The Psychopath Inside (6 page)

Another function of this posterior area is the understanding and conceptual creation of language. In the dominant hemisphere (the left side if you're right-handed), this language function enables us to master syntax and grammar, while in the nondominant hemisphere, this language function allows us to understand the song and rhythm of language, as well as humor. It appears that the dominant hemisphere function is more genetically determined, while the nondominant hemisphere function is more molded by environment. That is, you will learn to mirror the accents and cadence and patois of speech from your family and friends, but your basic ability for grammar and syntax is more genetically determined. One tends to adopt the song and rhythm of speech around the time one reaches puberty, but the range and capabilities of individuals vary widely. In the case of Henry Kissinger and his younger brother, Walter, who fled Nazi Germany in 1938, when Henry was sixteen and his brother was fourteen, the elder brother kept his pronounced Frankish accent while Walter sounded very American.

In the Rubik's Cube middle sector of the hemisphere, there are the somatic and motor areas that map the skin senses in the back half of this middle piece, and the map of the areas that control the muscles of the body. Just in front of this motor cortex is the premotor cortex, which is involved in the planning of motor movements and in learning the rules of how we swing a golf club and play the piano. These two motor-related cortices form a strip on each hemisphere in size and placement like the support arms of a set of earphones.

The anterior, or front, section is the prefrontal cortex and is responsible for the so-called executive functions of the brain, including knowing rules, making plans, and enabling short-term memory. This “scratch pad” memory lasts seconds or tens of seconds and helps us to remember phone numbers long enough to dial them and tells us, without looking, where we set our drink while we're eating or playing poker. The prefrontal cortex is the brain region most important for the elaboration of personality and character, and the control of impulse, obsessions, and antisocial behavior.

Besides being the locus of will, the prefrontal cortex is related to a myriad of functions we consider particularly well developed in primates, especially humans. These involve what has been called “memory of the future,” that is, projecting one's mind into the future to imagine, or experience, really, how one will remember an act that has not yet taken place. This is akin to the pleasant sensation one has when playing a game of chess and knowing that after just five moves one will cream his opponent. This knowledge of the imagined future resides in a circuit centered in the prefrontal cortex.

I suspect that humans' ability to do this relies, in part, on a mutation in the gene for catechol-O-methyltransferase, or COMT. This enzyme is responsible for breaking down dopamine in the frontal lobe after it has been released. There are two possible versions of the mutation, which, taken together, are referred to as the valine-methionine polymorphism. The methionine version of the gene leads to the production of a COMT enzyme that has a lower melting point, while the valine version codes for a COMT with a higher melting point. All this means is that, in those with the methionine version, COMT inactivates faster at normal brain temperature, allowing dopamine to hang around synapses triggering neuronal function for a longer period of time, since there is no enzyme to break down the neurotransmitter. The steady supply of dopamine enhances frontal lobe activity, including its capacities to brainstorm and premeditate. Thanks to this and other neurotransmitter-related mutations millions of years ago, early humans could plan further ahead and anticipate future events like war and famine. And because they could anticipate these events, they did things like invent weapons and learn to farm. Likewise, memory of the future allows us to appreciate a sense of time and helps explain our belief in religion, the afterlife, and eternity.

The next way we can slice the brain's hemispheres is into upper, middle, and lower thirds, more correctly referred to as the dorsal, intermediate, and ventral streams.

The upper, or dorsal, stream lies right under where you wear a ten-gallon hat. This “stream,” so called by Leslie Ungerleider of
the National Institute of Mental Health, is primarily concerned with processing “where” things are in your external environment, as well as their movements. The lower, or ventral, stream processes “what” things are in your external world, especially in the visual system. The intermediate stream codes for “when” things happen, but is also involved intimately with language and the mirror neuron system (explained in chapter 7).

The dorsal part of the prefrontal cortex and its interconnecting subcortical areas are associated with “cold cognition,” emotionless processing of thoughts, perceptions, short-term or executive memories, plans, and rule-making. This involves both generating these thoughts and also inhibiting other thoughts, depending on established rules for success and failure in the appropriate context. Life is full of rules and contingencies, whether in Scrabble or golf or business, and the dorsal prefrontal cortex tells you when it's okay to act on your urges—when you should place a tile or hit a ball or buy a stock—and when you shouldn't. The lower, or ventral, part of the prefrontal cortex, largely made up of the orbital cortex and ventromedial prefrontal cortex, is involved in similar functions, but more those enabling and disenabling “hot cognition”—emotional memory and socially, ethically, and morally programmed behaviors. Someone with a highly functioning dorsal prefrontal system would have superior planning and executive functions, whereas someone with a highly functioning ventral prefrontal system would have superior control over impulsive and inappropriate interpersonal and social behaviors. Likewise, lower functioning in these systems leads to not only a lack of
comprehension of these high-order behaviors, but an inability to control them under socially inappropriate circumstances.

