Healthy Brain, Happy Life: A Personal Program to to Activate Your Brain and Do Everything Better (2016)

MAKING YOUR BRAIN SMILE:
Your Brain’s Reward System

As I did every typical weekday, I was standing on the subway platform about to board the number 6 train for work. But that day, I was not in a good mood. Why were there so many people on the platform? That woman just took the seat that I was headed for and didn’t even look up—I hate when that happens!

Wait a second, why was I so grouchy? Was I hungry? Nope. Was I sleep deprived? No again. I realized that I was in such a foul mood because I had been traveling and it had been five days since I had been able to exercise. That was it! I was craving my regular exercise.

Since getting hooked on exercise, my body and brain now protest when I don’t get my regular fix. As I explained in Chapter 4, we know exercise improves mood by increasing dopamine, serotonin, and endorphins in the brain. I look forward to that infusion of good mood, energy, power, and positivity that follows whenever I work out. The down side is that if I don’t get my typical dose (four to six workouts a week on average), I start to feel annoyed and edgy; it’s like something is bothering me that I can’t identify. I go through what feels like exercise withdrawal. This response is what is typically referred to as a healthy addiction—something beneficial to your physical or mental health that you always make time for despite all the other obligations in your life. These activities are highly valued and sorely missed if something prevents them from happening. Yes, I have a healthy addiction to exercise. I also have a healthy addiction to massages.

It turns out that there are a lot of things in life in addition to exercise and massages that bring me great pleasure. They include (not surprisingly) delicious food, fresh cold watermelon juice, tickets to Broadway shows, river rafting, watching The Sound of Music with popcorn and hot chocolate, a surprising new finding from my lab, puppies, and Bach’s solo cello suites (note that this list is illustrative, not comprehensive).

What is on your pleasure list? It turns out that every single item on my list has one characteristic in common. Each one activates the reward circuit in my brain. Our reward center is an evolutionarily ancient system that goes back two billion years and is crucial to our survival. Evolution has designed this system so that we find pleasure in those basic functions that allow us to survive and propagate: food, drink, and sex are central to that list. Rudimentary versions of this reward system are seen in worms and flies. These are called fundamental or core pleasures. But, of course, as living, breathing beings in a consumer-driven world we derive pleasure from a whole lot more than just food, drink, and sex. Our much more diverse list of pleasures is called higher-order pleasure. We derive delight from the people we love to spend time with; the places we go to relax and rejuvenate; and all that we spend money, effort, and time on.

Typically, what we value most in our lives can be found on these lists of pleasures. What’s important to understand is that all of the key life decisions and choices that either bring more pleasure in our lives or limit it are influenced strongly by our brain’s reward system. While one could argue that pleasure and happiness should be at the top of our wish list of things to understand about the brain, in reality only recently has serious effort been made to explore the neurobiology of pleasure and happiness. Fortunately or unfortunately, a lot of our current, nuanced understanding about the science of happiness, like a lot of neuroscience research, comes from studies of when this system is broken. In other words, we have learned the most about the brain’s reward and pleasure systems from studies of addiction. In this chapter, I describe what we know about how the brain processes rewarding information for both fundamental and higher-order pleasurable stimuli as well as what we have learned about the brain’s reward system from the study of addiction, including how exercise might help.

THE REWARD SYSTEM: A PRIMER

Before we get into the neurobiology of reward, it’s important to define what we mean by reward. Reward is not a single process but a network made up of three distinct components. The first component is the one we most associate with reward and that is the hedonic pleasure component or liking. The second component is wanting, defined as the motivation for reward. The third process is learning, which includes the associations, representations, and predictions about past rewards that anticipate future rewards. The learning part of reward is carried out by two brain areas that we have already talked about a lot: the hippocampus and the amygdala. As we learned in Chapter 2, the hippocampus is important for making new associations and the amygdala lays down emotional memories, including those associated with highly pleasurable experiences. This introduction gives us a hint of how complex, interdependent, and interconnected the hippocampus and amygdala are as they contribute to many different kinds of brain computations.

