The Making of the Mind: The Neuroscience of Human Nature (21 page)

In all anxiety disorders, the capacity to travel back in time and bring fear-provoking past experiences to mind compounds the problem. A deep-seated
fear of heights, for example, may bring to mind a past episode in which one's life felt threatened by being on the top floor or roof of a tall building, or at the top of a roller coaster, or in the middle of a high bridge. A past bad experience can be replayed over and over again, deepening the fear, even though the fear-provoking situation is not immediately at hand. Our ability to travel back in time and recollect such fearful experiences using the default network of the neocortex becomes a way of triggering the fear reactions embedded in the networks of the limbic system. It is known that the medial temporal lobe that supports episodic memory sends projections back to the amygdala, and these could well trigger fear responses.
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Remembering past stressful episodes is only half the story, however, Mental time travel also enables the human mind to imagine the future, including mental scenarios of impending doom. The phobic might imagine that it is likely the feared object or event is lurking just ahead in their future. Efforts to avoid the encounter are then seen as essential and comforting. For example, the acrophobic might anticipate what high places might be encountered during the course of the day and think through how to avoid them. The use of mental time travel is especially pervasive in generalized anxiety, where fear is not restricted to a specific phobia. The ability to imagine scenarios of future problems is unleashed and the constant anticipating and dreading the worst takes its toll.

Besides episodic memory interplaying with the limbic system, a similar interaction occurs with advanced working memory of human beings and the interpreter of consciousness. As future threats are brought into mind in those suffering from severe anxiety, they are held there tenaciously and recycled through the verbal store of working memory. The inner voice of the interpreter narrates excessively about the bleak events of the future. Interpretations are assigned to these thoughts that only make them more persistent and more out of control. Those who worry excessively are familiar with these ways in which the advanced capability of human working memory and the capacity to carry on an inner dialogue can make life miserable. They become highly preoccupied with the negative “self-talk.”
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The anxiety disorders reflect breakdowns in our ability to regulate the emotions generated by the human brain. They illustrate that the unique
capacities of the modern human mind are not entirely beneficent. The neocortical systems that provide for advanced working memory, the interpreter of consciousness, and mental time travel can interact with the limbic structures of the brain in a way that harms psychological health. An even more striking example of this linkage can be seen when human beings are traumatized.

Post-traumatic stress disorder (PTSD) represents the residual effects of trauma. It is an anxiety disorder that can develop after a person has been exposed to the threat or actual experience of severe physical harm. Violent personal assaults in domestic or public settings, military combat, life-threatening accidents, and natural disasters, then, are among the traumatic events that can cause PTSD.

Intrusive thoughts and images of the trauma—even vividly recollected flashbacks—plague the victim. Feelings of emotional numbness and detachment are common, as if the mind seeks some relief in turning off the circuitry of emotional responses altogether. Sadly, the emotional numbness is often most severe when around the people with whom the sufferer had once been closest. The places, people, and thoughts associated with the trauma are avoided as much as possible. Signs of constant fear and apprehension are evident in the victim's state of irritability and hyperarousal. The sufferer feels jumpy and easily startled. Sleep provides no relief in that nightmares disturb slumber or insomnia prevents sleep in the first place. In PTSD, normal emotional regulation breaks down in the white waters of relived trauma much as a boat flounders in a hurricane. The capacity to relive a traumatic event as if it were happening all over again is the root cause of PTSD. While normally our human ability to recollect the past is a blessing, after the experience of severe trauma it can become a curse.

Experiencing or witnessing accidents, fires, tornadoes, earthquakes, or other natural catastrophes, or, even worse, traumas inflicted by human design, profoundly affects human emotions. Sexual molestation, rape, physical assault, and being threatened with a weapon all leave deep emotional scars in the mind of the victim. For those who identified rape as their most traumatic experience, 65 percent of men and 46 percent of women suffered PTSD as a result.
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Similarly, high rates of rates of PTSD followed childhood abuse for women (48 percent) and combat exposure for men (38 percent).

The threat to one's life in combat is an obvious form of trauma. But there is more. Witnessing the atrocities of war—seeing unknown enemies as well as close friends maimed, murdered, or massacred—goes far beyond just fearing for one's life. It exemplifies a total collapse of the social norms of civilization, including the sanctity of human life and the bonds of shared humanity. PTSD, as a concept and a label, was not formulated until after America's war in Vietnam, but the same symptoms were observed and identified as shell shock in World War I and as battle fatigue in World War II. Besides the unbidden flashbacks of trauma during waking hours, the reliving of traumatic experiences also haunts the dreams of those who suffer from PTSD. Combat veterans who suffer from PTSD are frequently plagued by frightening and disturbing nightmares that reoccur on a regular basis. They can persist for decades.

A US Air Force officer, Michael Gold, had flown numerous combat missions in a B-17 over Nazi Germany before being shot down on January 30, 1944.
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He was captured and spent the remainder of the war, more than a year, as a prisoner of war. After coming home, he went to college on the GI bill and then was accepted to the Rochester School of Medicine. He became a doctor and had a successful medical career. However, for decades after the war he suffered from recurrent nightmares about his war experiences.
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Here is a recounting of one of them:

He is trapped in the nose of a B-17, scrambling on his hands and knees. The plane is on fire, wallowing through the clouds, going down. Someone is screaming. His lungs fill with smoke; everywhere the smell of cordite and burning rubber. Spent shell casings clatter beneath him. Wind howls through the plane. He struggles toward the escape hatch. Crawling, crawling in the numbing cold. The hatch slips away, receding farther and farther, fading from view. Vanishes.
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The nightmare replayed elements of his actual experiences, but framed them in a hopeless, helpless narrative from which there was no escape. The severe stress of his combat experience was distilled into a vivid vignette that intruded regularly into his dream world. It was not until he reached his mid-seventies that he finally was diagnosed as suffering from PTSD. The nightmares and waking outbursts of temper that plagued him for so much of his life were finally
recognized as symptoms common among soldiers who had experienced combat, particularly those who had to endure captivity as a POW. Here, then, in PTSD, is a perverse consequence of the human capacity for mental time travel. Trauma can be recollected lucidly, in dreams as well as in waking moments, long after nontraumatic, ordinary experiences from early in life are long forgotten.

