Brain, sexual desire and love

BrainHeartLove and sexual desire are two of the most intense human emotional experiences. These two emotional experiences are strictly related and highly rewarding. Love is a state of intense interest and affection for another person while the sexual desire corresponds to a more impellent behavior finalized to the union with the other person as per the response to sexual thoughts and fantasies or to sexual stimulation (of course this can be triggered by loving someone). Love and sexual desire belong necessarily to the same affective dimension but they are not exactly superposed.  Some disassociation can intervene in specific contexts. It seems clear that sexual desire could have some short-term pleasurable goal in comparison to the longer-lasting emotional state of love could be. The best experience is undoubtedly fulfilling both emotional experiences (love and sexual desire) at the same time.
Where are love and sexual desire in the brain? How does it work, neurologically speaking?
Data of several fMRI, EEG and PET-studies on normal subjects converge in indicating that love and sexual desire share the same neurotransmitters, the same neural circuitries and patterns of neural activation.
The neural network of sexual desire and love is quite similar and include many areas of the extended limbic lobe but also brain centers, which are central for vegetative regulation, physical perception and, more of all, empathy.
Finally a great part of the brain (if not the whole) is activated by these two emotional experiences. The fact that both love and sexual desire are both dependent on the dopaminergic brain region involved in rewarding behaviors explains well why love and sexual desire share similar feelings with the experience of being intoxicated of cocaine or any other ecstatic drug.
An interesting retrospective review of functional studies on the subject (Cacioppo et al J Sex med 2012,9(4), 1048-54) showed that, despite a common functional neural network,  the posterior part of the left insula was activated significantly by feelings of sexual desire while feelings of love are activating more significantly the anterior parts of the insula.
The insula is a brain region of the extended limbic lobe. This region is pivotal in regulating vegetative functions important physical and emotional experiences (including also pain and empathy).
The authors tried to explain this incredible different activation of two distinct regions of the insula respectively by sexual desire (the posterior parts) and love (the anterior ones), by the patterns of different connections of these regions.
The anterior region of the insula, the one more activated by love feelings, connects with the frontal lobe circuitries, the tegmental ventral areas, and other dopaminergic-rich regions involved in motivation and rewarding (probably concerning more flexible behaviors and long-term hedonistic goals). Conversely, the posterior insular regions (the one more activated by sexual desire), although it connects with the same regions of reward than the anterior part of the insula,  it connects also with parts of the brain involved in motor-sensory experiences and regulation of body habits, probably related to short-term physical and more rigid pleasurable goals.
I would not discuss right now, whether the activation of the insular regions (or its functional anterior-posterior gradient for love or sexual stimulation) works differently for women and man. It would be interesting to learn something more with patients who have insular dysfunction, malformations or epileptic crisis originating from those areas. Love and sexuality are poorly explored in neurology.

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