What about the brain areas associated with liking and wanting? Studies done way back in the 1960s at McGill University by James Olds and Peter Milner (former husband of Brenda Milner of H.M. fame) were the first to identify what they called the pleasure or reward centers in the brain. This duo was looking for areas in the rat brain that, when stimulated, would inhibit the rat from doing whatever was associated with the stimulation. But as they were stimulating different brain areas, they instead found the opposite: brain areas that, when stimulated, would get the rat to keep doing whatever he was doing when the stimulation occurred. They found that if they allowed the rats to stimulate the electrodes implanted in these special brain areas themselves (the so-called self-stimulation experiments), the rats would obsessively stimulate the electrodes thousands of times and would forgo food to continue self-stimulating. These experiments first identified some of the brain areas important for reward and pleasure. The basic reward circuit includes a key brain area involved in perceiving and responding to reward stimuli called the ventral tegmental area (VTA). The VTA is located in the middle of the brain and contains the neurons that make the most important neurotransmitter for the experience of reward or pleasure: dopamine. The VTA-based dopamine-making (or dopaminergic) cells project to two important areas in the reward circuit: the nucleus accumbens as well as parts of the prefrontal cortex.

While those early studies by Olds and Milner were interpreted as identifying the pleasure centers in the brain, later work questioned whether these were centers for pleasure (liking) or desire (wanting). Dopamine release from the VTA is implicated in both functions. In fact, most recent work in this area of neuroscience has made progress in developing tasks and approaches to differentiate liking from wanting and suggests that these two states seem to use different parts of the same reward circuit in the brain.

How do you know if a part of the brain is associated with pleasure? First, you have to define when a stimulus is pleasurable. In humans, it’s easy, you just ask them. In animals, scientists use a trick from Charles Darwin’s book. Darwin did a famous study on facial expressions and noted that all animals make facial gestures in response to the environment, and we now know that many of the gestures have been conserved across species, including facial responses to pleasurable food, also called the yummy face. If you have seen a baby eating food that she enjoys, you know immediately the face that I mean. It turns out that you can identify that same face in rodents and ask if stimulation to particular pleasure centers enhance the enjoyment of food (in particular sugary food) beyond how they would typically experience it. It was found that stimulation of two key brain areas enhanced a rat’s liking of sweets. The first is a particular part of the nucleus accumbens and the other is in the ventral pallidum, a structure located deep in the forebrain (toward the front of the brain). But these are not the only areas involved in pleasure. fMRI studies in humans have identified a wide range of cortical areas that are also activated during pleasurable experiences. These include a part of the prefrontal cortex called the orbitofrontal cortex, the medial portion of the prefrontal cortex, the cingulate cortex, and the insula (which is deeply buried in the sides of the brain between the temporal and frontal lobes). Other fMRI studies have shown that parts of the orbitofrontal cortex are activated whenever subjects report the sensation of pleasantness associated with chocolate milk. But once a lot of chocolate milk has been consumed, this area is no longer active and corresponds to a point when the person reports no more pleasure from the treat.

A key open question is whether these pleasure areas are involved in simply encoding pleasure or if they are involved in causing the sensation of pleasure. The jury is still out. These areas are clearly involved in encoding pleasure, but we are still working on understanding exactly how the actual feeling of pleasure is generated in the brain.

While pleasure (somewhat sadly) is relatively understudied, the other side of the coin of reward, want, is extremely well studied in the form of addiction. In fact, we have learned the most about the workings of this part of the reward system through the study of this disease.

ILLUSTRATION OF THE MAJOR BRAIN STRUCTURES INVOLVED IN THE REWARD CIRCUIT

(Courtesy of Ashley Halsey)

TAKE-AWAYS: REWARD AREAS INVOLVED IN PLEASURE/LIKING

• Reward includes liking (pleasure), wanting (motivation), and learning about future rewards based on past experience.

• Early studies by Olds and Milner identified specific brain areas that rats, when given an opportunity to self-stimulate, would obsessively stimulate for hours on end. This was our first insight into the reward system.

• The full reward circuit is a complex set of brain structures that include the ventral tegmental area, nucleus accumbens, ventral pallidum, several parts of the prefrontal cortex, cingulate cortex, and insula.

• The key subareas of the brain associated with pleasure are a specific region of the nucleus accumbens, ventral pallidum, orbitofrontal cortex, cingulate cortex, and insula.

• A key unanswered question is which of these brain areas or their interactions are actually causing the sensation of pleasure.

