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THE BRAIN AND ORGASM

BRAIN REGIONS
Many regions of the brain are involved in sexuality and orgasm, although not all studies agree on the specific areas (at least in part because of differences in experimental design). In healthy individuals the sexual experience involves the insula, limbic system (including the medial amygdala, hippocampus, cingulate cortex, preoptic area and hypothalamus), nucleus accumbens, basal ganglia (especially the putamen), superior parietal cortex, dorsolateral prefrontal cortex, and cerebellum, in addition to lower brainstem (Bianchi-Demicheli, 2007). Intercourse involves more brain areas than other forms of sexual activity. In male primates, lesions of the male medial preoptic areas decrease the frequency of intercourse without affecting the frequency of masturbation or social interaction (Brody, 2006b). The medial temporal lobe, including the amygdala, has a role in sexuality and its activity can result in hypersexuality (Bianchi-Demicheli, 2007).


In both men and women, orgasm increases activity in the right hemisphere more than the left and involves the septal region, prefrontal, temporal, and parietal lobes, putamen, insula, and cerebellum (Bianchi-Demicheli, 2007). During ejaculation, virtually all of the cerebral cortex undergoes decreased activity while certain areas, such as the right prefrontal cortex, septum, midbrain-diencephalon region, putamen, insula, and cerebellum, increase their activity. The visual cortex shows increased activity even if a subject's eyes are closed (Bianchi-Demicheli, 2007).Some studies have identified gender differences in activated areas with the medial amygdala, hypothalamus, preoptic area, and anterior cingulated being more active in women and the visual cortex more active in men (Bianchi-Demicheli, 2007; Levin, 2007).

The reward system activated in love involves regions cerebral cortex, such as the medial insula, anterior cingulated, and hippocampus and regions of the subcortex such as the striatum and nucleus accumbens (Lehto, 2007). Dopamine levels increase with romantic feelings and love, as do levels of nerve growth factor. Some have compared the decreased the levels of serotonin in early stages of love to the decreased serotonin in patients with obsessive compulsive disorder (Lehto, 2007). Dopamine, serotonin, and ACh circuits all involved in sexual activity and serotonin seems to inhibit orgasm (Bianchi-Demicheli, 2007).

MALE
There are three major groups of sexual disorders: dysfunction, gender identity disorders, and paraphilias (Crowe, 2007). Many Americans suffer from some degree of sexual dysfunction. For example, one large survey concluded that among men, 10% suffered from erectile dysfunction, premature ejaculation by 8%, and decreased libido in 16% (Crowe, 2007).

FEMALE
Among women who suffer from some aspect of sexual dysfunction, decreased libido affected 33%, lack of orgasm and lack of pleasure in sex both over 20%, and pain during intercourse by 14% (Crowe, 2007). While an estimated 5-10% of women never experience orgasm, many experience multiple and serial multiple orgasms (Bianchi-Demicheli, 2007). Many women who have trouble achieving orgasm can do so with time while others never achieve orgasm. Pain may result from inadequate lubrication, the failure of the vagina to expand fully, inflammation in the pelvis, or vaginismus, the involuntary spasm of the pubococcygeus muscle (Ramage, 2007).

NERVOUS DISORDER
Neural conditions can affect sexual function. As many as 10% of those who seek psychiatric help have sexual dysfunction, although that may not be their primary disorder (Ramage, 2007). For example, women with obsessive-compulsive disorder often suffer from sexual dysfunction (Vulink, 2006). Women with epilepsy experience elevated rates of sexual dysfunction including decreased desire and lack of orgasms (Harden, 2005). However, some epileptic seizures actually cause orgasms; this rare type of seizure is known as sex seizures (Reading, 1997; Bianchi-Demicheli, 2007).


Individuals with spinal cord injuries can experience orgasm by stimulating the hypersensitive skin near the injury site, sometimes with a vibrator (Komisaruk, 1988).