Brain Activity Unique to Orgasm in Women: An fMRI Analysis

Abstract

Background: Although the literature on imaging of regional brain activity during sexual arousal in women and men is extensive and largely consistent, that on orgasm is relatively limited and variable, owing in part to the methodologic challenges posed by variability in latency to orgasm in participants and head movement.

Aim: To compare brain activity at orgasm (self- and partner-induced) with that at the onset of genital stimulation, immediately before the onset of orgasm, and immediately after the cessation of orgasm and to upgrade the methodology for obtaining and analyzing functional magnetic resonance imaging (fMRI) findings.

Methods: Using fMRI, we sampled equivalent time points across female participants' variable durations of stimulation and orgasm in response to self- and partner-induced clitoral stimulation. The first 20-second epoch of orgasm was contrasted with the 20-second epochs at the beginning of stimulation and immediately before and after orgasm. Separate analyses were conducted for whole-brain and brainstem regions of interest. For a finer-grained analysis of the peri-orgasm phase, we conducted a time-course analysis on regions of interest. Head movement was minimized to a mean less than 1.3 mm using a custom-fitted thermoplastic whole-head and neck brace stabilizer.

Outcomes: Ten women experienced orgasm elicited by self- and partner-induced genital stimulation in a Siemens 3-T Trio fMRI scanner.

Results: Brain activity gradually increased leading up to orgasm, peaked at orgasm, and then decreased. We found no evidence of deactivation of brain regions leading up to or during orgasm. The activated brain regions included sensory, motor, reward, frontal cortical, and brainstem regions (eg, nucleus accumbens, insula, anterior cingulate cortex, orbitofrontal cortex, operculum, right angular gyrus, paracentral lobule, cerebellum, hippocampus, amygdala, hypothalamus, ventral tegmental area, and dorsal raphe).

Clinical translation: Insight gained from the present findings could provide guidance toward a rational basis for treatment of orgasmic disorders, including anorgasmia.

Strengths and limitations: This is evidently the first fMRI study of orgasm elicited by self- and partner-induced genital stimulation in women. Methodologic solutions to the technical issues posed by excessive head movement and variable latencies to orgasm were successfully applied in the present study, enabling identification of brain regions involved in orgasm. Limitations include the small sample (N = 10), which combined self- and partner-induced stimulation datasets for analysis and which qualify the generalization of our conclusions.

Conclusion: Extensive cortical, subcortical, and brainstem regions reach peak levels of activity at orgasm. Wise NJ, Frangos E, Komisaruk BR. Brain Activity Unique to Orgasm in Women: An fMRI Analysis. J Sex Med 2017;14:1380-1391.

Keywords: Functional Magnetic Resonance Imaging; Human Female; Orgasm; Sexual Arousal; Sexual Behavior.

Figure 1

Regional activation at orgasm compared with early stimulation. Regional brain activity during the 20 seconds at the initiation of stimulation was subtracted from the 20 seconds of activity immediately after the button press indicating the start of orgasm (z = 2.3, P <.001). ant cing ctx = anterior cingulate cortex; hpc = hippocampus; n = nucleus; n acc = nucleus accumbens.

Figure 2

Regional activation at orgasm compared with recovery. Brain activity during the 20 seconds immediately after the button press indicating the end of orgasm was subtracted from the 20 seconds of activity starting at the onset of orgasm (orgasm > recovery; z = 2.3, P <.001). ctx = cortex; DMPFC = dorsal medial prefrontal cortex; OFC = orbital frontal cortex.

Figure 3

Regional activation “going over” to orgasm. Brain activity during the 20 seconds immediately before the button press indicating the onset of orgasm was subtracted from the 20 seconds of activity immediately after the button press (orgasm > late stimulation; z = 1.65, P < .01).

Figure 4

Lower brainstem regions activated during orgasm. Top panel shows orgasm > early stimulation (z = 1.5, P <.01). Bottom panel shows orgasm > late stimulation (z = 1.0, P < .01). n = nucleus; sn bilat = bilateral substantia nigra; stim = stimulation; vta = ventral tegmental area.

Figure 5

Composite view of the activity of selected brain regions in the 10 seconds immediately before and the 10 seconds immediately after the onset of orgasm. Note the gradual increase in overall activity leading up to orgasm, with variable patterns of increase after the onset of orgasm and some regions showing abrupt increases at orgasm onset (eg, accumbens; hypothalamus, paracentral lobule; N = 10). hypo = hypothalamus; paracentral = paracentral lobule; l_acc = left accumbens; l_amy = left amygdala; l_hip = left hippocampus; oplr = operculum (SII); r_acc = right accumbens; r_amy = right amygdala; r_hip = right hippocampus.