When modern neuroimaging techniques shed light on one of the brain’s greatest mysteries: romantic love.
Published on February 14, 2017
As part of a short course at Harvard University, Prof. Savoy was describing the hands-on sessions to the class: “You will have an MRI and a magnetoencephalography scanner available for a few hours. What would you like to study in the brain?”. In a silent classroom, I timidly suggested “Love!”. And there we went, designing an experiment and scanning our two infatuated “guinea pigs”. Unfortunately, our results were not very conclusive: our sample size was tiny, and our time frame was short.
However, several research groups have used advanced neuroimaging modalities to study the neural correlates of romantic love (Aron et al., 2005; Song et al., 2015).
Functional MRI (fMRI) is a neuroimaging technique based on magnetic resonance imaging. It can identify brain areas that are activated by a task, process, or emotion. In an experiment published in 2005, Aron and colleagues scanned 17 volunteers who were intensely in love (Aron et al., 2005). To activate their brain’s “love circuit”, they showed them pictures of their beloved. As a control task, they also showed them pictures of familiar individuals.
Photos of people they romantically loved caused the participants’ brains to become active in regions rich with dopamine, the so-called “feel-good” neurotransmitter. The activated areas included:
Song et al. confirmed these findings using another neuroimaging technique: resting-state fMRI (Song et al., 2015). The technique can depict the brain’s connectivity, without the need to stimulate the subjects inside the scanner. Functional connectivity within the reward, motivation, and emotion regulation network (dorsal anterior cingulate cortex, insula, caudate nucleus, amygdala, and nucleus accumbens) was significantly increased in the “in-love” group, when compared to a group of volunteers who were single at the time of scanning or who had recently ended a romantic relationship.
There is no one-to-one mapping between an anatomical area in the brain and a function. However, there are a few circuits in the brain that are relatively well-known. The one under the spotlight, in this case, is the brain’s reward circuit (Fisher, 2008; Edwards, 2015).
The structures that contribute to the reward circuit, namely the ventral tegmental area, nucleus accumbens, amygdala, hippocampus, and prefrontal cortex are exceptionally sensitive to behaviors that induce pleasure, such as alcohol, gambling…and sex!
The deep localization of the ventral tegmental area, in the reptilian core of the brain, somehow explains why romantic love escapes conscious control and rational thinking – we don’t get in love, we fall in love!
“Love is passion, obsession, someone you can’t live without”
Surprisingly, the same brain areas are activated when drug addicts feel the rush of cocaine. These findings led researchers to wonder if romantic love may itself qualify as a kind of addiction (Reynaud et al., 2010; Fisher et al., 2016). Although romantic love and substance abuse share several “symptoms”, such as euphoria, craving, tolerance, emotional and physical dependence, withdrawal, and relapse (Fisher et al., 2016), it certainly cannot be categorized as a disorder!
There is one aspect of love that even the most state-of-the-art neuroimaging techniques cannot depict: the chemical storm of neurotransmitters and hormones induced by the feeling. Although fMRI activations were observed in brain areas that are known to be dopamine-rich, there is no way to image an actual concentration of the neurotransmitter.
The initial “stress” induced by intense romantic love increases the levels of the stress hormone cortisol. As cortisol levels rise, levels of the neurotransmitter serotonin become depleted, explaining the quasi “obsessive-compulsive” behaviors associated with the feeling at its early stage (Edwards, 2015).
Love also induces the release in the bloodstream of two hormones: oxytocin and vasopressin. These hormones are mainly produced in the brain’s hypothalamus and stored in the pituitary. Oxytocin – the “love hormone” – also plays a role in pregnancy, nursing, and maternal bond.
As Helen Fisher stated in her famous TED talk (Fisher, 2008): “Romantic love is one of the most powerful sensations on earth”. Next time you feel it, remember that somewhere deep in your brain, neurons are firing to feed the spark and fuel the flame.
Revision # 0 – February 14, 2017
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