Neurobiology of love: the theory of the 3 cerebral systems
Love is one of the most complex phenomena that human beings are capable of feeling. This peculiar feeling has caused people to ask us how and why it happens. Science has also dealt with this phenomenon, and one of the best-known researchers in this line of research is Helen Fisher , a biologist and anthropologist who has spent more than 30 years trying to understand it.
The investigation of Helen Fisher
To try to explain this very complex feeling, Fisher focused on trying to figure out the brain mechanisms that are involved in the process of falling in love and love . For this, he subjected several subjects who were madly in love with IMRF scanners, to know the areas of the brain that are activated when the subject thinks about his beloved.
"Loving" and neutral photos
To perform the tests, Helen asked the study participants to bring two photographs: one of the beloved and another that did not have any special meaning, that is, a neutral face . Then, once the person was introduced into the brain scanner, the photograph 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.
Then the individuals were asked to observe a random number, and then they had to subtract it from seven in seven, to then look at the neutral photograph where they would perform a scan again. This was repeated several times to obtain a significant number of images of the brain and thus ensure the consistency of what was obtained while looking at both photographs.
The results of the investigation
There were many parts of the brain that were activated in the lovers who integrated the experiment. However, it seems that there are two regions that have a special importance in the sublime experience of being in love.
Perhaps the most important discovery was the activity of caudate nucleus . It is an extensive region, in the form of "C", which is very close to the center of our brain. It is primitive; It is part of what is known as the brain of reptiles, because this region evolved long before the proliferation of mammals, about sixty-five million years ago. The scans showed that there were parts of the body and tail of the caudate nucleus that became especially active when a lover looked at the picture of his lover.
The reward system of the brain is important in infatuation
Scientists have known for a long time that this brain region directs body movement. But until recently they have not discovered that this huge engine is part of the brain's "reward system" , the mental network that controls sexual arousal, the sensations of pleasure and the motivation to get rewards. And what is the neurotransmitter that is released during the activation of the caudate nucleus? Dopamine, a substance very involved in motivation, that is, helps us detect and perceive a reward, discriminate between several and wait for one of them. Generate the motivation to get a reward and plan the specific movements to get it. 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 the areas of the septum and the ventral tegmental area (AVT). This last 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 happens, the attention narrows, the person seems to have more energy, and You may experience feelings of euphoria and even mania .
The conception of love from this investigation
From her study, Helen Fisher radically changed the way of thinking about love. It used to be that love involved a range of different emotions ranging from euphoria to despair. After this study, It is concluded that love is a powerful motivation system, a basic impulse of pairing . But, why is it an impulse and not an emotion (or a range of emotions)?
- It is difficult for passion to disappear like any other impulse (hunger, thirst, etc), plus it is complicated to control. Unlike the emotions that come and go.
- Romantic love focuses on obtaining the reward of a specific reward: the loved one. On the contrary, emotions are linked to an infinity of objects, such as fear, which is associated with darkness or being assaulted.
- There is no differentiated facial expression for romantic love , different from the basic emotions. All basic emotions have an expression on the face that is specific only during the outbreak of that emotion.
- Last but not least, romantic love is a necessity, a craving , an impulse to be with the beloved.
The chemical waterfall of love
Everything I have described is related to what would be romantic love (or falling in love), what is felt in the first moments when we are obsessed by the loved one. For Helen Fisher, romantic love evolved in the brain to direct all our attention and motivation on a specific person. But this does not end here. To make love more complex, this brain system that generates a force as intense as romantic love it is also intrinsically related to two other basic impulses for mating : the sexual impulse (wish) and the need to establish deep ties with the couple (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 impulse are androgens, composed of estrogen, although testosterone is the most involved in this function, both in men and women. The areas that are activated in the brain when there is a sexual impulse 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 treat it, it is related to focusing the attention on one individual at a time, in such a way that time and energy are saved 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.
The attachment and its relationship with oxytocin and vasopressin
And finally, as the couple narrows the bond and deepens their relationship, Attachment arises, a system whose function is to allow two individuals to tolerate each other , at least enough time to achieve the upbringing of children during childhood. It has a close relationship with the decrease in dopamine and norepinephrine, which leads to a considerable increase in two hormones that allow such a function: oxytocin and vasopressin. The neuronal 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. The desire evolved to allow sexual reproduction with almost any more or less suitable pair. Romantic love allowed individuals to focus on only one partner at a time, in such a way that considerable time and energy was saved for courtship. And the attachment resulted in men and women being together long enough for the upbringing of a child during childhood.
The heart is in the brain
Independently of the fact that in general such systems appear in the way they have been explained (sexual desire, romantic love and finally attachment), it does not always occur in this order. Some friendships (attachment) over the years awaken a deep love that can lead to love or a friendship ruined by a broken heart. Even, it is possible to feel sexual attraction for one person, romantic love for another and a deep attachment for another . This theory that opens a question when trying to explain a behavior as interesting as little loved in a relationship, infidelity.
In short, it is interesting that we come to understand how a mass of so small of only 1.3 kg, ie 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.
Bibliographic references:
- Fisher, H. (2004). Why we love: Nature and Chemistry of Romantic Love. Santa Fe e Bogotá: Taurus Thought
- Fisher, H. (1994) Anatomy of Love: Natural History of Monogamy, Adultery and Divorce. Barcelona: Anagram
- Fisher, H. [TED]. (2007, January 16). Helen Fisher talks to us about why we love and cheat [Video file]. Recovered from //www.youtube.com/watch?v=x-ewvCNguug
- Pfaff, D. (1999), DRIVE: Neurobiological and Molecular Mechanisms of Sexual Motivation, Cambridge, Mass .: The MIT Press.
