The Chemistry of Cupid's Arrow

Biology 202
2006 Second Web Paper
On Serendip

The Chemistry of Cupid's Arrow

Fatu Badiane

"[It is better] to have loved and lost, than to have never loved at all," is one of the most common expressions one hears discussing the subject of love. Claimed to have been said by Samuel Butler and Saint Augustine, this quote embodies one of society's major obsessions: love. It is written about in the tabloids between movie starts, it is deeply discussed and described in poetry, and it is manipulated with aphrodisiacs and love potions. All of this focus on one of the many ranges of human emotion brings to mind the chemistry that underlies it. What is love and does it even exist? Or is it just a fantasy that can only truly be mastered by poets and artists? A look at the beginnings of love research, as well as current findings on brain scans, and neurotransmitters may shine some light on this interesting subject.

Love was first studied in the late 1970's by Dorothy Tennov. She came up with the word limerence to describe the state of being in love. Limerence is more closely related to having a crush, infatuation, or puppy love than it is to romantic or sexual love. Limerence is defined by the limerent reaction toward the limerent object, or object of affection. The reaction consists of intrusive thinking, fear of rejection, hope of success, physical symptoms, and sexual attraction. All of these physical and emotional factors play a role in the formation of one of three bonds with the limerent object: an affectionate bond, a limerent-nonlimerent bond, or a limerent-limerent bond. An affectionate bond is a relationship in which neither partner is limerent. It is more closely related to a strong friendship than an infatuation. The limerent-nonlimerent bond is a relationship in which only one partner is limerent, while the limerent-limerent bond has both partners in a state of limerence. Once one of these three bonds are formed the relationship can end up anywhere, it can last or quickly deteriorate. Tennov's study was one of the first scientific studies on love (3). This pioneer study cannot look deeply into the neurobiology of love, but it did do a decent job of looking at the emotions, thoughts, and physical attributes of those in love. Tennov's study opened the doors to current research that has the capabilities of looking inside the brain at the physical structures involved.

Helen Fisher, Arthur Aron, and Lucy Brown have conducted a recent study on the brain biology of love. They studied 17 young men and women who claimed to be madly in love through functional magnetic resonance imaging (fMRI). The fMRI takes brain scans of the subjects while they look at different pictures of people they know. Some of the images were of close friends and others of their beloved partner (4).

Fisher, Aron, and Brown found that intense romantic love is associated with activity in dopamine-rich areas of the brain. These regions are associated with the pathways of reward and motivation. The specific regions of the brain are the right caudate nucleus and the right ventral tegmental area. The conclusion reached from this study is that romantic love should be classified as a motivational drive paired with a range of emotions associated with the neurotransmitter dopamine. This means that love is a motivation which is primarily controlled by the neurotransmitter dopamine (4). Motivation alone, however, cannot explain attraction, the sweaty palms and beating heart, the feeling of flying that one gets when in love. But at least dopamine is one step in the right direction towards the final answer.

A look inside the brain has been informative in looking at some of the biological and chemical structures that are important for this phenomenon. But, the previously discussed research by Tennov and Fisher, Aron, and Brown has only looked at one half of the pair in love. It is now time to look at the interaction two people attracted to one another undergo. A look at the anatomy of attraction will lead to more clues about the other players in this game of love.

The scene for this classic love story will be a dinner party; a get together of good friends celebrating the host's birthday. There is cake, punch, and yummy hors d'oeuvres for all to enjoy. Bianca is settled in a corner chatting away with her two closest friends, when Damian walks through the door. After greeting the host and finding a seat to enjoy some punch and cake, he scans the room. Unconsciously, he is making mental calculations of all of the women he sees. He is looking at their facial bone structure as well as their waist to hip ratio. Both of these are crude judgments of a woman's health and fertility (5). These are important factors for men to consider in choosing the perfect mate. The chemistry starts when Bianca and Damian make eye contact with one another from across the room. The midbrain releases dopamine as the motivational drive for the two individuals to approach one another.

After a nice greeting and the flash of a smile, the hypothalamus starts working (5). The two are close enough to each other that they are picking up each others pheromones, or chemical substances that are produced by animals as a stimulus to illicit some sort of response(Webster's Ninth New Collegiate Dictionary). Pheromones, in humans, are odorless and therefore go unnoticed. They are another factor used to interpret the health and fertility of a potential mate (5). This first stage of love is called lust. Lust, however, quickly turns into attraction. At this stage, and Damian and Bianca's intriguing conversation about recent travels continues while the hypothalamus manipulates the body to its owners advantage. The hypothalamus causes the eyes to dilate, the heart to pump harder, and produces a slight sweat. Some of these factors such as the dilation and sweat are to make the person more attractive. The racing of the heart is a result of the stress that first encounters produce (5). All goes well for Damian and Bianca. At the end of the evening they each exchange numbers and make plans to call each other. At this stage romantic love starts. Damian and Bianca are both drowning in dopamine to promote strong feelings of pleasure (5). The happiness that they feel encourages them to call on another and schedule a date.

