Nicoletta Cera PhD, Ezio D. Di Pierro MD, Gianna Sepede MD, PhD, Francesco Gambi MD, PhD, Mauro Gianni Perrucci PhD, Arcangelo Merla PhD, Armando Tartaro MD, PhD, Cosimo Del Gratta PhD, Giuseppe Galatioto Paradiso MD, Carlo Vicentini MD, Gian Luca Romani PhD, Antonio Ferretti PhD
ONLINE April 17, 2012 – The Journal of Sexual Medicine Volume 9, Issue 6, pages 1602–1612, June 2012
While many neuroimaging studies have shed light on the brain correlates of male sexual behavior, few have looked at brain activity when men’s sexual arousal is inhibited, particularly in the case of psychogenic erectile dysfunction (ED). The current study aimed to investigate the dynamic role of brain areas related to sexual activity and inhibition by using functional magnetic resonance imaging (fMRI) and penile tumescence (PT) in men with psychogenic ED and men with no erectile difficulties.
Researchers wanted to know whether differences in penile response to visual sexual stimuli correlated to differences in brain activity between men with psychogenic ED and healthy men.
Materials and Methods
Thirty-six men participated in the study. The patient group consisted of 17 right-handed heterosexual men with psychogenic ED. Their mean age was 34.3. Their diagnosis of psychogenic ED meant that their ED was not caused by vasculogenic, neurogenic, hormonal, anatomical, or drug-induced issues.
The control group consisted of 19 healthy right-handed heterosexual men with a mean age of 33.6.
None of the participants had hormonal or metabolic disease.
Each group completed the International Index of Erectile Function, the Sexual Arousal Inventory and Symptom Check List 90-R, the State-Trait Anxiety Inventory, and the Behavioral Inhibition/Behavioral Activation Scale.
The men were shown three types of film clips: 6 erotic clips (consensual sexual activity between a man and woman involving petting, oral sex, and vaginal intercourse), 6 dance clips (a classical duet featuring a male and a female dancer with no sexual contact), and 15 naturalistic/neutral clips (landscapes).
While viewing the clips, the men pressed a button to signify the beginning of sexual arousal. After each clip, the men used a seven-point Likert scale to assess their sexual arousal. Penile tumescence, heart rate, and respiratory rate were monitored throughout the process.
Results and Discussion
For the purpose of this study, the researchers identified five phases of the erectile process:
• No erection (NE)
• Onset of erection (OE)
• Sustained erection (SE)
• Penile detumescence (DE)
• Baseline tumescence (DB)
During the erotic clips, the patient group experienced larger activation in the left superior parietal lobe, ventromedial prefrontal cortex, posterior cingulate cortex, and caudate nucleus. The control group experienced larger activation in the right middle insula, dorsal anterior cingulate cortex, and hippocampus.
There was larger activation in the left superior parietal lobe among patients than control group members, especially during later sexual response.
“Our results suggest the presence of dissociable patterns of activation for sexual arousal and inhibitions of sexual response, with specific temporal dynamics” the authors wrote.
The superior parietal lobe was found to have played an important role in the changes of sexual response stages, particularly at the “sustained erection” (SE) phase. The authors hypothesized that patients showed high levels of attentional control toward internal body states in correspondence of periods where controls showed the highest level of sexual arousal suggesting that control subjects disengaged these processes in order to redirect attentional resources to external erotic stimuli.”
The ventromedial prefrontal cortex had larger activity levels in patients during the erotic clips. consistently with the concept that [this region] plays a central role in the disengagement from the evaluation of the content of erotic stimuli and by redirecting attention to self-related experiencesThe patients also experienced more activity in the posterior cingulate cortex, which plays a role in autobiographical and emotional memories and the relationship between self and environment, and the caudate nucleus, which plays a role in the inhibition of sexual behavior.
The control group showed more activity in the right middle insula during the OE and SE periods, “confirming its important role for somatovisceral integration.” In line with past research, it appears that this region is important for both the OE and SE stages of erection.
The dorsal anterior cingulate cortex and hippocampus were also more active for the control group, suggesting a role in sexual response.
The left superior parietal lobe is important to the inhibition of sexual response. Its large activation in the patient group during the later stage of sexual response suggests “a high monitoring of the internal body representation, possibly affecting the behavioral response.”
The study findings shed light on “brain mechanisms involved in psychogenic ED.”