Motivation and emotion/Book/2015/Neurobiology of romantic love

Neurobiology of romantic love
What are the neurobiological components of romantic love?

Multimedia presentation (3 min)

Overview

Figure 1.

So what is romantic love? How and why are we motivated to experience romantic love? What neurobilogical responses occur when we experience romantic love and is it different to other forms of love?

Test your perceptions of what romantic love is

If you were asked what romantic love looked like or if you could describe the effects it had on a person what would you say? Would images of Romeo and Juliet and the Notebooks undying love flood your imagination?

These images might be what society associate with and attributes as romantic love because of the movies, literature and art, but these representations don't actually depict what love is, the various types of love or what it means physiologically.

This book chapter aims to explore romantic love in more detail. Defining romantic love, exploring the underlying motivation for humans and animals to search for romantic love and the neurobiology and chemistry of love. Exploring what love more generally but focusing on romantic love, examining the effects that occur when humans fall in love and how these affect the human body.

After reading this book chapter you will have greater insight into romantic love and why people are attracted to the people they are. You will have an understanding of the neurobiology behind the sensation we call love and will know a little more about the physical reactions romantic love causes in the body.

Case study

Melissa and Steve have been dating for two months and can't keep their hands off one another. They feel that they are completely in love and ready to get married. According to Sternberg's theory what kind of love are they actually in? What type of love will they be in once they have been married for 30 years and despite being extremely close, have four kids and are looking forward to retirement together they seldom make love? If you were Melissa or Steve would this kind of love be enough for you?

What is love?

If you were asked if you could relate to the feeling of falling in love and being loved, most individuals would say yes. However, when asked to define those feelings it becomes a struggle (Esch & Stefano, 2005).

The Oxford English Dictionary defines love as a strong feeling of affection and/or sexual attraction for someone. Thus, love is usually identified as an emotion and linked with the way humans feel about family, friends and romantic partners. However only in the last ten years has psychological and neurological research focused on the science of love (Esch & Stefano, 2005).

One hypothesis on what love is was proposed by leading experts in the theory of love, during their 2002 study into the experience of love they proposed that love is divided into three partly overlapping stages, these are lust, attraction, and attachment (Fisher, Aron, Mashek, Li & Brown, 2002).

Lust, also known as libido or sex drive, is defined by its desire for sexual gratification and pleasure. Attraction is about more specific romantic desires and compatibility for long-term attachments. However, attachment (romantic love) explores the level of trust and intimacy that is created during bonding for healthy relationships lasting for many years and even decades (Fisher, Aron, Mashek, Li and Brown, 2002). Despite this theory having some significant results it fails to take into account other theories on love and neurological components.

Is love an emotion?

When your to name four emotions what would you say? Sad, happy, angry and love perhaps. In a study by Fehr and Russell (1984) participants were asked to write down a list of emotions, interestingly one of the most common responses was ‘love’ despite the fact that love strictly speaking isn't an emotion but is a feeling which is a subset of emotion. Emotions are complex physiological and psychological responses to an event or events that effect human behaviour and, in some cases, cognitive ability.

Emotion is often seen to be a significant factor in motivation as it provides the fuel or passion required to pursue a goal (Fehr and Russell, 1984).

See also: http://www.nature.com/scientificamerican/journal/v298/n6/box/scientificamerican0608-88_BX2.html

Theories of love

Sigmund Freud developed one of the first theories of love. Freud's theory of the id, the ego and superego proposed that sexual desires where part of the id's pleasure principle were as the need for within the ego ideal (de Boer, van Buel & Ter Horst, 2012). Since then dozens of theories have emerged on love, some of the significant theories are explored below.

Evolutionary Requirement

Evolutionary psychology advises that love was developed as a survival tool. Human babies and infants are dependent on their parents for a significant portion of their life and it was therefore in the infant's best interest that the parents remained together. Compared to other mammals and animals, humans rely heavily on both parents for survival and for a greater period of time they are completely dependent on them (de Boer, van Buel & Ter Horst, 2012; Esch & Stefano, 2005).

