the species. Our migrations, through thousands of generations, from out of Africa to all corners of the globe, document the essential itinerant nature of
Homo sapiens
. In Homer's story of the wanderings of Odysseus, we see the consequence of our restless history. In the face of monsters and even the pleasures of the sea nymph Calypso, the mind of Odysseus persistently turns its arrow of time back into the past, as he longs to return home to his native island of Ithaca, where his wife Penelope faithfully waits for him. Homesickness is but one of many ways that nostalgia seizes the mind, however.
Nostalgia
refers to any recollection of autobiographical experience stored in episodic memory that attaches to an emotional wish to be there again in that time and place. Although returning home is one source of nostalgia, it can refer to people, events, and locales from other parts of life as well.

Psychologists have asked people to write a narrative of a nostalgic experience and then analyzed the content.
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Family members, friends, romantic partners, birthdays, vacations, and specific times and places of emotional significance, such as observing a special sunset, were the most common objects of reverie. Nostalgia is in fact a common emotional experience associated with mentally traveling back into one's past. Besides being found across different ethnic and cultural populations, it occurs as often as weekly in the majority of people.

Although homesickness is usually associated with sadness, researchers have learned that nostalgic recollections more often than not evoke the positive emotion of happiness rather than sadness.
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Also, some recollections of nostalgic events paradoxically give rise to feelings of both sadness and happiness. Such bittersweet narratives share a common structure, beginning with a disappointment or loss that elicits sadness, grief, or suffering, before moving forward to happy acceptance, triumph, and euphoria. In other words, nostalgic recollections seem to be a vehicle for redemption, a means of reliving negative emotional episodes from the past, coming to terms with them, and emerging from the reverie feeling better. It is particularly interesting that feelings of loneliness and, more broadly, negative moods in general, are often
the triggers for turning the arrow of time backward. Episodic memory, then, has a role in our mental health by grinding down psychological discomfort into equanimity.

Yet the mental time travel of episodic memory can harm mental health in depression. While nostalgia may provide us with redemption, meaning, and purpose in life, rumination can eviscerate us through the mental anguish of regret. Episodic memory provides us with a window on our past that we look through with some peril. It provides the interpreter of conscious experience an opportunity to rework personal history and imagine what might have been. It is through looking back that regret for past choices breeds and multiples. Regret can, of course, be a healthy emotion, such as when it is part of a confession of past mistakes and when it motivates repentance and the resolve to behave differently in the future. However, past wrong doings are not the only objects of rumination. Events from the past over which one had little, if any, control can haunt the human mind. For personalities prone to self-criticism and poor esteem, for one whose interpreter always finds fault for the past within the self, rumination becomes part of pathological anxiety and depression. Rumination is also associated with binge eating, binge drinking, and self-harm.
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For a person diagnosed with clinical depression, the arrow of time points backward persistently. Hope for the future requires the capacity to even think about the future. Yet in the clinically depressed patient, negative memories from the past spontaneously come to mind, and the person comes to believe that most of his or her life has been little more than endless succession of painful events. The negative mood of the present seems to grease the retrieval of the negative past, while the positive experiences are forgotten. Worse, rumination on these erupting painful memories further depresses the individual's emotional state, causing a malevolent spiral downward. In severe cases, the embattled mind of the clinically depressed can even come to prefer the self-destruction of suicide.

For most people, severe depression is rarely or never experienced. Although depression has been called the common cold of mental illness, and periods of negative moods and sadness are indeed a fact of human experience, most people escape the depth of depression that motivates its victims to take their
own lives. On the contrary, despite life's many assaults on human emotional stability—ranging from the daily hassles of working and surviving to the tragic deaths, divorces, bankruptcies, fires, hurricanes, tornados, earthquakes, assaults, and wars that sometimes befall us—people largely remain positive, optimistic, and resilient. How is it that such negative emotions can be so successfully regulated? We turn next to the limbic brain regions that emanate emotional experiences, and to the ways in which the neocortical parts of the modern ensemble modulate these feelings.

Interest, joy, fear, anger, disgust, and sadness are basic emotions that human beings express in a species-specific manner. The facial expressions of fear, sadness, and joy, for example, are immediately and accurately recognized regardless of the culture and language of the person experiencing and perceiving the emotions. The nonverbal expressions of emotion are behaviors that are coded into our human repertoire just as is walking on two legs. But the basic emotions are only a part of our repertoire. Variants and blends of these also color human consciousness, such as guilt, regret, jealousy, envy, pride, shame, hate, and love.

