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Biochemically, All Is Fair

The views expressed are those of the author and are not necessarily those of Scientific American.


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There’s nothing in this world so sweet as love. And next to love the sweetest thing is hate.
- Henry Wadsworth Longfellow

I stare hard into his hazel eyes. Those damned eyes. I blink, and I’m bombarded with flashes of those eyes through lenses of love, trust, fear and anger. My blood is pumping with passion, sped on by norepinephrine and vasopressin. The neurons in a round structure at the base of my forebrain are firing like crazy, a cacophony of neural activity. I glance down at his lips. Half of me wants to kiss him – half of me wants to break his jaw.

Part of the problem is that for intense emotions, my body reacts in a similar way. Heart rate and blood pressure skyrocket, driven by stress hormones. My muscles tense. My palms sweat. My cheeks flush. Objectively, it might be hard to tell what I am feeling. Subjectively, it’s hard, too.

Love him or hate him, two regions of my brain – the putamen and the medial insula – activate when I look at his face. Some have suggested that since the putamen regulates motor functions and contains neurons that activate when we plan actions, perhaps it is helping me decide between that punch and that kiss, but there seems to be more going on. The putamen is highly regulated by dopamine, one of the neurotransmitters linked to intense romantic feelings and the messenger of our neurological reward system. I smirk at the idea that, perhaps, I just find the thought of cold-cocking him deeply rewarding.

It is the activation of the insula, though, that is most intriguing. The insula is a bit of a neurological slut, and is intimately involved in our experience of number of basic emotions, including anger, fear, disgust, happiness and sadness. Scientists believe the insula acts as a translater, connecting sensations in our bodies to emotions in our brains. The insula turns a bad taste into disgust, or a gentle touch into arousal. But what makes the insula so interesting is that many believe these connections go both ways. Not only are my feelings affecting my body, the very act of processing my body’s reaction to the situation – my fast pulse, shallow breaths, sweaty palms – is changing how I feel.

As my sensations surge, parts of my cortex responsible for judgement and reason shut down – love and hate really are blind in that way. Studies have suggested love is more blind, though, as larger areas of the cerebral cortex deactivate. I know my thoughts aren’t logical anymore. They’re at the mercy of neurotransmitter tides, waxing and waning. Confusion is an understatement.

I blink hard and try to focus.

Even my hormones are flirting with both sides of the emotional spectrum. The flushed skin, pounding heart and rapid breathing are the fault of norepinephrine and adrenaline kicking on my fight or flight instinct. Passion is passion, and the same hormonal system is triggered by fear, anger, lust and desire. Whatever the fueling emotion, my body is primed, ready to spring into action.

My other hormones are no help, either. Oxytocin, the ‘love hormone’, long touted as the chemical responsible for affection, also has a dark side. While it strengthens feelings of love and trust, it also intensifies envy and suspicion, and may even lead to strong feelings of hatred like racism and xenophobia.

Similarly, the anger-pumping hormone testosterone has a romantic side. Testosterone levels strongly control feelings of lust and desire, but more importantly, women falling in love have higher circulating testosterone. Thus even a hormone so intertwined with agression and hate is instrumental in my experience of romance and pleasure. I briefly wonder if the increased testosterone level in my body is having side effects as I clench my fist.

Sure, love and hate have their differences, too. The giddy, happy romantic feelings come from different parts of the brain than deep passion. But as the intensity of the emotion rises, the fine line between love and hate blurs. It’s no wonder philosophers have been lumping them together for centuries, two sides of the same coin. As glorified as our idea of love might be, passionate love has the same biomarkers as addiction and obsessive compulsive disorder – and like with addiction and obsession, when the stakes are high, the smallest thing can push a person over the edge.

He shouldn’t have pushed me.

My amygdala turns on. Today, the dark side wins. I close my eyes as aggression ripples through my body. I didn’t want a fight, but my body disagreed. Rage fueled by love overwhelms me. It takes everything in my power not to fly at him. Feeling my self-control waning, I clench my teeth. Then, slowly, I open my eyes to see his have hardened, too. Alright, then. Here we go.

    (lyrics)

Like this post? Check out Time – And Brain Chemistry – Heal All Wounds

Christie Wilcox About the Author: Christie Wilcox is a science writer and blogger who moonlights as a PhD student in Cell and Molecular Biology at the University of Hawaii. Follow on Google+. Follow on Twitter @NerdyChristie.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. all4kindness2all 7:03 pm 07/26/2012

    Did you record the lyrics? Any chance you will add that to this post?

    [CW: Check the little link next to the player that says "lyrics" - they should be there.]

    Link to this
  2. 2. Sazzery 8:04 am 07/27/2012

    What a fabulous article!
    Wonderfully written and so funny!! (in the nicest possible way)
    It describes being in love to a ‘t’.
    Its fantastic, to have the knowledge, of the working of the brain – and , oh boy, there must be soooo much more
    we have to learn, and use………
    Way to go!!!!

    Link to this
  3. 3. daedalus2u 11:06 am 07/27/2012

    It makes a great deal of physiological sense that they are linked, and that both are more intense in women than in men, hence the quote: “Heaven has no rage like love to hatred turned, Nor hell a fury like a woman scorned.”

    https://en.wikipedia.org/wiki/William_Congreve

    The archetypal attachment behavior is maternal bonding. All mammals exhibit that, and it is necessary to produce the boding necessary for lactation. Lactation is extremely energy intensive. If a mother does not have the metabolic resources to sustain lactation until her infant is weaned, evolution has configured mothers to also have maternal anti-bonding, that is the rejection of a newborn infant if lactation is not sustainable.

    My hypothesis is that just as maternal bonding is the archetypal attachment behavior, so too maternal anti-bonding is the archetypal anti-attachment behavior.

    Pair bonding in females is mediated through oxytocin, and recapitulates parturition, just like maternal bonding. Probably maternal anti-bonding is mediated through oxytocin too, but is also influenced by metabolic status, stress status, cortisol, those kinds of things.

    In males, pair bonding is mediated through vasopressin and recapitulates territoriality.

    Link to this

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