Abstract
Although the brain is an important part of a person's sexual life, little is known
about the correlations between sexual response and brain activation. This study examines
brain responses through clinical testing to reveal several brain structures whose
activation is relevant to sexual arousal besides psychological testing according to
the common traditional values and standards of Iranian society. Based on an initial
self-report, 25 homosexual and 25 heterosexual males participated in this test to
elucidate the identity and sexual trends via the Minnesota Multiphasic Personality
Inventory (MMPI-2). Also, an fMRI technique—by presenting distinct homo- and heterosexual
sex erotic pictures during the test—was employed in neural correlates of sexual arousal
via blood oxygen level dependent (BOLD) signal measuring and Statistical Parametric
Mapping analysis. In five selected homosexuals by the most appropriate MMPI test score,
brain activities were significantly detected in the midbrain, amygdala, anterior cingulate
gyrus, frontal cortex, orbitofrontal cortex, globus pallidus, thalamus, and putamen
when the participant saw the erotic pictures during the test, which were responsive
to sexual arousal. Also, bilateral caudate nucleus, left angular gyrus, and bilateral
pallidum were activated but five selected heterosexuals showed no activation in these
areas (p < 0.001). Likewise, the MMPI method confirmed that homosexuality was relevant to
diverse life positions, and biological and socioeconomic aspects. The maximum positive
correlations were pairwise found in the parietal lobule by r = 0.61 (p < 0.05) and in the frontal gyrus by r = 0.64 (p = 0.10), and the minimum negative correlations were in globus pallidus by r = − 0.18
(p < 0.10) and r = − 0.16 (p < 0.10) for homosexuals and heterosexuals, correspondingly. These results may be
useful for understanding the different neural mechanisms of personality recognition
and sexual orientation changes while incorporating the individual's history and experience
simultaneously into the assessment.
Keywords sexual response - stimuli - fMRI - MMPI - brain reaction - cognition and psychiatric
disorders - psychosexual disorder
