It’s anything but simple, and, for years, scientists have tried to unlock the secrets behind why we fall in love, who we fall in love with and why some loves persist, while others fall, at times, spectacularly to pieces. To learn more about the science of love, and the most recent findings in the study of human brain function as it relates to addictive behavior (yes, love is an addiction), we asked Johns Hopkins neuroscience professor and author, Dr. David Linden, five questions about the science of love and what we can expect to see in the future when it comes to neuroscientific discoveries.

This is the fourth in the “Five Questions” series where we ask industry, thought and academic leaders five questions about what’s next.

1) When reviewing the scientific literature on the biology of love and sex, what did you find most surprising about the brain’s behavior when in love?

I was most surprised by what the brain suppresses when it is in love. The way we describe love in different cultures varies little. We all experience the suppression of appetite, obsession, giddiness and sexual desire. Our judgment is distorted in at least two ways: We accentuate the good traits about the person we love and diminish the bad ones, and we take a different view of the world, believing, for example, that our discretion in a relationship is greater than it really is.

“The Compass of Pleasure” by David Linden (Viking 2011)

When we look into the eyes of our beloved, a feedback loop occurs in the brain. This loop allows us to not only see all of the wonderful things about our beloved, but to have those positive feelings mirrored back to us. All of that is to say: When we are in love, we like ourselves better as well. And our moods are amplified. Anyone who has been in love can tell the highs are higher and, when things turn sour, the lows are lower.

Lucy Brown, a neurobiologist from the Albert Einstein College of Medicine, took on the challenge of finding out how these characteristics of intense romantic love correspond with brain function. To do this, Brown and her colleagues recruited men and women who were in the early stages of a relationship (on average, 7 months). The subjects all reported being “madly, deeply and passionately” in love.

Brown and her team found that the pattern of brain activity that occurred when the subjects viewed their beloved’s face was remarkably consistent with the lover’s self-reports. The brain activity that corresponds with those feelings of intense, euphoric pleasure, is similar to the way the brain responds to cocaine or heroin. Brown and her team also found that the activity in the brain that corresponded with our ability to distort the characteristics of our beloved and the world around us was similar to obsessive/compulsive disorder. Brown and her team also conducted their experiment in Beijing, China, and found identical results. It will be interesting to see, in future, the same study conducted comparing men and women who are gay, straight and bi-sexual.

Separate, social psychology studies have also found that people in long-term relationships observe the intense, initial feelings of romantic love to last between nine months to two years. That feeling is then replaced in most couples, by a less intense feeling of loving companionship. Given that, it raises interesting and important questions about our laws. While anyone can get married immediately, most states requires a 6-to-24 month waiting period before getting a divorce. Given the nature of how our brains work when we’re in love, perhaps it should be the other way around.

(Photos: Scientists play the love game)

2) What, if any, outstanding questions on the brain and love, do you most look forward to answering or seeing answered?

It’s this one: “Are there neurobiological correlates of successful long-term love relationships?” There is a small number of people who say that the feelings they have for their loved one today are just as intense as they were ten or twenty years ago – all the way back to the moment they first met. These couples nearly all appear to be telling the truth. When Brown’s team conducted an experiment called “lover’s-face brain imaging,” they found that most of the lovers who had been in a relationship for ten years or more no longer received the cocaine-like jolt that short-term lovers showed when they looked at their lover’s face. Again, I say cocaine-like because cocaine activates the same region of the brain, the VTA dopamine center, as intense love. The small group of people that reported still being intensely in love showed strong activity in that region of the brain when they laid eyes on their lover’s face. We still don’t know why that is the case. What is it about these couples that keeps the flame lit while, in other couples, it goes out?

3) What effect do you see recent discoveries in the neurobiology of love and sex having on human behavior or romance-related product development?

It is easier to co-opt existing systems in the body rather than create new ones out of whole cloth. With that said, oxytocin is among the most promising of chemicals produced by the human body when it comes to new product development around sexual behavior. Why oxytocin? It is the chemical that produces the blissful afterglow following orgasm, and is the chemical produced in mothers’ brains when they give birth, and is a key ingredient when it comes to a mother developing the life-long bond with her child. Oxytocin nasal sprays are currently on the market to help women who have difficulty breastfeeding. The sprays effectively introduce the chemical into the blood stream, helping to induce the “milk letdown reflex” necessary for nursing.

Researchers at the University of Zurich have discovered that subjects who use oxytocin before encounters with strangers are likely to be more trusting when playing a cooperative investing game, and continue to be so even after being betrayed. Also the fear centers in the amygdyla were deactivated. Overall the study revealed that oxytocin played a complex role in social cognition and behavior beyond just “trust.”

The chemical could also prove effective in treating individuals with social anxiety. One recent study showed that oxytocin helped subjects better infer others’ emotions by only showing them the eyes of another person. Oxytocin’s ability to do this, in conjunction with its ability to reduce fear and stress makes it a promising treatment for individuals with social anxiety or other social disorders.

(Read more on the future of medicine)

4) Finally, moving away from love, what technological advancement would you most like to see in neuroscience, and how far off do you believe it to be?

There is little daylight between love and addiction when it comes to the chemical reactions in the brain. Whether it be drugs, food, gambling or sex, almost identical reactions occur in the brain. We are starting to develop drugs to help individuals recover from addiction based on our understanding of the brains reactions. This involves reducing cravings, which lead to relapse. I think we can look forward to several new, safe and effective anti-addition drugs in the next 15 years that will be enormously useful.

5) In the most general sense, what lies ahead for human brain function?

Today, we have the ability to activate or inhibit neurons with light using optical and genetic tricks but the science activates general regions of the brain or groups of neurons. Activating individual neurons is a science that has yet to be realized.

Today, if you want to record activity of neurons in the human brain you either need to use a non-invasive method that does not open the skull, such as a brain scanner or an electroencephalograph (EEG), or an invasive method, such as an implanted array of electrodes. The non-invasive techniques, which are very crude, don’t tell you the fine-scale activity patterns of individual neurons. Rather, they give an overall view of the activity of millions of neurons in a brain region. Implanting electrodes gives high-resolution information but it requires major surgery. This makes it dangerous and expensive. Therefore, it’s only used in severe cases, such as control of chronic pain or Parkinson’s disease.

The same problem holds true of stimulating the brain. Non-invasive techniques like transcranial magnetic stimulation (TMS) activate large swaths of brain tissue and cannot selectively activate deep regions without concurrently activating overlying ones. Implanted electrodes, while able to activate much smaller and deeper brain regions, cannot precisely activate specific neurons.

If we could non-invasively record and stimulate (or inhibit) individual neurons in brain easily, that would allow a revolution not only in brain research, but in neurology, psychiatry and in the very fabric of society itself. Do you want to change your moods or feelings? No problem. Let’s say you want to concentrate with all of your mental effort. Easy as pie. Do you want a totally immersive virtual reality with emotions as well as sensations? That’s no problem — in the future, perhaps, but not today.

Read more from the Five Questions series:

Scientists play the love game

Washington Post | Date Lab

The fundamentals of innovations

The case against college

The past, present and future of 3-D printing

Read more news and ideas on Innovations

Read more Ideas@Innovations