This section explains what libido is, the reason why we have (or experience) this libido, and it explains the key mechanisms behind libido. The term libido and sex drive are used interchangeably throughout Truelibido.
Sexual desire, or libido, is the urge we feel as we anticipate the pleasurable sensations experienced when having sex. Anticipation is the key word as sexual desire is wanting, craving and wishing for sex. Most complex species, including human beings, are endowed with this sexual desire or libido. But why do we experience this libido?
The role of libido is to motivate us to procreate – to create new life and thereby sustain the life of the species. It is there in order for us to pass on our genes and continue life. We have libido to drive us to have sex. Libido is experienced as a very strong urge for sex, and as a result, we have sex. This drive has developed and become amplified in us through millions of years. Those individuals who in the past had the strongest sex drive, probably had more offspring than other individuals. From an evolutionary perspective, anything that can increase the frequency of intercourse during the female fertile days improves the chance of conception. Therefore the trait of a strong libido has been selected and strengthened by evolution through the survival of the fittest (or horniest).
Libido is different from physical arousal in the genitals, as libido takes place before this physical arousal happens. It is manifested in the brain before there is a substantial increase in blood flow to the penis.
Desire for sex is normally set off by some sort of stimulation. This can be a visual observation, it can be a touch or other sensory stimulation, it could stem from a thought, it could be a fantasy, etc. A person can also have an overall high degree of sex drive without there needing to be a particular stimulation present.
People normally differ in the degree of their sex drive. There is no single standard of sexual desire or libido, and desire differs not only from person to person but also in the same person over one’s life span. It can also vary hugely from one day to the next. There are a multitude of factors that impact and determine the strength of a person’s libido such as what a person eats and drinks, how well and how much that person sleeps, the stress levels that individual experiences, level of exercise, and a variety of other factors. In addition, libido can be influenced by particular personal experiences, psychological factors, culture, norms of society, religion, etc.
Libido is also considered one of the key indicators of general health and quality of life. A person in overall good health will normally have a normal libido. When libido is reduced or non-existent, this can often be an indication of impaired health. Libido is also generally considered to be a positive factor in most people’s lives, and people with no or little libido will often see this as something reducing overall quality of life.
The Mechanisms Behind Libido
Although one may think everything related to sexual desire happens between the legs, the experience of this desire actually occurs in the brain. All thoughts, feelings, and bodily sensations correlate with specific nerve cells being activated in the brain. Libido, like all experiences, is brought about by electric impulses flowing along paths of connected nerve cells between our ears.
Sexual desire or libido is the culmination of several different neural mechanisms in the brain. Each of these is controlled in different areas of the brain and is activated at different times of the experience. The initial urge for sex as well as the euphoric and pleasurable experience of sex itself stems primarily from the limbic system, which encompasses various parts of the brain such as the amygdala, hippocampus and limbic lobe. This area is common to all mammals and is considered one of the oldest areas of the brain. It regulates emotion, motivation, pleasure, reward as well as other functions.
When a potentially sexually rewarding sensory input is detected in the brain (for instance a sensual touch), nerve cells in one part of the limbic system send signals to another part of the limbic system where motivation, urge and craving are generated. The most dominant of these signals are the neurotransmitter dopamine as well as a neurotransmitter called glutamate. The individual will then experience a desire to engage in sexual behaviour. To learn more about dopamine on Truelibido, please go here.
Dopamine is one of the key ingredients in libido and is the agent that will normally cause the heart rate to increase when a male experiences desire for sex. Some people may also experience a blood pressure increase, breathing becoming more rapid, cheeks that flush or palms becoming sweaty. Additionally, this release of dopamine will often make a male experience minor relaxation and contraction of penile muscles and tissue and an associated small change in bloodflow to the penis.
In order for dopamine to be released (or synthesized), there needs to be a certain level of testosterone present, because testosterone is needed for dopamine release. Put differently, testosterone facilitates the release of dopamine, or provides an environment in which dopamine release can occur. Testosterone also needs to be present in order for nitric oxide to be released, and nitric oxide also participates in the release of dopamine (nitric oxide is needed in order to get an erection). Therefore testosterone is not only a key component in the process, but adequate levels of testosterone are paramount for proper functioning of libido as well as proper erectile functioning. To learn more about testosterone on Truelibido, please go here, and to learn more about nitric oxide on Truelibido, please go here.
Without some degree of libido it is difficult, if not impossible, to achieve an erection and therefore to engage in sex. If a person is not interested in sex or does not have an urge for sex, an erection will normally not take place. Libido and erectile dysfunction are also linked because they have many of the same drivers and depend on many of the same agents and processes. A lack of libido therefore often correlates with erectile dysfunction. To learn more about erectile dysfunction on Truelibido, please go here, and to learn more about penile erection on Truelibido, please go here.
