The Arrows of Love
As expected, a variety of neurotransmitters are involved in the generation of this unique experience. In particular, waves of dopamine secreted by the hypothalamus flood the brain and recruit certain areas causing a feeling of euphoria and jubilation. At the same time, the neurotransmitter serotonin is depleted, causing the obsessive behavior often described in people who are in love. This association stems from the observation that patients with obsessive-compulsive disorder have similar low serotonin levels. Vasopressin, a hormone associated with aggressive behavior among males, and oxytocin, responsible for the contractions during labor, have also been shown to increase when in love [1]. The above changes have been documented specifically for “romantic” and “maternal” love, indicating a close relation between them and constituting a possible parallel to Freud’s Oedipus complex.
The Coordinates of Love
These hormones and neurotransmitters exert their activity in a plethora of specific brain areas, including the medial insula, anterior cingulate cortex, hippocampus, striatum, and hypothalamus. This activity can be roughly summarized as the activation of the subcortical dopaminergic reward-related system and the areas that it projects to. In a parallel manner, brain areas such as the frontal and prefrontal cortex, amygdala and temporal poles are deactivated [2].
The known functions of most of these areas are consistent with the description of the feelings we experience when in love. For example, the striatum is associated with rewarding feelings and is activated by dopamine - so are the insula and the anterior cingulate gyrus, responsible for mediating emotions and somatosensory integration. On the other hand, the frontal and prefrontal cortex where logical planning and decision making take place are deactivated, partly explaining the irrational behavior and lack of judgment seen in many people that are in love. The parietal cortex and parts of the temporal lobe, linked to negative feelings and depression, are also deactivated [2,3].
On the other hand, the role of the amygdala, a known regulator of fear, is not as simple. Vasopressin and oxytocin seem to exert opposite actions on the activity of the amygdala, increasing and decreasing it respectively, with the effects of the latter prevailing eventually and leading to an experienced lessening of fear [1]. The majority of the above evidence is provided by the results of fMRI studies in which the participants were shown a picture or the name of their beloved partner or of their child.
Are there indeed Different Forms of Love?
Although “romantic” and “maternal” love and sexual arousal share common features in brain activity, there are crucial differences that distinguish them. In the case of maternal love, there is a stronger activation of the brain areas responsible for face recognition, consistent with the need to recognize quickly one's child’s facial expressions and act accordingly. Another region that was found to be activated only in the case of “maternal” love is the periaqueductal gray matter, an area involved in endogenous pain suppression.
Moreover, activation of the same hypothalamic regions has been documented in the case of sexual arousal and “romantic” love, but not in the case of maternal love. In all forms of love, however, the activation of the subcortical dopaminergic reward-related brain system and the deactivation of cortical areas that lead to an impairment in judgment is similar and pronounced, indicating the common aspects they share [3].
The Functional Role of Love
As pragmatic and harsh as it may sound, from an evolutionary point of view, love serves very specific purposes and its intensity as an emotion is totally justifiable. The strong activation of the reward systems that strengthen the bonding between the couple, and between the mother and the child, ensures the unity of the family, increasing their survival chances in a demanding environment [3]. Even the irrational behavior that makes a man defend his partner if a threat is presented, and a mother thoughtlessly sacrifice herself in order to protect her children, could be interpreted in the same way.
Looking in the Mirror
Although we sometimes regard love as a feeling over which we have no control, fMRI studies suggest otherwise. Cortical areas, such as the angular gyrus, that control complex cognitive behaviors such as social cognition and self-perception are activated even when we are presented with implicit love stimuli, suggesting that love is also a cognitive process.
The mirror neuron system consists of neurons that are activated by the execution and the observation of object-related movements and normally participates in the perception of our surroundings and our actions. This system has been postulated to additionally mediate emotion recognition and social cognition. Located mainly in the insula and anterior cingulate gyrus, areas also activated during the experience of love, it has been suggested that mirror neurons facilitate the understanding of feelings and the prediction of the intentions of others, also providing feedback for the generation of our own feelings [4].
In other words, love is a mutual feeling that gives positive feedback to itself; we need to feel loved in order to feel love in return and vice versa! No matter how logically we try to approach love, using strict scientific terms, in the end love conquers all!
[1] de Boer et al, Neuroscience, 2012
[2] Ortigue, J Sex Med, 2010
[3] Zeki, FEBS Lett, 2007
[4] Ortigue, Med Hypotheses, 2008
By Andreas Antonios Diamantaras, Master's Student Medical Neurosciences
This article originally appeared June 2014 in Vol. 07 - Issue 2 "Neuroscience of Love".
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