COGNITIVE APPRAISAL

Another example of a key neocortical intervention in emotion can be found in the attributions made about the source of physiological arousal and the severity of stressors encountered on a daily basis. The interpreter, a system of attention, language, and causal inference, plays an important role in the link between stressors and health. Just as the causes of external events are assessed by the interpreter, the sources of inner emotional arousal are also appraised. If the source of a rapid heart rate and perspiration is attributed by the interpreter to a negative emotion, such as anger or fear, welling up in the body, then the felt emotional intensity is stronger than if some external cause for the arousal is blamed.
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For example, after just finishing a two-hundred-yard sprint, the heart races and the body perspires, but the arousal is regarded by the interpreter as benign and nonemotional. The appraisals carried out by the interpreter can even color the valence of an emotional experience. If the interpreter assigns the cause of trembling to a threat, then fear ensues. The same trembling, after receiving positive news, would be interpreted as the bodily component of overwhelming joy. Similarly, tears can flow in happiness and in sadness, depending on the causal appraisal carried out by the interpreter.

Even the intensity of the primal emotion of fear can be reduced if the physiological arousal the person is experiencing can be attributed to some benign external source. For example, one study induced fear in college students by leading them to believe that they were about to receive an electric shock. The results showed that “subjects anticipating electric shock spent less time attempting to avoid the shock if they were led to believe that their arousal was due to white noise.”
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The white noise became for them a plausible explanation for why they were feeling uncomfortable, and this interpretation of their feelings led to reduction in fear.

Stressors are also appraised by the interpreter for their intensity and potential for damage. Are there financial resources that can reduce the jeopardy of being hit by an earthquake or a tornado? Are there friends, family members, or church members who can provide comfort at the death of a loved one? Is there any way to control the intensity of the stressor to reduce its effects or is one helpless in the face of it? Is it expected that the stressor is only temporary or is it instead likely to afflict one for weeks, months, or even years? The consequences of exposure to stressors can vary widely depending on the appraisals made. The self-talk generated during the course of cognitive appraisals has enormous consequences for how well people cope with the stressors of life.

As noted earlier in the book, the interpreter typically tries to talk about the world in the best possible light. These optimistic interpretations are called positive illusions. Strong positive illusions about health are related to happiness, contentment, and the capacity to function under duress.
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A strong belief in the capacity for self-control allows one to take steps to reduce the number and intensity of stressors in one's life. Without a belief that one can effect a change in the environment, it is difficult to mount an effective response. Optimism about the future similarly serves the function of shaping our appraisals of current stressors. A strong belief that things will be better in the future makes the present more bearable. Thus, positive illusions regarding mental health preclude a state of helplessness where nothing one can do matters, where circumstances are hopelessly beyond personal control, and where the future looks even worse than the present. When the interpreter functions in typical fashion by making overly optimistic and rosy attributions about events and the self, it is certainly not functioning in a way that is rational and in touch with reality. Yet these positive illusions are adaptive and protective.

A key executive function of working memory is inhibition. In depression, a negative mood can trigger a cycle of increasingly bleaker thoughts that are not easily inhibited. The inability to control the content of working memory plays a pivotal role in the downward spiral of clinical depression.
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Those at risk for depression manifest a weakness in the executive function of inhibiting irrelevant information, and they are easily distracted by thoughts that would best be ignored or quickly forgotten. The inner dialogue of verbal working memory instead recycles the negative content in a self-destructive pattern of rumination.
Thus, the ultimate effect of a negative emotion such as sadness is directly influenced by the functioning of the prefrontal cortex and working memory.

Those suffering from depression and anxiety disorders can often be treated through a psychotherapy that focuses on changing the negative attributions and ruminations of the interpreter. These are called cognitive behavioral therapies.
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For example, such therapies attempt to retrain the attributions made about the causes of life's events. Therapists challenge the negative self-talk in an effort to redirect the narrative of the inner voice. The goal of these methods is to instill a more accurate and less debilitating appraisal process and thereby alleviate the individual's anxiety or depression.

In addition to the self-talk and causal attributions of the interpreter, there is evidence that the executive functions of working memory intervene in altering emotional responses. The activation level of the amygdala can be reduced by reappraising a situation that normally would invoke a significant emotional response.
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For instance, a scene of women crying outside a church could elicit empathic feelings of sadness as one shares in their grief. However, if one is instead instructed to interpret the women as crying out of joy at the end of a wedding ceremony, then this shared grief can turn to shared joy. The lateral prefrontal cortex associated with executive attention has been shown to be activated during these efforts to change an emotion through reinterpretation. The degree of activation in the left lateral prefrontal cortex increased for those who were most successful at reappraising the scene and changing their emotional experience. As Elizabeth Phelps observed, “Reappraisal is similar to viewing the cup as half full as opposed to half empty,” and it can “alter the experience of emotion.”
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