Your brain in love

Love is often considered the core force behind keeping couples together, but what is it? Is it simply some chemicals in your brain, or and how can we go about studying it? Naked Scientist Connie Orbach joined Khalil Thirlaway to explain what science can tell us about love...

Connie - It can tell us an awful lot and not much at all, all at the same time, it would seem.  There seems to be three stages; so we've got the lust stage which I think you've already been talking about on the show.  It's the stage of attraction where you may be quite promiscuous, there's really high testosterone levels in males as well as females.

So after that we have the attraction stage and that's when the real high kicks in.  It's kind of the honeymoon period and you see really high levels of what's called monoamines at that point, which are chemicals in the brain.  You've got serotonin, dopamine also noradrenaline - these are all the kinds of things which give you a massive high and just make that period just absolutely amazing.

And finally, we have the attachment stage which is the bit which makes you want to stay together.

Khalil - So at this point in a relationship, what's going on in the brain and body chemistry?

Connie - Okay.  So there's a few different things going on and it's interesting that we say - love, it's all about chemistry because, actually, a lot of the time it is.  We've got huge changes in the chemical balances in our brain that happen around this time.  There's a few different really important hormones involved; we've got oxytocin which you may have heard of before - it's often called cuddling chemical.  It's the kind of thing that makes social bonding and social cohesion work; without it we're not very good in social situations.  We've also got vasopressin which is actually controlling heart rate and things like that, but we've seen it's really important in monogamous animals.  And when we've studied this, we've actually used an animal to study it  - the Prairie vole, and they're really cute little voles and what we find is that they actually nest together.  They stay together for life once they've got a partner and they bring up their children together, so they're kind of one of the best analogies that we have for humans.  What's also really useful with them is that there's a different type of vole, the Montane vole, which is really closely related but not monogamous.  So when we're looking at differences in the brains, we can compare the two and get a better idea of what's going on.

Now with these voles, if we knock out their ability to respond to the hormone I just mentioned, vasopressin, they actually can't form a monogamous bond - they don't stay together.  But, there's also something else which I find really interesting which is that dopamine gets involved here.  Now dopamine you might have heard of specifically with drug addiction and there's a reward pathway in the brain which is activated with dopamine. Now what we found in the Prairie voles is that before sex and after sex, dopamine can have a really different action.  Before sex, it's causing these Prairie voles to go out and be really promiscuous and find mates, and you know get out and meet people like we're always needing to do, or meet tiny little voles, I guess.  And after sex, it's actually causing them to be aggressive to other animals that are the same sex to them.  They essentially become jealous, possessive, Prairie voles.  The kind of thing that is the epitome of that horrible thing that happens in a relationship to your other half.

Khalil - I guess this one bit of the animal kingdom we don't quite want to emulate?

Connie - Yes, definitely!

Khalil - This idea of mating affecting your dopamine levels and almost making these voles addicted to their mate - kind of sounds like a drug?

Connie - Yes, it does.  And, I mean, I'm sure there's loads of songs talking about love as a drug.  It's hard to say that it's addictive because there's lots and lots of different things that set off the dopamine reward system and not all of them are addictive.  We have so many different myths thrown around like, chocolate's addictive.  And they may activate that pathway but there's a few other things that need to happen for something to be addictive, but it definitely gives you that high that addictive substances give you.