An emotion may enter into conscious awareness in the form of images, as the end result of a cascade of responses that begin in the brain, spread throughout the body, and are sensed and perceived by the brain.
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For example, a feeling of fear is initiated in the amygdala, which is buried deep in the limbic system of the brain. The system includes the hypothalamus, whose job is to bring about hormonal changes in the body. It does so by stimulating the pituitary gland, the overseer of a host of glands that together make up the endocrine system. The adrenal glands that lie on the kidneys spew out a stress hormone called cortisol that helps to raise the energy sources needed for immediate strenuous action. The hypothalamic-pituitary-adrenal cascade—known as the HPA axis—is one way that the emotion of fear manifests itself in the body. Another way is via the autonomic nervous system. Specifically, the sympathetic branch of the autonomic nervous system accelerates the heartbeat, suppresses digestion, stimulates the release of glucose into the blood stream, and releases epinephrine or adrenalin from the adrenal glands. The
muscles are primed for a fight-or-flight response. Feelings of fear can then be consciously represented within the brain. Such feelings are thus similar to the auditory images of sound or the visual-spatial images of sight, but they arise into consciousness from perceptions of the body, whether they are the tension of the musculature, the pounding of the heart, or the knot in the stomach.

The biological function of emotions is to participate in the regulation of our behavior. Emotional feelings help determine whether to avoid a situation out of fear or approach it out of interest.
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They thus help us to survive in much the same way that pain and pleasure do. The objects, events, and autobiographical experiences of our lives are linked with feelings of happiness, sadness, anger, and so on. For example, if an event elicits fear, the increase in heart rate and blood pressure that is part of the emotion facilitates a flight response to avoid the danger and threat to survival.

However, emotions—when not fully recognized and managed properly—can sometimes distort the outcome of thinking in the direction of irrationality, or worse, join forces with destructive impulses and thoughts. Carl Izard, a leader in the science of emotions, noted that

unfortunately, linking emotion feelings to maladaptive thoughts like those that characterize racism, sexism, ageism, unbridled profit motive, and plans for vengeance, revenge, or terrorism can wreak extensive havoc to individuals, ethnic groups, and all of human kind. For an abundance of evidence supporting the foregoing assertion, read history and watch or listen to any daily news program.
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THE ROOTS OF EMOTION

Emotion is not unique to human beings. Mammalian species, besides giving live birth, share common structures in the limbic brain that play an important part in emotions. Lying below the neocortex and above and around the brain stem and primitive forebrain regions, the limbic system provides a foundation for the use of emotion to regulate behavior. The basic life support responses of the brain stem can be viewed as reflexive, automatic means of survival, such as regulating the internal environment of the body to maintain homeostasis. Through the limbic responses, the organism gains more complex means of
regulating behavior through the feelings of fear, happiness, and other emotional states. For example, fear provides the signal for knowing what to approach and what to flee from—a regulation of behavior of immense importance for an individual's survival.

Despite the commonality and rudimentary nature of emotion, human emotion cannot be understood without an appreciation for the way the cognitive processes of the neocortex are laid over upon and modulate the responses of the limbic brain. In particular, the ensemble of the modern human mind shapes emotion in ways that render it different from the emotions of other mammals and even other primates. The advanced working memory of human beings is capable of holding in mind thoughts that can ramp up or dampen down an emotional response. The situation that gives rise to an emotional response can be cognitively appraised, and the outcome of this appraisal modulates the intensity of the feelings triggered. The interpreter makes causal inferences about the source of emotional arousal just as it does about other consciously perceived experiences. Mistaken attributions may not only diminish the intensity of an emotion, but even alter the basic emotion felt—what might have inspired fear can be experienced as exciting and attractive. The limbic circuitry for fear—perhaps the most adaptive emotion for an individual's biological survival—is now well documented by neuroscientists. Yet it is also known that the recycling of fearful thoughts in human verbal working memory can greatly exacerbate apprehension beyond any adaptive value. Phobias and generalized anxiety disorders are human afflictions enabled by the very power of our working memory. Similarly, mental time travel can strand one in the past, ruminating endlessly about negative emotional experiences that only serve to drive the afflicted deeper into depression. After experiences of severe trauma, mental time travel can so vividly capture the emotional horror in a flashback as to make the victim feel victimized all over again. All of these serve as examples of how the ensemble of the modern mind has altered the roots of emotion.

Richard Lazarus has explained that the limbic forebrain is really only the beginning of understanding human emotion. Such structures “provide a neural template that makes emotion in all species similar in fundamental ways.”
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However, he goes on to note that

there is nothing in this perspective that requires the reduction of all emotion to the lowest common denominator of comparatively simple animals and reptilian and mammalian brain structures. When such reduction occurs, it is at the expense of recognizing and investigating the primary role of cognition in emotion. It is about time that we began to formulate the rules about how cognitive processes generate, influence, and shape the emotional response in every species that reacts with emotion, in every social group sharing values, commitments, and beliefs, and in every individual member of the human species.
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FEAR AS A PRIMAL EMOTION

Perhaps the emotion best understood by science is fear. Although its valence is clearly negative, fear is a beneficial emotion in motivating avoidance of danger. Its adaptive value in keeping organisms alive and able to reproduce is likely the reason why it emerged so early in the evolution of life. Fear can be observed throughout the animal kingdom, from fruit flies to people. Reptiles, fish, and all mammals exhibit a phenomenon known as fear conditioning, which has provided neuroscientists with a window into the specific neural circuits that mediate the bodily response and subjective feeling of fear.