HOW ADDICTION MESSES WITH OUR BRAIN’S REWARD SYSTEM

The American Society of Addiction Medicine (ASAM) defines addiction in the following way:

Addiction is a primary, chronic disease of brain reward, motivation, memory and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social and spiritual manifestations. This is reflected in an individual pathologically pursuing reward and/or relief by substance use and other behaviors. Addiction is characterized by inability to consistently abstain, impairment in behavioral control, craving, diminished recognition of significant problems with one’s behaviors and interpersonal relationships, and a dysfunctional emotional response. Like other chronic diseases, addiction often involves cycles of relapse and remission. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death.

We know that release of dopamine is big part of our liking and wanting response. What drugs of abuse do, at least initially, is cause a much bigger dopamine hit (estimated to be two to ten times higher) than you typically get with a natural rewarding stimulus (for example, sex or chocolate), which is what helps make these drugs so intoxicating and irresistible. Many people (myself included) feel a form of addiction to exercise and negative withdrawal symptoms when we don’t get our regular fix, but because the dopamine response is typically nowhere near as high as those from drugs of abuse, these responses don’t come close to reaching the official ASAM definition of addiction. During the first stage of addiction, called acquisition, it’s the artificially high surge of dopamine that can be the first step toward real dependency.

For example, cocaine acts directly in places where dopamine is released (such as in the nucleus accumbens) and blocks the normal reuptake of dopamine into the brain cells, resulting in a lot more dopamine floating around the brain than is usual. It’s this high concentration of dopamine in the nucleus accumbens that causes the euphoric cocaine high. The normal brain is simply not used to that big a hit of dopamine, and the feeling you get is, as a consequence, unlike anything else you have ever felt. That’s part of the reason it is so intoxicating. By contrast, heroin targets the brain’s opioid receptors, which are found all over the reward circuit, including the VTA and the nucleus accumbens. Remember, receptors are the entry gates into the cells. Activation of the opioid receptors in the VTA stimulates the release of dopamine. Nicotine has yet another way to stimulate dopamine. When you smoke a cigarette, nicotine enters the bloodstream and activates receptors in the VTA called acetylcholine receptors, which in turn stimulate the release of dopamine. In this case, the dopamine release gives smokers that hit of pleasure with every puff. While all three of these addictive drugs give pleasure in the form of a high, each one provides a different kind of feeling because they are all activating the dopamine system in different ways, in different places in the circuit, and at different levels. It’s those differences in the precise way the anatomical pathways are activated and the level of that activation that produce the different “flavors” of reward. Recent work has suggested that a major role of these drugs of abuse is to stimulate the wanting part of the reward cycle. While intense liking is certainly part of early drug acquisition, this system seems to quickly focus on the wanting part, which researchers are still trying to precisely identify.

After acquisition, escalation is the next phase of addiction, when drug use increases. One of the reasons escalation happens is because the very first hit of drug that spikes your dopamine feels amazing, just like the very first bite of ice cream on a hot summer day, but the fifth, sixth, and seventh bites don’t feel the same; the only way to reclaim the initial feeling for a drug addict is to take more of the drug, more frequently. Over time your brain becomes less and less sensitive to the dopamine, and the decreased response drives you to take more and more of the drug to try to get back to that initial maximal dopamine response.

A major factor that helps determine predisposition to addiction is your genetic makeup. It is estimated that between 40 and 60 percent of a person’s risk for addiction is genetic. You might think that people who become addicted get particularly intense levels of pleasure from the drugs, but paradoxically, they have a specific genetic modification that makes their dopamine receptors less responsive than people without that genetic modification. For people with a genetic propensity for addiction, a particular hit of dopamine (through alcohol, cocaine, sweet foods, or any other dopamine-stimulating substance) will cause less of a high than that same hit of dopamine in others. The people with a genetic predisposition for addiction will need six drinks to get to a level of intoxication that comes with two drinks for others; they need four packs of cigarettes a day, not just one.

