Helen Fisher is a biological anthropologist I first encountered on www.TED.com (if you haven’t seen this website, go and check it out!).
She is very passionate about Love and her work appears to be popular, appearing in both credible sources such as the Journal of Neurophysiology to more popular ones such as O, the Oprah Magazine, and Elle. In 2006, she wrote an interesting review article about romantic love, mate choice, sex drive and attachment.
Fisher et al used fMRI to gain insight into the neurological activities behind romantic love to support her hypothesis regarding ‘mate choice’ and its underlying neural system.
Disregarding the focus on her specific hypothesis, there is some very interesting scientific information collected in her review article, entitled ‘Romantic love: a mammalian brain system for mate choice.’ The fMRIs of individuals self-acclaimed to be in love showed activation in the right ventral tegmental area (VTA) and caudate nucleus, regions associated with the brain’s ‘reward system.’
Interestingly, the caudate nucleus has also been shown to release dopamine on expectation of a monetary award. Such evidence suggests that being ‘in love’ is part of a ‘reward sytem’ based largely in the dopaminergic pathway. In monogamous prairie voles, it is found that a 50% increase dopamine in the nucleus accumben (affected by the VTA) follows copulation and preference for the sexual partner.
However, inhibiting dopamine in the nucleus accumbens results in a withdrawal of their ‘bond.’ If a new male, which the female has not ‘bonded with’ is present upon injection of a dopamine agonist (increasing dopamine levels), the female will form a new preference to him.
In the animal studies presented in this review, it is clear there is a strong relationship between neurotransmitters and hormones. Activation in the dopaminergic pathway causes the release of testosterone and oestrogen, and oestrogen and testosterone can impact dopamine levels. It is largely argued that a clear distinction is to be made between sex drive and romantic love, however, the brain activity presented shows that many areas between sex and love overlap.
Specifically, ‘the right subinsular region, including the claustrum, left caudate and putamen, right middle occipital/middle temporal gyri, bilateral cingulate gyrus, right sensorimotor and pre-motor regions and right hypothalamus,’ are activated during sexual arousal, overlapping with those activated in romantic love such as the caudate nucleus, putamen and cingular gyrus.
It appears (from the information in this review) that the brain activity involved in sexual arousal is far more complicated than in love and that the distinction isn’t as clear as the review presents. To make matters even more confusing, studies on maternal brain activity also demonstrated activity in the cingulatar gyrus and caudate nucleus. Activity in the caudate nucleus demonstrates some neurological evidence to the claim that parenting is rewarding.
Back to love, another two big players involved in the love game are vasopressin and oxytocin. Oxytocin is largely known as the trust neurotransmitter, expressed at high levels during and after birth to promote mother-infant bonding and reduce pain. Oxytocin is also expressed in males and has other roles such as effect of blood pressure along with vasopressin.
In voles, vasopressin appeared to be the commitment factor demonstrated through genetics. I wouldn’t have picked monogamy as a genetic factor, but it appears that V1 receptor gene which has a variant form (lacking a chain link) in the promiscuous meadow voles, may be responsible. Genetic transfection of a fully functioning V1 receptor gene leads to upregulation of vasopressin in male meadow voles and commitment with a specific female.
So how true is romantic love, or is it just a psychological manifestation of our pandering to our neurotransmitters, hormones and the social complexity of the modern world? It’s a nice concept but critically, I was unconvinced by the science used to demonstrate its pure existence.
It doesn’t appear to be its own emotion, but a combination of pleasure, reward, commitment and trust. I guess when I put ham and cheese between two slices of bread; I call it a sandwich, so I could put all those emotions together and call it love. Let’s talk about love baby… it’s a bit like a sandwich.