Struck by Cupid?
Venus, the Roman deity that embodies love and sexuality, calls upon her winged son Cupid to say: “My dear son, punish that contumacious beauty; give your mother a revenge as sweet as her injuries are great; infuse into the bosom of that haughty girl a passion for some mean, unworthy being, so that she may reap a mortification as great as her present exultation and triumph.” The question is, who is this mortal beauty who has injured the pride of the goddess of love herself? A woman named Psyche takes the stage, who represents a Hellenistic personification of the soul. Born into nobility, Psyche is adored and idolized by the people to the extent that proper worship of Venus is neglected. Offended by such disregard, Venus commissions her son to make Psyche fall in love with a contemptible human being. Cupid, preparing to obey, visits Psyche in her sleep only to find himself so startled by her beauty that – ironically – he is struck by his own arrow.
Or so is told in the tale of Cupid and Psyche appearing in Metamorphoses written by Apuleius in 2nd century A.D. But this isn’t the end of the story.
Cupid, against his better judgment (isn’t it always?), decides to protect Psyche by becoming her invisible husband. An oblivious Psyche fights the temptation to see the face of her husband, till one night she holds up a candle-light to see a man with an angelic face sleeping soundly in her bed. Hopefully, this Cupid wasn’t the chubby little angel we see flying around on our Valentine’s card (though this would explain her surprise), but what happens next is sadly comedic, or shall we say romantic. A surprised Psyche stumbles and accidently falls upon one of Cupid’s arrows to be struck by an unexplainable feeling. Love.
What is interesting here is how the allegory reflects an ancient but still persistent curiosity of how we perceive love. In the modern day Cupid continues to represent the concept of love otherwise known as Eros , the Greek word for desire. Popular culture has overused him in songs, cards, and online dating sites. Psyche, on the other hand, meaning ‘soul’ or ‘breath of life’ has given birth to the discipline of psychology which strives to understand human behavior and the motivations behind it.  Prodigious effort in the field of psychology over thousands of years has been devoted to the idea of why we love and how we love. Neurobiologists have only recently joined the arena by trying to help decode the molecular cues that places us in this particular state of mind.
So, then, what is in Cupid’s arrow that makes our minds so intensely focused on one individual? How is our brain physiologically and therefore emotionally changing when we are the target of this arrow?
Western psychoanalysts have conjured up various thoughts regarding the matter of why we fall in love. Theodor Reik’s Complementarity Theory of Romantic Love states that we’re looking for something we lack, someone who will fulfill the ideals that we have yet to achieve.  If we seek security, we look for commitment. If we are restless and want to experience the world – we look for someone who likes to travel. Another psychologist, Erich Fromm, views the act of falling in love as a creative tendency – a practice that requires “discipline, concentration, patience, faith, and the overcoming of narcissism.” No wonder it takes considerable patience and creative thinking on your part to rationalize why the person you like is not yet replying. Then there’s the idea of Freudian paradoxical love, where Eros (the drive of love, sexuality, and life) and Thanatos (the drive of destruction, violence and death) struggle against each other in a battle.  Don’t people say that there is a thin line between love and hate? One could go on and on, as there are as many theories of love as there are unique beings in the world. Psychologically, it seems like the key to understanding why we love whom we love is a compilation of factors: a sense of absence, a person’s personality, childhood, socio-economic background, and anything else that might influence the way choose whom to care most about.
From a neurobiological perspective, as has been widely publicized by the media in recent years, people have been trying to make a stab at explaining the brain in love. Love could be, but shouldn’t be (where’s the magic?) reduced to a series of biochemical events. Temporal distinction between the phases of love are made: whether its initial lust driven by sexual desire, an early-stage intense romantic attraction or a long-term form of bonding and attachment.  Of course there are those in-between stages when we are all pulling our hair out, but (shhh) we won’t talk about that. Depending on the stage at which we are at, different hormones and neurotransmitters modulate the three emotion-motivation systems.
Assuming that we are all too familiar with how lust works, which is mainly driven by sex hormones testosterone and estrogen, let us move on to the next phase; attraction. The dominant players during the attraction period are adrenaline, noradrenaline, dopamine and serotonin. If nothing else, the neurochemistry can help explain phenomena we associate with the emotion of early romantic love. Remember getting butterflies in your stomach when your sophomore crush finally asked you out? This is the result of an adrenaline rush in the ‘fight-or-flight’ response where more blood is needed in active muscles, hence the fluttery feeling caused by a reduction of blood in the stomach. The same holds for increased heart rate; heart beat is extrinsically regulated by the dual action of adrenaline and noradrenaline.