Genetic factors contribute in yet another way to addiction factors. It turns out that drugs like cocaine affect the expression of many different genes within the nucleus accumbens, and one of those genes affected expresses a protein called DeltaFosB, which all of us have in our brain. With each injection of cocaine, you get a buildup of DeltaFosB in your nucleus accumbens cells that stays around for six to eight weeks, all the time building up more and more every time cocaine is ingested. There is evidence that the accumulation of DeltaFosB is the actual switch that activates addictive behavior. For example, just elevating levels of DeltaFosB in the nucleus accumbens alone, with no previous drug treatment, makes mice start to ingest more and more drugs relative to control mice. This is thought to be a molecular switch that keeps the addictive behavior going even when no drug is around. This is why those who have stopped abusing drugs often turn to other addictive behaviors; their neural pathways have been altered. This same protein also seems to be involved in the rewiring of the brain that occurs with long-term addiction. With long-term cocaine use, the dendrites (those branchlike input structures on neurons) in the nucleus accumbens become bigger and bushier. This in turn makes the neurons even more receptive to information from other areas, and scientists suspect that the areas that become more influential are the inputs from the hippocampus and the amygdala. This means that all the memories for the events, contexts, and emotions associated with taking drugs have an even stronger influence on the nucleus accumbens. This is thought to be the biological basis of craving: When memories of the drug-taking events get activated by the enhanced pathways and there is no dopamine around, the person experiences a craving. It’s these long-term anatomical changes to the reward circuit that make recovery from addiction so difficult and relapse so easy.

While the vast majority of us will not become cocaine or heroin addicts, a different kind of addiction hits home for many more of us. It’s called sugar. Many people feel addicted to sugar at one point or another. I felt it when I went through my Twix candy bar phase when I was training with Carrie (see Chapter 4). Like most things that bring us pleasure, sugar also activates the same reward circuitry as cocaine and heroin, albeit to a lesser degree. However, in one disturbing recent study researchers showed that rats given the choice between intensely sweet liquid and cocaine actually chose access to the intensely sweet liquid more than even high doses of cocaine, showing that in some situations, the sugar and sweet taste can be more rewarding than even cocaine. The scientists hypothesized that this striking effect may be due to the fact that mammals (including both rodents and humans) evolved in an environment low in sugar and, therefore, we may be hypersensitive to high concentrations of sugars. They hypothesize that exposure to lots of sweets, as is common in the modern world, might cause a hypersensitivity of the reward system to sugars, causing the response they saw in their rats. It’s clear that an addiction to sugar is at least part of the problem in people with eating disorders, and scientists are starting to realize that sugar addiction can have serious consequences. We are still trying to understand the addictive qualities of sugar, how it relates to drugs of abuse, and how to cure that addiction when it happens. There are still no answers, but one promising avenue of research is the effects of exercise to curb addictive behaviors.

CAN EXERCISE CURB ADDICTION?

Some drug rehab centers are already strong believers in the power of exercise to treat addiction. For example, the Odyssey House, a New York City–based facility for treating addiction, runs a highly regarded program that trains recovering addicts to run marathons. It’s called the Run for Your Life program and was started by Odyssey House executive vice president, chief operating officer, and former drug addict himself John Tavolacci. Tavolacci credited marathon running with helping him beat his drug addiction. Odyssey House residents joke that before they sign up for the Run for Your Life program, the only running they did was away from the police. The program helps residents start slowly, with short but regular training runs through Central Park. They gradually build up to longer and longer runs, culminating in their ultimate event: the New York City Marathon. Talk about a runner’s high! The Odyssey House believes in the power of exercise to help treat addiction. But what’s the neuroscience behind this idea? The neuroscience is based on the interaction of exercise with the same reward system that drugs of addiction interfere with, and there is promising evidence that exercise intervenes at several key stages of addiction and becomes a replacement behavior.

First, strong evidence shows that adolescents involved in team sports or who exercise regularly are less likely than physically inactive teens to use cigarettes and illicit drugs. While these findings are suggestive, they don’t prove that physical exercise actually causes the decreased drug use, they suggest only a correlation. However, research in animals does provide causal evidence that exercise decreases the chances of developing an addiction. In these studies, rats given the choice between a running wheel and the ability to self-administer methamphetamine will administer fewer drugs than the rats without the access to the running wheel. Similar results were found for alcohol. This suggests the very exciting idea that exercise can work as an effective substitute for drugs. While this level of exercise in rodents (or sports participation in high school students) clearly does not produce the same dopamine burst as the drugs themselves, it seems that it does produce enough of a dopamine buzz to compete with the drug consumption. While we know a lot about how exercise can work to decrease initiation of drug taking in rodents, more studies are needed in humans that directly examine the effects of exercise intervention programs on decreasing drug use. But progress is slow because the studies are both difficult and costly.

