Dear Science, How come my girlfriend and her friends are all… uh, “synced up”?

Girl physiology got you down? Well, it shouldn’t, because this is a cool little bit of biology that will make you appreciate the animal in all of us. Imagine that you are a hamster. You’re a female hamster, and if you’re a female hamster, what you do is you ovulate every four days. So you’re sitting there ovulating every four days, and a scientist puts another female hamster in the cage with you. A few days pass, and next thing you know, both you and your hamster roomie are lengthening your ovulatory cycles until after about three weeks, you both ovulate within about a half hour of each other.

But here’s another cool part — if the same scientist then places a male hamster in the cage with you two, everything gets messed up and you all de-synchronize. And it’s not random who synchronizes whom — the more socially dominant female gets the other female to match up with her. This whole process is mediated by olfaction, namely, pheromones, and it’s been shown in a number of different animals — dogs, cats, pigs, and humans included. It works exactly the same way in us, and it’s called the Wellesley Effect, named after Wellesley College. In 1970, a group of researchers at the school demonstrated that over the course of the year, first-year female roommates synchronized their cycles, except for women who had close intimate relationships with males. And again, it’s not random who synchronizes whom — it tends to be women who are more socially extroverted and dominant.

Though I wouldn’t suggest trying to find out which of your girlfriend’s friends is syncing up all the others, at the very least this is an extraordinary example of the way our brains and bodies are constantly aware of the people and circumstances around us whether we know it or not. So… wake up and smell the pheromones!

Dear Science, What do drugs like Adderall actually do?

The brain operates at a baseline level of stimulation at all times. However, in ADHD patients, the brain is overstimulated, resulting in difficulties with concentration. Psychostimulants, which include drugs like Adderall and Ritalin, would put non-ADHD brains into a state of overstimulation, resulting in a rush not dissimi- lar from what drug users seek. But when an ADHD patient is given a stimulant, his or her brain activity drops dramatically to a state of under-stimulation for a few minutes, then gradually reaches a baseline level of stimulation that allows him or her to focus better.

Psychostimulants directly stimulate what’s popularly referred to in the brains as the “pleasure center,” i.e. the nucleus accumbens. This structure is enriched with receptors for dopamine, a chemical neurotransmitter in the brain that, contrary to popular belief, is responsible not for stimulation in the brain but for the inhibition of said excitation. Dopamine actually inhibits another inhibitory transmitter called GABA — and by inhibiting the inhibitor, dopamine excites the nucleus accumbens.

Normally, when dopamine is released by a neuron, it stimulates another neuron, leading to excitation. After initial release and binding to its receptor, dopamine returns to the original neuron and is recycled in what is known as “reuptake.” Amphetamines and ADHD drugs block reuptake, so instead of being sucked back up, dopamine just hangs out in your synapses, throwing an excitation party until the drug is eliminated from your system.