Neurobiology of Romantic Love

Dr. Prithika Chary*

Department of Neurology and Neuroscience, Kauvery Hospital, Chennai

*Correspondence: Email: drprithikachary@gmail.com

Love is an innate emotion hardwired into humans.

It takes many forms – maternal love – the first manifestation of love we experience/romantic love which we feel in our youth and a necessary social need to bond with others of the same species for procreation and propagation of the species to survive and thrive.

This bonding is essential as the human child is dependent for many years after birth and needs nurturing till, he/she can be independent. Parents also need to live in a community to be able to nurture, protect and raise a child, hence the saying “It takes a village to raise a child”.

Love is not always a joyful emotion and actually triggers the same neural pathways as stress. Several brain chemicals are involved in both stress and love and bonding and are produced by the neuroendocrine system.

These “mood” chemicals are responsible for the behavioural changes we notice in the many ways in which love is manifest.

  1. Cortisol is a steroid produced during stress.
  2. Dopamine is associated with pleasure and rewards, addiction and desire and arousal.
  3. Dopamine releases Norepinephrine which improves memory for new stimuli.
  4. Serotonin is a mood stabilizer and prevents obsessive compulsive thinking.

A lot of the initial research on the neurobiology of romantic love was done by Prof. Helen Fisher, an anthropologist at Rutgers University. She is a leading expert on the biology of love and attraction. One of her central ideas is that romantic love is a drive that is stronger than the sex drive.

Her research involved studying the brain circuitry of romantic love by studying the brains of 49 men and women: 17 of whom had recently fallen madly in love, 15 who had just gone through heart break, and 17 couples in a long-term relationship and still in love after an average of 21 years of marriage.

She said romantic love occurs in three stages and, the stages are mediated by several brain chemicals and hormones

  1. The stage of lust,
  2. The stage of attraction,
  3. The stage of attachment.

The choice of a partner to fall in love is determined by different criteria in the male and the female.

In the male, the visual areas of the brain are most active in choosing a suitable healthy female with attractive features.

In the female, the emotional areas are active in choosing a male who would be best suited to protect and care for her and the child.

In short, the initial magnetism is about making healthy babies through the connection.

There is a subconscious liking for their genes, and the look and smell of the person often resembles that of our parents.

Stage 1: Lust

The primary sex hormones Testosterone and Oestrogen come into play here. They flood the system and this manifests as the desire to touch each other, hold hands, look into each other’s eyes, and mirroring body language. This is a primal physical sexual attraction which may not be associated with a lot of emotion.

Stage 2: Attraction – Ecstasy, Euphoria, Excitement

During this stage Dopamine, Norepinephrine and Serotonin are released. Dopamine related to the reward pathway gives a sense of joy and pleasure about the encounter and increases when we feel good. Norepinephrine causes the autonomic signs of a racing heart, sweaty palms. Serotonin creates obsessive thinking about the love object, diminished sleep and appetite.

Stage 3: Attachment – Connection, Commitment

Two hormones Oxytocin and Vasopressin play a major role in developing attachment.

Oxytocin “the cuddle chemical” is produced during orgasm, parturition, emotional stress, social interaction, sexual activity, mating, breast feeding, and in the presence of pleasant and safe companionship and improves bonding. It induces a pleasurable relaxed feeling and increases sociability.

It also leads to maternal caring behavior, maternal aggression in protecting her child, attenuation of the stress response, and in social and pair bonding.

It promotes mating behavior, aggression, improves maternal bonding and allays anxiety.

Vasopressin has many responses in addition to developing trust, commitment and bonding and is associated with monogamous pair bonding. It is also associated with displays of aggression, affiliation, and protection. It is also involved in territorial and “flight or fight” responses and partner selection. It is released after sex and heightens a sense of responsibility, monogamy, protective and loyal behavior towards the partner.

When levels of Oxytocin and Vasopressin are high, they counter the levels of Dopamine and Norepinephrine and that is when passionate love progresses to attachment.