The first date takes place at a quaint little French restaurant where they enjoy a light meal of quiche lorraine and salade nicoise followed by a savory chocolate fondue. Throughout the wonderful evening, their brains are churning away dopamine to produce the natural high of being in love (5). After several more dates, the two become closer to each other and are in the stage of attachment. This is where dopamine retires and oxytocin comes into play. Oxytocin is important in producing the emotions of love and is increased by physical contact.

Eighteen months after Damian and Bianca met, the neurotransmitter cocktail produced by their brain will decrease. Just as a drug user needs more and more of a drug to feel the same high, the brains of a couple in love will become habituated to the dopamine and oxytocin that was so forcefully produced at the beginning of their relationship (5). It is at this point that the relationship will end or continue.

The new neurotransmitter that was introduced in this story is oxytocin. Oxytocin also works closely with another neurotransmitter, vasopressin. Dopamine, oxytocin, and vasopressin are the three best studied neurotransmitters known to play a role not only in Damian and Bianca's relationship, but in all love relationships. Their role, however, is better known in animal models, such as the monogamous prairie vole, than in humans. But, scientists believe they should play a similar role.

Dopamine is involved in pair formation, or bonding. It is the first neurotransmitter to be produced after a suitable mate has been identified. Experimentation in prairie voles has found that when dopamine activity is blocked, it interferes with pair bonding. The voles that were given dopamine blockers did not produce as strong of an interaction toward their mate as those who were not given blockers (1). In addition to this, dopamine is known to play an important role in the reward system of human brains, or the mesolimbic pathway. It also plays a role in mood. Dopamine is used to form bonds, reward positive interactions, and create that happy mood of being in love. These are the essential roles it plays in the primary phases of love (2).

Most importantly, however, dopamine is involved in pleasure, which is an essential part of love and encompasses all of its subroles. Pleasure is a subsystem of the reward and motivation pathways in the brain. These pathways are controlled by the autonomic nervous system (2). The autonomic nervous system is the part of the nervous system that governs involuntary actions (Webster's Ninth New Collegiate Dictionary). The secretion of dopamine is out of the control of the owner of the brain. These secretions result in changes within the body to stimulate certain emotions, such as pleasure. It is the integration that produces pleasure. This same euphoria and reward that is associated with love, plays a role in drug usage and the high the results from it (2).

The next vital neurotransmitter is oxytocin. Oxytocin is the neurotransmitter that is responsible for facilitating pair bonding. Experimentation in prairie voles has found that voles treated with oxytocin formed pair bonds quickly, whereas those with oxytocin blockers did not show as strong a partner preference. Those with the blockers were less faithful to their mates (1). In humans, it is believed that oxytocin works as a stress reducer. Love is considered to be a very stressful time. Symptoms produced by the body such as sweating, heart beat acceleration, increased bowel peristalsis, and sometimes even diarrhea are not pleasant to deal with when trying to catch someone's attention. Oxytocin is one of the neurotransmitters that is released to inhibit the stress responses, such as those listed, which are produced by other parts of the nervous system. Oxytocin encourages pair bonding, or social attachment, by acting as a stress reducer (2). Earlier, it was stated that oxytocin is released during times of physical contact, such as hugging or cuddling. Putting all of this information together, one can see that the stress that comes from being in love is reduced when oxytocin is released via the touch of the loved one. It is a comforting feedback loop.

Vasspopressin similarly plays a role in partner preference. Research done on prairie voles lead to the conclusion that vasopressin facilitates partner selection. The voles that received treatments of vasopressin were more faithful to a particular partner than those who did not receive the treatments (1).

All of these neurotransmitters, especially oxytocin and vasopressin, play a role in the autonomic nervous system. The autonomic nervous system (ANS) is the automatic control center of a person's brain. It is out of the control of the brain's owner. The ANS is key in social attachment and love, hence the fact that oxytocin and vasopressin are its most important players (1). In the ANS oxytocin plays a role in the reward and reinforcing pathway, as well as ensuring trust, loyalty, and devotion. The key pieces to a beneficial and lasting relationship.

Love indeed is not just a fantastical state that many experience. It is an emotional state that is to an extent organized by the brain. The bonds people make, the parts of their brains that play a role in these bonds, and the neurotransmitters that zip through their brains to illicit particular responses are very real. Evidence from the late 1970's to present day proves this point. Although science may have a grasp on how the brain interprets love, or what causes the initial attraction, the secret to what makes some relationships work while others fail is still a mystery. This may have less to do with the functioning of our brains and more to do with the workings of our minds and souls.

Works Cited
1) Carter, Sue C. (1998). Neuroendocrine Perspectives on Social Attachment and Love. Psychoneuroendocrinology. 23(8) 778 – 818.

2) Esch, Tobias, Stefano, George B. (2005). The Neurobiology of Love. Neuroendocrine Letter. 26(3). 175 – 192.

3)Wikipeida

4)Soceity for Neuroscience