字幕表 動画を再生する 英語字幕をプリント The human body is a wonder, but perhaps the most curious and quintessential aspect of the human experience is the orgasm. The body's sexual response is typically broken down in four stages: excitement, plateau of arousal, orgasm, and resolution. Following arousal, the brain stimulates bloodflow to the genitals, your heartbeat and breathing increase, and the central nervous system is fully engaged, sending signals of enjoyment to the brain's reward system. These thousands of nerve endings constantly relay pleasure signals to the brain, resulting in an orgasm. For men, the orgasm includes rapid contractions of the anal sphincter, the prostate, and the muscles of the penis. In conjunction with ejaculation, which sees the release of sperm and other seminal fluid, the whole process for men involves around three to ten seconds of intense pleasure. This is followed by a refractory period for minutes to hours in which another orgasm cannot be achieved. Women, on the other hand, do not experience a refractory period, allowing them to experience multiple consecutive orgasms. On avarage, these last for around twenty seconds (but sometimes much longer) and consist of rhythmic contractions between the uterus, vagina, anus, and pelvic muscles. But it's the brain that takes control -- or rather, lack thereof -- during orgasm. Using functional MRI scans, scientists are able to see brain activity in over 30 discrete regions. It's flooded with the anticipatory and feel-good chemical dopamine which makes you crave the feeling again. This is in tandem with the release of oxytocin; a hormone that mediates bonding and love between mates. PET scans show (surprisingly) that brain activity during an orgasm is the same between men and women. In both genders, the lateral orbitofrontal cortex is turned off which controls self-evaluation, reason, and control. Makes sense, as you often lose control during orgasm. This shuts down fear and anxiety, which is seen as the most essential aspect leading up to orgasm. The relaxation of the amygdala and hippocampus in women further reduce emotions, producing a trance-like state, while in men, it dampens aggressiveness Many areas of a woman's brain are shut down completely during an orgasm. These effects are less striking in men, likely because of the shorter duration and difficulty with measuring during brain scan. In women, an area called the periaqueductal gray (or PAG) is activated, stimulating the flight or fight response while the cortex -- which is associated with pain -- lights up, suggesting that there is a connection between pain and pleasure. Following this climax and muscle contraction, the body experiences deep relaxation, and heart rate slows to a resting pace. Who knew science could be so sexy? Got a burning question you want answered? Ask them in the comments or on Facebook and Twitter, and subscribe for more weekly science videos.