Endorphins

Endorphins are peptide hormones produced by the brain and anterior pituitary gland. They inhibit pain perception and are produced during physical or emotional stress e.g., labor and child birth. They are also produced during the stage of attachment and give a sense of calm and comfort and companionship. This also explains “separation anxiety” when lovers or friends or mother and child are separated. Endorphin levels can be boosted by listening to music, doing physical exercise, meditation, and other pleasurable activities

A great deal of research beyond this basic framework has implicated many other chemicals in addition in the total scenario of romantic love.

As mentioned earlier the initial stages of falling in love trigger the stress pathway releasing cortisol and adrenaline as well. This causes the flutter and restlessness one feels on suddenly meeting the love object – a mild form of anxiety!

Two more chemicals participate in the biology of romantic love

Pheromones

  1. These are invisible substances secreted by various glands in the body which are perceived by a structure called the vomeronasal organ in other members of the same species.
  2. In humans, skin glands (apocrine and sweat glands) have a unique individual signature “aroma” and are released from hairy parts of the skin, the axilla, groin.
  3. There are genetic, hormonal, metabolic, nutritional, and psychological factors which influence the pheromones.
  4. Female sex hormones are more important than male sex hormones and indicate a readiness of the female for sexual union.
  5. When pheromones are sensed by the vomeronasal organ, impulses are sent to the olfactory nerve and from there to the hypothalamus where it triggers emotions of attraction, sexual desire and arousal

Phenyl ethyl amine

  1. This is called the “love molecule” and is responsible for the high that lovers feel.
  2. It is a neurotransmitter and has an antidepressant effect increasing energy.
  3. In activates the release of Dopamine and Serotonin and inhibits their breakdown.
  4. It stimulates exploratory behavior in seeking out new experiences, and hence promotes neuroplasticity and brain health.
  5. It is also present in dark chocolate with more than 35% cocoa solids.

Neuroanatomy of Love

  1. The Hypothalamus produces Dopamine, Oxytocin and Vasopressin.
  2. The Pituitary Gland produces and controls all the hormones secondarily triggered e.g., Adrenaline, Norepinephrine, Cortisol.
  3. The Amygdala moderates fear and stress.
  4. The Reward circuit consisting of connections with each other between the prefrontal cortex, nucleus accumbens, ventral tegmental area, hippocampus, ventral pallidum and amygdala.

fMRI studies have shown that the regions involved in passionate love are dorsolateral middle frontal gyrus, insula, superior temporal gyrus, angular gyrus, occipital cortex, occipitotemporal cortex, ventral temporal regions, other regions also involved – caudate nucleus, thalamus, anterior cingulate, posterior hippocampus, precentral gyrus.

Specific regions were associated with different aspects of the stages of love

  1. The Nucleus Accumbens lit up in those who were madly in love but dumped recently.
  2. The Ventral Pallidum was highlighted in those madly in love even after 20 years suggesting it is associated with attachment.
  3. The Ventral Tegmental area is a key reward area and was highlighted mostly with new love.
  4. The Raphe nucleus was highlighted in longtime lovers giving a sense of calm.

Cognitive functions which are heightened are

  1. Body image: tend to see the partner’s body better than one’s own body.
  2. Self-representation: sees the partner as part of oneself and as completing self.
  3. Attention: increased almost total focus on partner, ignoring others.
  4. Social cognition: understands partners intentions.

Blood levels and their effects

  1. Cortisol levels are high and leads to increased stress and alertness and diminished pain sensitivity.

Brain chemicals and their effects

  1. Dopamine levels are high – lead to increased pleasure and motivation and diminished sadness.
  2. Oxytocin levels are high – leading to increased trust and attachment and less fear.
  3. Vasopressin levels are high – leading to increased sexual arousal and attraction and less anxiety.
  4. Serotonin levels are low – leading to aggression and obsessive thinking.

Source: Rutgers University Researcher Helen Fisher.

