Brain processing of audiovisual sexual stimuli inducing penile erection: a positron emission tomography study.
OBJECTIVE
Penile erection is dependent on commands from the central nervous system. Although basic studies of animals and neuroimaging studies of humans have been conducted to identify key brain regions associated with sexual arousal, to our knowledge no reliable studies of the first excitation phase of sexual arousal leading to penile erection have been reported.


METHODS
We used H(2)(15)O-positron emission tomography to analyze regional cerebral blood flow just before penile erection in heterosexual volunteers. The subjects viewed 3 different types of audiovisual materials-sexually explicit clips, nonsexual neutral clips and dynamic mosaic image control clips-presented in random order, and penile rigidity was monitored in real time with a RigiScan(R) Plus device. Positron emission tomography scanning was initiated simultaneously when each clip was started, and images obtained when the subjects showed appropriate penile response were analyzed and compared.


RESULTS
The advanced audiovisual cortices and cerebellar vermis in the right hemisphere were activated for sexually explicit-dynamic mosaic image control clip contrast, and only the right middle frontal gyrus was activated for sexually explicit- nonsexual neutral clip contrast. Several primary visual and audio regions were activated for dynamic mosaic image control-sexually explicit clip contrast and nonsexual neutral-sexually explicit clip contrast.


CONCLUSIONS
We speculate that advanced audiovisual activity with imagination, not primary visual and audio activity, occurs when men experience sexual arousal inducing penile erection. Furthermore, the cerebellar vermis may be a key region for induction of penile erection in humans.
Tsujimura
Akira
A
Department of Urology, Osaka University Graduate School of Medicine, Osaka University, Suita, Japan. akitsuji@uro.med.osaka-u.ac.jp
Miyagawa
Yasushi
Y
Fujita
Kazutoshi
K
Matsuoka
Yasuhiro
Y
Takahashi
Tohru
T
Takao
Tetsuya
T
Matsumiya
Kiyomi
K
Osaki
Yasuhiro
Y
Takasawa
Masashi
M
Oku
Naohiko
N
Hatazawa
Jun
J
Kaneko
Shigeo
S
Okuyama
Akihiko
A
D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000502:physiology*; D002560:Cerebrovascular Circulation; D006801:Humans; D008297:Male; D010410:Penile Erection / Q000502:physiology*; D010775:Photic Stimulation; D049268:Positron-Emission Tomography