Understand What Sex Does to Your Brain

 Overview

 You're sitting behind the wheel of your van at an everlasting traffic light. The only thing slower than the traffic is your perception of time's passage.

Then you notice her.

She appears at the curb, waiting to cross. No, she's not the love of your life. She's more like the heat of the moment. It's fortunate that your wife isn't there, otherwise you'd be in deep trouble as you take in the stranger's hips and breasts, and the way her waist scoops in to accentuate both. Time is enhanced; there's a pleasing buzz connecting your temples.

Your reaction is automatic, reflexive, and quite possibly the most powerful one you'll have this day. It temporarily blots out your long-range commitments—that 10-year marriage, that kid in second grade, that responsibility to keep eyes forward at traffic lights. You've surrendered control; you're captivated by the pleasure in the vision.

"You dog!" you may whisper under your breath, embarrassed by what you're envisioning as you sit there in your family van. But it might be more correct to say, "You dopamine fiend!" As a neuroscientist of 25 years, I know that your brain is command central for everything sexual.

When you spot the object of your desire, the neurotransmitter dopamine lights up areas deep within the brain, triggering feelings of pleasure, motivation, and reward. (Cocaine acts the same way.) You feel a rush, and your heartbeat quickens. Attraction, too, is a powerful drug. The brain stem also gets into the act, releasing phenylethylamine (PEA), which speeds up the flow of information between nerve cells. It's no wonder your neck and eyeballs track her every movement.

But she's not gawking back at you, and it's not just because you're driving a family bus with a paint scrape on the fender. Her brain acts very differently from yours. You're keyed in to beauty, shape, fantasy, and obsession; on some biological level that she may be unaware of, she's trolling for a mate who will sire healthy children and protect and provide for her and them. And yes, maybe even buy them a family van.

Her goals are programmed for the long range; yours are often shockingly short term, right up to and including thoughts of pedestrianophilia. And she knows it, which is why she presses those short-term buttons shotgun-style: She never knows when a suitable mate might be looking.

The whole encounter can leave you quivering with pleasure, hoping for more.

It can also hijack and ruin your life.

And between the "walk" and "don't walk" signals of delight and disaster, your brain is sorting information, making choices, spurring actions. But you don't want to passively accept all that, especially because your whole life is riding on the choices you make.

That's where I come in. I know the brain processes behind the temptations, and I can help you steer clear of trouble. After all, that woman in the crosswalk could help you realize your destiny, or derail it entirely. All the more reason to get to know that big sex organ between your ears so you can control the smaller, less important one between your legs.

Why You've Always Been Horny

You've been lit up on testosterone right from the start, even when you were just a multicelled notion in your mother's womb. The inherited Y chromosome that makes you male (thanks, Dad) triggers two bursts of testosterone that change your brain and body.

The first produces a male brain: one that's more interested in objects, actions, and competition. The left (parietal) lobe flourishes in the testosterone bath and helps you visualize objects in three dimensions (good for catching a football or watching a woman cross the street), and it boosts your aptitude in mathematics (that's how you estimate that she's about a 34DD). In addition, testosterone beefs up your hypothalamus, the area of the brain that's interested in sex. The hypothalamus is twice as large in men as it is in women.

Why Beauties Make You Stupid

You act like a goof with the Hooters waitress, leaving a tip that doubles the bar bill. But why? Beautiful women cause a man's limbic system (the amygdala and other brain-stem structures, which are in charge of emotion) to fire up at the same time that his PFC checks out, leaving the judgment area vacant. Las Vegas casinos hire beautiful cocktail waitresses, dress them in low-cut tops and miniskirts, and have them pass out free alcohol—all of which encourages men's self-control to take the day trip to Hoover Dam. No wonder the house has the edge.

How Your Nose Triggers an Erection

There's a direct connection between the olfactory bulb, at the top of your nose, and the septal area, the arousal center of your brain. When cells in your nose are stimulated, they send signals to your libido (and hers) to stand up and pay attention. You know what smells turn you on—the evidence is obvious.