Cortical Deactivation

This veritable tsunami of chemicals and brain areas are active during romantic love and certain protective functions are dampened throwing caution to the winds and making lovers jump into the relationship with poor judgement and no fear.

Cortical deactivation is seen in:

  1. The Amygdala: which controls fear.
  2. The mid temporal cortex: which controls negative emotions.
  3. The frontal lobe: which controls judgement.
  4. The posterior cingulate: which controls empathy.

It is this that accounts for the risk taking, uninhibited pursuit of the love object without too much worry about the consequences.

Homosexual romantic love

Heterosexual or Homosexual love is all the same to the brain.

Since the early 1990’s, a number of studies by several researchers found differences in the size of specific regions of the hypothalamus between homosexual men and heterosexual men, with homosexual men showing a more female pattern.

Differences in brain activation have also been observed, for example in response to pheromones or to visual presentation of male or female faces.

In both cases, homosexual men respond in a way that is more similar to heterosexual women, and homosexual women show responses more like heterosexual men.

Structurally and Functionally

  1. Male homosexual brain = Female heterosexual brain,
  2. Female homosexual brain = Male heterosexual brain.

Summing up the chemistry in the brain

The Dopamine pathways subserve:

  1. Mesocortical: cognition, memory, attention, emotional behavior, learning.
  2. Nigrostriatal: movement and sensory stimuli.
  3. Mesolimbic: pleasure and reward, seeking behaviours, addiction, emotion, perception.

The serotonin pathways subserve

Arousal, sleep, stress, attention, sexual behavior, mood regulation e.g., aggression, processing of sensory information in the cerebral cortex.

The norepinephrine pathways subserve

  1. The prefrontal cortex: wakefulness, attention, behavioural flexibility, cognitive control.
  2. The hypothalamus: wakefulness, stress response, neuroendocrine functions.
  3. Basal forebrain: wakefulness.
  4. Amygdala and hippocampus: episodic and emotional memories.
  5. Thalamus: sensory processing, wakefulness, stress detection, pain modulation.

In conclusion, lust is a temporary stage of romantic love whereas lasting love grows slowly, provides security, is patient, develops friendship, is more giving and has a future when two people fall in love.

So, what happens when you fall in love?

  1. You feel addicted due to dopamine.
  2. Love lowers your inhibitions (feeling drunk) due to PEA.
  3. Pupils dilate due to norepinephrine.
  4. Your stomach may act up – norepinephrine.
  5. You experience withdrawal symptoms when away from your lover – endorphins.
  6. Pheromones are triggered and sensed – you can recognize how your loved one smells/you like smelling your lovers’ clothes.
  7. Your heart rate and breathing synchs with your partners when you are together.
  8. Your brain lights up on fMRI on seeing the picture of your loved one.

Summary of The Love Cascade

  1. Pheromone attracts.
  2. Testosterone and estrogen cause lust.
  3. Norepinephrine drives us crazy.
  4. Phenylethylamine gives us a high.
  5. Norepinephrine and PEA stimulate dopamine production – activates serotonin – happy in love.
  6. If PEA kick lasts 12–18 months – if it fades – heartbreak and seeking new thrill – it can actually cause physical pain.
  7. Social disconnection (and the threat thereof) hurts in a very real way because it recruits some of the same neural mechanisms that respond to physical injury.
  8. If PEA sustained – progresses to comfort with partner – endorphins.
  9. Positive romantic sustained relationship – oxytocin and endorphins, and vasopressin – separation anxiety.

Love therefore has its beginnings, its end, and its prolonged existence in the brain!

ABOUT DR. PRITHIKA CHARY

neurobiology

Neurologist/Neurosurgeon/Epileptologist/Certified Soft Skills trainer and Image consultant/NLP Master Practitioner/ Founder and Chief Resource person EPICENTTRE, Creative Karma and ADL Neurotech/Motivational speaker/Life coach/Brain health coach

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