What do those butterflies in your stomach feel like when you lean in for your first kiss? Good enough to go in for a second one?
Neuroscientists and psychologists have been trying to unpack the various components of love for decades. For example, a few years ago, two research groups studied the brain activity of individuals reporting to be 'truly, deeply and madly in love' while they viewed pictures of their loved ones. [1, 2] Both studies found that reward-based brain regions were activated, and concluded that this activation of reward circuitry may explain "the power of love to motivate and exhilarate."  Stanford University took this a step farther and sponsored "The Love Competition," in which they scanned peoples' brains while they were "loving on" their special someone to see who could activate these reward centers the most.
From an evolutionary standpoint, this type of love makes sense. Without it, propagation of the human species might not go so well. From a practical standpoint, when it comes to forming relationships, this is the same type of circuitry that we use to learn a variety of things, including what food is safe to eat and which people to avoid. And from an experiential standpoint, it usually doesn't get much better than being head-over-heels in love. Or does it?
Think back to the last time you began a romantic relationship. Suddenly, you were full of energy; life seemed wonderful. You'd go on and on about how amazing your special person was to anyone who would listen. You couldn't get that person out of your head. And you couldn't wait for that next text, phone call or date. Your friends may have even said that you were addicted to this person. This makes sense, given that the reward circuitry associated with love is the same as that which gets activated when we smoke crack cocaine.
In a TED talk, Helen Fisher summed it up nicely: "romantic love is one of the most addictive substances on earth."
This also fits with the irritability that comes when your special someone doesn't call you when he or she says they would, or the funk that you go into when that person is away for several days. All the highs and lows of being in love are just like being strung out on heroin. How great is this?
Now, contrast this to the type of love demonstrated by folks like Mother Theresa or The Dalai Lama. Described by Christians as agape or 'selfless,' this type of love seems a bit different. There aren't records of Mother Theresa getting mad crushes and spending her days daydreaming about that perfect someone. We don't see the Dalai Lama going into a funk when someone doesn't reciprocate his affections (a good example here is his relationship with the Chinese government). He seems pretty content --all the time.
Not caught up in the personal highs and lows of romance, people like Mother Theresa and the Dalai Lama have a track record of getting a lot of work done -- for the benefit of many, many people.
Do these experiential differences between selfless and 'attached' love also show up in the brain? Recently, in our lab at Yale University, we studied the brain activity of novice and experienced meditators while they performed 'loving kindness' (metta) meditation.  As practiced traditionally in Buddhist communities for centuries, and more recently in the West as part of Insight meditation and mindfulness-based stress reduction programs (among others), individuals were given the following instructions: "Please think of a time when you genuinely wished someone well. Using this feeling as a focus, silently wish all beings well, by repeating a few short phrases of your choosing over and over. For example: May all beings be happy, may all beings be healthy, may all beings be safe from harm." Similar to many forms of prayer, the intent of this practice is to specifically foster selfless love --just putting it out there and not looking for or wanting anything in return.
Interestingly, the reward parts of the brain that previously were shown to become active with romantic love (and in studies of cocaine addicts) were notably quiet during loving kindness practice. And importantly, the brain regions that get activated with self-referential processing (i.e. how does this affect me) were significantly deactivated in experienced meditators, compared to novices. This may help to explain what is seen with this practice when we truly, selflessly wish for the wellbeing of others, we're not getting that same "hit" of excitement that comes with a tweet from our romantic love interest, because it's not about us at all.
And if you're wondering where the reward is in being selfless, just reflect on how it feels when you see people out there helping others, or when you hold the door open for someone the next time you are at Starbucks.
For more by Dr. Judson Brewer, click here.
1. Aron, A., et al., Reward, Motivation, and Emotion Systems Associated With Early-Stage Intense Romantic Love. Journal of Neurophysiology, 2005. 94(1): p. 327-337.
2. Bartels, A. and S. Zeki, The neural basis of romantic love. NeuroReport, 2000. 11(17): p. 3829-3834.
3. Bartels, A. and S. Zeki, The neural correlates of maternal and romantic love. NeuroImage, 2004. 21(3): p. 1155-1166.
4. Garrison, K.A., et al., BOLD signal and functional connectivity associated with loving kindness meditation. Brain and Behavior, 2014. In press.