Orgasms and Nerves

What happens in the brain during an orgasm?

Without nerves sending impulses back to the spinal cord and brain, an orgasm wouldn’t be possible. Just like any other area of the body, the genitalia contain different nerves that send information to the brain to tell it about the sensation that’s being experienced. This helps to explain why the sensations are perceived differently depending on where someone is being touched. A clitoral orgasm, for example, differs from a vaginal orgasm because different sets of nerves are involved.

Pleasure Center of the Brain: Light It Up

You may have heard that the brain has a pleasure center that lets us know when something is enjoyable and reinforces the desire for us to perform the same pleasurable action again. This is also called the reward circuit, which includes all kinds of pleasure, from sex to laughter to certain types of drug use. Some of the brain areas impacted by pleasure include:

Although scientists have long been studying the pleasure center, there hadn’t been much research about how it relates to sexual pleasure, especially in women. In the late 1990s and the mid-2000s, a team of scientists at the University of Groningen in the Netherlands conducted several studies of both men and women to determine brain activity during sexual stimulation. The team used PET scans to illustrate the different areas of the brain that would light up and shut off during sexual activity. In all of the tests, the subjects were scanned while resting, while being sexually stimulated and while having an orgasm.

Interestingly, they discovered that there aren’t too many differences between men’s and women’s brains when it comes to sex. In both, the brain region behind the left eye, called the lateral orbitofrontal cortex, shuts down during orgasm. Janniko R. Georgiadis, one of the researchers, said, “It’s the seat of reason and behavioral control. But when you have an orgasm, you lose control” [source: LA Times]. Dr. Gert Holstege stated that the brain during an orgasm looks much like the brain of a person taking heroin. He stated that “95 percent is the same” [source: Science News].

There are some differences, however. When a woman has sex, a part of the brain stem called the periaqueductal gray (PAG) is activated. The PAG controls the “flight or fight” response. Women’s brains also showed decreased activity in the amygdala and hippocampus, which deal with fear and anxiety. The team theorized that these differences existed because women have more of a need to feel safe and relaxed in order to enjoy sex. In addition, the area of the cortex associated with pain was activated in women, which shows that there is a distinct connection between pain and pleasure.

The studies also showed that although women m­ay be able to fool their partners into thinking they’ve had an orgasm, their brains show the truth. When asked to fake an orgasm, the women’s brain activity increased in the cerebellum and other areas related to controlling movement. The scans didn’t show the same brain activity of a woman during an actual orgasm.

But what about people who can’t reach orgasm at all?

Neither Here Nor There: Anorgasmia and Non-genital Orgasms

I­n some cases, we know what causes anorgasmia (the inability to reach orgasm). Drugs like Celexa, Zoloft and Paxil — known as SSRIs, or selective seratonin reuptake inhibitors — are often used to treat depression, anxiety and other mental illnesses. Like most drugs, however, they can have side effects. For some people, this includes sexual ones, including anorgasmia. But why? SSRIs can decrease the brain’s production of dopamine, the neurotransmitter that provides pleasurable feelings and reinforces a person’s desire to once again perform the action that brought him or her pleasure. Sometimes the problem goes away on its own, or it can be resolved by switching to a different antidepressant or taking another drug in addition to the SSRI. However, a small number of people experience post-SSRI sexual dysfunction (PSSD) that lasts for days, weeks, months or even years after discontinuing use of an SSRI. The cause of this dysfunction isn’t understood, as stopping the SSRI allows dopamine production to return to normal.

The Dutch studies about orgasms (mentioned earlier), along with others, have also been the basis for continuing research in helping women who are anorgasmic. Dr. Barry Komisaruk at Rutgers University is currently studying women who are anorgasmic and women who are constantly aroused sexually but are unable to reach orgasm. The latter group of women were each put in an MRI scanner where they could see their brain activity on a monitor. Their brain scans showed that the brain thought they were in fact constantly being sexually stimulated. The women then used imagery and other neurofeedback exercises to calm their brains. Dr. Komisaruk believes that anorgasmic women could also learn to read and react to their brain activity to try to reach orgasm.

Perhaps more unusual-sounding than orgasmia is the concept of orgasms that have nothing to do with the genitalia at all. Some people can orgasm from being touched in other places on the body, such as the nipples. In this case, researchers believe that the sensations in the nipples are transmitted to the same areas of the brain that receive information from the genitals. However, people have also reported actually feeling orgasms in other parts of their bodies, including their hands and feet. Several people have even described having orgasms in limbs that were no longer there. One reason may be the layout of the cortical homunculus, a map that shows how different places of the brain’s sensory and motor cortices correspond to the organs and limbs of the body. A person who feels an orgasm in a phantom foot, for example, may have experienced a remapping of the senses because the foot is located next to the genitals in the homunculus. The foot is no longer there to provide sensation, so the area for genital sensation took over the space.

Although we now know more about how orgasms impact the brain than ever before, there’s still a lot that we don’t know. For example, scientists are still debating the evolutionary reason behind the female orgasm. But it’s probably safe to say that most people aren’t too concerned about the “why” — they’d prefer to focus on the whos, whats and whens of sex.

Original ARTICLE on How Stuff Works

Picture Credit: 3D4MEDICAL.COM/GETTY IMAGES