This paper examines the neurochemical and electrical processes in the brain that underlie sexual response and pleasure. Rather than being primarily a physical phenomenon, sexual experience is fundamentally driven by the limbic system and the release of key neurochemicals including dopamine, oxytocin, prolactin, opioids, and others. The paper traces the four phases of sexual response—excitement, plateau, orgasm, and resolution—and details how specific brain chemicals activate reward circuits, intensify sensation, facilitate bonding, and ultimately return the body to baseline. The analysis demonstrates that the brain, not the sexual organs, is the true seat of sexual pleasure and response.
The events that occur during sex and subsequent orgasm are strongly tied to the brain more than the organs themselves. In sexual encounters, individuals are often consumed with the interaction of sex organs to produce pleasurable sensations and eventual climax. However, the production of pleasure is not limited to what occurs at nerve endings in the organs. It includes the release of strong chemicals and the interaction of electrical impulses. Sex is more chemical and electrical than most people will imagine.
The limbic system regulates all the body's functions. Its dedicated purpose is to maintain life and encourage reproduction of creatures. This is accomplished through a simple pleasure-pain response system: pain is avoided and pleasure is rewarded. This is the foundation of the sexual experience. The sexual experience is divided into four phases: excitement, plateau, orgasmic, and resolution (EPOR).
In the excitement phase, the stimuli received by the individual creates arousal and increases sexual responsiveness. In the plateau phase, arousal becomes very intense, and continued stimulation will cause the individual to proceed toward the next phase of orgasm. If, however, the stimulation is lessened or inadequate, orgasm does not occur. During the orgasmic phase, there is a climax of the process, where seconds of excitement meld into expanding circles of pleasure. The final phase is the resolution phase, where the body essentially returns to normal. Hormone levels fall off, and in males, they may be unable to regain an erection for some time.
In the first phase of sexual response, the excitement phase, dopamine is released in large quantities. Dopamine activates the reward circuits in the brain (Robinson & Wilson, 2005). The reward circuits are the focal point of the limbic system and impel most of our behaviors. When the individual engages in pleasuring, the levels of dopamine increase in the body. Dopamine in turn stimulates the reward circuits in the limbic system, and the action is recognized as pleasurable. Further stimulation releases additional dopamine, which heightens the sensations and creates the desire to repeat the behavior. The individual is moved from the excitement phase into the plateau phase.
In the plateau phase, particularly in males, there is a release of a cocktail of neurological chemicals. Dopamine is pivotal to the process, but there is also nitric oxide, oxytocin, adrenocorticotrophin, and melanocyte-stimulating hormone, which add to the process by affecting penile muscle tone and facilitating the action of dopamine within the body (Coad, Dunstan, & McCandlish, 2010, p. 120). Together, these chemicals control and boost the sexual experience. It should be noted that while dopamine dominates the desire to have sex, it is another group of chemicals that govern enjoyment. Opioids are the brain's equivalent of morphine and endorphins. Dopamine may propel the behavior, but the opioids are necessary for experiencing orgasm.
During orgasm, opioids boost the reward circuit to add to the effect of dopamine. In the orgasmic phase, the body releases a surge of dopamine. However, after orgasm, dopamine levels fall precipitously, and individuals lose interest in sexual encounters for a time. As levels of dopamine fall, prolactin and oxytocin levels increase. Oxytocin levels increase for a short period after orgasm and produce the bonding effect (Allchin, 2011). Prolactin functions as a dopamine suppressor. It halts the action of dopamine and brings the body back to a normal level. This marks the beginning of the resolution phase.
Additionally, during the resolution phase, enkephalin levels become elevated in the brain and hypothalamus. These opioids are demonstrated to prevent the action of oxytocin; this limiting of oxytocin action may decrease the feelings of satisfaction. It should be noted that opioids produce different effects in variant sections of the brain. Where they produce pleasure in one section, they may have the reverse effect in another part of the brain (Zimmer, 2009). This is the basic manner in which the cycle occurs; however, each individual's experience is different.
The differences are contingent upon personal sensitivity to neurochemicals, the nature of the interaction between the partners, and other factors. Dopamine remains the major neurochemical that is responsible for the push toward sexual interaction. Bolstered by a cocktail of other chemicals, the physical is transformed into the chemical. Thus, the brain becomes the seat of sexual interaction and not the organs themselves. If the chemicals were absent, sex would not be pleasurable.
Allchin, D. (2011). The domesticated gene. The American Biology Teacher, 73(2), 120–123.
"Hormonal changes and neurochemical differences"
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