Biology of attachment

Biological models of attachment tend to see view love as a necessary human drive for advancement and survival. Biology theorists suggest there are three stages of love; these are lust, attraction and attachment (de Boer, van Buel & Ter Horst, 2012; Fisher, Aron, Mashek, Li & Brown, 2002).

The first stage lust is the physiological feeling of sexual desire and attraction, this stage is generally based unconsciously on a person’s appearance and pheromones for mating. Attraction occurs after the initial lust stage has started to fade and a deeper connection to the individual is felt (Fisher, Aron, Mashek, Li & Brown, 2002).

This stage takes more conscious factors in such as common likes and dislikes, similar goals and styles and common pursuits for family and intellectual pursuits suitable for long-term commitment, and research indicates that a variety of chemical are consistently released into the brain during this stage. The last stage that biology theorists identified is attachment, occurring in long lasting relationships where a certain level of commitment and understanding is made (de Boer, van Buel & Ter Horst, 2012; Madey & Rodgers, 2009).

Sex drive verse reproduction

The human sex drive is a product of the pleasure associated with having sex and achieving orgasm. The pleasure associated with sex ensures that reproduction continues despite the disadvantages associated with procreation. These disadvantages include the dangers and pain associated with childbirth, the risk of sexually transmitted diseases (STDs) and the time and resources required for child rearing, yet society continues to thrive (Fisher, Aron & Brown, 2006).

Psychological theoretical approaches to loves

Maslow's Hierarchy of needs

Maslow's Hierarchy of Needs- Image 2

Maslow's Hierarchy of needs was one of the first theories to explore what motivated people, however this theory also explored where the requirement for romantic love and companionship fell within this hierarchy of needs. Maslow proposed there was set needs and requirements that motivated human survival and that those needs ranged from seeking rewards, unconscious desires and basic needs. Only when one set of needs is fulfilled do humans have the ability to seek to fulfil the next set of needs (Lester, 2013).

Over the years Maslow's Hierarchy of needs has been refined to hold seven levels (sets) of needs these include:

1. Biological and Physiological needs (Human survival- water, food, sex)
2. Safety needs (Physical safety, health and shelter)
3. Love and belonging needs (Friendship, Family, companionship, love)
4. Esteem needs (Self-esteem and self-respect)
5. Cognitive needs (Gaining knowledge and improvement of self)
6. Aesthetic needs (Appreciation for beauty and balance)
7. Self-Actualization needs (Reaching fulfilment in one’s life)
   

Triangular Theory of Love- Image 3

Level three focuses on love and belonging this includes all forms of love from friendships, familial love, romantic love, consummate love and companionate love (Lester, 2013).

Maslow's hierarchy of needs identifies where romantic love fits into a larger picture of human needs however this theory alone cannot provide any answers as to what love is, how it is measured or the neurobiology of it. Maslow's hierarchy of needs is the foundation for understanding these things however.

Sternberg's triangular theory of love

The psychologist Robert Sternberg proposed the Triangular theory of love. This theory like the biology of attachment has three components however it is usually represented in the form of a triangle (de Boer, van Buel & Ter Horst, 2012; Madey & Rodgers, 2009)(see image 3).

These components are:

1. The Intimacy component (the top of the pyramid) signifies a close, connected, intimate relationship.
   
2. The Passion component (bottom left hand corner of the pyramid) signifies sexual attraction, love and passion for the other person.
   
3. The Commitment component (bottom right hand corner of the pyramid) signifies the decision of chose to be with person, promises for the future and plans for long-term commitment to the other (de Boer, van Buel, Ter Horst, 2012; Madey & Rodgers, 2009).
   

Sternberg's theory critically review by peers has been proven to be an effective measure of love, however refinements have been made over the years to triangle that is now so well-known and used.

Forms of love

The level and type of love experienced are dependent on how much an individual is corresponds to each particular component and the level at which the three components interact (Esch & Stefano, 2005). The different types of love define below in table 1 explore the different combinations and strength of these three components.

The different types of love

Table 1 -According to Sternberg formulated triangular theory of love.

