The short answer is yes - if you're a rat. Rats and humans differ in some ways. Yet our mammalian physiology is sufficiently similar that what happens in rats often happens in people.
The sex-brain study, done at Princeton's Psychology Department by Leuner, Glasper, and Gould, was performed with active, night-time rats. Males spent time with females that were either sexually receptive or non-receptive (unlike us but like most animals, rats get sex-obsessed only at hormonally defined intervals.) Whether sexual contact was a one night stand or ongoing for two weeks, cell growth popped out in the hippocampus, a major brain memory area for rats and humans. As Woody Allen would say, it worked every time.
Sex and Stress
The authors were excited to discover that first night's sex appeared to overcome the brain zapping effects of cortisol. Cortisol is a major stress hormone, and in very high dose may lead to brain cell death. Though cortisol does hundreds of useful things like resetting immunity it has recently gotten a bad public rap, perhaps peaking when skin expert Dr. Nicholas Perricone dubbed it "the death hormone."
First night sex caused cortisol to go way up, but the male rats still managed to grow new brain cells. For them, sex defeated stress.
And such positive effects continued. Over the two week study interval, sexual activity increased brain cell growth and lowered rat versions of anxious behavior, while cortisol decreased to normal ranges.
Different Ways to Grow Brain Cells
Sex is not the only way to grow the brain. In rats and in humans, running and walking seems to work. With humans even a 20-30 minute walk appears to grow more hippocampal brain cells, apparently during sleep. Rest revives us more than we know.
Another way to grow rat brain cells is through reward "self-stimulation." In humans this will probably require techniques as developed as those of the movie "Inception." Suffice to say that in rats, self stimulation of brain pleasure centers grows more brain cells.
How Does Sex Grow Brain Cells?
Several mechanisms are potentially involved. In sex, there is exercise, and the Princeton rats coupled vigorously for an average half hour. Sex also markedly increases oxytocin levels, a hormone that makes people feel warm, fuzzy, and close to other humans, as well as dopamine, a critical neurotransmitter for the reward system. Lowering cortisol may also make it easier to grow new brain cells.
Sex and Sleep
So far, rat studies show the brain cell growth to occur during sleep. Sleep is also critical to learning, and the cell growth seen so far has been limited to brain memory areas. Sleep is a major form of rest that is critical to rebuilding most human tissues.
What to Do When Your Partner Invites You to Grow More Brain Cells
If your partner gives you a come hither look and talks about building new brain cells, you may think they're inviting you to the bedroom. They might, however be inviting you to a walk in the sunshine. That walk should 1. Grow more brain cells 2. Increase vitamin D 3. Improve mood and reset body clocks 4. Improve immunity and increase natural killer cell activity. 5. Give you a chance to talk about your relationship, which many males love to do.
Sex as Social Rest
Rat sex differs from human sex. The real meaning of love in creating understanding, trust, and psychological support make sex a form of social rest unlike any other. Social rest and social support are critical to improving survival and making us feel whole.
In "You, the Owner's Manual," Roizen and Oz describe how if 55 year old males had sex 700 times a year, their "real age" might decrease by sixteen years. Unfortunately their subject sample was zero, and such feats may be beyond most boomers. But as the definition of rest is what rebuilds and renews our bodies, sex really does count. So Lady Gaga, please take note. In a recent Vanity Fair interview the diva declaimed "I have this weird thing that if I sleep with someone they're going to take my creativity from me."
For lots of people, creativity increases with intimacy and romance - and you grow new brain cells, too. That might improve your memories in astonishing ways.