Excerpt: 'The Compass Of Pleasure'

Bangkok, 1989. The afternoon rains have ended, leaving the early evening air briefly free of smog and allowing that dis­tinctive Thai perfume, frangipani with a faint note of sewage, to waft over the shiny streets. I hail a tuk-tuk, a three-wheel motor­cycle taxi, and hop aboard. My young driver has an entrepreneur­ial smile as he turns around and begins the usual interrogation of male travelers.

"So . . . you want girl?"

"No."

"I see." Long pause, eyebrows slowly raised. "You want boy!"

"Uh, no."

Longer pause. Sound of engine sputtering at idle. "You want ladyboy?"

"No," I answer, a bit more emphatically, nonplussed at the idea that I give the impression of desiring this particular commodity.

"I got cheap cigarettes . . . Johnnie Walker . . ."

"No thanks."

Undaunted, he moves on to the next category of his wares, now with lowered voice.

"You want ganja?"

"No."

"Coke?"

"No."

"Ya baa [methamphetamine tablets]?"

"Nope."

A whisper now. "Heroin?"

"No."

Voice raised back to normal. "I can take you to cockfight. You can gamble!"

"I'll pass."

Just a little bit irritated now. "So, farang, what you want?"

"Prik kee noo," I respond. "Those little 'mouse shit' peppers. I want some good, spicy dinner."

My driver, not surprisingly, is disappointed. As we tear through the streets to a restaurant, blast­ing through puddles, I'm left wondering: Aside from various shades of illegality, what do all his offers have in common? What is it exactly that makes a vice?

We humans have a complicated and ambivalent relationship to pleasure, which we spend an enormous amount of time and re­sources pursuing. A key motivator of our lives, pleasure is central to learning, for we must find things like food, water, and sex re­warding in order to survive and pass our genetic material to the next generation. Certain forms of pleasure are accorded special sta­tus. Many of our most important rituals involving prayer, music, dance, and meditation produce a kind of transcendent pleasure that has become deeply ingrained in human cultural practice.

As we do with most powerful forces, however, we also want to regulate pleasure. In cultures around the world we find well-defined ideas and rules about pleasure that have persisted through­out history in any number of forms and variations:

Pleasure should be sought in moderation.

Pleasure must be earned.

Pleasure must be achieved naturally.

Pleasure is transitory.

The denial of pleasure can yield spiritual growth.

Our legal systems, our religions, our educational systems are all deeply concerned with controlling pleasure. We have created detailed rules and customs surrounding sex, drugs, food, alcohol, and even gambling. Jails are bursting with people who have vio­lated laws that proscribe certain forms of pleasure or who profit by encouraging others to do so.

One can fashion reasonable theories of human pleasure and its regulation using the methods of cultural anthropology or social history. These are valid and useful endeavors, for ideas and prac­tices involving human pleasure are certainly deeply influenced by culture. However, what I'm seeking here in The Compass of Pleasure is a different type of understanding — one less nuanced, perhaps, but more fundamental: a cross-cultural biological expla­nation. In this book I will argue that most experiences in our lives that we find transcendent — whether illicit vices or socially sanc­tioned ritual and social practices as diverse as exercise, meditative prayer, or even charitable giving — activate an anatomically and biochemically defined pleasure circuit in the brain. Shopping, or­gasm, learning, highly caloric foods, gambling, prayer, dancing 'til you drop, and playing on the Internet: They all evoke neural signals that converge on a small group of interconnected brain areas called the medial forebrain pleasure circuit. It is in these tiny clumps of neurons that human pleasure is felt. This intrinsic pleasure circuitry can also be co-opted by artificial activators like cocaine or nicotine or heroin or alcohol. Evolution has, in effect, hardwired us to catch a pleasure buzz from a wide variety of ex­periences from crack to cannabis, from meditation to masturba­tion, from Bordeaux to beef.

This theory of pleasure reframes our understanding of the part of the human body that societies are most intent upon regulating. While we might assume that the anatomical region most closely governed by laws, religious prohibitions, and social mores is the genitalia, or the mouth, or the vocal cords, it is actually the medial forebrain pleasure circuit. As societies and as individuals, we are hell-bent on achieving and controlling pleasure, and it is those neu­rons, deep in our brains, that are the nexus of that struggle.

These particular neurons also comprise another battleground. The dark side of pleasure is, of course, addiction. It is now becom­ing clear that addiction is associated with long-lasting changes in the electrical, morphological, and biochemical functions of neu­rons and synaptic connections within the medial forebrain plea­sure circuit. There are strong suggestions that these changes underlie many of the terrifying aspects of addiction, including tolerance (needing successively larger doses to get high), craving, withdrawal, and relapse. Provocatively, such persistent changes appear to be nearly identical to experience- and learning-driven changes in neural circuitry that are used to store memories in other brain regions. In this way, memory, pleasure, and addic­tion are closely intertwined.

However, addiction is not the only force responsible for experience-driven changes within the brain's pleasure circuits. The combination of associative learning and pleasure has created nothing less than a cognitive miracle: We can be motivated by pleasure to achieve goals that are entirely arbitrary — goals that may or may not have an evolutionary adaptive value. These can be as wide-ranging as reality-based television and curling. For us hu­mans (and probably for other primates and for cetaceans as well), even mere ideas can activate the pleasure circuit. Our eclecticism where pleasure is concerned serves to make our human existence wonderfully rich and complex.

I like to tell the students in my lab that the golden age of brain research is right now, so it's time to get down to business. This sounds like a cheap motivational gimmick, but it's true. Our ac­cumulating understanding of neural function, coupled with en­abling technologies that allow us to measure and manipulate the brain with unprecedented precision, has given us new and often counterintuitive insights into behavioral and cognitive phenom­ena at the levels of biological processes. Nowhere is this more evident than in the neurobiology of pleasure. One example: Do you, like many, think that drug addicts become drug addicts be­cause they derive greater reward from getting high than others? The biology says no: They actually seem to want it more but like it less.

This level of analysis is not only of academic interest. Under­standing the biological basis of pleasure leads us to fundamentally rethink the moral and legal aspects of addiction to drugs, food, sex, and gambling and the industries that manipulate these pleasures in the marketplace. It also calls for a reformation in our concepts of such virtuous and prosocial behaviors as sharing resources, self-deprivation, and the drive for knowledge. Crucially, brain imaging studies show that giving to charity, paying taxes, and receiving information about future events all activate the same neural plea­sure circuit that's engaged by heroin or orgasm or fatty foods. Per­haps, most important, analysis of the molecular basis of enduring changes in the brain's pleasure circuitry holds great promise for developing drugs and other therapies to help people break free of addictions of many sorts, to both substances and experiences.

When I was a postdoctoral fellow at the Roche Institute of Mo­lecular Biology in the early 1990s, I was fortunate to work with Sid Udenfriend, a pioneer in the biochemistry of the brain and a real mensch. Sid's favorite pedagogical phrase, usually intoned at the bar, was "It's always good to know a little chemistry." I couldn't agree more. It would be possible to write a book exploring the brain's pleasure circuits that was free of not only molecules but also basic anatomy, but that sort of spoon-feeding would require ignor­ing some of the most interesting and important issues, and so that's not what you'll find here. If you come along for the ride and work with me just a bit to learn some basic neuroscience, I'll do my best to make it lively and fun as we explore the cellular and molecular basis of human pleasure, transcendent experience, and addiction.

From Compass of Pleasure by David Linden. Copyright 2011 by David J. Linden. Reprinted by arrangement with Viking, a member of Penguin Group (USA) Inc.

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