Another key phase of addiction that may be the most challenging is withdrawal from drug use. It is so challenging because it has been reported that up to 70 percent of recovering addicts relapse to drug use within one year after treatment. This is a period during which craving and depression can drive people back to drugs. The good news is that there is strong evidence in humans that exercise can have beneficial effects on withdrawal symptoms, particularly in smokers. Exercise has been shown to decrease cigarette cravings, withdrawal symptoms, and negative affect. The bad news is that nicotine is the only drug of abuse that has been studied thus far.

However, there are specific features of exercise that suggest that it would have a similarly positive effect during withdrawal from a much wider range of drugs. Specifically, all the data showing that exercise can decrease signs of depression and stress. Stress is a key trigger for relapse in recovering addicts, and as discussed, exercise works to decrease stress in myriad ways. With less stress comes less depression.

So, it is clear that exercise could be useful during the initiation, escalation, and recovery/withdrawal of addiction. All the neuroscience data suggest that this is because exercise uses many of the same pathways and activates the same reward centers of the brain as drugs, without a real addiction developing.

TAKE-AWAYS: BRAIN AREAS IMPORTANT FOR THE WANTING PART OF REWARD

• Drugs become addictive by overactivating the reward system that puts into motion immediate and very long-lasting genetic and anatomical changes in the reward circuits if the drug use continues.

• Because exercise activates the same reward circuits as addictive drugs it can help decrease the chances that drug use is initiated, it can curb the escalation of drug use if it has already started, and it can curb cravings in some cases and decrease stress levels that can decrease the chances of relapse.

• Exercise can become addictive itself and caution must be used when trying to design a program to replace drug addiction. It is important to monitor and minimize the shift to an exercise addiction.

ACTIVATING MY REWARD SYSTEM BY GIVING BACK

Life outside the lab was now just plain fun for me, with more and more social time and a growing circle of friends. We spent time eating, drinking, going to movies, and seeing shows together in the city. While I loved every minute of my new social life (I was finally starting to make up for my hermitlike early years at NYU), I found some of my greatest pleasures in activities in which I could give something back to the world. Since the summer of 2009 I have been teaching a free weekly and year-round exercise class for the NYU students, faculty, and staff. It’s also free and open to anyone outside of NYU. At first the class was a great way to practice leading an exercise class right before the start of my “Can Exercise Change Your Brain?” class. But it became so much fun that I just kept on doing it. Many students in my “Can Exercise Change Your Brain?” class continued taking my weekly exercise class long after the semester was over, and I’ve met many students from all over the school whom I would have never met otherwise.

Some of my most memorable experiences from my weekly exercise class have come from the transformations that I have seen in my students. When I first started teaching the class, Pascale, a very bright, gregarious postdoctoral fellow in my department at NYU, was the only guy who came to class regularly. This did not bother him at all. Week after week, he took his place in the center of the front row and did the class with gusto. One morning, we both got on the elevator in our building at NYU, and Pascale asked if he could tell me something.

“Of course,” I said.

He said, “You saved my life!”

I thought he was joking around. Or perhaps my lab had loaned him something he needed for his experiments. He went on to explain that when he started my classes he weighed close to fifty pounds more than he did now. Only then did I realize that the sweat shirt and pants he was wearing were hanging off him like a scarecrow. Then he showed me his old NYU ID, and the difference hit me like a ton of bricks. His face looked so much thinner and angular (in a healthy way) now! I don’t know how I could have missed it. He went on to explain that he was in bad shape when he started taking class, in part because his work and school schedule meant he had not been exercising at all. He told me it was my regular class, together with the motivation of seeing one of the professors in his department teaching it each week, that kicked him into gear to exercise and start losing weight himself. He supplemented his classes with me with other exercises at home, but he credited my class with jump-starting his progress.

Pascale not only has kept the weight off but is keeping fit in new and innovative ways. He recently told me he had just gotten a treadmill for his desk at work so he could walk and work at the same time. He invited me to his office to check it out, and it was impressive. A beautiful shiny new treadmill that he had set up in front of his desk computer so he could keep walking during the many hours a day spent at his desk working, reading, and typing. For the last several years I have used a standing desk while I work to help decrease the inevitable slouching that happens when I type while sitting down, but I never considered adding a treadmill to my setup. Pascale has definitely inspired me!