A laboratory rat is first played a sound that has little if any impact on its blood pressure or its tendency to freeze in place, ceasing movement until danger has passed. This sound then is presented as a conditioned stimulus (CS) that precedes a painful shock, the unconditioned stimulus (UCS) that automatically generates fear, as can be seen in a sharp spike in blood pressure and several seconds of freezing in place. After several of these pairings of CS and USC, classical fear conditioning results in the same physiological changes when only the sound or CS is presented by itself. This animal model of fear conditioning has provided a way to determine the specific regions of the brain involved in the experience of fear.

An understanding of fear requires an integrated view of the limbic system and other parts of the brain.
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Although the limbic structures of the amygdala and the hippocampus are essential parts of fear conditioning, the diencephalon and telencephalon also play a role. Specifically, the sound follows a pathway from the ear via the auditory nerve to the midbrain then
to the thalamus and finally to the auditory neocortex. The output from the thalamus also goes to a cluster of neurons in the amygdala of the limbic system called the lateral nucleus. The signals from the auditory thalamus to the lateral nucleus offer a high-speed connection to the initiation of fear and the freezing of movement. Although the thalamus cannot process the identity of the stimulus that launched a fear response, it can quickly, in a single step, link to the critical structure of the amygdala.
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At the same time, a parallel computation is underway in the neocortex, where detailed and accurate representations of the external world are constructed for conscious perception.
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This involves connections from the auditory thalamus to the auditory neocortex and then back to the amygdala. Many neural links are involved in this neocortical pathway, and so the registration of fear in the amygdala takes more time than via the subcortical pathway. Imagine walking in the woods in autumn and seeing a curved object lying in the leaves and hearing the soft sound of leaves rustling. Before we are able to identify the object causing the sound as a snake, the subcortical circuit has already jacked up our blood pressure and frozen our movements or prompted a jump backward away from the threatening sound.

Although the amygdala is essential to fear conditioning, another kind of learning is also taking place. Episodic memory—the capacity to store and later retrieve into consciousness a recollection of an event from the past—is consolidated by the hippocampus and stored in the neocortex. Specific episodes from the past and the factual content of our knowledge about the world make up the declarative memory system, which operates independently of the nondeclarative system that includes fear conditioning. Damage to the hippocampus interferes with one's ability to recall a past traumatic event, but the emotional learning of fear conditioning proceeds just the same outside of conscious awareness. On the other hand, when the declarative system is intact, people store memories of past trauma not as hot emotions but as cold facts. Joseph LeDoux distinguished the two in the following example:

If a person is injured in an auto accident in which the horn gets stuck, he or she may later react when hearing the blare of car horns. The person may remember the details of the accident, such as where and when it occurred
and who was involved. These are declarative memories that are dependent on the hippocampus. The individual may also become tense, anxious, and depressed as the emotional memory is reactivated through the amygdalic system. The declarative system has stored the emotional content of the experience, but it has done so as a fact.
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The parallel pathways for fear conditioning, on the one hand, and the formation of declarative memories in the form of facts and specific episodes from our life experience, on the other, illustrate how complex even the primal experience of fear can be in the mammalian brain. The limbic system interacts with the neocortical regions even in rats, and such interactions are especially important in the human brain. The ensemble of parts that constitute the modern human mind can markedly alter emotional responses. The result is that the emotional life of a human being is not easily reduced to the output of the primitive limbic forebrain.

For example, in the mental disorders of generalized anxiety, phobia, and panic attack, the powerful human system of episodic memory is turned against the sufferer. In these afflictions, the healthy fear response that keeps us out of harm's way mushrooms into a toxically maladaptive and debilitating emotion. For phobics, emotional learning leads to irrational fear of highly specific situations, such as the claustrophobic fear of enclosed spaces. Fear may manifest itself also as generalized anxiety during which one may be unable to pinpoint exactly what objects or events are provoking the sense of apprehension. The intensity of these responses can vary. In the most extreme responses—called panic attacks—there is a four-alarm fire of emotional upheaval. Hyperventilation and hot flashes, feelings of intense anxiety and nausea, and the sensations of choking and fainting can overtake the victim in the throes of a panic attack. Agoraphobics’ fear of open, public spaces is compounded by the dread that they may suffer a panic attack in public, where escape without notice is difficult. Seeking safe havens, sufferers of agoraphobia often confine themselves to their homes. In these and other examples, the maladaptive side of fear is all too evident.