Positron emission tomography studies of orgasm show no single centre lighting up. In 12 healthy women, orgasm was mainly linked to profound decreases in neocortical blood flow, particularly in the left lateral orbitofrontal cortex, inferior temporal gyrus and anterior temporal pole, while blood flow in the left deep cerebellar nuclei correlated with rectal pressure variability (Georgiadis 2006). In men, ejaculation produced primary activation in the mesodiencephalic transition zone including the ventral tegmental area and remarkably strong increases in the cerebellum (Holstege 2003). The 2 patterns overlap in the cerebellum and in reduced orbitofrontal blood flow.
The evidence comes from 5 PET studies of small samples: 12 women in Georgiadis 2006, 11 women and 11 men in the Huynh 2013 pituitary study, and merged datasets in Georgiadis 2009. All used [15O]-H2O to measure regional cerebral blood flow, an indirect indicator of neural activity, in heterosexual volunteers who lay in a scanner while a partner stimulated them manually. This text will not claim to explain subjective pleasure, and it treats hormone changes as assumptions in the 11 women and 11 men of the pituitary study rather than measured events.
How is the brain imaged during orgasm, and what does it measure?
These studies use positron emission tomography with [15O]-H2O to track regional cerebral blood flow, an indirect indicator of neural activity rather than a measure of neurotransmitters. A typical design compares nonsexual rest, genital stimulation without orgasm, attempted or imitated orgasm as controls, and orgasm itself, with a partner performing manual stimulation while participants lie in the scanner.
A woman’s shadow in warm light; orgasm in the brain is not explained by a single centre. — Photo: Mrt Ziolko / Pexels
Sample sizes are small. Georgiadis 2006 scanned 12 healthy women across 4 conditions; the Huynh 2013 pituitary study examined 11 women and 11 men. Participants were heterosexual volunteers, stimulation was manual and delivered by a partner, and the setting was a laboratory scanner. Popular claims that the whole brain lights up, that the hippocampus and amygdala activate, or that a hormone surge is visible need checking against these data, because the small samples scanned in these PET studies of regional cerebral blood flow show a different pattern.
What pattern does the female brain show during orgasm?
In 12 women, clitoral stimulation raised blood flow in the left secondary and right dorsal primary somatosensory cortex (Georgiadis 2006). Orgasm itself, by contrast, was mainly associated with profound decreases in neocortical blood flow, particularly in the left lateral orbitofrontal cortex, the inferior temporal gyrus and the anterior temporal pole.
Blood flow in the left deep cerebellar nuclei correlated with rectal pressure variability, an extracerebral marker of orgasm contractions, and flow in the ventral midbrain and right caudate nucleus correlated with perceived sexual arousal. The authors proposed that reduced left lateral orbitofrontal flow signifies behavioural disinhibition, that the deep cerebellar nuclei relate to orgasm-specific muscle contractions, and that ventral midbrain and caudate involvement points to a role for dopamine. These are interpretations of the pattern seen in 12 women, not direct measurements of inhibition or dopamine.
In the pituitary study, orgasm compared with rest increased blood supply to the pituitary gland in 11 women, while clitoral stimulation, orgasm attempt and faked orgasm showed no such increase. The authors assume this activation serves to produce higher plasma oxytocin and prolactin, but hormone concentrations were not measured in these 11 women.
What happens in the male brain during ejaculation, and how does it differ from women?
During ejaculation in men, PET shows primary activation in the mesodiencephalic transition zone including the ventral tegmental area, remarkably strong increases in the cerebellum, and neocortical activity only in right-sided areas, while amygdala activity decreased rather than increased (Holstege 2003).
Merged datasets show that commonalities between women and men were most evident during orgasm: activation in the anterior lobe of the cerebellar vermis and deep cerebellar nuclei, plus deactivation in the left ventromedial and orbitofrontal cortex. Gender differences were marked during tactile genital stimulation, with left fronto-parietal areas activating more in women and the right claustrum and ventral occipitotemporal cortex more in men. The only prominent difference during orgasm was male-biased activation of the periaqueductal gray matter; the authors concluded that differential responses relate principally to the stimulatory phase rather than the orgasmic phase.
