How Does Your Brain Tell You That You Are in Love?

Do modern techniques reveal what happens in the brain when we fall in love?

Posted May 19, 2016

Being in love is a highly disordered state. It transforms lives, alters judgment, consumes attention.  The incomparable, ‘honey-tongued’ William Shakespeare, who died almost exactly 400 years ago, wrote:

Love is a smoke raised with the fume of sighs;
Being purged, a fire sparkling in lovers' eyes;
Being vex'd a sea nourish'd with lovers' tears:
What is it else? a madness most discreet,
A choking gall and a preserving sweet.


Numerous other poets, novelists and essayists have made similar points.  Here’s G.K Chesterton, famous in his life-time, now less often read, emphasizing how little control we have about whom we fall in love with:

Love does take us and transfigure  and torture us.  It does break our hearts with an unbearable beauty, like the unbearable beauty of music.  But in so far as we have certainly something to do with the matter; in so far as we are in some sense prepared to fall in love and in some sense to jump into it; in so far as we do to some extent choose and to some extent even judge – in all this falling in love is not truly romantic, it is not truly adventurous at all.

Or you might prefer a more cynical approach, offered by the novelist Julian Barnes:

If you ask me—and I have now had time to think about this—love, or what people call love, is just a system for getting people to call you Darling after sex

But, you might ask: what happens in the brain? Could we peer into someone’s brain and tell that he or she was ‘in love’?  Is there a ‘love center’ that needs to be active if one is truly in love?

The rather recent techniques of brain scans have suggested one way that neuroscientists might take a look.  The usual method is to put people in a scanner and show them pictures of various people, one of whom is their romantic loved one, and see how the brain reacts.

But before we see what this has told us, we need to have a clear idea of what brain scans actually show.  The technique most usually used is fMRI (functional magnetic resonance imaging).  This, it is sometime said, tells you which part of the brain ‘lights up’ under various conditions, and therefore is in an active state.  The first problem is: it doesn’t.  This is not the place to go into technical detail, but fMRI shows altered oxygen levels in the small veins in the brain, not the brain itself.  From this, scientists infer that the underlying brain is active.  That’s a reasonable deduction, but it’s not a direct observation, and we are still unsure of the exactly how changes in oxygenation correspond to activity in the brain, and whether these can change between individuals or across time.  So treat the evidence cautiously.

The result? In response to the right photo, there is increased activity (but see above!) in areas of the brain we know to be associated with reward, and sex, and memory, but decreased activity in other areas associated with fear, or dislike.  These are mostly more ancient parts of the brain, involved with getting things (food, water, sex) that are essential either for your survival or that of the species. But it’s not all so primitive.   Areas of the brain associated with social cognition, attention and self-representation also show changes.   So great swathes of the brain seem to be involved in love; maybe that’s why it’s so all-consuming.  Interestingly, examining the brains of people who have just broken off a relationship shows a different pattern, so maybe there’s a brain state for a broken heart (a ‘broken’ brain, really).

I guess that’s what you might have predicted, but it’s reassuring to have at least some kind of imprint of love in the brain.  But there are two great gaps: the pattern of brain activity (indirect, of course…) does not distinguish ‘love’ from other emotions; and we cannot, so far, say anything about what makes one brain fall in love with a particular sort of person (though psychology has a lot to say about that).  The mystery of what love means in the brain goes on…