Are you a prairie vole or a meadow vole?

Can you believe that less than 5% of all mammals are long term monogamous?  Whereas 90% of birds stay with their mate for life.  These are a few of the interesting tidbits I came across while doing some reading homework on sexual motivation.

I think voles are much cuter than lab rats, don't you?

But I think the most interesting story starts with a couple of voles.  Voles are small mammals similar to mice.  The genetic variation between a meadow vole and a prairie vole is nearly zero yet they display almost completely opposite behavioral characteristics.  Prairie voles are how we human would like to view ourselves.  They pair-bond with their mates and act more or less monogamous by sharing a nest and defending one another.  When they have a litter, they demonstrate better parenting and care for their young for a longer time than their meadow counterparts.

In fact, I think this song fits my characterization of meadow voles:

They don't make for life, share a nesting ground, or care for their young any longer than is strictly necessary.  Yet these two species are nearly identical in genetic make up.  What's causing the difference in their behavior?

Well a bit of research into their brain structures revealed a rather interesting set of differences.  The prairie voles had more receptors for two very specific signal molecules when compared with their meadow counterparts.  In the female prairie voles, there were more oxytocin receptors in circuits related to the reward pathways in their brains.  I mentioned oxytocin in a valentine's day post so feel free to reference back to that for more details on its effects.  But the basics show that it increases motherly behavior in the females.

The other change was found in the male prairie voles.  They show increased numbers of vasopressin receptors in the ventral pallidus.  This signal has sometimes been linked to aggression in the context of mate-protective behavior.  Thus it makes the males more likely to stick around and protect the family.

The brain images on the left are of the males and on the right are the females.

Turns out, there's a short "microsatellite" piece of DNA code that allows for the additional production of these receptors and the bonding behavior seen in the prairie voles.  And while you may think, what's this got to do with me?  Well, there's currently evidence coming to light that that these same systems are in play in human systems as well.  Surely it's a more complicated system but what does your DNA code your behavior towards?  Do you know?

Roses are red, Violets are blue, Neurotransmitters make me love you!

In honor of today's Hallmark-funded holiday which is customarily filled with bright pink hearts and chalky candy handed out to all grade-schoolers, I decided to write about what makes us feel "in love."  Yes, you can read all the romance novels you want (*cough*Twilight*cough*) which expound on his chocolate eyes or her sensuous curves.  But when we move back to the basics, it's really just a soup of neurochemicals stirring around in your brain that cause that spark of love in your life.

Who actually eats these?

And truth be told, the biochemistry of attraction and love is still under research.  However we can safely say that there are 3 key neurotransmitters that make Valentine's Day special for all those people out there with their significant others.

The first and likely most recognizable is dopamine.  It plays many roles in the chemical signaling of the brain but is primarily associated with the reward pathway.  Whenever you get that rush of happiness from the first bite of chocolate cake, that's the dopamine kicking in.  In fact, addiction and the need to up the dosage of drugs over time like cocaine comes from the brain desensitizing due to the over use of dopamine.  And in the romantic sense, dopamine is the "drug" part of love.  It's the passionate, euphoric love that makes you believe there's nothing better than being with your partner.

How many roses do you think are sold each
 valentine's day?

And yet that's not quite enough.  Can you remember the first time you asked that girl to dance at the winter formal?  Or how about the anticipation before your first kiss?  Odds are your heart was pounding like a jack-hammer.  Norepinephrine is the neurotransmitter that provides this autonomic response.  It focuses your attention and physically primes you with those classic signs of nervousness.  Next time your hands turn clammy when you reach out towards your love interest, you can blame norepinephrine.

But these two neurochemicals play havoc on your brain if they're constantly swamping the circuits.  To keep an even keel yet stay connected to your significant other, we need oxytocin.  This compound is a long lasting messenger which doesn't give the same high as the others, but leads to a feeling contentment. Sometimes called the "cuddling neurotransmitter," oxytocin provides us with the companionship aspect of romantic relationships.  Without it we wouldn't have the same peace and stability in our long-term relationships.

Ok, so there are actually many more circuits and neurochemicals involved in love. It's an emotion not easily reduced to formulas and equations.  In my opinion, we could lecture on the biological components involved all day, but honestly I prefer to just listen to some Maroon 5 and eat chocolate covered strawberries!

If you want to hear more on this subject, I suggest checking out the original source:
http://www.radiolab.org/blogs/radiolab-blogland/2007/aug/28/this-is-your-brain-on-love/
Radiolab is a non-profit public radio program hosted by WNYC.  If you'd like to donate to their phenomenal program, please go to: https://pledge3.wnyc.org/epledge/desktop/radiolab/