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Throughout this chapter and the last, you have seen that the interrelationships between biological processes and psychological processes central for personality, such as our emotions and motivations, are becoming increasingly visible. It has become possible to explore the relations between brain, evolution, and personality through the development of assessment methods that now enable researchers at the Biological Level to investigate these links systematically. In recent years, a revolution has occurred in such measurement that opens new routes for seeing brain–behavior connections.

New Windows on the Brain

Technological advances in brain imaging now allow researchers to use methods that capture even subtle nerve activity in the brain. As noted in Chapter 2, the technique of functional magnetic resonance imaging (fMRI) measures the magnetic fields created by the functioning nerve cells in the brain and with the aid of computers depicts these activities as images. These images enable researchers to see the brain areas that are most active as the person performs different kinds of mental tasks and experiences different kinds of perceptions, images, thoughts, and emotions, from fears to anticipated gratifications.

Brain imaging makes it possible to trace the relations between activity at the Biological Level and what the person is doing, thinking, and feeling in different situations. The new windows on the brain allow a much more precise and detailed analysis of the links between activity in the brain and mental activity at the psychological levels reviewed throughout this text. For example, Kuhnen and Knutson (2005) measured

6.12 Describe fMRI and PET techniques for measuring brain processes.

brain activation with the fMRI while participants were making financial decisions that vary in risk-taking strategy. They found clear links between risky, nonoptimal financial decision-making strategies and activation of specific brain areas (the nucleus accumbens).

Their results suggested that activities in ‘‘distinct neural circuits. . . promote different types of financial choices and indicate that excessive activation of these circuits may lead to investing mistakes’’ (Kuhnen & Knutsen, 2005, p. 763). Our brains may show we are making costly mistakes before we realize it ourselves or see the unfortunate consequences.

A second technique to link brain and behavior is the PET procedure, or positron emission tomography, which also was briefly introduced in Chapter 2. This technique creates images and maps of brain functioning by assessing metabolic activity in different

Woman entering an fMRI brain scanner.

(Source: Charles Thatcher/Stone/Getty Images)

areas. It records the radioactivity in the brain that occurs after the participant has been given a nontoxic but radioactively labeled form of glucose, which is the energy source for the brain’s activity. These methods are being used by cognitive neuroscientists, increas-ingly working in collaboration with psychologists from the areas of social-personality and clinical psychology (e.g., Kosslyn et al., 2002; Ochsner & Lieberman, 2001).

Particularly exciting is the recognition that in these studies individual differences in personality are not ‘‘noise’’ that needs to be removed to decipher the mechanisms involved. On the contrary, attention to personality and the differences between individu-als in responsiveness on these brain measures allows a much deeper and more complete understanding. For example, in studies of mental imagery using the amount of blood flow measurable in different areas of the brain, it was found that

monitoring individual differences in blood flow in relevant areas . . . provides enormous power in predicting behavior. . . individual differences not only can be used to establish that a particular type of representation is used during the task. . . but also can help identify the neural underpinnings of such processing. (Kosslyn et al., 2002)

The Amygdala and Personality

The new methods for examining brain activity and its links to mental and emotional reactions are proving to have major implications for personality psychology. To illustrate, a particularly important brain area for personality researchers is the amygdala (which means ‘‘almond’’ in Latin). This small almond-shaped region in the forebrain is buried deep under the prefrontal cortex (Figure 6.2). It is crucially important in fear learning (LeDoux, 1996). The central nucleus of this brain structure reacts almost instantly to

Biological Assessment and Change 䉳 137 Medial view

Prefontal cortex

Amygdala

Hippocampus

Figure 6.2 The amygdala is important in fear and emotional reactions.

signals that warn of danger, immediately sending out behavioral, physiological (auto-nomic), and endocrine responses. The amygdala mobilizes the body for action, readying it to flight or fight. It also seems to be involved in appetitive behaviors. Studies of individ-ual differences in amygdala activation are casting new light on mind–brain connections in personality, as the following study illustrates.

Linking Inhibition to Amygdala Activation

In Kagan’s work with inhibited, shy children (discussed in the previous chapter), researchers also examined how the childrens’ inhibited behavior is related to biological processes and specifically to activation in the amygdala area of their brains (Schwartz, Wright, Shin, Kagan, & Rauch, 2003). Infants who were observed at 2 years of age in the lab to determine their level of inhibition were tested again when they were 22 years of

6.13 In Kagan’s study, how does amygdala activation differ between inhibited and uninhibited individuals?

age. That follow-up included assessing brain activity in a fMRI session while participants looked at either familiar faces (that they had been exposed to in an earlier session) or unfamiliar faces. The study examined how much activity was in the amygdala—the part of the brain that responds fast to threat and fear stimuli—for the 22-year-old participants while they completed the face task. The researchers found greater amygdala activation among the inhibited participants (compared to the uninhibited) while they were looking at unfamiliar faces. There were no significant differences in amygdala activation between inhibited and uninhibited participants in response to familiar faces.

The findings made it clear that temperamental differences in inhibition and shyness are related to an overreactive amygdala when inhibited people are faced with novelty in the form of unfamiliar faces.

Biological Therapies

As we saw, some psychological dispositions have biological roots. If problematic behav-iors, such as severe depression, in part reflect biological dispositions and biochemical problems, might they also respond to biological treatment? Researchers have actively pursued this question.