As for her, a study at the University of California at Berkeley found that women become aroused when exposed to a chemical called 4.16-androstadien-3-one (AND). The good news? AND occurs naturally in men's sweat, hair, and skin. Take her someplace cold on your date—the favorite jacket or sweater you'll conveniently have on hand to lend her should be loaded with the stuff.

Why You Love Porn

Guys aren't shallow; it's just that the visual parts of their brains are strong and tend to twang their emotions. Using sophisticated imaging equipment, researchers at Emory University in Atlanta found that the amygdala, which controls emotions and motivation, is much more activated in men than in women when they view sexual material for 30 minutes, even though both sexes report similar levels of interest.

This may be one of the reasons men are much more captivated by pornography than women: For men, it's not just porn, it's personal. Back in the real world, women hijack men's brains by appealing to their strong visual sense. But women can take in a guy's visuals and think, Yeah, but how much does he have in his 401(k)? To avoid the tyranny of the visual, you need to kick-start your responsible prefrontal cortex by asking yourself, What's my goal in a relationship? That can divert you from those short-term, erotic visions.

Why You Lose Your Erection in Bed

Maybe little Willie is nervous during his big moment onstage. Performance anxiety is about the fear of being judged or not living up to expectations. The body is programmed to see anxiety as a threat, and the nervous system sets up the fight-or-flight response, sending out chemicals to protect us: Our heart races, muscles tense, and blood is shunted from our hands, feet, and penis to the large muscles of the shoulders and hips so we can fight or run away. That's not such a good strategy in bed, however.

Why You Can Be Addicted to Love

As with obsessive-compulsive disorder, love decreases brain levels of serotonin, the neurotransmitter responsible for mood and flexibility. Low serotonin means you can get stuck on ideas—you become obsessed. Which is just fine, unless she suddenly dumps you. That's when the short supply of serotonin makes you vulnerable to depression. In extreme cases, the serotonin shortage can trigger obsessive behaviors, such as exhibiting extreme jealousy or even stalking.

To get those serotonin levels back up before the police come, try exercising more, eating more carbs, and generally distracting your lonesome thoughts. (Road trip!) All of them will boost your serotonin levels.

Why You Should Marry After 25

Quite simply, a man's brain is incomplete before then. Sure, his sexual organs are all present and accounted for, but his prefrontal cortex (PFC) is still developing. Which is too bad, because that's the part of his brain that's involved in judgment, impulse control, organization, planning, forethought, and learning from mistakes. And it won't be fully developed until he's 25.

Why Touch Strengthens the Bond

Oxytocin is your brain's love juice: the bonding and attachment hormone. When you feel connected, empathic, in love, the oxytocin jets are spurting. Women have naturally higher levels of this chemical: It boosts nonsexual bonding between a mother and newborn, and it's responsible for putting babies to sleep after they nurse.

Though both men and women secrete an extra jolt of oxytocin during orgasm, we men go through a 500 percent surge—which explains our special talent for falling asleep immediately after sex. If she complains that she doesn't feel close enough, ask for her help readjusting your oxytocin levels.

Why Women are the Dumpers

Women have greater access to the more negative right side of the brain, one of the reasons they suffer from depression twice as much as men. The right hemisphere also allows women to see the gestalt, or big picture, of relationships, so they tend to know before men when a relationship is not working out.

Should You Stay or Should You Go?

Only your prefrontal cortex knows for sure. Men who have healthy activity in their PFCs have greater empathy, can focus for longer periods of time, and tend to make better husbands. Men who have overactive PFCs tend to be obsessive, oppositional, and argumentative. This can turn them into major chick repellents.