Type of love	Characteristics of the triangle	What it means
Nonlove	None	Nonlove characterises the large majority of human interactions and relationships.
Liking/friendship	Intimacy	Characterized as true friendship (closeness, bonding, and warm relationship, without feelings of passion)
Infatuated love	Passion	Passionate arousal or attraction and an absence of intimacy or commitment.
Empty love	Commitment	Characterized by commitment without intimacy or passion.
Romantic love	Intimacy and Passion	Romantic love means the individuals are not only physically attracted to each other (with passion)and are also bonded emotionally but without sustaining commitment.
Companionate love	Intimacy and Commitment	This is an intimate love but not passionate however is stronger than liking/ friendship love because of the long-term commitment and care.
Fatuous love	Passion and Commitment	Whirlwind romances and marriages, the commitment is usually based solely on passion but little to no intimacy and knowledge of the other.
Consummate love	Intimacy, Passion and Commitment	The only form of love that has all three elements. The "ideal relationship". These couples continue to have passion well into a decade of marriage and continue to increase the level of intimacy and commitment held.

Remember the earlier case study earlier, now that you understand Sternberg triangular theory of love you will you know that Melissa and Steve were originally in the Romantic love stage and their relationship developed into companionate love. This indicates that they don't have alot of passion in their relation anymore, for some people this kind of love is wonderful and enough later in life. Would this be enough for you?

Romantic love

What is romantic love?

Love is a complex neurobiological phenomenon that relies on two parties trust, pleasure and reward activities within the human brain (Esch & Stefano, 2005). Several chemical produced by the human body and controlled by the brain have been identified as playing critical roles in the development and continuation of romantic love and attachment to a person (Gonzaga, Turner, Keltner, Campos & Altemus, 2006; Wang & Young, 2004).

According to research there are three phases in romantic love relationships (Wang & Young, 2004).

1. Phase one- Infatuated love: Typically this is characterised by intense passion, a rise in intimacy both physically and psychologically and an increase desire to see one another. Displays of affection such as holding hands, kissing and the inability to concentrate on anything else are behavioural signs displayed in this phase. This phase generally lasts 6 months and is characterised by high nerve growth factor (NGF) and low serotonin levels as indicated below.
2. Phase two- Passionate love: Generally last several years before developing into companionate love.
3. Phase three- Companionate love: Companionate love (sometimes known as Affectionate love) follows passionate love. It occurs when a couple have been together for a significant period of time, reaching a mutual understanding, respect and level of care for one another. Long-term relationship to survive and continue to thrive.

Following the three phases there is another triangle with intimacy, passion, and commitment points. These points meet the phases to provide the categories (types) of love as seen in Table 1 and the combination of these can be seen in Image 3. Sternberg believed that love was fluid and evolved and changed over time, moving from one form to another and sometime backwards before progression forwards. However all couples in love will experience intimate, passionate, and committed love similarly (Fisher, Aron & Brown, 2006; Gonzaga, Turner, Keltner, Campos & Altemus, 2006).

Sternberg’s Triangular theory of love identifies seven types of love. These types are created using the combinations of the three phases and the three points of love and can change. There is also a description of non-love is listed below, along with the other kinds of love (Gonzaga, Turner, Keltner, Campos & Altemus, 2006).

Depictions of Romantic love in artistic pursuits

Romantic love is depicted in movies, books, painting, art, poetry and many more artistic pursuits often by passionate embraces or grand discolorations, but is this a true reflection of romantic love or are these merely other forms of love we are confusing for romantic love? Take Romeo and Juliet for example.

What is your favourite depiction of romantic love? Shakespeare's- Romeo and Juliet or perhaps Nicholas Sparks- The Notebook

Romeo and Juliet

What if you were told that Romeo and Juliet according to Sternberg's Triangular theory of love weren't actually in love (romantic love) as usually depicted but instead were in phase one the intimacy stage where strong feelings of desire, passion and excitement are exhibited and behavior is often bold to and one sighted to the detriment of one's self. Compare that with the type of love displayed in the notebook, are they the same kind of love?

