Sex and neurotransmitters: the science behind our orgasms

Sébastien Laymond delves deep into the neurological and biological intricacies of our sex lives

Orgasms are just one of the many indescribable sexual wonders that animals have the pleasure of experiencing. Granting us access to an elevated state of pleasure and euphoria, its effects are truly insatiable. The orgasm (as a phenomena) has been the subject of multiple articles and books, thus giving rise to a multiplicity of theoretical approaches to help further understand its origins and impact — scientific, cultural, and historical alike. Interestingly, this research (e.g., Hannah Frith, Orgasmic bodies: The orgasm in contemporary Western culture [Palgrave Macmillan 2015]) has shown that these different approaches can be amalgamated to form one harmonious whole.

 Broadly speaking, an orgasm can be generally defined as “a state motivated toward the experience of sexual pleasure” (Bancroft, 2005). However, beyond this definition, we can recognise that there are two main scientific points to realise in reaching an orgasm. Firstly, orgasms are generally associated with, amongst other things, changes in blood pressure and heart rate, effects that are both sex-contingent. Secondly, they mainly occur in four stages: excitement, plateau of arousal, orgasm, and resolution.

Like with every sensation felt by our species, living and experiencing the physical world around us is an intricate dance between the body and the brain; the two operate inseparably from each other. From here, we can decipher that orgasms are both an anatomical and neurological question that begs our curious assessment and deeper analysis. 

The brain

 Advances in neuroscience and its corresponding experimental technology have allowed scientists to discover neurological activity in over 30 discrete regions of the brain using Functional Magnetic Resonance Imaging (fMRI). Amongst the numerous wonders that they have unveiled lies the neurochemical procedure underpinning orgasms. Like a pot of chemical soup stirring around in the brain, neurohormones, neurotransmitters, and other hormones, that take effect downstream in the body, all play a major role in the brain’s story of sexual pleasure. A recent scan performed by researchers from Rutgers University on a relatively young adult woman in 2011 revealed that the brain releases prolactin, dopamine (the “feel-good” hormone), oxytocin (the “love/bonding” hormone), and other similar neuropeptides before, during, and after orgasm.

 Knowing this, more questions arise — why and how does this all happen?

 Admittedly, trying to understand why these neurochemicals are released upon orgasm could be seen as a rather fruitless exercise, given that the answer is contained within the very question: they are released precisely because of the “action” taking place. In a nutshell, if we look at the case of dopamine and oxytocin, we can see that it is the pleasure-filling activity that triggers the secretion of such neurochemicals. Dopamine is released when the brain’s rewarding area expects a corresponding reward. Alternatively, oxytocin arises in response to the activation of sensory nerves, this being a result of “loving” environmental stimuli.

 But how is it that they create the orgasmic feelings we all know and love? 

 Like all other actions, feelings, and movements of the body, orgasms and how they biologically occur can be broken down into what happens at the synapse. A synapse is a place either where two neurons meet or where a neuron meets a muscle or gland. You have an almost uncountable number of these in your body and they each play incredibly vital roles in your very being. What happens at the synapse, essentially, is that chemical substances are transferred from one nerve cell (neuron) to another via neurotransmitters. The way in which this occurs is a lot more complicated and detailed than one might initially think. 

In essence, they can be seen as “nano-messengers” that travel within synaptic vesicles (a bubble) fired by each neuron. When a neuron (for this example, we can call it “Neuron One”) meets its adjacent neuron (“Neuron Two”), they — in a rather metaphorical sense — “make love”, causing Neuron One to deposit the neurochemical contents of its synaptic vesicle across a synaptic cleft, which is then picked up and bound to receptors on Neuron Two. Upon crossing the cleft and binding to Neuron Two’s receptors, a nerve impulse is generated. The process is quick (≈ 0.5 ms per synapse) and catroptic. From Neuron One to Neuron 100, nerve impulses travel along a spiralling chain of neurons until it reaches the muscle or gland that it was destined for. Thus, to put it briefly, when an orgasmic feeling is neurochemically brought from Neuron One to Neuron Two and so forth, the feel-good message will have been sent.

 All the aforementioned pleasurable chemicals cited previously (prolactin, dopamine, oxytocin, etc) follow along the same neural pathway. It is when they reach their final destination that we experience an orgasm – irrespective of sex.

 Equally irrespective of sex, general brain activity during orgasm primarily impacts the later orbitofrontal cortex (controlling reasoning and rational evaluation), amygdala (processing emotions), and hippocampus (storing memories). Subsequent to the orgasm, these functions gradually decrease in activity. Consequently, the loss in activity induces a trance-like state of “euphoria” that we, as human beings, naturally crave. 

The body

 Interestingly, orgasms can manifest externally in different manners depending on the biological sex of the person (cf. the infamous “orgasm gap” theory) and the type of sex being had. There reportedly exists (give-or-take) 8 different types of orgasms. Those that have been statistically proven to be the most pleasurable are those that combine penetration with the stimulation of other body parts (e.g. the nipples, anus, clitoris, etc).

 This being said, people with penises and people with vaginas do orgasm in manifestly different ways. Indeed, for people with penises, during the build-up to orgasm, arousal will stimulate blood flow down to the genitals, which – besides fully engaging the nervous system and facilitating greater pleasure – will result in increased penis size. Upon reaching an utmost level of excitement, the urethra receives semen from the seminal vesicles and the vas deferens, which is then externalised through ejaculation. This is generally accompanied by rapid contractions of the anal sphincter, prostate gland, and penis muscles, causing three to ten seconds of intense pleasure. A refractory period will then ensue, preventing a second orgasm from occurring. After climax, the body will experience deep relaxation and a slowing heart rate.

 In people with vaginas, the orgasm manifests through clitoral retractions (i.e. the clitoris “disappears”) alongside contractions of the vaginal, uterus, pelvic, and anal muscles. These contractions are primarily a consequence of the production of oxytocin. Oxytocin serves as a mechanism to stimulate contractions within the uterine muscles, a function not only important for orgasm but also playing a crucial role in childbirth. The people may also ejaculate during orgasm, although the majority reportedly do not. Interestingly, those with vaginas do not experience a refractory period like those with penises do, thus allowing the possibility of consecutive orgasms in those with vaginas. 

“The feeling of an orgasm is quite indescribable and still leaves many unanswered scientific questions for researchers to dig their teeth into.”

Like a circus of bodily effects and emotions, orgasms can feel like the trapeze show of tremendous heights or the roaring lion jumping through rings of fire, all while maintaining the pristine coordination and biological cooperation required to reach a climax of happiness. 

Isn’t science so sexy?

Sébastien Laymond

Sébastien Laymond is the Editor of the 'SciTech' column for Trinity News, and is currently in his Junior Sophister Year reading law.