Joy, Guilt, Anger, Love (4 page)

One of the group’s first experiments that helped identify the role of emotion in decision-making focused on gambling. Not everyone is a professional gambler, but we all face decisions that require the assessment of risk and of potential gains and losses, as well as choices that may conceal harmful, counterproductive and irreversible consequences. Such are the uncertainties of life.

Damasio and his colleagues gave the players in the gambling experiment a starting sum of $2,000 and four decks of cards, asking them to draw from any of the four decks.
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Each card drawn revealed a reward or a request to hand over an amount of money. The ultimate goal was to end the game with the highest profit. A secret pattern lurked among the cards. One pair of decks contained cards with the best rewards, up to $100. However, this pair also included cards that requested the gamblers to hand over equally large amounts of money. So, while these two decks gave the impression of being profitable, they also carried the highest risks. At first sight, the gamblers had no way of telling when an unfavourable card would turn up. By contrast, with the other two, less treacherous, decks of cards, the highest win was only $50, but the losses were never harshly punitive. Overall, drawing from the low-win decks would prove more profitable.

The gamblers in the experiment consisted of two groups: people with their brains intact and patients with lesions in their medial prefrontal cortex. Like Phineas Gage, the latter experience difficulties in taking decisions. Damasio realized this when, for instance, he invited them out for lunch and asked them to pick the restaurant. Testing Damasio’s patience, they would spend more than half an hour reciting the pros and cons of several restaurants. One, they warned, had good prices but was always empty, so it might not be too good, but, on the other hand, it was more likely to have a free table; another was pricey but had generous portions.
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In the end, despite all their lucubration, the patients couldn’t make up their minds. One of them, whom Damasio named Elliot, was a bit like Gage. He was an otherwise entirely intelligent, pleasant and charming man with a sharp memory, but he was unable to hold on to a job, keep a wife or plan his time properly. He acted foolishly and irresponsibly and could not be trusted.

Anyway, back to the experiment. As the gamblers carried on playing, an important hint that made Damasio suspect the involvement of some kind of emotional arousal in their choices came from their bodies – to be precise, from their skin. Attached to each gambler’s skin was a machine that measured changes in skin conductance response, or SCR. SCR is a sophisticated expression for sweat. If you are nervous or stressed, or in general emotionally stimulated, one of the things that happens to your body, even if it is not perceptible to the naked eye, is that your skin sweats slightly. In a laboratory, this can be measured as it happens. Over the course of the game, the gamblers with intact brains preferred to pick cards from the advantageous decks. At a conscious level, they didn’t know exactly what was going on or why it would be wiser to take that decision. But their bodies did. As measured by the SCR, each time they picked from the risky decks, fear emanated from their skin and that emotional edge guided their choice towards the less hazardous decks. On the contrary, as you would expect, the judgement of the patients was less sharp. When their hands reached for the more punitive decks, there was little or no skin reaction. They kept drawing cards from the bad decks, even when they started to realize how harmful they could be.

So, failure to experience the emotional cues of a situation results in poor deliberation.

Not only was emotion important in guiding a decision, but in a way it already knew which was the best decision to take, and took it first. Call it intuition, a sixth sense or just plain foreboding. Whatever it is, it helps reason to make a choice.

Damasio’s hypothesis is that this intuition is actually finely etched in our brains, like grooves of a song incised on a vinyl record. In fact, he calls it the ‘somatic marker hypothesis’ (the Greek word
soma
means body). Each time we face a situation, we register its positive or negative emotional charge. It’s as if we stored emotional knowledge in our brain. The behaviour in the game of the two kinds of gamblers suggested that the acquisition of this knowledge must somehow require a functional prefrontal cortex – in connection with the limbic brain – and that, in possession of this knowledge, the prefrontal cortex works like a guide that controls our actions. Indeed, the acquired information becomes precious knowledge for when a similar situation arises again. The harsh losses they incurred taught the gamblers with intact brains about the risk of drawing from the bad decks. The gamblers with lesions in their medial prefrontal cortex could not register, nor retrieve, that information, and so kept making the same mistake.

In real life we face countless situations in which emotional knowledge comes in handy. These range from relatively simple choices, such as which colour to paint the living room, where to spend a holiday or which painting to buy, to more committed decisions about who to date, which property to buy or whether or not to accept a job offer. In each of these cases, emotional hints can guide our actions. It’s almost as if the grooves of that once-incised song play a warning sign silently in our ears, suggesting what we should do.

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Damasio’s ground-breaking experiments entirely revised the predominant theories that confined decision-making to the realm of rationality and established a new theory according to which emotion is essential in decision-making and our most seemingly rational choices. Emotion and reason are not two exclusive functions of the brain. There exists a mutual dependency between the two. Relying on the computational qualities of your brain makes you develop sophisticated analyses. But, as Damasio’s experiments show, you would not be able to take any good decision. In extreme cases, no decision at all. You would be blocked or lost in the careful assessment of the myriad advantages and disadvantages of each option, just like those patients who couldn’t make up their minds about the restaurants. It does happen from time to time that we take decisions without being able to provide the ultimate explanation for having taken them. Emotion helped us take them, unconsciously, behind the foreground of rationality. So, emotion makes its own judgement, as it were, and has equal authority to rationality. In fact, reason can’t operate without emotion’s persuasive advice.

But what these experiments also did was to remap the fixed geography of brain function. They showed that a region in the prefrontal cortex, which everyone believed was exclusively responsible for the analytic, logical duties of the brain, does indeed participate in emotion. Without it, the emotional edge that contributes to decision-making somehow can’t be integrated into the process.