If you answered no, you were correct. The type of love displayed at the end of the notebook is romantic love. The two characters in are in the commitment component of Sternberg's Triangular theory of love or when exploring the type of love it can only be that of consummate love. Noah and Allie represent the ideal relationship and example of romantic love, having been through the other stages of loves and maintaining their passion for one another. If their passion for one another had been lost over the course of time then their love would have changed into companionate love.

Neurobiology

What does the neurobiology of romantic love look like?

The brain in love-neuroanantomy

Image for Anatomy and Functional Areas of the Brain

Limbic system

The limbic system is a system of complex of nerve networks within the human brain. It includes the amygdala, hypothalamus, olfactory bulbs, thalamus, fornix, cingulate gyrus, cortex, caudate nucleus, basil ganglia, dentate gyrus, hippocampus and the parahippocampal gyrus. The limbic system controls basic emotion such as fear and pleasure (to name a few) and basic urges or drives such as reproduction and hunger (de Boer, van Buel & Ter Horst, 2012; Esch & Stefano, 2005).

Hypothalamus

The hypothalamus is a small peanut shaped part of the brain that lies just beneath the thalamus and cerebrum. The hypothalamus controls the strength of the heart beat including its speed and the rhythm and depth of breathing through the autonomic nervous system which are physical responses to attraction and are unconscious/involuntary in nature (de Boer, van Buel & Ter Horst, 2012; Esch & Stefano, 2005; Fisher, Aron & Brown, 2006).

The hypothalamus also maintains the secretion of hormones in the body through the pituitary gland which is a pea-sized component of the human brain located at the base of the brain. The hypothalamus is responsible for the physiologic functions including sex drive, lust and the associated chemicals developed and released and its activity is increased during arousal (Fisher, Aron, Mashek, Li & Brown, 2002).

Brain chemistry- The love hormones and chemicals

All relationships change the brain and chemical levels of the human body (Young, Wang & Zuoxin, 2004). Oxytocin, vasopressin and dopamine combined are significant in successful pair-bonding and monogamy (Beauregard, Courtemanche, Paquette, & St-Pierre, 2009; Carter, 1998).

Oxytocin and Vasopressin

Oxytocin is a natural chemical the body produces in the hypothalamus, oxytocin is then stored in the pituitary gland ready for dissemination throughout the body. Oxytocin is critical in the development of attraction and reproduction, playing a role in the creation of intimacy, bonding and attachment, sexual pleasure and during neonatal (before birth) and antenatal (after birth) development (Gouina, Carter, Pournajafi-Nazarloo & et al, 2010; Heinrichs, von Dawans & Domes, 2009; Wang & Young, 2004).

Oxytocin is often called the love transmitter or the trust hormone because when released it induces feelings of trust and reduces feelings of fear (Gouina, Carter, Pournajafi-Nazarloo & et al, 2010; Heinrichs, von Dawans & Domes, 2009).

Vasopressin is critical for the strong healthy cardiovascular function and in maintaining good blood pressure whereas oxytocin is required for the development of emotional bonds between individuals, however its principle action is to trigger the release of milk following birth and in triggering contractions for birthing a child (de Boer, van Buel & Ter Horst, 2012; Zeki, 2007).

Oxytocin is often described as the love transmitter as it increases the sexual desire, arousal and receptivity in females and assists in the creation of sexual arousal and erections in males (Wang & Young, 2004). Vasopressin however is released by the brain during sexual activity (Carter, 1998; Gouina, Carter, Pournajafi-Nazarloo & et al, 2010; de Boer, van Buel & Ter Horst, 2012).

Vasopressin assists to induces partner preference and selection in males on the other hand Oxytocin induces partner preference and selection in females. There is usually one oxytocin neuropeptide for every three vasopressin neuropeptide in bonding (Acevedo, Aron, Fisher & Brown, 2011; Esch & Stefano, 2005; Zeki, 2007; Heinrichs, von Dawans & Domes, 2009).