Which brainstem areas drive the contractions of the pelvic floor?
A localized region in the left dorsolateral pontine tegmentum and another in the right ventrolateral pontine tegmentum were active during ejaculation in men and orgasm in women. The authors named the dorsolateral region the pelvic organ-stimulating center and the ventrolateral region the pelvic floor-stimulating center, which produces pelvic floor contractions through direct projections to pelvic floor motoneurons (Huynh 2013).
In clinical sex therapy, specialists sometimes see that the idea of the whole brain lighting up at the peak draws people into monitoring themselves during sex, and that this self-monitoring makes letting go harder.
[More research needed: these studies measured regional cerebral blood flow and did not directly measure the role of neurotransmitters such as dopamine and serotonin.]
The editorial position of the Behckam.com site is that brain imaging only shows what happened under laboratory conditions and is not a yardstick for judging any individual experience as right or wrong.
No single center of orgasm appears. In 12 women, orgasm mainly lowered neocortical blood flow, especially in the left lateral orbitofrontal cortex, while cerebellar and ventral midbrain flow correlated with contractions and perceived arousal; in men, ejaculation activated the cerebellum.
Does part of the brain switch off during orgasm?
Partly. In 12 women, orgasm was associated with profound reductions in neocortical blood flow, particularly in the left lateral orbitofrontal cortex, which the authors interpreted as behavioural disinhibition (Georgiadis 2006); in men, amygdala activity decreased. Nothing is literally switched off during orgasm.
Is the brain response to orgasm the same in women and men?
Mostly. Cerebellar activation and left ventromedial and orbitofrontal deactivation appeared in both genders, and the only prominent orgasm-phase difference was male-biased periaqueductal gray activation. Pituitary blood supply rose in 11 women and not in 11 men (Huynh 2013).
Are oxytocin and dopamine released during orgasm?
Not directly shown. The authors assume pituitary activation in 11 women reflects oxytocin and prolactin output; no such activation appeared in 11 men. Ventral tegmental activation in men suggests dopamine-related circuits as a proposal only, because these studies measured blood flow, not neurotransmitters.
What the imaging evidence clarifies and what it does not
The 5 PET datasets clarify that orgasm in 12 women and ejaculation in men involve cerebellar activation, reduced left orbitofrontal and ventromedial blood flow, and brainstem regions linked to pelvic contractions, rather than a whole-brain event. They do not measure neurotransmitters, hormone concentrations, subjective pleasure or people outside these small heterosexual volunteer samples. What remains hopeful is that replication with larger and more varied samples could test whether these blood-flow patterns hold.
Looking for professional support with your relationship or mental health?
Georgiadis JR, Kortekaas R, Kuipers R, Nieuwenburg A, Pruim J, Reinders AA, et al. Regional cerebral blood flow changes associated with clitorally induced orgasm in healthy women. Eur J Neurosci. 2006;24(11):3305-16. PMID: 17156391. DOI: 10.1111/j.1460-9568.2006.05206.x
Holstege G, Georgiadis JR, Paans AM, Meiners LC, van der Graaf FH, Reinders AA. Brain activation during human male ejaculation. J Neurosci. 2003;23(27):9185-93. PMID: 14534252. DOI: 10.1523/JNEUROSCI.23-27-09185.2003
Georgiadis JR, Reinders AA, Paans AM, Renken R, Kortekaas R. Men versus women on sexual brain function: prominent differences during tactile genital stimulation, but not during orgasm. Hum Brain Mapp. 2009;30(10):3089-101. PMID: 19219848. DOI: 10.1002/hbm.20733
Huynh HK, Willemsen AT, Lovick TA, Holstege G. Pontine control of ejaculation and female orgasm. J Sex Med. 2013;10(12):3038-48. PMID: 23981195. DOI: 10.1111/jsm.12300
Huynh HK, Willemsen AT, Holstege G. Female orgasm but not male ejaculation activates the pituitary. A PET-neuro-imaging study. Neuroimage. 2013;76:178-82. PMID: 23523775. DOI: 10.1016/j.neuroimage.2013.03.012
Image credits: The featured image was generated with artificial intelligence. First image: Photo: Mrt Ziolko / Pexels