Connecting with others involves both cold (rational) cognition, where one person understands what others might be thinking and what an appropriate response might be, and hot (emotional) cognition, where one can experience empathy with another's feelings and attitudes—that is, actually “feel” them much like the other person would experience them. Someone with damage to the hot system, let's say in the orbital cortex, might not be able to predict others' thoughts but will have the most trouble sharing his feelings. A dichotomy may exist between empathy, a fundamental connection with the pain of others and arising very early in life, and “theory of mind,” a more elaborated medial prefrontal system that allows us to consider others' thoughts and beliefs, even if they're different from our own. People with autism lack theory of mind but not empathy, while people with psychopathy lack empathy but not theory of mind. Without empathy you can still have sympathy, though—the ability to retrieve emotional memories, including those that can predict what painful event is probably about to befall another person, and the will to help that person.

These brain circuits mature at different times during development, and although there are major maturational events that take place in the terrible twos, puberty, late adolescence, the twenties, and the mid-thirties, some are not completely integrated until one is in the sixties, which appears to be the typical average peak time of human insight, cognition, and understanding in many realms of life.

The central cube in the Rubik's Cube brain consists of the subcortical structures that lie deep in the cortex, and these include the basal ganglia, the thalamus, and the brain stem. The basal ganglia are a region important for understanding how cognition and emotion interact to facilitate or turn off behavior. It is a yin-yang area in dynamic balance where dopamine and the endorphins may have opposite effects on adjacent neurons, and where motivation, drive, hedonism, addictions, sensory-motor activity, and all sorts of fascinating behaviors get their oomph.

There are millions of so-called loops of neuronal connections that pass through the basal ganglia, integrating cortical command information with other subcortical way stations such as the thalamic structures (called the thalamus, epithalamus, subthalamus, and hypothalamus), brain stem, and cerebellar circuits.

Some of these loops are closed, or direct, feedback loops connecting the same brain areas over and over, while others are open loops where the information is passed to adjacent brain channels for integrating, say, different modalities of perception, emotion, consciousness, attention, planning, and will.

Within each loop there are parallel channels, one of which leads to motor action and is thus a “Do It” channel, and its partner, which keeps you from doing something, and is thus a “Don't Do It” channel. These two converge on motor neurons that add up the “Do Its” (excitation) and the “Don't Do Its” (inhibition) and determine whether you move. Since dopamine turns
on
the “Do It” channel, and simultaneously turns
off
the “Don't Do It” channel in the loops, dopamine is the key neurotransmitter that flips
the switch when you are lying on your couch watching the game and decide you want to go get a beer. People whose dopamine cells die do not have this ability to get up from the couch. These people have Parkinson's disease. They have the will to get up (prefrontal cortex), and they have the plan (premotor cortex) and command signal (motor cortex) to get up and start walking, but they don't have the dopamine to activate and deactivate these “Do It” and “Don't Do It” channels to get the movement started.

There are millions of these closed and open loops in the brain connecting the cortex and subcortical areas, and in this way broad areas of the brain become involved in even the seemingly simplest of behaviors we take for granted. This is why when we look at a PET scan or fMRI scan or EEG, just a finger tap can activate many brain areas in both cortical and subcortical areas.

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As I looked at the scans of killers Amen sent, there were a few features I expected to see in the psychopaths. They would have decreased activity in the orbital cortex—the part of the prefrontal cortex just above the orbits, or eye sockets—and the nearby ventromedial prefrontal cortex. These are involved in inhibition, social behavior, ethics, and morality. I expected psychopaths would also have damage to the front of the temporal lobe, including the amygdala, which processes emotions, leading to cold behavior. I'd seen these neural deficits in other scans of psychopathic killers, and they'd also been identified in more formal research by other labs.

So I pointed to the scans I thought belonged to the psychopathic killers. When we looked up their code numbers, I'd nailed
it. When a neuroanatomist sees a pattern, he goes crazy. I could have been studying butterflies and I still would have gotten excited. Patterns are where we get our buzz. And that's when I really became interested in psychopathy.

Combining these scans with others of diagnosed psychopaths I'd collected over the years, I noticed a more intricate pattern. In psychopaths, I saw a loss of activity that extends from the orbital cortex into the ventromedial prefrontal cortex and into a part of the prefrontal cortex called the anterior cingulate. The loss then continues along the cingulate cortex to the back of the brain as a thin strip, then loops down into the lower part of the temporal lobe into the very tip of the temporal lobe and the amygdala.

FIGURE 3C
: Brain areas dysfunctional in psychopaths.

FIGURE 3D
: PET scans of normal brains and that of a psychopath.

All of these areas of loss make up the major chunk of brain called the limbic, or emotional, cortex, since this is the main area regulating emotion. This loop of loss of cortical function comes full circle, as I noticed that the “connector” strip of cortex between the orbital, cingulate, and temporal cortex—the insula—also showed signs of damage or low function in these psychopathic killers. In previous studies of psychopaths' brains, most attention had been on the orbital and ventromedial prefrontal cortex and
the amygdala. I filled in the picture, identifying other areas related to anxiety and empathy, and explaining how psychopaths could sometimes remain so cool and collected. The simplicity and elegance of this pattern exhilarated me as I felt I had perhaps discovered a sliver of the Holy Grail for understanding awful, predatory human behavior.