Joy, Guilt, Anger, Love (29 page)

Speed was a common diversion. Today, the use of amphetamines to enhance concentration and performance is on the rise even among college students and faculty.
¹⁹
A survey conducted among over a thousand readers of the scientific journal
Nature
revealed that one in five of the respondents – most of them presumably scientists – made use of some kind of performance enhancers.
²⁰

 • • • 

I have talked a lot about the anticipation of pleasure, but what is it that pervades moments of ecstasy as they happen? As we have learnt, the anticipation of pleasure and pleasure itself are two different matters. And this difference has been studied at the level of brain tissues and molecules. Broadly speaking, if dopamine is the molecule of motivational pleasure, opioids are the molecules taking care of comforting, blissful sensations.

To make a parallel with a common experience in today’s world, dopamine is what supposedly bathes your brain when, having posted something humorous on your Facebook wall, you log on repeatedly in anticipation of unpredictable reactions from your friends. Opioids are probably released when you see the red notifications of each comment or ‘like’. The whole thing makes you crave more. Dopamine will make you post something else.

Historically, those who consumed opium mostly retained fond memories of the experience.

Opioids work by binding to dedicated receptors in the brain. In chapter 4, I mentioned how opioids powerfully fight pain. Morphine, for instance, is a very strong painkiller. But opiates also influence pleasure as much as they influence pain. From morphine, through the addition of just two small acetyl groups, derives heroin – smack. Fortunately, we don’t need to resort to opium, morphine or heroin to benefit from some of the analgesic, calming and comforting effects of opioids. Our bodies produce their own molecules that resemble opium, bind to the same receptors and work to dampen our sensations of pain. These home-made opioids are called endorphins. In the absence of pain, they are bearers of pleasure and comfort.

As I briefly mentioned earlier, giving opiates to the young of various mammalian species separated from their mothers reduced their protest against the separation. They calm us down. Opiates are also released when somebody simply strokes us. A caress is enough to open the gates to a flood of opioids.

 • • • 

With a few obvious differences, a night of wild oblivious sex, a Beethoven sonata and a succulent meal have much in common, when it comes to their map on the brain. I am going to very briefly illustrate how.

Opioids abound during sex. When we reach an orgasm, the brain looks as if it is on heroin. Much of sex obviously takes place between the legs, but it resonates throughout the body and the pleasure deriving from it travels back and forth between our genital organs and the head. The wires for such communication are nerves which relay sensations of touch and stimulation from our genital organs to the brain via our spinal cord. Long distances are covered by neural highways connecting the brain to parts of the body such as the scrotum, penis, clitoris, vagina, cervix and rectum. The clitoris alone is innervated by thousands of such wires.

In late 2011, at the annual conference of the Society for Neuroscience, an exciting movie was shown to the attending delegates. It was a short clip showing images of the brain during all phases of a woman’s orgasm, from its initial approach through to its climax and its fading, a total of five minutes.
²¹
The clip was presented by the psychologist Barry Komisaruk, working with Beverly Whipple. Komisaruk has monitored the brain’s activity in women who successfully stimulate themselves in an fMRI scanner – a remarkable event given the claustrophobic nature of the scanner, but totally possible. At first sight, it looked as though there was in fact no region in the brain that did not light up. Everything seemed to be in ecstatic turmoil. But a closer examination better reveals the neural geography which delineates itself across the timespan of the clip. To go through in detail all the brain areas flooded with oxygen in an orgasm – around thirty on a rough count – would be a boring list, far-flung from the bliss experienced during one. There have been several studies looking at this and some of the results contradict each other, requiring future refinement. However, some brain areas are a constant. For instance, when the orgasm reaches its peak, the reward centre is definitely involved. Of note is the quietness of the orbitofrontal cortex. This being the part of the brain that exercises control over much of our behaviour – Freud’s superego – it is kind of reassuring that it should shut off during orgasm, a moment of temporary bliss, oblivious to any kind of mental restraint. Similarly, data coming from inspection of the brain during male ejaculation reveal no involvement of the amygdala. Orgasmic moments bring us to a fearless place.
²²