Oxytocin and vasopressin interact with the dopamine reward system, making falling in love, sex and romantic love a rewarding experience (Gouina, Carter, Pournajafi-Nazarloo & et al, 2010; de Boer, van Buel & Ter Horst, 2012; Wang & Young, 2004)

Dopamine

Dopamine is an organic chemical that carries messages influence reward, affects neurological processes such movement control, emotional response, and the ability to experience pleasure and pain. Dopamine is also the chemical that influences addiction (drugs and other such vices). Biologically speaking new lovers are truly addicted to one another and can experience withdrawal symptoms much the same as drug addicts going through drug withdrawal when the don't get to see one another (Zeki, 2007; Young, Wang & Zuoxin, 2004).

Dopamine is releases as part of a neurological reward system setup by the brain, and when bonding occurs between couples dopamine is released as a reward. Pair bonding therefore neurologically speaking can be considered to be the result of a conditioned brain. For instance the reinforcement of sex (the unconditioned stimulus) and the smell of the aftershave of the partner (Conditioned stimulus) evoke thoughts of them and the release of dopamine makes you want them more, its part of the dopamine motivation and reward system (de Boer, van Buel & Ter Horst, 2012; Esch & Stefano, 2005; Zeki, 2007; Young, Wang & Zuoxin, 2004).

The release of dopamine induces the release of oxytocin whereas the release of oxytocin increase dopamine levels in the body (Young, Wang & Zuoxin, 2004).

Testosterone

The hypothalamus controls testosterone levels through the pituitary and testicles.

Testosterone is a key component in male development, behaviours (such as aggression and competitiveness) and sexual interaction. Lower levels of testosterone are found in males who are in the intimacy stage of a new relationship opposed to women who are found to have elevated levels of testosterone (Esch & Stefano, 2005; Zeki, 2007).

Testosterone is affected by sexual activity however it’s not the only thing that affects it. Have you ever heard that professional athletes don’t engage in sexual activity before a big game? Well there might just be some truth in it after all as testosterone levels rise and fall when taking part in competitive activities just as much as sexual activity. Low testosterone can cause a loss of motivation, competitiveness and even lack of energy (de Boer, van Buel & Ter Horst, 2012; Esch & Stefano, 2005; Zeki, 2007).

Serotonin

In early stages of a new romantic relationship a depletion of serotonin occurs. The level of depletion is significant and similar to those found in patients diagnosed with obsessive compulsive disorders (OCD) indicating that serotonin is important to the obsessive nature of new love (de Boer, van Buel & Ter Horst, 2012; Zeki, 2007).

Serotonin levels are linked to appetite and mood, it therefore not a surprise that individuals with broken hearts have little appetite and are solemn in their mood. Love, after all, can be type of obsession (de Boer, van Buel & Ter Horst, 2012; Zeki, 2007).

Table 2.

Biochemistry of romance
In-love symptoms and behaviors	chemical production (Neurotransmitter)
Exhilaration, euphoria, feelings of connection	High dopamine and norepinephrine (noradrenaline) levels
Increased energy, loss of appetite, wakefulness and alertness	Dopemine, norepinephrine (noradrenaline) and high serotonin levels
Anxiousness, trembling, flush of color on face or cheeks, butterflies of the tummy, uncontrolled sweating of palms, face or neck, weakness in joints, rising heart rate, rapid and shallow breathing, dizziness, motivation to reorder priorities and possessiveness.	Dopamine
Anxiety, fear (of the person, awkwardness, rejection, humiliation), uncertainty, emotionally reactive and sensitivity, shyness	Dopamine and low serotonin levels
Separation anxiety, despair, feelings of loneliness and longing	Low endorphins
Intense focus and attention, long eye contact, pupil dilation	Possible low levels of dopamine and norepinephrine (noradrenaline)
Heightened attention to detail and memory, preoccupation with feelings to the executions of everything else, hope and fantasy	Dopamine, norepinephrine (noradrenaline) and low levels of serotonin
Male sexual stimulation (arousal), ability to engage in sexual activity and feeling of Lust	Testosterone
Heightened bonding facilitation, learning ability, memory creation and retrieval mechanisms, increase in female receptivity to sexual advances and activity, creation and development of emotional bonding between individuals	Oxytocin
Female sexual arousal and increase of sex drive,increase in female receptivity to sexual advances and activity and feelings of lust	Estrogen

In studies where participants undergo brain imagining (fMRI), romantic love shows activation in a significant portion of the limbic system and brain. The medialinsula, hippocampus, stratum, anterior cingulate cortex and the hypothalamus all light-up, interestingly these are all areas of the brain important in the reward system (Fisher, Brown, Aron, Strong & Mashek, 2010).

