Neurobiology of love: the theory of the 3 brain systems

How does our brain react when we fall in love?

Love is one of the most complex phenomena we humans are capable of feeling. This peculiar feeling has led people to wonder how and why it happens. Science has also dealt with this phenomenon, and one of the best-known researchers in the field of love is one of the best known researchers in this line of research is Helen Fisher, a biologist and anthropologist.a biologist and anthropologist who has spent more than 30 years trying to understand it.

Helen Fisher's research

To try to explain this complex feeling, Fisher focused on trying to understand the brain mechanisms involved in the process of falling in love and love.. To do this, she subjected several subjects who were madly in love to IMRf scans, to find out which areas of the brain are activated when the subject thinks about his or her loved one.

"Loving" and neutral photographs.

To conduct the tests, Helen asked the study participants to bring two photographs: one of the loved one and one that had no special meaning, i.e., a neutral face.. Then, once the person was introduced into the brain scanner, the picture of the loved one was first shown on the screen for a few seconds while the scanner recorded the Blood flow in different regions of the brain.

The individuals were then asked to look at a random number, then subtract it by seven, and then look at the neutral photograph where they would be scanned again. This was repeated several times to obtain a significant number of brain images to ensure consistency in what was obtained while looking at both photographs.

The results of the research

Many parts of the brain were activated in the lovers who participated in the experiment. However, it seems that there are two regions that are particularly important in the sublime experience of being in love.

Perhaps the most important finding was the activity of the caudate nucleus. This is a large, C-shaped region that lies very close to the center of our brain. It is primitive; it is part of what is known as the reptilian brain, because this region evolved long before the proliferation of mammals, some sixty-five million years ago. The scans showed that there were parts of the body and tail parts of the caudate nucleus that became especially active when a lover looked at a picture of his or her crush.

Brain reward system is important in falling in love

Scientists have long known that this brain region directs body movement. But it was only recently that they discovered that This huge motor is part of the brain's "reward system", the mental network that controls sexual arousal, feelings of pleasure and motivation to achieve rewards.And what is the neurotransmitter that is released during activation of the caudate nucleus? Dopamine, a substance heavily involved in motivation, i.e., it helps us to detect and perceive a reward, discriminate between several and expect one of them. It generates the motivation to get a reward and plans the specific movements to get it. The caudate is also associated with the act of paying attention and learning.

In this study, activity was also found in other regions of the reward system, including areas of the septum and ventral tegmental area (VTA). The latter region is also associated with the release of an enormous amount of dopamine and norepinephrine, which is distributed throughout the brain, including the caudate nucleus. When this occurs, attention narrows, the person appears to have more energy, and may experience feelings of euphoria and even mania..

The conception of love from this research

From her study, Helen Fisher radically changed the way we think about love. Previously, love was seen as involving a range of different emotions from euphoria to despair. Following this study, the conclusion was reached that love is a powerful motivational system, a basic drive for matching.. But why is it a drive and not an emotion (or a range of emotions)?

• It is difficult for passion to disappear like any other impulse (hunger, thirst, etc.). (hunger, thirst, etc), plus it is complicated to control. Unlike emotions that come and go.

• Romantic love focuses on obtaining the gratification of a specific reward: the loved one. In contrast, emotions are linked to an infinite number of objects, such as fear, which is associated with darkness or being assaulted.

• There is no differentiated facial expression for romantic love, as distinct from the basic emotions.There is no distinct facial expression for romantic love, as opposed to basic emotions. All basic emotions have a facial expression that is specific only during the onset of that emotion.

• Last but not least, romantic love is a need, a craving, an impulse to be with one's partner.an impulse to be with the loved one.

The chemical cascade of love

Everything I have described is related to what would be romantic love (or infatuation), that which is felt in the first moments when we become obsessed with the loved one. For Helen Fisher, romantic love evolved in the brain to focus all our attention and motivation on a specific person. But it doesn't end here. To make love even more complex, this brain system that generates a force as intense as romantic love is also intrinsically related to two other basic mating drivesThe sexual drive (desire) and the need to establish deep bonds with a partner (attachment).

Sexual desire is what allows an individual to perpetuate the species through reproduction with an individual of the opposite sex. The hormones involved in this drive are androgens, composed of estrogen, although it is mainly testosterone that is most involved in this function, both in men and women. The areas that are activated in the brain when there is sexual drive are: the anterior cingulate cortex, other subcortical regions, and the hypothalamus (involved in the release of testosterone).

In the case of romantic love, as we discussed, it is related to focusing attention on one individual at a time, thus saving time and energy for courtship. The neurotransmitter par excellence is dopamine, although it is accompanied by norepinephrine and a decrease in serotonin. The areas that are functional to this system are: mainly the caudate nucleus and in turn the ventral tegmental area, the insula, the anterior cingulate cortex and the hippocampus.

Attachment and its relationship with oxytocin and vasopressin

And finally, as the couple becomes closer and their relationship deepens, attachment, a system whose function is to allow two individuals to tolerate each other, emerges.It has a close relationship with a decrease in dopamine and norepinephrine, which leads to a considerable increase in two hormones that allow such a function: oxytocin and vasopressin. It has a close relationship with the decrease of dopamine and norepinephrine, which leads to a considerable increase of two hormones that allow such a function: oxytocin and vasopressin. The neural circuits that produce such neurotransmitters are the hypothalamus and the gonads.

Each of these three brain systems evolved to fulfill a specific function for mating. Desire evolved to allow sexual reproduction with almost any more or less suitable mate. Romantic love allowed individuals to focus on only one partner at a time, thereby saving considerable time and energy for courtship. And attachment resulted in men and women being together long enough for the rearing of a child during infancy.

The heart is in the brain

Regardless of the fact that in general such systems appear in the way they have been explained (sexual desire, romantic love and finally attachment), they do not always occur in this order. Some friendships (attachment) over the years awaken a deep love that can lead to love or to a friendship ruined by a broken heart. Even, it is possible to feel sexual attraction for one person, romantic love for another, and deep attachment for a different person.. This theory opens a question mark when trying to explain a behavior as interesting as unloved in a relationship, infidelity.

In short, it is interesting that we come closer to understanding how such a small mass of only 1.3 kg, i.e. the brain, can generate something as complex as love, an impulse so strong as to be the subject of so many songs, novels, poems, stories and legends.

Bibliographical references:

• Fisher, H. (2004). Why We Love: Nature and Chemistry of Romantic Love. Santa Fe e Bogotá: Taurus Pensamiento
• Fisher, H. (1994) Anatomía Del Amor: Historia Natural De La Monogamia, El Adulterio y El Divorcio. Barcelona: Anagrama
• Fisher, H. [TED]. (2007, January 16). Helen Fisher talks about why we love and cheat [Video file]. Retrieved from https://www.youtube.com/watch?v=x-ewvCNguug
• Pfaff, D. (1999), DRIVE: Neurobiological and Molecular Mechanisms of Sexual Motivation, Cambridge, Mass.: The MIT Press.