My weekly exercise class is not the only way I give back. In fact, the reason I am familiar with the great work at the Odyssey House is that I organized a group of several exercise instructors to provide six months of free exercise classes for Odyssey House clients at the main Harlem branch. I loved getting to know my O House regulars, and it truly warmed my heart to see how grateful they were for the classes and all the teachers who donated their time.

Of course, I had to look into what was happening to my brain when I felt happy about giving back to the community. There are findings to explain the brain areas involved in those warm and fuzzy feelings that I always get when I’m giving back. Studies done at the University of Oregon measured brain activity in people given the opportunity to voluntarily donate to a charity. Many previous studies had shown that giving subjects money activates the brain’s reward circuit. That makes sense! Who doesn’t like getting money? What this study showed was surprising: When people voluntarily gave money to a charity on their own, it activated the same reward circuit as getting the money themselves. This is neuroscientific proof that giving is as rewarding as getting. In other words, generosity is rewarding and good for the brain. From a very personal perspective, I wholeheartedly agree with this finding. But it’s not just blatant donation that I find rewarding. That very first time I stepped up and started teaching my fellow anatomy students what I knew about the structure of the liver, I remember getting a little jolt of pleasure. I thought it was pleasure from the act of teaching, but it was really pleasure from the act of giving. I think most teachers, and certainly all great teachers, are great because they are doing something that they love doing. Teaching is what is activating their reward systems, and it’s the altruistic nature of the job that seems to be the key.

BRAIN HACKS: ALTRUISM

Try some of these four-minute Brain Hacks to activate your reward system through altruism.

• Pay the toll for the person behind you.

• Help a stranger in the street.

• Smile and greet someone you don’t know in the street.

• Be kind to someone you dislike (extra points for this one!).

• Pick up trash on the street or on the beach.

• Tape your extra spare change to the jungle gym in the park for kids to find.

• Write a handwritten thank-you note to someone.

• Share your knowledge with someone.

LOVE, ROMANCE, AND THE REWARD SYSTEM

On the dating front, I was convinced that all the exciting new and sometimes altruistic adventures in my social life would soon attract equally exciting adventures in my romantic life. As I’ve mentioned, I am a firm believer in the idea that you attract into your life the kind of person that you are. I loved my life now, the person I was becoming and all the new friendships I had formed. I was ready and willing to start my next romantic relationship, and before too long someone new came into my life.

His name was Michael and we were introduced by a mutual friend.

The very first thing I noticed about Michael was his positive energy. He had a kinetic personality but also made you feel like you were the center of the universe when he was talking to you. He was funny and very sweet. The first time we met for a casual lunch, all I remember was how easy it was to talk to him. We chatted all through the meal and all the way out the door after lunch was over. When we finally reached that point where we had to walk in opposite directions, I remember thinking he actually looked sad to say good-bye to me!

It was the most endearing first-date moment that I have ever had.

For the next date we planned to meet up for a drink but I was (conveniently) starving so we went out for dinner instead. Despite his energy, Michael was quite shy at first, which was great because it provided a calm atmosphere as we got to know each other. We seemed to have lots of important things in common. We were both passionate about our jobs, mine in science and his in government, we both loved living in New York and had both spent time living in Washington, D.C. We also seemed to have the same family and life values. I particularly admired his close and loving relationship with his extended family. And he could really make me laugh.

Talk about activating the reward centers in the brain! I had this image of the dopamine neurons in my VTA firing like mad. In fact this image I had of my own VTA activation was accurate. Neuroscientists have started to study the parts of the brain activated in the early stages of intense romantic love, just like what I was experiencing, and it turns out that studies done in England, the United States, and China give surprisingly consistent results. All of these studies showed that the parts of the brain that become activated when subjects are looking at a picture of their beloved, compared to the activation seen when subjects are looking at a picture of an acquaintance, include the VTA and the caudate nucleus (also a major target of the VTA’s projections). All studies agree that VTA activation represents the high reward value associated with seeing your sweetheart when you are in the throes of early romantic love. The caudate nucleus, like the VTA, has been associated with reward and motivation. For example, another study reported that when a monetary reward was predictable (in other words, if you find yourself a rigged slot machine that gives a payout every time you play), this same region of the caudate nucleus gets activated. So things that are a sure bet for high levels of reward activate the caudate nucleus. In addition to observing the consistent areas of activation when someone is looking at a photo of her beloved, researchers noted a consistent inhibition of the amygdala. The idea is that fear, processed by the amygdala, is decreased during periods of intense love. Based on my own personal experience, I would agree with this interpretation. These findings suggest that during the early stages of intense romantic love, your dopamine reward and motivation systems are working in overdrive and your fear response is inhibited. No wonder I felt so good!

