There are three phases to falling in love and different hormones are involved at each stage.
Events occurring in the brain when we are in love have similarities with mental illness.
When we are attracted to somebody, it could be because subconsciously we like their genes.
Smell could be as important as looks when it comes to the fanciability factor. We like the look and smell of people who are most like our parents. Science can help determine whether a relationship will last.
In the attraction stage, a group of neuro-transmitters called ‘monoamines’ play an important role:
Dopamine – Also activated by cocaine and nicotine.
Norepinephrine – Otherwise known as adrenalin. Starts us sweating and gets the heart racing.
Serotonin – One of love’s most important chemicals and one that may actually send us temporarily insane.
Conscious thoughts about a romantic partner activate brain regions related to reward and motivation. Ortigue et al. investigated whether unconscious priming by a partner’s name could also affect motivation. They found that priming by either a beloved or a favorite hobby improved reaction times in identifying whether a string of letters was a word or not compared against priming by a neutral friend.
The authors suggest this effect happens because a beloved’s name “may call for a goal-directed state” and produce “dopaminergic-driven facilitation effects.
The theory of a biological basis of love has been explored by such biological sciences as evolutionary psychology, evolutionary biology, anthropology and neuroscience. Specific chemical substances such as oxytocin are studied in the context of their roles in producing human experiences and behaviors that are associated with love.
After this step, the neurotransmitters norepinephrine and PEA (phenylethylamine) lead to focused attention. Individuals start to ‘zero-in’ on the person they desire, and at the same time, often have a feeling of euphoria. Norepinephrine is a stimulant, so it also causes individuals to feel alert, potentially unable to sleep, and enables them to notice and remember even the smallest of details about their partners. PEA is responsible for the feelings of giddiness, and may cause the loss of appetite. If the relationship doesn’t last, and PEA levels fall and are partly responsible for the feelings of depression that can be experienced.
A feedback loop begins to form, with a brain reward system becoming involved. This reward system is influenced by the central nervous system and the contents of the bloodstream, such as the level of various neurotransmitters. The reward system sends chemical messages, via neurotransmitters, to various parts of the body, including the stomach, skin, genitals and other organs, which causes them to send messages back to the brain. To phrase it simplistically, if stimulation of the genitals feels good, for example, then the reward system receives this information and causes one to seek more of what was pleasurable. Interestingly, anticipation alone can cause a biological response and stimulate the reward system.
A study led by Semir Zeki and Andreas Bartels of University College London concluded that at least two areas of the brain become more active when in love. These were foci in the media insula, which the brain associates with instinct, and part of the anterior cingulate cortex, which is associated with feelings of euphoria.
Ortigue et al. found that an unconscious prime of the name of a romantic partner activated similar brain regions as when subjects were consciously aware of seeing partners’ faces.[18] Subliminal priming with either a beloved’s name or a favorite hobby activated emotion and motivational brain regions: caudate nucleus, insula, bilateral fusiform regions, parahippocampal gyrus, right angular gyrus, occipital cortex, and cerebellum. However, the love prime evoked more activation in bilateral angular gyri and bilateral fusiform regions than the hobby prime.
These regions are associated with integrating abstract representations, and the angular gyrus in particular is involved with abstract representations of the self. The authors also found a correlation (r=0.496, p=0.002) between activation of a region of the angular gyrus with a passionate-love scale measuring subjective feelings of love.