Placing the orgasm under the scrutiny of science and understanding how it works may help those who have troubles reaching them, such as women with spinal cord injuries. Until not long ago, women with spinal cord injuries were advised to give up on a satisfying sexual life, because everyone thought the severance of the nerves passing through the spinal cord disrupted the pleasure wires. However, Komisaruk and Whipple discovered an alternative orgasmic pathway: the route of the vagus nerve. In Latin,
vagus
means ‘vagabond’, ‘wandering’ or ‘itinerant’. Indeed, the vagus nerve travels and spans a considerable distance in our bodies. Originating in the brainstem, the ‘power-switch’ of the brain, more or less at the base of our skull, it departs from the medulla and then weaves itself down the neck along vital paths such as the jugular vein, to then innervate chest, abdomen and our guts. Since the vagus nerve takes the ‘guts’ route, it bypasses the spinal cord. Indeed, when the injured women stimulated themselves in the brain scanner and reached orgasm, the medulla, which is where the vagus nerve projects in the brain, was active.
²³

 • • • 

‘Music is the shorthand of emotion,’ said Leo Tolstoy. It is hard to disagree.

In previous chapters, I mentioned how visual art and theatrical performance have the power to elicit strong emotions. Hardly anybody can resist the spellbinding power of music. A pleasant melody, the perfect pitch, a convincing rhythm can be sources of ecstatic pleasure. Why we enjoy music so much remains a mystery. The evolutionary function of music is not evident. In
The Descent of Man
Darwin writes that ‘musical notes and rhythm were first acquired by the male or female progenitors of mankind for the sake of charming the opposite sex. Thus musical tones became firmly associated with some of the strongest passions an animal is capable of feeling . . . ’
²⁴
So music may have originated in courtship.

Translating the emotional impact of music into words, or into neuronal language, is bound to be a meagre approximation. To feel the rapturous force of music, one just has to listen to it. But imagine you are at the Proms, sitting on the floor with your eyes closed. The conductor reaches his spot while the orchestra prepares. Everybody is waiting for the same thing. Then he lifts his stick and marks the start of the first movement with a slight controlled gesture of his hand. And the first notes, synchronously played, obediently emanate from the strings and travel across the auditorium to kindle you. Whether it is a symphony, a piano sonata or a song, if you appreciate music you may be familiar with the chills, those tingles and shivers you get down the spine or behind the neck beyond your control when you are stirred by music. Nobody really knows exactly why and how such musical frisson happens, but, if anything, it is certainly a proof of emotional arousal in response to music, and a sign of pleasure. The phenomenon was first studied empirically in 1980 and found to be widely common in the population.
²⁵
Chills may be very brief or last for a few seconds. They can actually extend to the limbs and spread throughout the body. Often they are accompanied by piloerection, a fancy word for goose-bumps. Chills seem to occur in response to specific points in the structure of a musical piece. They happen when in the music there are sudden dynamic changes or new and unexpected harmonies.
²⁶
They have also been reported in response to sad music more often than in response to happy music. Opioids partake of these ecstatic harmonious moments and so does the pleasure centre. A group of researchers monitored the blood flow in the brains of people while they listened to music they liked and which gave them the chills. The music chosen by the participants in the study included Rachmaninov’s Piano Concerto No. 3 in D minor and Barber’s Adagio for Strings. The areas of the brain that were involved as the listeners experienced chills are no different from those stimulated during the enjoyment of food or sex. While the amygdala and the orbitofrontal cortex were quiet, areas of the pleasure centre such as the nucleus accumbens, which are replete with dopamine and with opioid receptors, were highly engaged.
²⁷
Interestingly, if music listeners are given an opioid antagonist – that is, a molecule that prevents opioids from binding to their receptors – they experience fewer chills.
²⁸