In these studies, the authors describe intense, romantic love as: “Euphoria, intense focused attention on the preferred individual, obsessing about him or her, emotional dependency on and craving for emotional connections with this beloved and increased energy.” They note that the combination of obsessive behavior with strong dopamine activation resembles key features of the early stages of . . . addiction.

I definitely had all the symptoms:

Obsessive about Michael and spending time with him—check!

Craving emotional attention from him—check!

Lots of energy—check!

Yes, I was definitely in that early addictionlike phase of intense romantic love.

But as I started to fall in love, I lazily started daydreaming about what it would be like to ride off in the sunset with my new prince charming and spend the rest of my days with him—to have and to hold till death do us part. Well, turns out that we also know about the brains of long-term happily married couples who report feelings of intense romantic love with their partners (lucky ducks!). Some of the same researchers who did one of the studies on early intense romantic love wanted to know if those same brain activations could still be observed twenty years into a relationship. What they discovered is that when one of the long-term lovebirds looked at a picture of her spouse the same brain areas were activated as those in people who are still in the early stages of an intense romantic love: the VTA and the caudate nucleus. But in addition, the researchers started to see other activated brain areas, such as the globus pallidus and the substantia nigra. These latter areas are interesting because they have been identified in studies that examine brain areas involved in maternal love. This suggests that long-term relationships activate the brain systems thought to be involved in social attachment. These brain areas have many receptors for two chemicals strongly implicated in attachment and pair bond formation—oxytocin and vasopressin. So such studies show that as a long-term romantic bond grows stronger, brain areas associated with deep personal attachment are activated. Now that’s a pattern of brain activity that I aspire to!

This honeymoon phase with Michael was fantastic. Isn’t it always? It was enhanced by romantic trips to Chicago, Miami, and San Francisco; long good-night phone calls when we were apart; and lots of intense time focused on each other when we were together.

We were not only in love but we were getting serious.

As our relationship progressed, inevitably, some differences started to emerge. They were challenging but not necessarily deal breakers. As you know, I am a foodie always in search of that great new restaurant. He lived for a great burger and fries (though he was in surprisingly good shape, given his preferred diet). I loved to go out with friends and meet new people—the more social invitations I got, the happier I was. He felt socializing was a chore, didn’t have a lot of close personal friends (bad sign), and would rather just spend time at home with me. I loved adventure travel and outdoor exploration of new cultures. He needed nice hotels and preferred to go on cruises. We managed fine through this, with me spending time with my friends on my own and us still spending time alone, though always compromising on where we would eat—Shake Shack (him) or Babbo (me), In-N-Out Burger (him) or the French Laundry (me). In the end we were always happy with a long binge-watching session of our favorite television series, something we almost always agreed on.

However, in the heady haze of love and reward responses swirling through my brain during those first six to nine months, there was one red flag that I probably should have paid more attention to early in the relationship.

From the beginning, Michael was very clear about the fact that he was separated but not yet divorced from his wife. He described the divorce as in progress and sure to happen sooner rather than later. I was more than happy to take him at his word. But as months and then a year and then a year and half went by, it became clear that nothing about this divorce was going to happen sooner; it was going to be later, an indeterminate amount of time later. It turned out to be way more complicated than I had ever imagined it would be. Michael maintained that the papers would be signed by this date and then by that date. Those dates went by so often with no progress at all, I had to start wondering if he was really getting divorced.

Then we started to fight about it. Regularly.

It became the focus of our relationship.

At that point, I could have just said, “You know what? I don’t date separated men that aren’t able to get a divorce.” And I would have been done with it.

But when we were together he made me feel so loved. I just didn’t want to give up.

Instead I said, “I need evidence of your commitment to me.”

He said, “I can do that!” And about a week later we moved in together.

We experienced another honeymoon period.

I loved living with him. Or maybe I loved the idea of living with him. But the fact was that his road to divorce remained unrelentingly slow and was like the gorilla in the room. To be fair, I had no doubt that he wanted to get divorced, but his long-term inability to deliver on his never-ending promises to get the deed done started to wear on my trust in a serious way.

