Imaging the Brain in Love

Dr. Laurent Hermoye, CEO

Dr. Laurent Hermoye
CEO

Laurent Hermoye

When modern neuroimaging techniques shed light on one of the brain’s greatest mysteries: romantic love.

The Brain in 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).


Scanning the Brain in Love

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:

  • the ventral tegmental area (VTA), in the midbrain. The area is associated with pleasure, focused attention, and the motivation to pursue and acquire rewards. Its A10 cells produce dopamine. The two primary efferent fiber projections of the VTA are the mesocortical and the mesolimbic pathways, which correspond to the prefrontal cortex and nucleus accumbens, respectively.
  • the caudate nucleus and the putamen, two nuclei of the deep brain, which together form the striatum.


Resting-State fMRI

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.


The Brain’s Reward Circuit

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!


Is Love an Addiction?

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!


The Chemistry of Love

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.


References

  • Aron et al. Reward, motivation, and emotion systems associated with early-stage intense romantic love. J. Neurophysiol. 2005, 94: 327–337.
  • Edwards. Love and the brain. On the Brain – The Harvard Mahoney Neuroscience Institute Letter 2015.
  • Fisher. The brain in love. TED 2008.
  • Fisher et al. Intense, passionate, romantic love: a natural addiction? How the fields that investigate romance and substance abuse can inform each other. Front. Psychol. 2016, 7: 687.
  • Reynaud et al. Is love passion an addictive disorder? Am. J. Drug Alcohol Abuse 2010, 36: 261–267.
  • Song et al. Love-related changes in the brain: a resting-state functional magnetic resonance imaging study. Front. Hum. Neurosci. 2015, 9.


Revision # 0 – February 14, 2017

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