FMRI's have shown that there is a significant overlap between the various types of love with the dopamine reward system activating for romantic and material kind of love. However, activation occurs in the hypothalamus for romantic love and sexual arousal but not for maternal and other forms of love (de Boer, van Buel & Ter Horst, 2012; Fisher, Brown, Aron, Strong & Mashek, 2010).

Thinking back to the case study and now that you know a little more about the neurobiology and chemistry of the brain can you think of anything that might increase the level of passion in the relationship?

No? Remember that oxytocin is often described as the love transmitter as it increases the sexual desire and vasopressin is released by the brain during sexual activity meaning if Melissa and Steve wanted to improve their passionate love then all they need to do is increase the level of arousal and sexual activity. The more you have the more you want (Carter, 1998; Gouina, Carter, Pournajafi-Nazarloo & et al, 2010; de Boer, van Buel & Ter Horst, 2012).

Chemical basis of love

Conclusion

The idea of love is a rewarding one but the how and why humans love has been an eternally elusive. It's safe to say that love is a series of complex neurobiological activities that occur in the background without you ever having to think about them, however it's more than a series of neurons and transmitters.

The human body produces a multitude of chemicals to assist in the creation and maintenance of love, chemicals such as dopamine, oxytocin, vasopressin, testosterone, estrogen, nerve growth factor, serotonin and cortisol. Even with all the help provided by the human body the issue of finding the one worthy of the release of dopamine and oxytocin still remains. Humans have high expectations of romantic love and what it means, believing it to be passionate, all consuming and a mix of sweet and ravenous all at once but perhaps society is mixing up romantic love with passionate love because they just don't know any better.

Research into the neurobiology of love has included researchers from disciplines such as biology, neurobiology, psychology and philosophy, however the original question still remains, "what is love?". Further research into what love actually is and how we can apply those answers to the average person's everyday romantic needs in the future is needed, especially as divorce rates continue to climb. Perhaps if society understands the various types of love and how to evolve the passion in relationships that have long ago left it behind it will be different. Remember making love with your partner produces oxytocin and dopamine which make you want to engage more frequently in passionate activities. The more you get the more you want and the passion grows.

Neurobiology and brain chemistry plays a huge role in who you pick as your romantic partner and oxytocin and dopamine should be your favourite chemicals as they are the love and pleasure chemicals of the body.

Quiz

Point added for a correct answer:
Points for an incorrect answer:
Ignore the questions' coefficients:

1 Who’s theory is the Triangular Theory of Love?

	Jean Piaget
	Robert Sternberg
	Lev Vygotsky
	Sigmund Freud

2 What chemicals are involved in the bonding of partners?

	Oxytocin, Dopamine and Estrogen
	Serotonin, Noradrenaline and Norepinephrine
	Oxytocin and Testosterone
	Vasopressin and Oxytocin

3 What part of human brain produces and controls the chemical Oxytocin?

	Thalamus
	Hypothalamus
	Cerebellum
	Pituitary Gland

4 How many types of love are there according to Sternberg’s Theory?

	7
	8
	6

See also

• Unconscious Sources of Attraction (Book Chapter, 2015)
• Love and Lust (Book Chapter, 2015)
• Love (Book Chapter, 2011)

References

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Beauregard, M., Courtemanche, J., Paquette, V., & St-Pierre, E. L. (2009). The neural basis of unconditional love. Psychiatry Research- Neuroimaging 172(2), 93–98. doi:10.1016/j.pscychresns.2008.11.003.