It turned out that moving in together was the beginning of the end for us. The broken promises and aborted deadlines just started eroding everything else. All those differences we noted at the beginning of our relationship (social engagement, food choices, preferred vacation destinations) that seemed manageable at the time now became unbearable. I wasn’t going to be the other woman any longer.

I think at some point I just realized I was not in love with him anymore.

When I made that realization, I knew I had to break it off with Michael.

Despite all the clear signs that it was time for me to end the relationship, it was unbelievably hard to break up with him. In the beginning I had fallen deeply and passionately in love with him. I really thought we were going to get married. I felt a deep and terrible loss. But at the same time I knew it was the right thing to do.

I went through a very difficult time after we broke up. He had moved out of my apartment, but I still had plenty of reminders of him all around me. There were the knickknacks that he bought me as gifts from his travels, the restaurants and stores that I passed where we had gone regularly, and even the times of day that he would always call me at work or at home. These were all the things that I had associated with that love that I felt for Michael. All the reminders, like the cues that cause craving and relapse in addicts, brought back a memory of my feelings. Maybe my love affair had been more like an addiction than I realized. In fact, all the reminders produced a deep longing in me. Not a longing to get back together with him, but a longing to feel that same intense romantic love that we had together.

My recovery from this breakup was long and slow. I continued to work out regularly, and I added more yoga to my exercise routine. I signed up at the last minute for a yoga retreat at a cute little inn called Good Commons in Vermont and had a great time. I met a bunch of interesting and yoga-minded people. I enjoyed the retreat so much I signed up again for a meditation retreat at the same place. These things together all started to help me feel happy and whole again. But it was a slow process. Honestly, I didn’t feel completely recovered from the breakup for nearly a year.

As I was slowly but gradually healing, I realized that something else had changed for me. Namely, I finally (it was about time!) got clear about what I needed in a romantic relationship. First of all, there would be no more unavailable men of any kind. In a sense, Michael was just as unavailable as Daniel, the musician. Maybe I was seduced by the idea of seeing if I could win these unavailable men over to my side. All I knew was that I was not going to tolerate that kind of unavailability in my relationships from now on. That meant that I would no longer date married men, separated men, men who were too involved in their work for a real relationship, or men who were attached or unavailable in any other ways.

Michael also taught me an important lesson: Just because you fall deeply in love with someone doesn’t mean it’s going to work out. You have to know clearly what you need to be happy in a relationship and be ready to walk away—for the good of all concerned—if those elements are not there for both of you.

In addiction we know that the connection between the prefrontal cortex and the rest of the reward circuit becomes impaired, and this prevents the prefrontal cortex from using its decision-making powers to put the brakes on risky behavior. I suspect that while romantic love is stimulating the release of dopamine in our reward centers, it is also impairing our decision-making and evaluative abilities because we are so hooked on that feeling of love. At least that’s how I felt. I could have used some help from my own prefrontal cortex during my relationship with Michael, but instead I ignored some pretty clear signs and made choices that I thought would keep what love there was left for as long as possible.

Well, we live and learn.

TAKE-AWAYS: CHARITY, GENEROSITY, AND LOVE

• Acts of true charity and generosity can powerfully activate the brain’s reward system.

• Activation of the reward system may underlie the warm fuzzy feeling accompanying the act of giving to a good cause.

• Early intense romantic love can also powerfully activate the brain’s reward system as well as stimulate the release of oxytocin and vasopressin, brain chemicals with links to social bonding.

• Intense love may have commonalities with aspects of addiction, including the obsessive behavior.

• The strong ties formed with places, events, and items associated with your beloved may cause regret and longing if the relationship ends, similar to cravings in addiction.

• We can recover from even the worst breakups and retrain our brains to learn from our mistakes.

BRAIN HACKS: MORE IDEAS FOR STIMULATING THE PLEASURE CENTERS OF YOUR BRAIN

We all know the things that stimulate our own pleasure centers. These are the things we dream we are doing or experiencing on a Monday morning instead of work. Here are some examples from my own personal list.

• Eating a meal you love.

• Drinking great Bordeaux (just having a few sips, as opposed to the whole bottle, will make it even more pleasurable!).

• Making love.

• Getting a full body massage.

• Watching your favorite movie of all time.

• Watching an exciting sports match.

• Playing your favorite sport.

• Reading a great book that you can’t put down.