The Neurophysiology of Orgasm

Abstract

Despite decades of research, the neurophysiology of orgasm remains unknown. Animal models with the urethrogenital reflex in rats and facial expressions of orgasm in macaques have provided remarkable contributions, but the models can only explain a part of the overall perceptual experience of orgasm in humans. Human studies on the other hand have mostly focused on subjective reports, and while a few instruments have been developed (but seldom used), the distinction between orgasm and intense sexual pleasure has not always been demonstrated. Recent advances in functional imagery have further contributed to our understanding of orgasm, but a final comprehensive model bringing together all the findings and explaining the neurophysiology of orgasm is still lacking. This paper reviews the literature on orgasm, from animal studies to human data, including those from men and women with spinal cord lesions who offer a natural experimental model to study climax. The data lead us to propose a model of orgasm as a non-pathological analog of autonomic hyperreflexia (AHR), involving a sympathetic storm arising from genital stimulation and triggering genital, autonomic, and muscular responses that are normally submitted to immediate and massive supraspinal inhibition (thereby leaving only the pleasurable experience of orgasm). The model is consistent with the physiological recordings of orgasm in men and women, the neurophysiology of ejaculation in men, and data from functional imagery and from clinical conditions involving unexplained reports of orgasm, in particular from prostatectomized men, prepuberal boys, women in labor, women who suffered sexual abuse, and individuals complaining of orgasmic cephalgia.