Sex in the Brain - Part One

My son Malcolm thinks I've become a science nerd. He teases me because I can't stop reading books about the brain and I talk about neuroscience all the time. But I can't help it! Because of the research I've done for the Brain Chemistry For Lovers show, I've fallen down the rabbit hole into the rapidly evolving world of neuroscience.

And what a world it is! Because of the latest advances in brain scanning technology, scientists can now look inside the brain and get a more complete picture of who we are and what makes us tick. Discoveries are being made every day that help to answer some of the questions that we humans have been asking for centuries. Questions like...

Who are we? Why are we the same yet different? Is it nature or nurture that ultimately shapes us as humans? And then there are the more pressing questions like....why doesn't he ever put the toilet seat down? Why does she always nag about the dishes? and...why oh why can't he find stuff in the refrigerator when it's staring him in the face?

Ok - maybe those last few questions aren't exactly earth shattering, but they do end up leading us to THE all encompassing question...what makes women and men so different from each other?

One book that helped to answer some of those questions for me (and that I still think about when faced with that open toilet seat) is called:

The Female Brain
by Louann Brizendine, M.D.

Dr. Brizendine is a neuropsychiatrist, neurobiologist and founder of the Women's and Teen Girls Mood and Hormone Clinic in San Francisco CA. She knows the questions, has the tools to research the answers, and works with a ready made group of female subjects to study.

In her book, she writes about the female brain and what it undergoes as it develops from it's life in the womb, through childhood, the teen years, childbearing, menopause and beyond. It's fascinating stuff. I wish I could go back in time and give this to my teenage self and my new parent self. Knowing the chemical story behind what I was going through would have been helpful to say the least. But it's still a VERY useful resource. Now that I'm in the throes of another female life “change” – it couldn't have arrived on my nightstand at a better time.

But I digress. Back to the subject at hand...

Though this is more of a book about the female brain than a book about the differences between the male and female brain, quite a few comparisons end up being made....

“More than 99% percent of male and female genetic coding is exactly the same. Out of the 30,000 genes in the human genome, the less than one percent variation between the sexes is small. But that percentage difference influences every single cell in our bodies - from the nerves that register pleasure and pain to the neurons that transmit perception, thoughts, feelings and emotions.”

That 1% variation manifests in many different ways. Here's what Dr. Brizendine writes about how it makes men and women different when it comes to sex.

“The sex-related centers in the male brain are actually about two times larger than the parallel structures in the female brain. When it comes to the brain, size does make a difference in the way women and men think about, respond to, and experience sex......Males have double the brain space and processing power devoted to sex as females. Just as women have an eight-lane superhighway for processing emotion while men have a small country road, men have O'Hare airport as a hub for processing thoughts about sex whereas women have the airfield nearby that lands small and private planes.....This makes for interesting interactions between the sexes.”

Interesting interactions indeed!

These sex related differences first show up as early as eight weeks after conception. Up until then, we have unisex brains. Starting at eight weeks, a “fetal fork in the road” occurs.

“A huge testosterone surge in the eighth week will turn this unisex brain male by killing off some cells in the communication centers and growing more cells in the sex and aggression centers. If the testosterone surge doesn't happen, the female brain continues to grow unperturbed. The fetal girl's brain cells sprout more connections in the communication centers and those that process emotion.”

Hmmmm.....that explains a few things about gender differences. But there seem to be so many variations on this gender theme. What about the body that's genetically male but whose brain hasn't gotten that huge testosterone surge? What about the tom boy who never likes to play with dolls and prefers rough and tumble interaction?  Are our personalities and sexual orientation influenced by how much of these hormones are present at different stages of development when we're in utero?

Dr. Brizendine takes a brief look at these questions, but there are others that go unanswered. Namely, what about those women who don't bear children? Especially those for whom not having a child was a conscious choice? Female brains and bodies are hardwired for bearing children, but not all women desire to have them. What do their brains look like as they go through the different stages of life? And what about those male brains? The examples of the men she writes about don't resemble most of the men that I know. Am I living in a bubble where only the men who are in touch with their feminine brains live?

Some scientists hypothesize that there is a continuum. While we may have male or female bodies, our brains aren't just one gender or the other, but a mix of the two. In my next blog, Sex In The Brain - Part Two, we'll take a closer look at this continuum through a fascinating documentary that aired a couple of years ago on the BBC called “Secrets of the Sexes: Brain Sex”.

Stay tuned!