 • • • 

Imagine you have starved for a couple of days. You haven’t eaten anything, none of the fancy sandwiches you usually have for lunch, none of the delicious cakes from the bakery downstairs, or the curry at your favourite Indian restaurant with all those spices, not a fruit, not even a piece of bread. Then, when you have sensibly decided to return to food, you treat yourself to a bowl of boiled broccoli which you normally detest. You will eat it, and gladly. Food is weird. It is our most basic fuel, but also a luxury good. It is something we sadly can eat almost distractedly in front of our laptops, but also an indulgence some of us are prepared to spend a lot of money on, if it promises an exclusive pleasure. It is both a bare necessity and a reason for sophisticated satisfaction.

Scientists study this aspect of food by making the distinction between wanting and liking. We want food when we need it. But then we may like strawberries and dislike pineapple. Again, such distinction is mediated by the two components of the reward system, dopamine and the opioids, and this too became clear in experiments with rats. If you shut off their dopamine, rats are still able to distinguish a sugary from a bitter taste, and prefer the former. By contrast, if the opioid system is impaired, the rats will lose appetite and the pleasure-related preference for sweet food.
²⁹
Opioids are needed to appreciate flavours, too. In an experiment rats were presented with two foods to choose from. They were nutritionally identical, but had different flavours, of which the rats preferred one. If then the rodents were given a substance that activated the opioid system, they would go for their preferred food. If instead they were given a substance that shut down the opioid system, they would take either food.
³⁰

 • • • 

Unfortunately, as I emphasized earlier, pleasure and pain are two sides of a double-edged sword. If abused, pleasure responds with a cold revenge. Whatever at first provided a sense of comfort can later stab you in the back. Opioids increase dopamine levels, thereby fuelling your desire. After repeated exposure to a type of pleasure, your pleasure centre becomes accustomed to it. It is smothered. In addition, after a high comes the low. So, to escape the painful symptoms of withdrawal and to satisfy the increasing desire, you’ll just want more and more of the initial reward, whatever that is, but you won’t take pleasure in it any more. Drugs interfere with the neurotransmission of dopamine, modifying the structure of neurons in the dopamine system. Addictive pleasures condition your response to cues that remind you of that reward. Even just the sight of the reward sends you on a craving trip. Desire and motivation get out of control.

Whose side are you on?

A group of neurologists were incredulous when they came across some stroke patients whose brain damage made them exhibit extreme emotional symptoms, but at one end only of the emotional spectrum: either pathological crying or pathological laughing.
³¹
Those who couldn’t stop crying, or cried at inopportune moments, were patients whose stroke had affected the left-hand side of the brain. Alongside their bouts of tears, they also manifested feelings of despair, hopelessness and self-blame. By contrast, in those patients who experienced peals of laughing, the damage in the brain was on the right-hand side. Patients were euphoric and showed elation, a tendency to joke as well as to minimize their own symptoms. Such oddities made neurologists nurture a suspicion: that when it comes to regulating emotion, the brain takes sides. Broadly, the left side is responsible for positive emotions, while the right side takes care of negative emotions.

It’s the first time that I have mentioned this peculiar ‘handedness’ of the brain. As you know, the brain is divided into two identical hemispheres. That means that each of its structures comes as a pair – two amygdalas, two hippocampi, two striata, a pair of cortices and so on – one in each hemisphere. When we speak about the functions of each structure or its involvement in a given cerebral activity, we commonly mean both sides of the brain. But in some cases the involvement is in one hemisphere only. So the hemispheres are identical, but each of them accomplishes a set of different jobs. The most well-known example of a function governed by one side of the brain alone is the faculty to produce speech and to comprehend language, which in most people is the responsibility of the left hemisphere – as discovered in the nineteenth century by the neurologists Paul Broca and Karl Wernicke who have given their names to the particular areas concerned.