Likewise, men who have low activity in the PFC tend to be impulsive (more vulnerable to affairs), easily distracted (lousier at listening), easily bored (more "business" trips to Vegas), and constantly scamming for that attraction high (more given to looking for love in all the wrong places). To keep your PFC firing on all cylinders, protect it from injury, which can come from using too much alcohol, nicotine, or caffeine. Better still, exercise your PFC by setting goals and following through on them.

Why the Guys in Bands Get Lucky

In a study in Finland, eight male volunteers underwent brain scans while they were having orgasms. (Must have been a fun study.) Overall bloodflow in the brain decreased during orgasm, but it skyrocketed in the right prefrontal cortex—as it does in creative people (like musicians) when they do their creative thing. Now, exactly why did you give up those guitar lessons?

Why She Moans During an Orgasm

It almost certainly doesn't have anything to do with you. In addition to its duties as an orgasm assistant, the right hemisphere has also been called the "God" area of the brain. When scientists stimulate the right hemisphere, their subjects have more religious or spiritual experiences. So it's not too much of a leap to guess that when she moans "Oh, God" in the throes of sexual ecstasy, she may be connecting pleasure to a deeper spiritual place in her brain. Music and dancing can jumpstart the right hemisphere, which means the nuns at your high school were right to discourage it.

Why Her Orgasms are Like Paxil

Sexual climax has an antidepressant effect. Orgasms cause intense activity in the deep emotional parts of the brain, which then settle down when the sex is over. Antidepressants calm the same part of the brain. This calming effect may be why people who regularly have sex experience less depression.

Why It's Better if She Swallows

Prostaglandins, fatty acids found in semen, are absorbed by the vagina and may have a role in modulating female hormones and moods. I also feel duty-bound to report that women who perform oral sex on their mates are less likely to suffer from preeclampsia, a condition that causes a dangerous spike in women's blood pressure during pregnancy. Plus, sperm carries TGFbeta, a molecule that can boost the activities of her natural killer cells, which attack the rogue cells that give rise to tumors. Don't make her beg. Offer.

Why a Foot Massage is Foreplay

When you rub the arch of her right foot, you affect her about 30 inches higher, and a little to the left. The foot-sensation area of the brain is next door to the clitoral (and penile) region, which may be a big reason that women are so focused on shoes—yours and hers.

Carrie Bradshaw was on again, off again with any number of men, but her Manolos endured. And perhaps now we know why Imelda sought solace in 1,060 pairs of shoes. But even if you're not a Filipino dictator, you can make this work for you.

"There are 36,000 nerve endings in the foot," says Kathleen Miller-Read, a massage therapist and spokeswoman for the American Massage Therapy Association. "By exploring these, you can find sore spots all over the body."

If your girlfriend has her feet crammed in high heels all day, she's bound to have aching toes and a sore back. Use your thumb and forefinger to gently pull, twist, and rub below her toes. For her back, focus on the heel of her foot, moving your knuckles in a circular motion all over the heel. She'll let you know when it's working.

Where Your Kinkiness Come From

Weird sexual fetishes or fantasies are brain symptoms. They fall into the category of impulsive-compulsive disorders: impulsive when you can't control the behavior and compulsive when, even though you may want to, you can't stop.

A person who's prone to voyeurism, exhibitionism, bestiality, transvestism, S and M, or infantilism (deriving sexual pleasure from being treated like a baby) often has too much activity in the emotional parts of the brain, as we see in people who have obsessive-compulsive disorders, and too little activity in the PFC, or judgment center. A study of 26 men with unusual sexual fantasies found that using medications to balance these two areas of the brain gave the men significant relief. But then, so did wearing an adult diaper and being handed a rattle. You can't tell with some people.

How to Control Your Brain

Even though men are programmed to look at beautiful women and populate the earth, the human brain, especially the prefrontal cortex, has evolved to the point where, with proper training, we can be thoughtful, goal oriented, and focused on our families. You are not a rodent, doomed to follow the pattern of hormone receptors in your brain. Ask yourself: What are my goals for my relationships? Stay focused on loving and protecting the people in your life, and it's mind over what really matters.