Could a brain scan reveal love? │ How Love Makes Us Human with Dr Anna Machin

What happens inside your head when you fall in love?

When we first lock eyes with someone across a crowded room and feel that sense of attraction, it's the unconscious area of our brain, the limbic system, that sits at the core of the brain, that lights up. And in particular an area known as the nucleus accumbens, a little circular structure. This is round with oxytocin and dopamine receptors, which make sure that those messages of attraction flood your brain. However, over the first few days of your attraction, that signal starts to move, and it moves to an area known as the head of the caudate. This is still in your unconscious brain, but it's critical that it moves here because the caudate has links to the neocortex, the outer folded area of your brain where your conscious mind sits. This enables your unconscious and conscious mind to communicate about the love experience. And in particular when we look at the neocortex, it's the prefrontal cortex which is important. And this connection between the two areas is critical to the experience of human love because we are able to experience love, at both the conscious and unconscious levels.

So yes, it's about passion and motivation and addiction, but it's also about trust and empathy, goal orientation and companionship. And when we look at the brain, we see differences in the signatures that we see for a romantic and parental love. So, for example if we look at the love between a parent and a child, what we see in the brain is activation of an area of the limbic system known as the pag. This is important because this is where nurturing behaviour sits, enabling parents to care for their children, to empathise with them. But interestingly we do see a difference in activations in the brain depending on whether you're a mum or a dad. So, both parents do have activation in the areas linked to empathy, however in the mum's brain we see a lot of activity in the very core of the brain, the unconscious area, and that's linked to the experience of nurturing and risk detection. When we look at a dad's brain yes, we do see activity in that nurturing area, but really most of the activity is occurring in the outer areas of the brain, the neocortex. This is where your social cognition sits. And this suggests that maybe parenting for fathers is more of a cognitive conscious process.

These differences actually, point to the different evolutionary histories of fathering and mothering. Mothering is as old as time, however fathering in the human line probably evolved about half a million years ago, therefore, it sits in the evolutionary younger area of the brain, the neocortex.

When we look at romantic love in the brain, we see a lot of activity in the hippocampus and the hypothalamus. Again, both are in the unconscious area of the brain. The hippocampus is important in building those memories which underpin a lot of long-term relationships, and the hypothalamus is there because it's involved in releasing the sex hormones which underpin lust. But what's really interesting in romantic love is we also see deactivations. So, it's not all about areas of the brain being active, but also some areas which are quietened. And these relate to our sense of risk and to our ability to mentalise, to be able to mind read, to tell what somebody is thinking or what they might do next. This means that actually love is truly blind. While your friends may be able to spot that maybe the person you've decided to go out with is not quite right for you, possibly they're not being truthful to you, you are incapable of doing this because the bit in your brain that's able, for example, to spot somebody who's cheating, is shut down. The fact that we see different activations depending on whether we're seeing romantic or parental love means that these sorts of love really do have neural fingerprints. We can see those on the scanner screen, but we also see differences between the activations if we're considering interacting with a friend or a member of our family. Both of these are platonic forms of love; however, we do see differences in the level of activation, the amount of attention, the amount of energy that's being put into maintaining these relationships.

So, if we ask someone to interact with their friends, what we see on the scanner screen is much, much more activation than if they're interacting with their family. And this is because maintaining our friendships is a cognitively more energetic thing, we give more time and attention to it. So, we take a lot of time for example making sure that the reciprocation of favours is pretty much equal, so we're not being taken for a ride. However, when it comes to our family where we see less activation, this is because we actually trust them more because of that genetic connection, which means we actually need to spend less time and energy checking that reciprocity and making sure that the favours are equally balanced. So basically, a brain scan would reveal when we fall in love. And did you know, love can also make us fall into synchrony?

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