Bancroft J. The endocrinology of sexual arousal. J Endocrinol. 2005 Sep;186(3):411-27.
Brunetti M, Babiloni C, Ferretti A, Del Gratta C, Merla A, Olivetti Belardinelli M, Romani GL. Hypothalamus, sexual arousal and psychosexual identity in human males: a functional magnetic resonance imaging study. Eur J Neurosci. 2008 Jun;27(11):2922-7. DOI: 10.1111/j.1460-9568.2008.06241.
Dominguez J, Riolo JV, Xu Z, Hull EM. Regulation by the medial amygdala of copulation and medial preoptic dopamine release. Journal of Neuroscience. 2001;21:349–355.
Dominguez JM, Hull EM. Stimulation of the medial amygdala enhances medial preoptic dopamine release: implications for male rat sexual behavior. Brain Research. 2001;917:225–229.
Dominguez JM, Muschamp JW, Schmich JM, Hull EM. Nitric oxide mediates glutamate-evoked dopamine release in the medial preoptic area. Neurosci 2004; 125: 203-210.
Du J, Lorrain DS, Hull EM. Castration decreases extracellular, but increases intracellular, dopamine in medial preoptic area of male rats. Brain Research. 1998;782:11–17.
Everitt BJ. Sexual motivation: a neural and behavioural analysis of the mechanisms underlying appetitive and copulatory responses of male rats. Neurosci Biobehav Rev 1990; 14: 217-232.
Gray PB, Garcia JR. Evolution & Human Sexual Behaviour, Harvard University Press, 2013.
Halaris A. Neurochemical aspects of the sexual response cycle. CNS Spectr. 2003 Mar;8(3):211-6.
Hansen S. Hypothalamic control of motivation: the medial preoptic area and masculine sexual behavior. In Sodersten P, editor. Behavioral neuroscience in Scandinavia. Scandinavian Journal of Psychology 1982; Suppl 1: 121-126.
Hull EM, Du J, Lorrain DS, Matuszewich L. Extracellular dopamine in the medial preoptic area: implications for sexual motivation and hormonal control of copulation. Journal of Neuroscience. 1995;15:7465–7471.
Karama S, Lecours AR, Leroux JM, Bourgouin P, Beaudoin G, Joubert S, Beauregard M. Areas of brain activation in males and females during viewing of erotic film clips. Hum Brain Mapp 2002, 16:1–13.
Krüger TH, Hartmann U, Schedlowski M. Prolactinergic and dopaminergic mechanisms underlying sexual arousal and orgasm in humans. World J Urol. 2005 Jun;23(2):130-8.
McKenna K: Central nervous system pathways involved in the control of penile erection. Annu Rev Sex Behav 1999, 10:157–183.
Meisel RL, Sachs BD: The physiology of male sexual behavior. In The Physiology of Reproduction, Second Edition. Edited by Knobil E, Neill JD. New York: Raven Press; 1994:3–105.
Motofei IG, Rowland DL. The physiological basis of human sexual arousal: neuroendocrine sexual asymmetry. Int J Androl. 2005 Apr;28(2):78-87.
Mouras H, Stoléru S, Bittoun J, Glutron D, Pélégrini-Issac M, Paradis AL, Burnod Y. Brain processing of visual sexual stimuli in healthy men: a functional magnetic resonance imaging study. Neuroimage. 2003 Oct;20(2):855-69.
Pfaus JG, Scepkowski LA. The biologic basis for libido. Current Sexual Health Reports 12/2005; 2(2):95-100. DOI: 10.1007/s11930-005-0010-2.
Pfaus JG. Pathways of sexual desire. J Sex Med. 2009 Jun;6(6):1506-33. DOI: 10.1111/j.1743-6109.2009.01309.
Rowland DL. Neurobiology of sexual response in men and women. CNS Spectr. 2006 Aug;11(8 Suppl 9):6-12.
Stahl SM. The psychopharmacology of sex, Part 1: Neurotransmitters and the 3 phases of the human sexual response. J Clin Psychiatry. 2001 Feb;62(2):80-1.
Suck Won Kim, Carlos H. Schenck, Jon E. Grant, Gihyun Yoon, Peter I. Dosa, Brian L. Odlaug, Liana R.N. Schreiber, Thomas D. Hurwitz, James G. Pfausll. Neurobiology of Sexual Desire. NeuroQuantology, June 2013, Volume 11, Issue 2, Pages 332-359.