The findings are surprising because pleasure is classically thought of as the province of the left hemisphere - it's more active when recalling happy memories, meditating on love for another, and mania. The left hemisphere is even preferentially more active among people free of depression and less active among the unhappy. So if the brain were a more cooperative organ, the left hemisphere should light up like the Fourth of July during an orgasm. Instead, it goes quiet. Why?

Up until several years ago, neuroscience had little scientific data on the neurophysiology of bliss, sexual or otherwise. Yep, you guessed it, historically, neuroscience has been hobbled by nerds avoiding sensitive topics, like sex... which is probably one of the most important factors of the human condition. Fortunately, new research on orgasm is now emerging that focuses on self-awareness, alterations in bodily perception and decreased sense of pain.

The effect of orgasm on self-awareness is especially intriguing, as the stream of consciousness usually exists as a running critique organizing conscious experience. Essentially, we are always telling stories to ourselves about ourselves. Even as you read this, you are actually talking to yourself.

Escaping self-awareness is usually done with drugs and alcohol. However, it's now proven that meditation offers relief from this self-preoccupation and one of the few tools for creating a durable boost in happiness—perhaps by dampening activity in regions implicated in judgment, comparison, planning and self-scrutiny. Left prefrontal cortex activation correlates with happiness and Tibetan Buddhist monks have created the greatest measured spike in activity in this region produced by simple thought when meditating on compassion. The reported depth of meditation also corresponds to activity in the brain’s pleasure centers, such as left forebrain bundle, anterior insula and precentral gyrus. This overt pleasure is accompanied by a shift in emotional self-regulation; meditators are more aware of thoughts and feelings conceptually, but less emotionally disrupted by them, according to one study.

The research is also showing that pleasure is also linked to a loss of awareness of the boundaries of our body, and this, too, involves both sides of the brain. Orgasm and meditation dissolve this sense of physical boundary, but the activation patterns are distinct. Meditation does so in a somewhat cerebral way, altering bodily self-awareness by enhancing activity in specific brain regions, such as right angular gyrus—regions that become most lively during attempts to imagine ourselves from a stranger’s perspective, during out of body experiences or déjà vu, and in a neurologically obscure disorder in which patients lack awareness of their own paralysis or bodily infirmity.

But during orgasm, the cerebellar deep nuclei and vermis, also in the cerebellum, glow. The cerebellum used to be thought of as the “motor bit” tacked onto the back of the brain. The deep nuclei are mysterious, but they seem involved in planning and initiating movement, motor learning, rhythm, synchronizing and smoothing of movement. The vermis tracks the movement of the body through space outside of conscious awareness. Unlike meditation, orgasm seems a heightened sense of being within one’s body rather than the sense of being outside of it. The disconnected awareness meditation (“I am not my thoughts, I am not this experience”) is antithetical to the self-forgetting of sex.

Thus, this new research about the brain in orgasm vs meditation reflects the two opposing paths to non-duality - right brain and left brain paths. One path calls to us to transcend the body and the other path draws us to focus into the body, on the present moment, hoping to achieve transcendental clarity. It's beautiful that both directions lead to the same place... bliss.

More: http://www.scientificamerican.com