After Elliot, several other patients were observed in a search for clues that could confirm the original findings.
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In some cases the lesions in the prefrontal cortex resulted in syndromes characterized by pronounced aggression and impulsivity. A 56-year-old man with the initials J and S – I’ll call him Jay – was taken to a London hospital’s emergency department after he was found unconscious with damage to the front of his head.
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An inspection of his brain revealed damage to the orbitofrontal cortex (as well as to the left amygdala), the lowest and most frontal part of the PFC, behind the eyes. His behaviour became bizarre while he was still in hospital: for instance, he was found riding a hospital trolley. Like Gage and Elliot, he failed to plan ahead properly, sometimes taking trips around London without any particular destination or any idea of when he would come back. He was also unable to hold down a job. Basically, damage to Jay’s PFC compromised his ability to plan, keep things in mind and pay attention. But he was also irritable and aggressive. He became uncooperative with the hospital staff, whom he frequently assaulted and wounded. He had lost all sense of what could be dangerous for others. He showed no respect for the safety of those around him and no remorse or guilt for his actions, even when he hit nurses. On one occasion he kept pushing a patient around in her wheelchair, despite her screams of protest. He wasn’t sensitive to clues about the social acceptability of his behaviour, nor did he accept responsibility for his actions.
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Further evidence of the role of the PFC in controlling aggression was found in a group of murderers who had committed unplanned, impulsive murders. Their brains showed abnormalities and decreased functionality in various areas of the PFC.
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Evidence accumulated from observation of several individual patients points to the PFC normally performing an inhibitory function on tissues of the limbic system, including the amygdala. However, when the PFC is lesioned or something else goes wrong with it, the amygdala is released from this inhibition, making it harder to control aggression.
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The general picture that comes out of this research is that the prefrontal structures exert a regulatory or modulating role on the limbic regions. The prefrontal cortex constrains impulsive outbursts. This is possible because these two systems are not isolated from each other. On the contrary, they are delicately connected to allow the integration of their functions. The ultimate outcome of an action must be finely tuned by both the limbic structures and the prefrontal structures.

The establishment of control, and the wise use of restraint, may come in handy across a spectrum of actions that call for it, from the most trivial choice to the most despicable act of violence. For instance, it is thanks to the prefrontal cortex that we resist the temptation to spend money we don’t have, or opt for a sugar-free coffee to minimize glucose intake with the aim of preserving our figure.
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Without the PFC, we would have a hard time completing a task. We would also be indifferent to the good or bad value of things. Or we couldn’t restrain our anger.

An angry bunch

There is another level at which people differ in the way they develop and manifest anger and violence. From the anatomy of the brain we need to move down to something invisible: genes.

Genetics is all about looking for differences. To learn about the function of a gene, geneticists study what happens when something goes wrong with it, when it is absent or when it has undergone changes, or, in biological parlance, mutations. A strong clue to a genetic component of aggression came from the Netherlands. A group of men from the same large family presented persistent and pronounced aggressive behaviour.
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They displayed an elevated predisposition to aggressive outbursts, excessive anger and violent, impulsive behaviour, such as rape, assault and attempted murder, burglary, arson and exhibitionism.
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A few also presented mild mental retardation. The fact that the trait kept manifesting in the same family made Hans Brunner, a scientist working in Amsterdam, suspect that their behaviour might have been the outcome of some anomaly in their genetic make-up, so he set out to sequence the men’s DNA. What he found was remarkable. All of them carried a faulty version of a gene responsible for the production of an enzyme called monoamine oxidase A (MAOA). The mutation was in their X chromosome, the genetic material we inherit from our mothers.

Among other things, enzymes break down other molecules. MAOA breaks down neurotransmitters, such as dopamine, norepinephrine and serotonin – molecules that allow brain cells to communicate with each other – all contributing in one way or another to the quality of our moods and personality. The Dutch men’s mutation was an infrequent but rather powerful anomaly. Basically, these men did not produce any MAOA.
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After this rare discovery, more scientists looked into whether other versions of the MAOA gene existed in the human population.
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While the sequence of genes across individuals is pretty much identical, there may be tiny differences at the level of the DNA bases – the units that make up a DNA molecule – that make each of us unique and different from everyone else. These differences constitute what is called genetic variation. Often these changes are without effect. Sometimes, however, they result in the alteration or loss of the functionality of a molecule.

Indeed, in the population at large there is genetic variation for MAOA; that is, there are slight differences from one individual to another in the relevant DNA sequence of that gene. The MAOA gene comes mainly in two forms: a longer version producing high levels of the enzyme and a shorter version producing low levels. If you have less enzyme, there will also be less effective and slower degradation of neurotransmitters in your brain. In one study conducted in 1993, men with the low-activity version were found to be more likely to engage in impulsive and aggressive behaviour. As additional evidence, rodents whose MAOA gene has been engineered out have elevated levels of serotonin and males manifest a dramatic increase in aggressive behaviour.
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After the discovery of its implication in aggression and violence, the MAOA gene was rapidly given the nickname the ‘warrior gene’ and a flurry of articles have been published all claiming association of the low-MAOA form with aggression and violent behaviour, as if aggression and violence could be the result of bad genes only.

In the 1990s, when these discoveries were made, there was great excitement about the role of genes and their influence on behaviour. Well over forty years after the discovery of the structure of DNA in 1953 and the realization that this molecule was the carrier of the genetic information, the global scientific community was working towards the next big milestone: decoding the genome, that is the sequence of an individual’s entire genetic material. With the race on to complete the Human Genome Project, you could breathe the enthusiasm in laboratories. Genes ruled.