Neuroscience of Love

This month, I am doing some course development, and I am spending quite some time on a first year Neurosciences course. Studying the brain was my passion 10 years ago. I didn’t pursue it in graduate school because I was somewhat troubled by the ethics of cutting someone’s brain open while they were conscious, sticking electrodes in there, and sending electricity to “see what happens”. I’m being facetious, of course, because this sort of thing does help neurosurgeons map the brain of their patient during neurosurgery. …But it just seemed to me that we know very little about.. well, what makes us us.

Neuroscience of Love
For the past week-end, I have been preparing a class on sex and hormones. It’s fundamentally a class on the neurochemistry of love. This field has really blossomed since I last studied it. Using imaging technologies like functional MRIs, scientists have been studying what happens in the brain of people who say they are “in love”. I was astounded by some of the findings I read about, and I thought I would record them here. Perhaps someone else will find them amazing, too.

Love is Blind and Stupid
First, perhaps not surprisingly, it turns out that the portions of the brain involved in reward (yes, those are the ones that are affected by elicit drugs) get turned on. It feels good to be with someone you love. Ok, this is no surprise to me. But what I found really cool is that people seem to grow “a little more stupid” by being in love. A portion of their pre-frontal cortex, usually involved in making social judgements and decisions (critically evaluating other people) gets shut off when one is "in love". So in essence, love truly is blind and stupid!

You Smell Nice! - Advertising your Genome
On another related matter, that of choosing your lover… It turns out that people find the smell of people who have a different MHC gene (major histocompatibility complex – this is a gene that is involved in immunity – defending you against outside invaders like viruses and bacteria) more appealing. Why would that be? The idea is that by choosing a mate with a different MHC gene, a couple will increase the diversity of their babies’ MHC genes, increasing the babies’ odds of a good immune system. So, you ask, is this the elusive human pheromone? Not likely, since a pheromone is defined as a chemical that triggers a behaviour in another member of the species. Displaying your MHC scent does not make members of the opposite sex flock to you, it only advertises your genome to everyone. One might wonder then, why the perfume industry is doing so well. Wouldn’t perfume mask these kinds of intrinsic scents? It turns out that people tend to select commercially-available perfumes that complement and even enhance their MHC smell. So in essence, Chanel, Lancome, Elizabeth Arden and company are helping you advertise to the world: “Hey, there are my genes… Interested in what you smell?”

Isn’t that amazing?