Carter, C. S. (1998). Neuroendocrine perspectives on social attachment and love. Psychoneuroendocrinology, 23(8), 779–818. doi:10.1016/s0306-4530(98)00055-9

Esch, T., & Stefano, G. B. (2005). The neurobiology of love. Neuroendocrinology Letters, 26(Young, Larry J; Wang, Zuoxin, 2004), 175-192.

Fehr, B., & Russell, J. A. (1991). The concept of love viewed from a prototype perspective. Journal of Personality and Social Psychology, 60 (Young, Larry J; Wang, Zuoxin, 2004), 991, 425-438. doi:10.1037/0022-3514.60.3.425

de Boer A1, van Buel EM, Ter Horst GJ. (January 2012). Love is more than just a kiss: a neurobiological perspective on love and affection. “Neuroscience”, “10” (201), 114-24. doi: 10.1016/j.neuroscience.2011.11.017.

Fisher, H. E., Brown, L. L., Aron, A., Strong, G, & Mashek, D. (2010). Reward, addiction, and emotion regulation systems associated with rejection in love. Journal of Neurophysiology, 104(1), 51–60. doi:10.1152/jn.00784.2009.

Fisher, H., Aron, A., & Brown, L. L. (2006). Romantic love: A mammalian brain system for mate choice. Philosophical Transactions of the Royal Society/B-Biological Sciences, 361 (1476), 2173–2186. doi:10.1098/rstb.2006.1938.

Fisher, H. E. Aron, A., Mashek, D., Li, H., & Brown, L. L. (2002). Defining the brain systems of lust, romantic attraction, and attachment. Archives of Sexual Behavior, 31(Esch, T., & Stefano, G. B., 2005), 413–419. doi:10.1023/A:1019888024255.

Gonzaga, G. C., Turner, R. A., Keltner, D., Campos, B., & Altemus, M. (2006). Romantic love and sexual desire in close relationships. Emotion, 6(2), 163-179. doi:10.1037/1528-3542.6.2.163

Gouina, J., Carter, C. S., Pournajafi-Nazarloo, H., Glaser, R., Malarkey, W. B., Loving, T. J., Stowell, J., & Kiecolt-Glaser, J.K. (2010). Marital Behavior, Oxytocin, Vasopressin, and Wound Healing. Psychoneuroendocrinology, 35(S. Zeki., 2007), 1082-1090. doi:10.1016/j.psyneuen.2010.01.009

Heinrichs, M., von Dawans, B., & Domes, G. (2009). Oxytocin, vasopressin, and human social behavior. Frontiers in Neuroendocrinology, 30(Wang, Z., & Young, L. J., 2004), 548-557. doi: 10.1016/S0079-6123(08)00428-7

Kosfeld, M., Heinrichs, M., Zak, P. J., Fischbacher, U., & Fehr, E. (2005). Oxytocin increases trust in humans. Nature, 435, 673-676. doi:10.1038/nature03701

Lester, D. (2013). Measuring maslow's hierarchy of needs. Psychological Reports, 113(1), 15-17. doi:10.2466/02.20.PR0.113x16z1

Madey, S. F., & Rodgers, L. (2009). The effect of attachment and sternberg's triangular theory of love on relationship satisfaction. Individual Differences Research,7(2), 76-84.

S. Zeki.(12 June 2007). The neurobiology of love, “FEBS Letters”, “581” (14), 2575-2579. doi.org/10.1016/j.febslet.2007.03.094.

Wang, Z., & Young, L. J. (2004). The neurobiology of pair bonding. Nature Neuroscience, 7(10), 1048-1054. doi:10.1038/nn1327

Young, Larry J; Wang, Zuoxin (October 2004). The neurobiology of pair bonding. Nature Neuroscience, 7(10), 1048–1054. doi:10.1038/nn1327.

External Links

QUIZ- Psychology - Romantic love

TED Talk- Helen Fisher-studies the brain in love

TED Talk- Helen Fisher- Tells us why we love cheat

TED Talk- Mary Roach: 10 things you didn’t know about orgasm

TED Talk- Isabel Allende: Tales of passion

TED Talk- Jenna McCarthy: What you don’t know about marriage