Before drawing conclusions from studies though, it is important to consider how scientists have been hand-picking individuals “in love”. Emotional responses such as euphoria, intense focused attention of certain individuals, obsessive thinking, dependency, and craving for union is categorized into quantifiable indices such as the Passionate Love Scale (PLS) and the Affect Intensity Measure (AIM).  As funny as it may sound, behavioral indices such as these along with psychological and physiological changes are rigorously assessed to determine if a person is experiencing love for the sake of science.
Returning to our discussion of attraction, addiction is another mental condition with which we tend to draw parallels with being in early romantic love and rightfully so.The neurotransmitter dopamine is a key regulator in the reward and pleasure circuits of the brain. There is an extensive set of brain structures heavily influenced by dopamine; collectively called the limbic system. The function of these structures is closely tied to emotions, behavior, and memory. Among these brain regions is the nucleus accumbens which is one of the most critical components in generating a sense of pleasure, no doubt involved in sexual arousal and recreational drug use.  An increased level of dopamine in this area is observed while people are experiencing love. Helen Fisher’s group at Rutgers University made an observation where A10 cells of the ventral tegmental area (VTA) were activated in people feeling intensely love according to the indices mentioned before.  This area is also part of the limbic system which is central in the pathway of addiction and dopamine production.
Now that we’ve established an idea of how the early-stage attraction is processed in our brains, what about bonding and attachment? Two hormones, namely oxytocin and vasopressin, are thought to be responsible for this particular phase. An upcoming post will deal with this topic more extensively, but as a preview, more evidence is being gathered upon the role of oxytocin and vasopressin in mother-child bonding and long term commitment of couples. This has been shown to happen in rodents through processing of social cues necessary for individual recognition by differentially regulating receptors for the two hormones. 
To cut the story short, the simplified picture of how we fall in love is that we go through phases of lust, attraction, and attachment through the interaction of different hormones and neurochemicals. Personally, I feel like I’ve gone through these phases with substances such as chocolate and caffeine more than with actual people, but perhaps that’s just me. Everything I’ve laid out till now you’ve might have heard of one-way or another. Self-perception explained through various psychoanalytical theories and neurotransmitters modulating our emotional state is not that surprising.
But what else could contribute to the idea of love?
Let’s revisit the story of Cupid and Psyche and with a bit of imagination for a moment.
Cupid visits Psyche bearing ill-will but ironically fall in love at first sight. Sure, visual images are indeed powerful sensory stimuli but what if it were to be ‘love at first smell’? If Psyche had on an unbearably attractive perfume (as many perfume companies boast of their aphrodisiac scents)that created a fatal bond? Unfortunately, contrary to popular notion, actual human pheromones have yet to be discovered – although there are some suspects being carefully scrutinized. Or what if Psyche held up a candle-light to Cupid’s face and in fact fell in love with his immune system? There was a wacky but somewhat persuasive article two years ago about how increased facial attraction was inter-correlated with higher testosterone levels reflecting a more productive antibody response to vaccines. 
Anyways, the point I’m trying to make here with these alternative ideas is that we actually haven’t quite figured out why we fall in love. Neuroscientists are well aware of the dangers of oversimplifying complex emotions such as love. Most human studies so far are based on fMRI scans which bear intrinsic limitations. So called ‘brain activity’ is measured in humans through functional Magnetic Resonance Imaging(fMRI) and Positron Emission Tomography (PET). What these tools measure are basically an increase in blood flow or metabolism in one brain region relative to another. When you read somewhere that certain brain cells were “activated” – this is therefore an indirectly drawn conclusion that high metabolism in a certain areas of the brain represents functioning neural correlates.
Technically speaking, fMRI cannot easily differentiate between function-specific processing and neuromodulation, between bottom-up and top-down signals,and it may potentially confuse excitation and inhibition.  We are barely grazing the surface of elucidating how different neuronal ensembles behave in certain contexts, let alone teasing apart the factors driving individuals to make emotional decisions. At the end of the day, the truth is we really don’t know why we say “I Love You”. Till then perhaps the wisest course of action is to buy your significant other a box full of chocolates, relax, and try not to think of why, what and how. It is possible that we don’t actually want to know.
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