When it comes to falling in love, the brain may be just as involved as the heart, new research finds.
Ortigue said the analysis, detailed in a recent issue of the Journal of Sexual Medicine, will be followed up by a study that suggests it takes about a fifth of a second to fall in love.
Ortigue and her colleagues found that when a person falls in love, different areas of the brain release euphoria-inducing chemicals such as dopamine, oxytocin (the so-called love hormone), adrenaline and vasopressin (known from animal studies to cause aggression and territorial behavior).
Other studies have suggested blood levels of nerve growth factor (NGF), a protein that plays a role in the survival and maintenance of brain cells, also increase. Those levels were found to be significantly higher in couples who had just fallen in love. Ortigue said this molecule also plays an important role in the social chemistry between humans, or the phenomenon of love at first sight.
"These results confirm love has a scientific basis," she added.
Different types of love
And not all love is created equal. The analysis found that different parts of the brain are activated for different types of love. For example, in the first brain study of romantic love, researchers recruited 17 volunteers who were "truly, deeply and madly in love" with a partner. [Related: Romantic Love Is an Addiction]
When gazing at their significant others, participants showed brain activity in the so-called dopaminergic subcortical system shown to be active in people who were under the influence of euphoria-inducing drugs such as cocaine. Other brain regions broadly activated included: the posterior hippocampus linked to memory and mental associations; brain areas linked to emotions; and those linked to reward processing, such as the insula and anterior cingulated cortex.
A 2004 study published in the journal Neuroimage focused on maternal love in the brains of 20 mothers. Brain activity was monitored while moms looked at pictures of their own child, of another child of the same age with whom they were acquainted, their best friend, and of another acquaintance.
Brain regions associated with maternal love included those related to higher cognitive or emotional processing. Compared with passionate-love brain activity measured in a prior study, the researchers found maternal love but not the romantic kind showed up in the periaqueductal gray matter (PAG) – an area that contains receptors for mother-child bonding.
What does unconditional love look like?
In a 2009 study of unconditional love, Mario Beauregard of the University of Montreal and colleagues had 17 participants look at pictures showing children and adults with intellectual disabilities. In another part of the study, the participants had to look at those same pictures but this time they had to generate feelings of unconditional love toward the images. Results showed significant brain activity in some of the brain's reward systems (also linked to passionate and mama-child love), along with the PAG implicated in maternal love.
Since higher-order cortical regions of the brain were implicated in love, the researchers point out in the journal article: "This reinforces the fact that love is more than a basic emotion. Love also involves cognition."
Ortigue's follow-up study, about the speed of love in the human brain, is expected to be released soon. Both findings could help scientists understand why we get so heartbroken after a breakup and possibly lead to ways of treating the resulting depression and emotional stress, Ortigue said.
In addition some of the same emotional-processing and reward networks found to be involved in love have also been shown to play a role in sexual responses. As such, the researchers say their findings may help advance research in sexual medicine and couple therapy.
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