TABLE 6.3 Some Drugs Used in Pharmacotherapy

Type of Drug Application Therapeutic Effects Antidepressants (cyclics,

monoamine oxidase inhibitors)

Depression Appear effective for elevating mood in some people

Antipsychotics (phenothiazines)

Schizophrenia Well substantiated: get patients out of hospitals, have practically eliminated need for restraints in hospitals

Minor tranquilizers (benzodiazepines)

Anxiety, tension, milder forms of depression

Seem to slow down transmission of nerve impulses in the brain

Lithium Manic behavior Reduces mood swings

Methadone (a synthetic narcotic)

Heroin addiction May eliminate craving for heroin; blocks ‘‘highs’’

Note: These drugs are classified according to their effects on behavior, not according to their chemical composition. Chemically dissimilar drugs can produce similar effects.

Biological treatments attempt to change an individual’s mood or behavior by direct intervention in bodily processes. Pharmacotherapy, or treatment with drugs, has so far proved to be the most promising biological therapy for psychological problems. The types of drugs used for specific purposes are summarized in Table 6.3.

Antidepressants

The antidepressants, or psychic energizers, are used to elevate the mood of depressed individuals. Two of the largest categories are the cyclics and the monoamine oxidase inhibitors, or MAOIs (Lader, 1980). Fluoxetine (trade name Prozac) is currently one of

6.14 Describe the drugs commonly used for therapeutic purposes.

the most favored and widely used cyclic antidepressants, which increases the chemical neurotransmitter serotonin (Kramer, 1993). Excessively low serotonin levels seem to be related to such feelings as chronic pessimism, rejection sensitivity, and obsessive worry.

Antidepressants have been shown to have varying degrees of efficacy and to produce various side effects (e.g., Davis, Klerman, & Schildkraut, 1967; Klein, Gittelman, Quitkin,

& Rifkin, 1980; Levine, 1991). The MAOIs, for example, appear highly effective in certain types of depressed individuals, although their side effects can include a dangerous rise in blood pressure when foods high in tyramine, such as red wine and cheese, are consumed (Howland, 1991; Kayser et al., 1988; Potter, Rudorfer, & Manji, 1991). Lithium, an alkali metal in a drug category of its own, is used to stabilize mood swings and occasionally to treat severe depression (Grilly, 1989).

Antipsychotics

The phenothiazines (most notably chlorpromazine) have proved to be so useful in manag-ing patients with schizophrenia that they are referred to as antipsychotic drugs. Their use in mental hospitals has been widespread since the 1950s and has changed the character of many hospitals, eliminating the need for locked wards and straitjackets. Discharged patients are often on maintenance dosages of these drugs and must occasionally return to the hospital for dose level adjustments.

The major tranquilizers have potentially serious side effects that may include motor disturbances, low blood pressure, and jaundice. There are also unpleasant subjective effects such as fatigue, blurred vision, and mouth dryness, which may explain why

Evolutionary Theory and Personality 䉳 139 patients on their own may simply stop taking these drugs and often have to return to the

hospital for an extended stay.

Tranquilizers

The barbiturates were the first widely used so-called ‘‘minor tranquilizers’’—drugs that relieve relatively mild anxiety. However, these drugs were replaced by the benzodi-azepines, which proved more effective with fewer side effects (Lader, 1980). For many years, the most widely used of these drugs was a synthetic chemical known by its trade name, Valium. It became the medicine most frequently prescribed in the United States for several years as Americans spent almost half a billion dollars a year on it.

Valium, like its predecessors the barbiturates, acts on the limbic system of the brain and is useful in the treatment of anxiety, panic disorder, and some convulsive disorders (Gitlin, 1990). Although Valium seemed less harmful than the barbiturates, it also proved to have side effects and to be potentially addictive. It can endanger a developing fetus and can have adverse effects of confusion and agitation, especially in the elderly. Now other benzodiazepines such as Xanax, Klonodin, and Ativan are popular alternatives, although their potentially severe side effects also require extremely cautious monitoring.

The use of antidepressant medication in treatment of extreme anxiety or panic attacks also may be effective (Gitlin, 1990).

Other Common Drugs

Other widely used drugs include the psychostimulants, such as Ritalin, which are used in treating impulse disorders and severe attention deficits. Methadone, a drug that blocks the craving for heroin and prevents heroin ‘‘highs,’’ is often used to overcome heroin addiction, either by weaning the person off it or by maintaining him or her on a fixed dose; however, methadone itself is addictive, and the process can take a long time (Lawson & Cooperrider, 1988).

As this brief survey suggests, some drugs appear to be positive contributors to a treatment program for some disorders. However, no drug by itself constitutes an adequate complete treatment for psychological problems. To the extent that the person’s difficulties reflect problems of living, it would be naive to think that drugs can substitute completely for learning and practicing more effective ways to cope with the continuous challenges of life. And the fact that most drugs have negative side effects (Maricle, Kinzie, & Lewinsohn, 1988) makes it all the more important to seek psychological treatment for psychological problems whenever possible, often in conjunction with a medically supervised form of pharmacotherapy.

In spite of the problems encountered by efforts to treat psychological problems chemically, there is much exciting progress, and the new field of neuropharmacology is thriving (e.g., Cooper, Bloom, & Roth, 1996). For example, biological responses in panic disorders are becoming better understood and, in turn, the effects of various chemicals (such as sodium-lactate) on panic states are becoming known (e.g., Hollander et al., 1989). As a result, treatments for a wide range of anxiety and mood disorders are taking into account both biochemical and psychological processes (Barlow, 1988; Klein & Klein, 1989; Simons & Thase, 1992).