Excerpt – The Biology of Desire

Howard’s suitcase lay on the floor beside the bed. She sat on the bed, leaned over, unzipped it, and picked up the phone in one sequence. She pulled out items of clothing and piled them on the floor, until she saw the vinyl sheen of a toilet kit. She pulled it out, slowly, carefully, and placed it on the floor, next to the pairs of socks that tumbled out with it. Damn! She’d have to put everything back exactly as she’d found it. But first things first. Her right hand pulled the zipper open and began to dig, while her left held the phone that would be her excuse, if anyone—

And then the door opened. Just then. Howard stood at the threshold for a frozen moment, looking directly at her right hand.

What are you doing?” he said. “What the fuck are you doing?” His voice rose with every word. “Are you crazy?” He lurched into the room.


Why are you going through my suitcase?” His voice settled into an accusation, righteous but still baffled.

She couldn’t speak.

Is it money? Is that what you’re looking for? Here, have some money!” He was shouting now. The door had closed, mercifully, but here was this man yelling at her.

Here! How much do you need?” He dug bills out of his wallet and threw them at her.

I—” She felt paralyzed.

You what?!” Droplets of spit landed on her face, and then she looked down at the mess she’d made. The zipper of the toilet kit was open. For a moment, a helpless longing rose in her throat. If only I’d had two more minutes. And then the world came off its hinges: she suddenly saw that things would never be the same again. Never again, from this moment on.

Familiar excuses rose like bubbles, but they burst before they got to the surface. There was no way out. Nothing she could say would work this time.

I have a drug problem,” she said softly. There, it was out. Her hands began to shake, adrenaline pumping. But this didn’t feel quite like fear. It felt like shock, slapping her; and shame, gathering now in little pools.

I have a drug problem,” she repeated, tasting it. “I was looking for drugs.”

Howard just stared at her, uncomprehending.

My husband knows,” she added, and hearing her own voice pleading for leniency, she began to see herself as others would see her. Because Michael didn’t know. Not really. Not the extent of it. Not the desperate need, the thefts, the lies. But now he would know. And so would everyone else.

In previous chapters I described the neurocircuitry of desire, from its origins in the midbrain and accumbens to the OFC—the orbitofrontal cortex—where value and expectancy are forged from raw emotion. Donna’s OFC was a veteran where drugs were concerned. Its responses were practiced, even stereotyped. For several years now, its synapses had generated a glow of anticipation whenever drugs were nearby. But the signal didn’t stop there. When drugs were on the horizon, OFC activation continued flowing upward into the higher reaches of her prefrontal cortex (toward the top of the head—dorsally). Each time she thought about, dreamed about, or obtained pharmaceutical opiates, each time she sat back in that familiar cloud of comfort, the stream of activation traveled to these higher prefrontal regions, modifying connections with every wave.

Over multiple occasions, the anticipated relief afforded by drugs (or other addictive goals) continues to etch patterns in the OFC. The OFC is a glutton for emotional learning, so it is subject to synaptic changes from infancy onward. But the changes now taking place in Donna’s brain continued northward, along a grand boulevard of nerve fibres. One of the regions along this path lies on either side of the midline or fissure that divides the two cortical hemispheres, like strips of farmland along a river valley. This region is called the medial prefrontal cortex (medial PFC), and, because of its location, between the swampy terrain of the OFC, at the bottom of the PFC, and the drier headlands of reason and judgement near the top, this region becomes dedicated to a task both cognitive and emotional: understanding oneself and other people. In this way it resembles the learning that occurs, not in infancy and early childhood, but in middle childhood, when the brain encodes new constellations of social knowledge.

The medial PFC is the core of the social brain, where interpersonal reality is sorted into two fundamental entities: self and other. The medial PFC is where we make sense of others’ actions, translate them and interpret them as to intentions and goals, and evaluate our own actions and goals in response. Here we formulate our perspectives, our prejudices, attempting to connect with those we admire or love and distance ourselves from those we distrust. Psychologists believe that we come to understand the inner lives of other people by playing out their intentions and motivations on the instrument of the self, imagining what it would be like if this were me. At the same time, as developing children, we formulate our sense of self by borrowing, combining, and revising the characteristics we perceive or imagine in others. That’s how we design our identities, by the age of eight or nine, and how we redesign them as we continue to develop in adolescence and adulthood.

Along with a region at the rear corner of the temporal lobe (the temporal-parietal junction), the medial PFC becomes activated when people think about others’ characteristics and intentions and about their own characteristics and intentions. In fact, the medial PFC is part of a much larger web that comes alive when we imagine, daydream, and rehearse possible interactions with others. But the medial PFC is particularly important for connecting our self-image with our emotional goals. We define ourselves in synch with those goals, and that self-definition gets cemented by the strengthening of synaptic connections between the medial PFC and other regions.

This network gets reconfigured as teenagers solve their challenging social problems, tweaking their identities while shopping for shoes. And for Donna it became reconfigured once again with drugs, revising her sense of self, her values, and her view of other people. Drugs were allies that provided the warmth her parents had withheld. They were big news in Donna’s emotional world. So the pathways created by her attraction to drugs modified her identity: she began to see herself as a taker, not just a giver, a controller, not just a victim—at least when drugs were around. These aspects of her identity had already begun to emerge in adolescence, fertilized by her teenage experiments at controlling herself and others, but they had remained mostly hidden behind her “good girl” persona. Now they bloomed more fully in the half-light of her addictive thinking—a branch growing from the trunk of her personality at an odd angle, deformed but resilient.

The medial PFC is activated when we judge ourselves, adjust ourselves, become ourselves. So it’s not surprising that it gets reconfigured by the repetition of an experience with immense social and emotional meaning. That experience might be falling in love, either with a lover or a child, or breaking the law, or joining a religious sect. Or it might be drug use, since drugs directly stimulate core bodily sensations and usually perturb interpersonal relationships. Experiences of this sort are the agents of developmental change in identity, morality, even personality. But such experiences need not be outlandish to influence development, and they have nothing to do with disease.

Waves of desire shaped Donna’s medial PFC into a matrix supporting two self-portraits: Donna the benefactor, who took care of others, fulfilled their needs, and repressed her own, and Donna the defiant, who took care of herself because no one else would. “It became a double life,” she told me. “I was still a good person, still taking care of people, still successful…People would be shocked to find out about this other me.” She slipped back and forth between these two personae, each barely acknowledging the existence of the other. Not quite a split personality. Rather, a kind of chameleon road trip. She still wanted to be accepted and loved, but it was no longer the only game in town. She continued to practice her warm smiles and generous offerings. Yet when drugs were available, when that singular stream of activation geysered up her prefrontal midline, she could put all that aside. And instead find satisfaction, even triumph, in deceiving those around her, and getting away with it—a new solution to a very old problem.

Now, under Cousin Howard’s accusatory glare, the two configurations of Donna’s identity collided and burst. Donna the druggie had never been hauled out of the closet, onto the stage of familial scrutiny. Her druggie self could not be seen, could never be reconciled with the conventional morals of her in-laws, her siblings and cousins, her parents, and her husband—especially her husband. So now she would suffer. The gush of shame and fear came precisely from the tear in the wall that had kept those worlds apart. If they found out she was a drug addict there would be no forgiveness. She had taken them all for a ride.